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First published 2005
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Tel: +47 2295 9900
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Authors
Listed in each individual chapter
Project Production and Graphic Design
Paul Grabhorn, Joshua Weybright, Clifford Grabhorn (Cartography)
Editing
Carolyn Symon (lead editor), Lelani Arris, Bill Heal
Photography
Bryan and Cherry Alexander (Cover and Chapter 1)
Assessment Integration Team
ACIA Secretariat
Robert Corell, Chair
Pål Prestrud,Vice Chair
Gunter Weller, Executive Director
Patricia A. Anderson, Deputy Executive Director
Barb Hameister, Sherry Lynch
International Arctic Research Center
University of Alaska Fairbanks
Fairbanks, AK 99775-7740, USA
Tel: +907 474 5818
Fax +907 474 6722
http://www.acia.uaf.edu
Patricia A. Anderson
Snorri Baldursson
Elizabeth Bush
Terry V. Callaghan
Paul Grabhorn
Susan Joy Hassol
Gordon McBean
Michael MacCracken
Lars-Otto Reiersen
Jan Idar Solbakken
Gunter Weller
American Meteorological Society, USA
Centre for Climate Research in Oslo, Norway
University of Alaska Fairbanks, USA
Liaison for the Arctic Council, Iceland
Environment Canada, Canada
Abisko Scientific Research Station, Sweden
Sheffield Centre for Arctic Ecology, UK
Grabhorn Studio, Inc., USA
Independent Scholar and Science Writer, USA
University of Western Ontario, Canada
Climate Institute, USA
Arctic Monitoring and Assessment Programme, Norway
Permanent Participants, Norway
University of Alaska Fairbanks, USA
Recommended Citation: ACIA, 2005. Arctic Climate Impact Assessment. Cambridge University Press, 1042p.
http://www.acia.uaf.edu
iii
Preface
Earth’s climate is changing, with the global temperature now rising at a rate unprecedented in the experience of
modern human society.These climate changes, including increases in ultraviolet radiation, are being experienced particularly intensely in the Arctic. Because the Arctic plays a special role in global climate, these changes
in the Arctic will also affect the rest of the world. It is thus essential that decision makers have the latest and
best information available regarding ongoing changes in the Arctic and their global implications.
The Arctic Council called for this assessment and charged two of its working groups, the Arctic Monitoring and
Assessment Programme (AMAP) and the Conservation of Arctic Flora and Fauna (CAFF), along with the
International Arctic Science Committee (IASC), with its implementation. An Assessment Steering Committee
(see page iv) was charged with the responsibility for scientific oversight and coordination of all work related to
the preparation of the assessment reports.
This assessment was prepared over the past five years by an international team of over 300 scientists, other
experts, and knowledgeable members of the indigenous communities.The lead authors were selected from
open nominations provided by AMAP, CAFF, IASC, the Indigenous Peoples Secretariat, the Assessment Steering
Committee, and several national and international scientific organizations. A similar nomination process was
used by ACIA to select international experts who independently reviewed this report.The report has been thoroughly researched, is fully referenced, and provides the first comprehensive evaluation of arctic climate change,
changes in ultraviolet radiation, and their impacts for the region and for the world.Written certification has
been obtained from the ACIA leadership and all lead authors to the effect that the final scientific report fully
reflects their expert views.
The scientific results reported herein provided the scientific foundations for the ACIA synthesis report, entitled
“Impacts of a Warming Arctic”, released in November 2004.This English language report is the only official document containing the comprehensive scientific assessment of the ACIA.
Recognizing the central importance of the Arctic and this information to society as it contemplates responses to
the growing global challenge of climate change, the cooperating organizations are pleased to forward this report
to the Arctic Council, the international science community, and others around the world.
Financial support for the ACIA Secretariat was provided by the U.S. National Science Foundation and National
Oceanic and Atmospheric Administration. Support for ACIA-related workshops, participation of scientists and
experts, and the production of this report was provided by the governments of the eight Arctic nations, several
other governments, and the Secretariats of AMAP, CAFF, and IASC.
The Arctic Council
The Arctic Council is a high-level intergovernmental forum that provides a mechanism to address the common
concerns and challenges faced by arctic people and governments. It is comprised of the eight arctic nations
(Canada, Denmark/Greenland/Faroe Islands, Finland, Iceland, Norway, Russia, Sweden, and the United States
of America), six Indigenous Peoples organizations (Permanent Participants: Aleut International Association,
Arctic Athabaskan Council, Gwich’in Council International, Inuit Circumpolar Conference, Russian
Association of Indigenous Peoples of the North, and Saami Council), and official observers (including France,
Germany, the Netherlands, Poland, United Kingdom, non-governmental organizations, and scientific and other
international bodies).
The International Arctic Science Committee
The International Arctic Science Committee is a non-governmental organization whose aim is to encourage
and facilitate cooperation in all aspects of arctic research among scientists and institutions of countries with
active arctic research programs. IASC’s members are national scientific organizations, generally academies of
science, which seek to identify priority research needs, and provide a venue for project development and
implementation.
iv
Arctic Climate Impact Assessment
Assessment Steering Committee
Representatives of Organizations
Robert Corell, Chair
Pål Prestrud,Vice-Chair
Snorri Baldursson (to Aug. 2000)
Gordon McBean (from Aug. 2000)
Lars-Otto Reiersen
Hanne Petersen (to Sept. 2001)
Yuri Tsaturov (from Sept. 2001)
Bert Bolin (to July 2000)
Rögnvaldur Hannesson (from July 2000)
Terry Fenge
Jan-Idar Solbakken
Cindy Dickson (from July 2002)
International Arctic Science Committee, USA
Conservation of Arctic Flora and Fauna, Norway
Conservation of Arctic Flora and Fauna, Iceland
Conservation of Arctic Flora and Fauna, Canada
Arctic Monitoring and Assessment Programme, Norway
Arctic Monitoring and Assessment Programme, Denmark
Arctic Monitoring and Assessment Programme, Russia
International Arctic Science Committee, Sweden
International Arctic Science Committee, Norway
Permanent Participants, Canada
Permanent Participants, Norway
Permanent Participants, Canada
ACIA Secretariat
Gunter Weller, Executive Director
Patricia A. Anderson
ACIA Secretariat, USA
ACIA Secretariat, USA
Lead Authors*
Jim Berner
Terry V. Callaghan
Henry Huntington
Arne Instanes
Glenn P. Juday
Erland Källén
Vladimir M. Kattsov
David R. Klein
Harald Loeng
Gordon McBean
James J. McCarthy
Mark Nuttall
James D. Reist (to June 2002)
Frederick J.Wrona (from June 2002)
Petteri Taalas (to March 2003)
Aapo Tanskanen (from March 2003)
Hjálmar Vilhjálmsson
John E.Walsh
Betsy Weatherhead
Alaska Native Tribal Health Consortium, USA
Abisko Scientific Research Station, Sweden
Sheffield Centre for Arctic Ecology, UK
Huntington Consulting, USA
Instanes Consulting Engineers, Norway
University of Alaska Fairbanks, USA
Stockholm University, Sweden
Voeikov Main Geophysical Observatory, Russia
University of Alaska Fairbanks, USA
Institute of Marine Research, Norway
University of Western Ontario, Canada
Harvard University, USA
University of Aberdeen, Scotland, UK
University of Alberta, Canada
Fisheries and Oceans Canada, Canada
National Water Research Institute, Canada
Finnish Meteorological Institute, Finland
Finnish Meteorological Institute, Finland
Marine Research Institute, Iceland
University of Alaska Fairbanks, USA
University of Colorado at Boulder, USA
Liaisons
Snorri Baldursson (Aug. 2000 - Sept. 2002)
Magdalena Muir (Sept. 2002 – May 2004)
Maria Victoria Gunnarsdottir (from May 2004)
Snorri Baldursson (from Sept. 2002)
Odd Rogne
Bert Bolin (to July 2000)
James J. McCarthy (June 2001 – April 2003)
John Stone (from April 2003)
John Calder
Karl Erb
Hanne Petersen (from Sept. 2001)
*Not
Conservation of Arctic Flora and Fauna, Iceland
Conservation of Arctic Flora and Fauna, Iceland
Conservation of Arctic Flora and Fauna, Iceland
Arctic Council, Iceland
International Arctic Science Committee, Norway
Intergovernmental Panel on Climate Change, Sweden
Intergovernmental Panel on Climate Change, USA
Intergovernmental Panel on Climate Change, Canada
National Oceanic and Atmospheric Administration, USA
National Science Foundation, USA
Denmark
all lead authors are members of the Assessment Steering Committee. For a full list of authors see Appendix A.
v
Contents
Chapter
1
An Introduction to the Arctic Climate Impact Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
2
Arctic Climate: Past and Present . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
3
The Changing Arctic: Indigenous Perspectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .61
4
Future Climate Change: Modeling and Scenarios for the Arctic . . . . . . . . . . . . . . . . . . . . . . . . . . . . .99
5
Ozone and Ultraviolet Radiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .151
6
Cryosphere and Hydrology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .183
7
Arctic Tundra and Polar Desert Ecosystems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .243
8
Freshwater Ecosystems and Fisheries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .353
9
Marine Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .453
10
Principles of Conserving the Arctic’s Biodiversity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .539
11
Management and Conservation of Wildlife in a Changing Arctic Environment . . . . . . . . . . . . . . . .597
12
Hunting, Herding, Fishing, and Gathering: Indigenous Peoples and Renewable Resource Use in
the Arctic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .649
Appendix
13
Fisheries and Aquaculture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .691
14
Forests, Land Management, and Agriculture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .781
15
Human Health . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .863
16
Infrastructure: Buildings, Support Systems, and Industrial Facilities . . . . . . . . . . . . . . . . . . . . . . . . . .907
17
Climate Change in the Context of Multiple Stressors and Resilience . . . . . . . . . . . . . . . . . . . . . . .945
18
Summary and Synthesis of the ACIA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .989
A
Chapter Authors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1021
B
Biographies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1025
C
Reviewers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1029
D
Species Names . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1031
E
Acronyms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1037
F
Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1039
Chapter 1
An Introduction to the Arctic Climate Impact Assessment
Lead Authors
Henry Huntington, Gunter Weller
Contributing Authors
Elizabeth Bush,Terry V. Callaghan,Vladimir M. Kattsov, Mark Nuttall
Contents
1.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2
1.2.Why assess the impacts of changes in climate and UV
radiation in the Arctic? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
1.2.1. Climate change . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
1.2.2. UV radiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
1.3.The Arctic Climate Impact Assessment . . . . . . . . . . . . . . . . . . .6
1.3.1. Origins of the assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
1.3.2. Organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
1.3.3.Terminology of likelihood . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
1.4.The assessment process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
1.4.1.The nature of science assessment . . . . . . . . . . . . . . . . . . . . . . . . . .7
1.4.2. Concepts and tools in climate assessment . . . . . . . . . . . . . . . . . . .7
1.4.3. Approaches for assessing impacts of climate and UV radiation . . .8
1.5.The Arctic: geography, climate, ecology, and people . . . . . . . .10
1.5.1. Geography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
1.5.2. Climate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
1.5.3. Ecosystems and ecology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
1.5.3.1.Terrestrial ecosystems . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
1.5.3.2. Freshwater ecosystems . . . . . . . . . . . . . . . . . . . . . . . . . . .11
1.5.3.3. Marine ecosystems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
1.5.4. Humans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
1.5.5. Natural resources and economics . . . . . . . . . . . . . . . . . . . . . . . . .15
1.5.5.1. Oil and gas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
1.5.5.2. Fish . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
1.5.5.3. Minerals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
1.6. An outline of the assessment . . . . . . . . . . . . . . . . . . . . . . . . . . .16
1.6.1. Climate change and UV radiation change in the Arctic . . . . . . . .16
1.6.2. Impacts on the physical and biological systems of the Arctic . . . .16
1.6.3. Impacts on humans in the Arctic . . . . . . . . . . . . . . . . . . . . . . . . . .17
1.6.4. Future steps and a synthesis of the ACIA . . . . . . . . . . . . . . . . . . .17
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
2
Arctic Climate Impact Assessment
I have heard it said by many Russians that their climate
also is ameliorating! Will God, then, ... give them up
even the sky and the breeze of the South? Shall we see
Athens in Lapland, Rome at Moscow, the riches of the
Thames in the Gulf of Finland, and the history of
nations reduced to a question of latitude and longitude?
Astolphe de Custine, 14 July 1839 de Custine, 2002
1.1. Introduction
The Arctic Climate Impact
Assessment (ACIA) is the first
comprehensive, integrated
assessment of climate
change and ultraviolet (UV)
radiation across the entire
Arctic region.The assessment
had three main objectives:
1.To provide a comprehensive and authoritative
scientific synthesis of available information about
observed and projected changes in climate and
UV radiation and the impacts of those changes on
ecosystems and human activities in the Arctic.
The synthesis also reviews gaps in knowledge and
the research required to fill those gaps.The intended audience is the international scientific community, including researchers and directors of research
programs.The ACIA Scientific Report fulfills this goal.
2.To provide an accessible summary of the scientific
findings, written in plain language but conveying
the key points of the scientific synthesis.This summary, the ACIA Overview Report (ACIA, 2004a),
is for policy makers and the general public.
3.To provide policy guidance to the Arctic Council to
help guide the individual and collective responses
of the Arctic countries to the challenges posed by
climate change and UV radiation.The ACIA Policy
Document (ACIA, 2004b) accomplishes this task.
An assessment of expected impacts is a difficult and
long-term undertaking.The conclusions presented here,
while as complete as present information allows, are
only a step – although an essential first step – in a continuing process of integrated assessment (e.g., Janssen,
1998).There are many uncertainties, including the
occurrence of climate regime shifts, such as possible
cooling and extreme events, both of which are difficult if
not impossible to predict. New data will continue to be
gathered from a wide range of approaches, however, and
models will be refined such that a better understanding
of the complex processes, interactions, and feedbacks
that comprise climate and its impacts will undoubtedly
develop over time. As understanding improves it will be
possible to predict with increasing confidence what the
expected impacts are likely to be in the Arctic.
This assessment uses the definition of the Arctic established by the Arctic Monitoring and Assessment Programme, one of the Arctic Council working groups
responsible for the ACIA. Each of the eight arctic coun-
3
4
2
1
Fig. 1.1. The four regions of the Arctic Climate Impact Assessment.
tries established the boundary in its own territory, and
the international marine boundary was established by
consensus.The definition of the arctic landmass used
here is wider than that often used but has the advantage
of being inclusive of landscapes and vegetation from
northern forests to polar deserts, reflecting too the
connections between the Arctic and more southerly
regions. Physical, biological, and societal conditions
vary greatly across the Arctic. Changes in climate and
UV radiation are also likely to vary regionally, contributing to different impacts and responses at a variety
of spatial scales.To strike a balance between overgeneralization and over-specialization, four major
regions were identified based on differences in largescale weather- and climate-shaping factors.Throughout
the assessment, differences in climate trends, impacts,
and responses were considered across these four
regions, to explore the variations anticipated and to
illustrate the need for responses targeted to regional
and local conditions.The four ACIA regions are shown
in Fig. 1.1.There are many definitions of the Arctic,
such as the Arctic Circle, treeline, climatic boundaries,
and the zone of continuous permafrost on land and seaice extent on the ocean.The numerous and complex
connections between the Arctic and lower latitudes
make any strict definition nearly meaningless, particularly in an assessment covering as many topics and
issues as this one. Consequently, there was a deliberate
decision not to define the Arctic for the assessment as a
whole. Each chapter of this report describes the area
that is relevant to its particular subject, implicitly or
explicitly determining its own southern boundary.
3
Chapter 1 • An Introduction to the Arctic Climate Impact Assessment
1.2.Why assess the impacts of changes in
climate and UV radiation in the Arctic?
(Osterkamp, 1994), and reduction in extent of sea ice
in the Arctic Ocean (Rothrock et al., 1999;Vinnikov et
al., 1999).The warming has been accompanied by
increases in precipitation, but a decrease in the duration
of snow cover.These changes have been interpreted to
be due at least in part to anthropogenic intensification
of the global greenhouse effect, although the El Niño–
Southern Oscillation and the inter-decadal Arctic
Oscillation also affect the Arctic.The latter can result in
warmer and wetter winters in its warm phases, and
cooler, drier winters in its cool phases (see Chapter 2).
1.2.1. Climate change
There are four compelling reasons to examine arctic
climate change. First, the Arctic, together with the
Antarctic Peninsula, experienced the greatest regional
warming on earth in recent decades, due largely to various feedback processes. Average annual temperatures
have risen by about 2 to 3 ºC since the 1950s and in
winter by up to 4 ºC.The warming has been largest
over the land areas (Chapman and Walsh, 2003; see also
Figs. 1.2 and 1.3).There are also areas of cooling in
southern Greenland, Davis Strait, and eastern Canada.
The warming has resulted in extensive melting of glaciers (Sapiano et al., 1997), thawing of permafrost
Second, climate projections suggest a continuation of the
strong warming trend of recent decades, with the largest
changes coming during winter months (IPCC, 1990,
1996, 2001a,b). For the B2 emissions scenario used by
the Intergovernmental Panel on Climate Change (IPCC)
and in the ACIA (see section 1.4.2), the five ACIAdesignated general circulation models (GCMs; see section 1.4.2) project an additional warming in the annual
mean air temperature of approximately 1 ºC by 2020,
2 to 3 ºC by 2050, and 4 to 5 ºC by 2080; the three
time intervals considered in this assessment (see Figs.
1.4 and 1.5).Within the Arctic, however, the models do
show large seasonal and regional differences; in fact, the
differences between individual models are greatest in the
polar regions (McAvaney et al., 2001).The reduction in
or loss of snow and ice has the effect of increasing the
warming trend as reflective snow and ice surfaces are
replaced by darker land and water surfaces that absorb
more solar radiation. At one extreme, for example, the
model of the Canadian Centre for Climate Modelling
and Analysis projects near-total melting of arctic sea ice
by 2100. Large winter warming in the Arctic is likely to
accelerate already evident trends of a shorter snow season, retreat and thinning of sea ice, thawing of permafrost, and accelerated melting of glaciers.
Fig. 1.2. Annual average near surface air temperature from stations on land relative to the average for 1961–1990, for the region
from 60º to 90º N (updated from Peterson and Vose, 1997).
(a)
Annual
(b)
Winter (Dec–Feb)
(ºC)
+4
+3
No Data
+2
No Data
+1
0
-1
-2
Fig. 1.3. Change in observed surface air temperature between 1954 and 2003: (a) annual mean; (b) winter (Chapman and Walsh, 2003,
using data from the Climatic Research Unit, University of East Anglia, www.cru.uea.ac.uk/temperature).
4
Arctic Climate Impact Assessment
marine environment, the Bering Sea, North Atlantic
Ocean, and Barents Sea have some of the most productive fisheries in the world (Weller and Lange, 1999).
As this assessment makes clear, all these systems and the
activities they support are vulnerable to climate change.
Third, the changes seen in the Arctic have already led to
major impacts on the environment and on economic
activities (e.g.,Weller, 1998). If the present climate
warming continues as projected, these impacts are likely
to increase, greatly affecting ecosystems, cultures, lifestyles, and economies across the Arctic (see Chapters 10
to 17). On land, the ecosystems range from the ecologically more productive boreal forest in the south to the
tundra meadows and unproductive barrens in the High
Arctic (Fig. 1.6). Reindeer herding and, to a lesser
extent, agriculture are among the economic activities in
terrestrial areas.Tourism is an increasing activity
throughout the region. Some of the world’s largest gas,
oil, and mineral deposits are found in the Arctic. In the
Global
Arctic
In the Arctic there are few cities and many rural communities. Indigenous communities throughout the Arctic
depend on the land, lakes and rivers, and the sea for
food and income and especially for the vital social and
cultural importance of traditional activities.The cultural
diversity of the Arctic is already at risk (Freeman, 2000;
Minority Rights Group, 1994), and this may be exacerbated by the additional challenge posed by climate
change.The impacts of climate change
will occur within the context of the
societal changes and pressures that
arctic indigenous residents are facing
in their rapid transition to the modern
world.The imposition of climate
change from outside the region can
also be seen as an ethical issue, in
which people in one area suffer the
consequences of actions beyond their
control and in which beneficial opportunities may accrue to those outside
the region rather than those within.
1981–2000 Average
Fig. 1.4. Average surface air temperatures projected by the five ACIA-designated
climate models for the B2 emissions scenario (see Chapter 4 for further details).
The heavy lines are projected average global temperature increases and the thinner lines the projected average arctic temperature increases.
(a)
(b)
Annual
Fourth, climate change in the Arctic
does not occur in isolation.The Arctic
is an important part of the global climate system; it both affects and is
affected by global climate change.
Changes in climate in the Arctic, and
in the environmental parameters such
Winter (Dec–Feb)
(ºC)
+12
+10
+8
+6
+4
+2
0
Fig. 1.5. (a) Projected annual surface air temperature change from the 1990s to the 2090s, based on the average change projected
by the five ACIA-designated climate models using the B2 emissions scenario. (b) Projected surface air temperature change in winter from the 1990s to the 2090s, based on the average change projected by the five ACIA-designated climate models using the B2
emissions scenario.
5
Chapter 1 • An Introduction to the Arctic Climate Impact Assessment
Ice
Polar desert/semi-desert
Tundra
Boreal forest
Temperate forest
Fig. 1.6. Present day natural vegetation of the Arctic and
neighboring regions from floristic surveys (based on Kaplan
et al., 2003; see Chapter 7 for greater detail).
as snow cover and sea ice that affect the earth’s energy
balance and the circulation of the oceans and the atmosphere, may have profound impacts on regional and
global climates. Understanding the role of the Arctic
and the implications of projected changes and their
feedbacks, regionally and globally, is critical to assessing
global climate change and its impacts. Furthermore,
migratory species provide a direct biological link
between the Arctic and lower latitudes, while arctic
resources such as fish and oil play an economic role of
global significance. Impacts on any of these may have
global implications.
1.2.2. UV radiation
The case for assessing UV radiation is similarly compelling. Stratospheric ozone depletion events of up to
45% below normal have been recorded recently in the
Arctic (Fioletov et al., 1997). Dramatic change in the
thickness of the stratospheric ozone layer and corresponding changes in the intensity of solar UV radiation were
first observed in Antarctica in the mid-1980s.The depletions of ozone were later found to be the result of
anthropogenic chemicals such as chlorofluorocarbons
reaching the stratosphere and destroying ozone. Ozone
depletion has also been observed in the Arctic in most
years since 1992. Owing to global circulation patterns,
the arctic stratosphere is typically warmer and experiences more mixing than the antarctic stratosphere.
The ozone decline is therefore more variable in the
Arctic. For example, severe arctic ozone depletions were
observed in most of the last ten springs, but not in 2002
owing to early warming of the stratosphere.
Although depletion of stratospheric ozone was expected
to lead to increased UV radiation at the earth’s surface,
actual correlations have become possible only recently
because the period of instrumental UV measurement is
short. Goggles found in archaeological remains in the
Arctic indicate that UV radiation has been a fact of
human life in the Arctic for millennia. In recent years,
however, UV radiation effects, including sunburn and
increased snow blindness, have been reported in regions
where they were not observed previously.
Future increases in UV-B radiation of 20 to 90% have
been predicted for April for the period 2010 to 2020
(Taalas et al., 2000). Ultraviolet radiation can have a
variety of harmful impacts on human beings, on plants
and animals, and on materials such as paints, cloths, and
plastics (Andrady et al., 2002). Ultraviolet radiation also
affects many photochemical reactions, such as the formation of ozone in the lower atmosphere. In the Arctic,
human beings and ecosystems have both adapted to the
very low intensity of the solar UV radiation compared
with that experienced at lower latitudes.The low intensity of UV radiation in the Arctic is a consequence of the
sun never reaching high in the sky as well as the presence of the world’s thickest ozone layer.The Arctic as a
whole may therefore be particularly susceptible to
increases in UV radiation.
Other factors that affect the intensity of UV radiation
include cloudiness and the amount of light reflected by
the surface. Climate change is likely to affect atmospheric circulation as well as cloudiness and the extent
and duration of snow and ice cover, which in turn will
6
Arctic Climate Impact Assessment
2003) and the United Nations Environment Programme
(UNEP, 2003).These assessments, and the research that
they comprise, provide a baseline against which the findings of the ACIA can be considered.
1.3.2. Organization
affect UV radiation.Thus, UV radiation is both a topic of
concern in itself and also in relation to climate change
(UNEP, 2003).
1.3.The Arctic Climate Impact Assessment
1.3.1. Origins of the assessment
The idea to conduct an assessment of climate and UV
radiation in the Arctic grew from several initiatives in
the 1990s.The International Arctic Science Committee
(IASC) had been engaged in climate studies since it was
founded in 1991, and conducted regional arctic impact
studies throughout the 1990s.The Arctic Monitoring
and Assessment Programme (AMAP) also conducted a
preliminary assessment of climate and UV impacts in
the Arctic, which was published in 1998.The need for a
comprehensive and circum-Arctic climate impact study
had been discussed by IASC for some time, and IASC
invited AMAP and CAFF (Conservation of Arctic Flora
and Fauna) to participate in a joint venture. A joint
meeting between the three groups was held in April
1999 and the IASC proposal was used as the basis for
discussion. A revised version of the proposal was then
submitted to the Arctic Council and the IASC Council
for approval. A joint project between the Arctic Council
and IASC – the Arctic Climate Impact Assessment –
was formally approved by the Arctic Council at its
meeting in October 2000.
In addition to the work of the groups responsible for its
production, the ACIA builds on several regional and
global climate change assessments.The IPCC has made
the most comprehensive and best-known assessment of
climate change on a global basis (e.g., IPCC, 2001a,b),
and has provided many valuable lessons for the ACIA.
In addition, regional studies have examined, among
other areas, Canada (Maxwell, 1997), the Mackenzie
Basin (Cohen 1997a,b), the Barents Sea (Lange and the
BASIS Consortium, 2003; Lange et al., 1999), and
Alaska (Weller et al., 1999). (The results of these
regional studies are summarized in Chapter 18.) Ozone
depletion and UV radiation have also been assessed globally by the World Meteorological Organization (WMO,
The ACIA started in October 2000 and was completed
by autumn 2004.Together, AMAP, CAFF, and IASC set
up the organization for the ACIA, starting with an
Assessment Steering Committee (ASC) to oversee the
assessment.The members of the ASC included a chair,
vice-chair, and executive director, all the lead authors
for the ACIA chapters, several scientists appointed by
the three sponsoring organizations, and three individuals
appointed by the indigenous organizations in the Arctic
Council. A subset of the ASC, the Assessment Integration
Team, was created to coordinate the material in the various chapters and documents produced by the ACIA.
The Arctic Council, including its Senior Arctic Officials,
provided oversight through progress reports and documentation at all the Arctic Council meetings.
Funding was provided to the ACIA through direct and
indirect support by each of the eight arctic nations.
As the lead country for the ACIA, the United States provided financial support through the National Science
Foundation and the National Oceanic and Atmospheric
Administration, which allowed the establishment of an
ACIA Secretariat at the University of Alaska Fairbanks.
Contributions from the other arctic countries, as well as
from the United Kingdom, supported the involvement
of their citizens and provided in-kind support, such as
hosting meetings and workshops.
Much of the credibility associated with an assessment
comes from the reputation of the authors, who are
well-recognized experts in their fields of study. Broad
participation of experts from many different disciplines
and countries in the writing of the ACIA documents
was established through an extensive nomination
process. From these nominations, the ASC selected lead
and contributing authors for each chapter of the assessment.The chapters were drafted by around 180 lead
and co-lead authors, contributing authors, and consulting authors from 12 countries, including all the arctic
countries.The ultimate standard in any scientific publication is peer review.The scientific chapters of the
ACIA were subject to a rigorous and comprehensive
peer review process, which included around 200
reviewers from 15 countries.
1.3.3.Terminology of likelihood
Discussion of future events and conditions must take
into account the likelihood that these events or conditions will occur. Often, assessments of likelihood are
qualitative or cover a range of probabilities.To avoid
confusion and to promote consistent usage, the ACIA
has adapted a lexicon of terms from the US National
Assessment Team (NAST, 2000) describing the likeli-
Chapter 1 • An Introduction to the Arctic Climate Impact Assessment
hood of expected change.The stated likelihood
of particular impacts occurring is based on
expert evaluation of results from multiple
lines of evidence including field and laboratory experiments, observed trends, theoretical analyses, and model simulations.
Judgments of likelihood are indicated using a
five-tier lexicon (see Fig. 1.7) consistent with
everyday usage.These terms are similar to those
used by the IPCC, though somewhat simplified, and
are used throughout the ACIA.
7
Fig. 1.7. Five-tier lexicon describing the likelihood of expected change.
1.4. The assessment process
1.4.1. The nature of science assessment
The ACIA is a “science assessment” in the tradition of
other major international assessments of current environmental issues. For example, the IPCC, the international
body mandated to assess the relevant information for
understanding the risk of human-induced climate change,
recently released its Third Assessment Report (IPCC,
2001a,b).The WMO and UNEP jointly released their latest assessments of the issue of stratospheric ozone depletion (WMO, 2003; UNEP, 2003).Two Arctic Council
working groups, AMAP and CAFF, have also recently
completed science assessments of, respectively, pollution
and biodiversity in the circumpolar Arctic (AMAP, 2002,
2003a,b, 2004a,b,c; CAFF, 2001). All of these, and
indeed all other assessments, have in common the purpose of providing scientific advice to decision makers
who need to develop strategies regarding their respective
areas of responsibility.The ACIA responds directly to the
request of the Arctic Council for an assessment that can
provide the scientific basis for policies and actions.
The essence of a science assessment is to analyze critically and judge definitively the state of understanding on an
issue that is inherently scientific in nature. It is a pointin-time evaluation of the existing knowledge base, highlighting both areas of confidence and consensus and areas
of uncertainty and disagreement in the science. Another
aim of an assessment is to stimulate research into filling
emerging knowledge gaps and solving unresolved issues.
A science assessment thus draws primarily on the available literature, rather than on new research.To be used
within an assessment, a study must have been published
according to standards of scientific excellence. (With
regard to the incorporation of indigenous knowledge,
see the discussion in section 1.4.3.) Publications in the
open, peer-reviewed scientific literature meet this standard. Other resources, such as technical publications by
government agencies, may be included if they have
undergone review and are publicly available.
1.4.2. Concepts and tools in climate
assessment
The arctic climate system is complex.The processes of
climate and the ways in which various phenomena affect
one another – the feedbacks in the system – are still not
fully understood. Specific feedbacks are introduced by
the cryosphere and, in particular, by sea ice with its
complex dynamics and thermodynamics. Other complex
features include the internal dynamics of the polar atmosphere, stratification of both the lower troposphere and
the ocean, and phenomena such as the dryness of the air
and multiple cloud layers. All these add to the challenge
of developing effective three-dimensional models and
constructing climate scenarios based on the outcome of
such models (Randall et al., 1998; Stocker et al., 2001).
“Climate scenario” means a plausible representation of
the future climate that is consistent with assumptions
about future emissions of greenhouse gases and other
pollutants (emissions scenarios) and with the current
understanding of the effects that increased atmospheric
concentrations of these components have on climate
(IPCC-TGCIA, 1999). Correspondingly, a “climatechange scenario” is the difference between conditions
under a future climate scenario and those of today’s climate. Being dependent on a number of assumptions
about future human activities and their impact on the
composition of the atmosphere, climate and climatechange scenarios are not predictions, but plausible
descriptions of possible future climates.
Selection of climate scenarios for impact assessments is
always controversial and vulnerable to criticism (Smith et
al., 1998).The following criteria are suggested (Mearns
et al., 2001) for climate scenarios to be most useful to
impact assessors and policy makers: (1) consistency with
global warming projections over the period 1990 to 2100
ranging from 1.4 to 5.8 ºC (IPCC, 2001a); (2) physical
plausibility; (3) applicability in impact assessments, providing a sufficient number of variables across relevant
temporal and spatial scales; (4) representativeness,
reflecting the potential range of future regional climate
change; and (5) accessibility. It is preferable for impact
researchers to use several climate scenarios, generated by
different models where possible, in order to evaluate a
greater range of possible futures. Practical limitations,
however, typically mean researchers can only work with a
small number of climate scenarios.
One starting point for developing a climate change scenario is to select an emissions scenario, which provides a
plausible projection of future emissions of substances
such as greenhouse gases and aerosols.The most recent
IPCC emissions scenarios used in model simulations are
those published in the Special Report on Emissions
Scenarios (SRES, Naki5enovi5 et al., 2000).The SRES
8
Arctic Climate Impact Assessment
emissions scenarios were built around four basic paths of
development that the world may take in the 21st century.
It should be noted that no probabilities were assigned to
the various SRES emissions scenarios.
During the initial stage of the ACIA process, to stay
coordinated with current IPCC efforts, it was agreed
that the ACIA should work from IPCC SRES emissions
scenarios (Källén et al., 2001). At that time, most of the
available or soon-to-be-available simulations that allowed
their own uncertainties to be assessed used the A2 and
B2 emissions scenarios (Cubasch et al., 2001):
• The A2 emissions scenario assumes an emphasis on
economic development rather than conservation.
Population is projected to increase continuously.
• The B2 emissions scenario differs in having a greater
emphasis on environmental concerns than economic concerns. It has intermediate levels of economic growth and a population that, although
continuously increasing, grows at a slower rate
than that in the A2 emissions scenario.
Both A2 and B2 can be considered intermediate scenarios. For reasons of schedule and limitations of data storage, ACIA had to choose one as the central emissions
scenario. B2 was chosen because at the time it had been
more widely used to generate scenarios, with A2 as a
plausible alternative as its use increased.
Once an emissions scenario is selected, it must be used
in a climate model (atmosphere–ocean general circulation model, or AOGCM; those used in this assessment
are coupled atmosphere-land-ice-ocean models) to
produce a climate scenario. Considering the large and
increasing number of models available, selecting the
models and model outputs for the assessment was not a
trivial matter.The IPCC (McAvaney et al., 2001) concluded that no single model can be considered “best”
and that it is important to utilize results from a range
of coupled models.
Initially, a set of the most recent and comprehensive
AOGCMs whose outputs were available from the IPCC
Data Distribution Centre were chosen. Later, this set
was reduced to five AOGCMs (two European and three
North-American) for practical reasons.The treatment
of land surfaces and sea ice is included in all these models, but with varying degrees of complexity.The five
ACIA-designated models and the institutes that run
them are:
• CGCM2 (Canadian Centre for Climate Modelling
and Analysis)
• CSM_1.4 (National Center for Atmospheric
Research, USA)
• ECHAM4/OPYC3 (Max-Planck Institute for
Meteorology, Germany)
• GFDL-R30_c (Geophysical Fluid Dynamics
Laboratory, USA)
• HadCM3 (Hadley Centre for Climate Prediction
and Research, UK).
In the initial phase of the ACIA, at least one simulation
using the B2 emissions scenario and extending to 2100
was accomplished with each of the five ACIA-designated
models. For climate change scenarios, the ACIA climate
baseline is 1981–2000. Any differences from the more
familiar IPCC baseline of 1961–1990 were small.Three
20-year time slices are the foci of the ACIA for the 21st
century: 2011–2030, 2041–2060, and 2071–2090, corresponding to near-term, mid-term, and longer-term
outlooks for climate change. A complete description and
discussion of the modeling work under ACIA, as well as
its limitations, are provided in Chapter 4.
Other types of scenario were also used by chapter
authors or by the studies on which the chapters of the
assessment are based.These include analogue scenarios
of a future climate, based on past (instrumentally
recorded) or paleo (geologically recorded) warm climates (i.e., temporal analogue scenarios) or current climates in warmer regions (i.e., spatial analogue scenarios). Although instrumental records provide relatively
poor coverage for most of the Arctic, their use avoids
uncertainties associated with interpreting other indicators, providing a significant advantage over other
approaches. Overall, analogue scenarios were used
widely in the ACIA, supplementing the scenarios produced by numerical models. No single impact model
was used in the impacts chapters of the assessment;
each chapter made use of its own approaches. Further
work in this area might consider the need and ability to
develop impact models that can be used to address the
diversity of topics addressed in this assessment. Another
need is for models and scenarios that are able to show
more detailed regional and sub-regional variations and
that can be used for local impact assessments.
1.4.3. Approaches for assessing impacts of
climate and UV radiation
The study of climate and UV radiation involves detailed
measurements of physical parameters and the subsequent analysis of results to detect patterns and trends
and to create quantitative models of these trends and
Chapter 1 • An Introduction to the Arctic Climate Impact Assessment
9
their interactions. As Chapters 2, 4, 5, and 6 show, this
is not a trivial undertaking.The next step, using measurements and models to assess the likely impacts of
changes in climate and UV radiation, is even more complex and uncertain. Ecosystems and societies are changing in ways great and small and are driven by many cooccurring factors regardless of variability in climate and
UV radiation. Determining how changes in climate and
UV radiation may affect dynamic systems relies on several sources of data and several approaches to analysis
(see further discussion in Chapter 7).
Most experimental and empirical data can reveal how
climate and UV radiation affect plants, animals, and
human communities. Observational studies and monitoring can document changes in climate and UV radiation over time together with associated changes in the
physical, biological, and social environment.The drawback to observational studies is that they are opportunistic and require that the correct parameters are
tracked in a system in which change actually occurs.
Establishing causal connections is harder, but can be
done through studies of the physical and ecological
processes that link environmental components.
Experimental studies involve manipulations of small
components of the environment, such as vegetation
plots or streams. In these cases, the researcher determines the simulated climate or UV radiation change or
changes, so there is great control over the conditions
being studied.The drawback is that the range of climate
and UV radiation conditions may not match that anticipated by various scenarios used for regional assessments, limiting the applicability of the experimental
data to the assumptions of the particular assessment.
The use of analogues, as described at the end of the previous section, can help identify potential consequences
of climate change. Looking at past climates and climate
change events can help identify characteristic biota and
how they change. Spatial analogues can be used to compare ecosystems that exist now with the ecosystems
where similar climate conditions are anticipated in the
future. A strength of analogues is that they enable an
examination of actual changes over an ecosystem, rather
than hypothetical changes or changes to small experimental sites.Their weakness is that perfect analogues
cannot be found, making interpretation difficult because
of the variety of factors that cannot be controlled.
For assessing impacts on societies, a variety of social
and economic models and approaches can be used.
Examining resilience, adaptation, and vulnerability
(see further discussion in Chapter 17) offers a powerful
means of understanding at least some of the dynamics
and complexity associated with human responses to
environmental and other changes. As with changes to
the natural environment, examining societal dynamics
can be achieved through models, observations, and the
use of analogues.
1Many
These scientific approaches can be complemented by
another source of information; indigenous and local
knowledge1.This assessment makes use of such knowledge to an unprecedented degree in an exercise of this
kind. Some extra attention to the topic is therefore warranted here. Indigenous residents of the Arctic have for
millennia relied on their knowledge of the environment
in order to provide food and other materials and to survive its harsh conditions. More recent arrivals, too, may
have a wealth of local knowledge about their area and its
environment.The high interannual variability in the
Arctic has forced its residents to be adaptable to a range
of conditions in climate and the abundance and distribution of animals. Although indigenous and local knowledge is not typically gathered for the specific purpose of
documenting climate and UV radiation changes, it is
nonetheless a valuable source of insight into environmental change over long periods and in great local
detail, often covering areas and seasons in which little
scientific research has been conducted.The review of
documented information by the communities concerned
is a crucial step in establishing whether the information
contained in reports about indigenous and local knowledge reliably reflects community perspectives.This step
of community review offers a similar degree of confidence to that provided by the peer-review process for
scientific literature.
Determining how best to use indigenous knowledge in
environmental assessments, including assessments of the
impacts of climate and UV radiation, is a matter of
debate (Howard and Widdowson, 1997; Stevenson,
1997), but the quality of information generated in careful studies has been established for many aspects of environmental research and management (e.g., Berkes,
1999; Huntington, 2000; Johannes, 1981). In making
use of indigenous knowledge, several of its characteristics should be kept in mind. It is typically qualitative
rather than quantitative, does not explicitly address
uncertainty, and is more likely to be based on observations over a long period than on comparisons of observations taken at the same time in different locations.
Identifying mechanisms of change can be particularly
terms are used to refer to the type of knowledge referred to in this assessment as “indigenous knowledge”. Among the terms in use in the
literature are traditional knowledge, traditional ecological knowledge, local knowledge (often applied to the knowledge of non-indigenous persons),
traditional knowledge and wisdom, and a variety of specific terms for different peoples, such as Saami knowledge or Inuit Qaujimajatuqangit.
Within the context of this assessment, “indigenous knowledge” should be taken broadly, to include observations, interpretations, concerns, and
responses of indigenous peoples. For further discussion see Chapter 3.
10
Arctic Climate Impact Assessment
surrounded by the land masses of Eurasia and North
America, except for breaches at the Bering Strait and in
the North Atlantic. It encompasses a range of land- and
seascapes, from mountains and glaciers to flat plains,
from coastal shallows to deep ocean basins, from polar
deserts to sodden wetlands, from large rivers to isolated
ponds.They, and the life they support, are all shaped to
some degree by cold and by the processes of freezing
and thawing. Sea ice, permafrost, glaciers, ice sheets, and
river and lake ice are all characteristic parts of the
Arctic’s physical geography.
difficult. It is also important to note that indigenous
knowledge refers to the variety of knowledge systems in
the various cultures of the Arctic and is not merely
another discipline or method for studying arctic climate.
Using more than one approach wherever possible can
reduce the uncertainties inherent in each of these
approaches.The ACIA has drawn on all available information, noting the limitations of each source, to compile a
comprehensive picture of climate change and its impacts
in the Arctic. Existing climate models project a wide
range of conditions in future decades. Not all have been
or can be studied empirically, nor can field studies examine enough sites to be fully representative of the range of
changes across the Arctic. Instead, using data from existing studies to assess impacts from regional scenarios and
models requires some extrapolation and judgment. In
this assessment, the chapters addressing impacts may not
be able to assess the precise conditions projected in the
scenarios upon which the overall assessment is based.
Instead, where necessary they will describe what is
known and examine how that knowledge relates to the
conditions anticipated by the scenarios.
1.5.The Arctic: geography, climate,
ecology, and people
This section is intended for readers who are unfamiliar
with the Arctic. Summaries and introductions to specific aspects of the Arctic can be found in reports published by AMAP (1997, 1998, 2002) and CAFF (2001),
as well as the Arctic Atlas (State Committee of the USSR
on Hydrometeorology and Controlled Natural Environments, 1985) published by the Arctic and Antarctic
Research Institute in Russia. The Arctic: Environment,
People, Policy (Nuttall and Callaghan, 2000) is an excellent summary of the present state of the Arctic, edited
by two ACIA lead authors and with contributions from
contributing ACIA authors.
1.5.1. Geography
The Arctic is a single, highly integrated system comprised of a deep, ice covered, and nearly isolated ocean
The Arctic Ocean covers about 14 million square kilometers. Continental shelves around the deep central
basin occupy slightly more than half of the ocean’s area –
a significantly larger proportion than in any other ocean.
The landforms surrounding the Arctic Ocean are of
three major types: (1) rugged uplands, many of which
were overrun by continental ice sheets that left scoured
rock surfaces and spectacular fjords; (2) flat-bedded
plains and plateaus, largely covered by deep glacial, alluvial, and marine deposits; and (3) folded mountains,
ranging from the high peaks of the Canadian Rockies to
the older, rounded slopes of the Ural Mountains.The climate of the Arctic, rather than its geological history, is
the principal factor that gives the arctic terrain its distinctive nature (CIA, 1978).
1.5.2. Climate
The Arctic encompasses extreme climatic differences,
which vary greatly by location and season. Mean annual
surface temperatures range from 4 ºC at Reykjavik,
Iceland (64º N) and 0 ºC at Murmansk, Russia (69º N)
through -12.2 ºC at Point Barrow, Alaska (71.3º N),
-16.2 ºC at Resolute, Canada (74.7º N), -18 ºC over
the central Arctic Ocean, to -28.1 ºC at the crest of
the Greenland Ice Sheet (about 71º N and over 3000 m
elevation). Parts of the Arctic are comparable in precipitation to arid regions elsewhere, with average annual precipitation of 100 mm or less. The North Atlantic
area, by contrast, has much greater average precipitation than elsewhere in the Arctic.
Arctic weather and climate can vary greatly from year
to year and place to place. Some of these differences
are due to the poleward intrusion of warm ocean
currents such as the Gulf Stream and the southward
extension of cold air masses. “Arctic” temperature
conditions can occur at relatively low latitudes (52º N
in eastern Canada), whereas forestry and agriculture
can be practiced well north of the Arctic Circle at
69º N in Fennoscandia. Cyclic patterns also shape climate patterns, such as the North Atlantic Oscillation
(Hurrell, 1995), which strongly influences winter
weather patterns across a vast region from Greenland
to Central Asia, and the Pacific Decadal Oscillation,
which has a similar influence in the North Pacific and
Bering Sea. Both may be related to the Arctic
Oscillation (see Chapter 2).
Chapter 1 • An Introduction to the Arctic Climate Impact Assessment
11
1.5.3. Ecosystems and ecology
1.5.3.2. Freshwater ecosystems
Although the Arctic is considered a single system, it is
often convenient to identify specific ecosystems within
that system. Such classifications are not meant to imply
clear separations between these ecosystems. In fact, the
transition zones between terrestrial, freshwater, and
marine areas are often dynamic, sensitive, and biologically productive. Nonetheless, much scientific research,
and indeed subsequent chapters in this assessment, use
these three basic categories.
Arctic freshwater ecosystems are extremely numerous,
occupying a substantial area of the arctic landmass.
Even in areas of the Arctic that have low precipitation,
freshwater ecosystems are common and the term “polar
deserts” refers more to the impoverishment of vegetation
cover than to a lack of groundwater. Arctic freshwater
ecosystems include three main types: flowing water
(rivers and streams), permanent standing water (lakes and
ponds), and wetlands such as peatlands and bogs (Vincent
and Hobbie, 2000). All provide a multitude of goods and
services to humans and the biota that use them.
1.5.3.1.Terrestrial ecosystems
Species diversity appears to be low in the Arctic, and on
land decreases markedly from the boreal forests to the
polar deserts of the extreme north. Only about 3%
(5900 species) of the world’s plant species occur in the
Arctic north of the treeline. However, primitive plant
species of mosses and lichens are relatively abundant
(Matveyeva and Chernov, 2000). Arctic plant diversity
appears to be sensitive to climate.The temperature gradient that has such a strong influence on species diversity
occurs over much shorter distances in the Arctic than in
other biomes. North of the treeline in Siberia, for example, mean July temperature decreases from 12 to 2 ºC
over 900 km. In the boreal zone, a similar change in
temperature occurs over 2000 km. From the southern
boreal zone to the equator, the entire change is less than
10 ºC (Chernov, 1995).
The diversity of arctic animals north of the treeline
(about 6000 species) is similar to that of plants
(Chernov, 1995). As with plants, the arctic fauna
account for about 3% of the global total, and evolutionarily primitive species are better represented than
advanced species. In general, the decline in animal
species with increasing latitude is more pronounced
than that of plants. An important consequence of this is
an increase in dominance. “Super-dominant” species,
such as lemmings, occupy a wide range of habitats and
generally have large effects on ecosystem processes.
Many of the adaptations of arctic species to their current
environments limit their responses to climate warming
and other environmental changes. Many adaptations have
evolved to cope with the harsh climate, and these make
arctic species more susceptible to biological invasions at
their southern ranges while species at their northern
range limit are particularly sensitive to warming. During
environmental changes in the past, arctic species have
changed their distributions rather than evolving significantly. In the future, changes in the conditions in arctic
ecosystems may affect the release of greenhouse gases to
the atmosphere, providing a possibly significant feedback
to climate warming although both the direction and
magnitude of the feedback are currently very uncertain.
Furthermore, vegetation type profoundly influences the
water and energy exchange of arctic ecosystems, and so
future changes in vegetation driven by climate change
could profoundly alter regional climates.
Flowing water systems range from the large, northflowing rivers that connect the interiors of continents
with the Arctic Ocean, through steep mountain rivers,
to slow-flowing tundra streams that may contain water
during spring snowmelt.The large rivers transport heat,
water, nutrients, contaminants, sediment, and biota into
the Arctic and together have a major effect on regional
environments.The larger rivers flow throughout the
year, but small rivers and streams freeze in winter.
The biota of flowing waters are extremely variable:
rivers fed mainly by glaciers are particularly low in
nutrients and have low productivity. Spring-fed streams
can provide stable, year-round habitats with a greater
diversity of primary producers and insects.
Permanent standing waters vary from very large water
bodies to small and shallow tundra ponds that freeze to
the bottom in winter. By the time the ice melts in summer, the incoming solar radiation is already past its peak,
so that the warming of lakes is limited. Primary production, by algae and aquatic mosses, decreases from the
subarctic to the high Arctic. Zooplankton species are
limited or even absent in arctic lakes because of low
temperatures and low nutrient availability. Species abundance and diversity increase with the trophic status of
the lake (Hobbie, 1984). Fish species are generally not
diverse, ranging from 3 to 20 species, although species
such as Arctic char (Salvelinus alpinus) and salmon (Salmo
salar) are an important resource.
12
Wetlands are among the most abundant and productive
aquatic ecosystems in the Arctic.They are ubiquitous and
characteristic features throughout the Arctic and almost
all are created by the retention of water above the
permafrost.They are more extensive in the southern
Arctic than the high Arctic, but overall, cover vast areas –
up to 3.5 million km2 or 11% of the land surface. Several
types of wetlands are found in the Arctic, with specific
characteristics related to productivity and climate. Bogs,
for example, are nutrient poor and have low productivity
but high carbon storage, whereas fens are nutrient rich
and have high productivity. Arctic wetlands have greater
biological diversity than other arctic freshwater ecosystems, primarily in the form of mosses and sedges.
Together with lakes and ponds, arctic wetlands are summer home to hundreds of millions of migratory birds.
Arctic freshwater ecosystems are particularly sensitive to
climate change because the very nature of their habitats
results from interactions between temperature, precipitation, and permafrost. Also, species limited by temperature and nutrient availability are likely to respond to
temperature changes and effects of UV radiation on dead
organic material in the water column.
1.5.3.3. Marine ecosystems
Approximately two-thirds of the Arctic as defined by
the ACIA comprises ocean, including the Arctic Ocean
Arctic Climate Impact Assessment
and its shelf seas plus the Nordic, Labrador, and Bering
Seas.These areas are important components of the
global climate system, primarily because of their contributions to deepwater formation that influences global
ocean circulation. Arctic marine ecosystems are unique
in having a very high proportion of shallow water and
coastal shelves. In common with terrestrial and freshwater ecosystems in the Arctic, they experience strong
seasonality in sunlight and low temperatures.They are
also influenced by freshwaters delivered mainly by the
large rivers of the Arctic. Ice cover is a particularly
important physical characteristic, affecting heat
exchange between water and atmosphere, light penetration to organisms in the water below, and providing a
biological habitat above (for example, for seals and
polar bears (Ursus maritimus)), within, and beneath the
ice.The marginal ice zone, at the edge of the pack ice,
is particularly important for plankton production and
plankton-feeding fish.
Some of these factors are highly variable from year to
year and, together with the relatively young age of arctic marine ecosystems, have imposed constraints on the
development of ecosystems that parallel those of arctic
lands and freshwaters.Thus, in general, arctic marine
ecosystems are relatively simple, productivity and biodiversity are low, and species are long-lived and slowgrowing. Some arctic marine areas, however, have very
high seasonal productivity (Sakshaug and Walsh, 2000)
and the sub-polar seas have the highest marine productivity in the world.The Bering and Chukchi Seas, for
example, include nutrient-rich upwelling areas that
support large concentrations of migratory seabirds as
well as diverse communities of marine mammals.
The Bering and Barents Seas support some of the
world’s richest fisheries.
The marine ecosystems of the Arctic provide a range of
ecosystem services that are of fundamental importance
for the sustenance of inhabitants of arctic coastal areas.
Over 150 species of fish occur in arctic and subarctic
waters, and nine of these are common, almost all of
which are important fishery species such as cod. Arctic
marine mammals escaped the mass extinctions of the
ice ages that dramatically reduced the numbers of arctic
terrestrial mammal species, but many are harvested.
They include predators such as the toothed whales,
seals, walrus, sea otters, and the Arctic’s top predator,
the polar bear. Over 60 species of migratory and resident seabirds occur in the Arctic and form some of the
largest seabird populations in the world. At least one
species, the great auk (Pinguinus impennis), is now
extinct because of overexploitation.
The simplicity of arctic marine ecosystems, together
with the specialization of many of its species, make them
potentially sensitive to environmental changes such as
climatic change, exposure to higher levels of UV radiation, and increased levels of contaminants. Concomitant
with these pressures is potential overexploitation of
some marine resources.
13
Chapter 1 • An Introduction to the Arctic Climate Impact Assessment
1.5.4. Humans
Some two to four million people live in the Arctic today,
although the precise number depends on where the
boundary is drawn.These people include indigenous peoples (Fig. 1.8) and recent arrivals, herders and hunters
living on the land, and city dwellers with desk jobs.
Humans have occupied large parts of the Arctic since at
least the last ice age. Archeological remains have been
found in northern Fennoscandia, Russia, and Alaska
dating back more than 12 000 years (e.g., Anderson,
1988; Dixon, 2001;Thommessen, 1996). In the eastern
European Arctic, Paleolithic settlements have been
recorded from as early as 40 000 years ago (Pavlov et al.,
2001). In Eurasia and across the North Atlantic, groups
of humans have moved northward over the
past several centuries, colonizing
new lands such as the Faroe
Islands and Iceland, and
encountering those
already present in northern Fennoscandia and Russia and
in western Greenland (Bravo and Sorlin, 2002;
Huntington et al., 1998).
In the 20th century, immigration to the Arctic has
increased dramatically, to the point where nonindigenous persons outnumber indigenous ones in many
regions.The new immigrants have been drawn by the
prospect of developing natural resources, from fishing
to gold to oil (CAFF, 2001), as well as by the search for
new opportunities and escape from the perceived and
real constraints of their home areas. Social, economic,
and cultural conflicts have arisen as a consequence of
competition for land and resources (Freeman, 2000;
Minority Rights Group, 1994; Slezkine, 1994) and the
incompatibility of some aspects of traditional and modern ways of life (e.g., Huntington, 1992;
Nuttall, 2000). In North America,
indigenous claims to land
and resources have been
addressed to some
Saami Council
Inuit Circumpolar Conference
Aleut International Association
Russian Association of Indigenous
Peoples of the North
Gwich'in Council International
Arctic Athabaskan Council
Fig. 1.8. Locations of indigenous peoples in the Arctic, showing affiliation to the Permanent Participants, the indigenous peoples'
organizations that participate in the Arctic Council.
14
Arctic Climate Impact Assessment
extent in land claim agreements, the creation of largely
self-governed regions such as Nunavut and Greenland
within nation states, and other political and economic
actions. In Eurasia, by contrast, indigenous claims and
rights have only recently begun to be addressed as matters of national policy (Freeman, 2000).
disparities between northern and southern communities
in terms of living standards, income, and education are
shrinking, although the gaps remain large in most cases
(Huntington et al., 1998).Traditional economies based
on local production, sharing, and barter, are giving way
to mixed economies in which money plays a greater role
(e.g., Caulfield, 2000).
Many aspects of demography are also changing. Over the
past decade, total population has increased rapidly in
only three areas: Alaska, Iceland, and the Faroe Islands.
Rapid declines in population have occurred across most
of northern Russia, with lesser declines or modest
increases in other parts of the North (see Table 1.1).
Life expectancy has increased greatly across most of the
Arctic in recent decades, but declined sharply in Russia
in the 1990s.The prevalence of indigenous language use
has decreased in most areas, with several languages in
danger of disappearing from use. In some respects, the
Despite this assimilation on many levels, or perhaps in
response to it, many indigenous peoples are reasserting
their cultural identity (e.g., Fienup-Riordan et al., 2000;
Gaski, 1997).With this activism comes political calls for
rights, recognition, and self-determination.The response
of arctic indigenous groups to the presence of longrange pollutants in their traditional foods is a useful
illustration of their growing engagement with the world
community. In Canada particularly, indigenous groups
led the effort to establish a national program to study
Table 1.1. Country population data (data sources as in table notes).
Country
Region
Total
population
ALL
Arctic
3494107
Indigenous
population
USA
Alaska (excluding Southeast)
553850
Canada
Total
105131
59685
2000
481054
2001
106705
1990
1996
6540
2001
30766
6175
1996
37100
18730
2001
39672
19000
1996
Nunavut
26665
22720
2001
24730
20690
1996
9632
8750
2001
8715
7780
3214
2945
49813d
2001
2822
2002
55419
Labradorc
Greenland
Faroe Islands
Finnmark,Troms, Nordland
56542
47300
0
2002
43700
286275
0
2001
266783
2002
468691
462908
North of the Arctic Circle
Russia
73235
28520
Iceland
Finland
Year of
previous
estimate
Northwest Territories
Northern
Sweden
Previous
indigenous
figurea
Yukon Territory
Nunavik, Quebec
Norway
Previous
figurea
3885798
103000b
Denmark
Year of
census/
estimate
48029d
0
1990
35000e
1990
1990
2001
6000e
North of the Arctic Circle
263735
64000 g
Lapland
191768
4083ei
2000
200000 h
4000ei
Murmansk Oblast
Nenets Autonomous Okrug
Yamalo-Nenets Autonomous Okrug
Taimyr (Dolgano-Nenets) A.O.
Sakha Republic (Arctic area)
Chukotka Autonomous Okrug
1535600
2002
1995
379461
10000ef
Total
1994
1994
254733
62000 g
Norrbotten
1996
1996
1990
1995
1999711
67164j
1989
1989
893300
2002
1164586
1899j
41500
2002
53912
6468j
1989
1989
507400
2002
494844
30111j
39800
2002
55803
8728j
1989
66632
3982j
1989
163934
15976j
1989
k
53600
2002
2002
Data sources: AMAP, 1998; US Census Bureau, 2002 (www.census.gov); Statistics Canada, 2002 (www12.statcan.ca); Statistics Greenland, 2002 (www.statgreen.gl);
Faroe Islands Statistics, 2002 (www.hagstova.fo); Statistics Iceland, 2002 (www.statice.is); Statistics Norway, 2002 (www.ssb.no); Statistics Sweden, 2002 (www.scb.se);
Statistics Finland, 2002 (www.stat.fi); State Committee for Statistics, 2003 (www.eastview.com/all_russian_population_census.asp).
aData
from AMAP, 1998; bestimated by adding the number of Alaska Natives to a proportion of those listed as “mixed race” (calculated using the statewide figure for those
of mixed race who are in part Alaska Native); cincludes Davis Inlet, Hopedale, Makkovik, Nain, Postville, and Rigolet; d“indigenous” refers to people born in Greenland,
regardless of ethnicity; eindigenous population is an estimate only; festimate by the Saami Parliament for 1998 – the difference relative to the 1990 value probably reflects a
difference in the method of estimate rather than an actual population increase; gestimate only, using the same percentage of the Norrbotten population in each case,
rounded to the nearest thousand; hyear of previous census/estimate unclear – population of Lapland reported as “slightly more than 200000”; ithis value for the Saami
population is for the four northernmost counties of Lapland (the “Saami Area”).There are an additional 3400 Saami elsewhere in Finland; jIndigenous figures refer only to
the numerically-small peoples, i.e., not the Yakut, Komi, et al.; kfor the districts of Anabarsk, Allaykhovsk, Bulun, Ust-Yansk, and Nizhnekolymsk.
Chapter 1 • An Introduction to the Arctic Climate Impact Assessment
15
contaminants, the results of which were used by those
groups to advocate and negotiate international conventions to control persistent organic pollutants (Downie
and Fenge, 2003).The arguments were often framed in
terms of the rights of these distinct peoples to live without interference from afar.The use of international fora
to make this case emphasizes the degree to which the
indigenous groups think of themselves as participants in
global, in addition to national, affairs.
At the same time that indigenous peoples are reaching
outward, traditional hunting, fishing, herding, and gathering practices remain highly important.Traditional
foods have high nutritional value, particularly for those
adapted to diets high in fat and protein rather than carbohydrates (Hansen et al., 1998). Sharing and other forms
of distributing foods within and between communities
are highly valued, and indeed create a highly resilient
adaptation to uncertain food supplies while strengthening
social bonds (e.g., Magdanz et al., 2002).The ability to
perpetuate traditional practices is a visible and effective
way for many indigenous people to exert control over
the pace and extent of modernization, and to retain the
powerful spiritual tie between people and their environment (e.g., Fienup-Riordan et al., 2000; Ziker, 2002).
It is within this context of change and persistence in the
Arctic today that climate change and increased UV radiation act as yet more external forces on the environment that arctic residents rely upon and know well.
Depending on how these new forces interact with existing forces in each arctic society and each geographical
region, the impacts and opportunities associated with
climate change and UV radiation may be minimized or
magnified (e.g., Hamilton et al., 2003).The degree to
which people are resilient or vulnerable to climate
change depends in part on the cumulative stresses to
which they are subject through social, political, and
economic changes in other aspects of their lives. It also
depends in part on the sensitivity of social systems and
their capacity for adaptation (see Chapter 17).The
human impacts of climate change should be interpreted
not in sweeping generalizations about the entire region,
but as another influence on the already shifting mosaic
that comprises each arctic community.
1.5.5. Natural resources and economics
In economic terms, the Arctic is best known as a source
of natural resources.This has been true since the first
explorers discovered whales, seals, birds, and fish that
could be sold in more southerly markets (CAFF, 2001).
In the 20th century, arctic minerals were also discovered
and exploited, the size of some deposits of oil, gas, and
metal ores more than compensating for the costs of
operating in remote, cold regions (AMAP, 1998; Bernes,
1996). Military bases and other facilities were also constructed across much of the Arctic, providing employment but also affecting population distribution and local
environments (e.g., Jenness, 1962). In recent decades,
tourism has added another sector to the economies of
many communities and regions of the Arctic (Humphries
et al., 1998).The public sector, including government
services and transfer payments, is also a major part of
the economy in nearly all areas of the Arctic, responsible
in some cases for over half the available jobs (Huntington
et al., 1998). In addition to the cash economy of the
Arctic, the traditional subsistence and barter economies
are major contributors to the overall well-being of the
region, producing significant value that is not recorded
in official statistics that reflect only cash transactions
(e.g., Schroeder et al., 1987;Weihs et al., 1993).
The three most important economic resources of the
Arctic are oil and gas, fish, and minerals.
1.5.5.1. Oil and gas
The Arctic has huge oil and gas reserves. Most are located in Russia: oil in the Pechora Basin, gas in the lower
Ob Basin, and other potential oil and gas fields along
the Siberian coast. Canadian oil and gas fields are concentrated in two main basins in the Mackenzie Delta/
Beaufort Sea region and in the Arctic Islands. In Alaska,
Prudhoe Bay is the largest oil field in North America
16
Arctic Climate Impact Assessment
Peninsula but also in Siberia. Canadian mining in the
Yukon and Northwest Territories and Nunavut is for lead,
zinc, copper, diamonds, and gold. In Alaska lead and zinc
deposits in the Red Dog Mine, which contains two-thirds
of US zinc resources, are mined, and gold mining continues.The mining activities in the Arctic are an important
contributor of raw materials to the world economy.
1.6. An outline of the assessment
This assessment contains eighteen chapters.The seventeen chapters that follow this introduction are organized
into four sections: climate change and UV radiation
change in the Arctic, impacts on the physical and biological systems of the Arctic, impacts on humans in the
Arctic, and future steps and a synthesis of the ACIA.
and other fields have been discovered or remain to be
discovered along the Beaufort Sea coast. Oil and gas
fields also exist on Greenland’s west coast and in
Norway’s arctic territories.
1.5.5.2. Fish
Arctic seas contain some of the world’s oldest and richest
commercial fishing grounds. In the Bering Sea and Aleutian Islands, Barents Sea, and Norwegian Sea annual fish
harvests in the past have exceeded two million tonnes,
although many of these fisheries have declined (in 2001
fish catches in the Bering Sea totaled 1.6 million tonnes).
Important fisheries also exist around Iceland, Svalbard,
Greenland, and Canada. Fisheries are important to many
arctic countries, as well as to the world as a whole.
For example, Norway is the world’s biggest fish exporter
with exports worth four billion US dollars in 2001.
1.5.5.3. Minerals
The Arctic has large mineral reserves, ranging from gemstones to fertilizers. Russia extracts the greatest quantities of these minerals, including nickel, copper, platinum,
apatite, tin, diamonds, and gold, mostly on the Kola
1.6.1. Climate change and UV radiation
change in the Arctic
The arctic climate is an integral part of the global climate, and cannot be understood in isolation. Chapter 2
describes the arctic climate system, its history, and its
connections to the global system.This description lays
the foundation for the rest of the treatment of climate in
this assessment. Chapter 3 lays another essential foundation for the assessment by describing how climate
change appears from the perspective of arctic indigenous peoples, a topic also included in other chapters.
Chapter 4 describes future climate projections, developed through use of emissions scenarios of greenhouse
gases, and climate modeling. Several modeling simulations of future climates were developed specifically for
this assessment, and these are described in detail.
Chapter 5 provides the counterpart to Chapters 2 and 4
on observations and future projections of UV radiation
and ozone, and their effects.The causes and characteristics of ozone depletion are discussed, together with
models for the further depletion and eventual recovery
of the ozone layer following international action.
1.6.2. Impacts on the physical and
biological systems of the Arctic
The primary impacts of climate change and increased
UV radiation in the Arctic will be to its physical and biological systems. Chapter 6 describes the changes that
have already been observed, and the impacts that are
expected to occur in the frozen regions of the Arctic,
including sea ice, permafrost, glaciers, and snow cover.
River discharge and river and lake ice break-up and
freeze-up are also discussed. Chapter 7 discusses impacts
on the terrestrial ecosystems of the Arctic, drawing on
extensive research, experimental data, observations, and
indigenous knowledge. Biodiversity, risks to species,
including displacements due to climate change, UV radiation effects, and feedback processes as the vegetation
and the hydrological regime change are discussed.
Chapter 8 examines freshwater ecosystems in a similar
fashion, including a discussion of freshwater fisheries in
the Arctic. Chapter 9 covers the marine systems of the
Chapter 1 • An Introduction to the Arctic Climate Impact Assessment
Arctic, and includes topics from the physical ocean
regime, including the thermohaline circulation, to sea
ice, coastal issues, fisheries, and ecosystem changes.
1.6.3. Impacts on humans in the Arctic
The implications of climate change and changes in UV
radiation for humans are many and complex, both direct
and indirect. Chapter 10 addresses the challenges to biodiversity conservation posed by climate change, especially given the relative paucity of data and the lack of
circumpolar monitoring at present. Chapter 11 outlines
the implications of climate change for wildlife conservation and management, a major concern in light of the
substantial changes that are expected to impact upon
ecosystems. Chapter 12 looks at traditional practices of
hunting, herding, fishing, and gathering, which are also
likely to be affected by ecosystem changes, as well as by
changes in policies and society. Chapter 13 describes the
commercial fisheries of the arctic seas, including seals
and whales, with reference to climate as well
as to fishing regulations and the
socio-economic impacts of
current harvests of fish
stocks. Chapter
14 extends
17
the geographic scope of the assessment to the northern
boreal forest, examining both that ecosystem and the
implications of climate change for agriculture and
forestry. Chapter 15 discusses the implications of climate
and UV radiation on human health, both for individuals
and for communities in terms of public health and cultural vitality. Chapter 16 explores the ways in which climate may affect man-made infrastructure in the Arctic,
both in terms of threats to existing facilities such as
houses, roads, pipelines, and other industrial facilities,
and of future needs resulting from a changing climate.
1.6.4. Future steps and a synthesis of the
ACIA
Chapter 17 presents an innovative way of examining
societal vulnerability to climate change. It gives some
initial results from current research but primarily illustrates prospects for applying this approach more broadly
in the future. Chapter 18 contains a synthesis and summary of the main results of the ACIA, including implications for each of the
four ACIA regions and
directions for future
research.
18
Acknowledgements
Many of the photographs used in this chapter were supplied by Bryan
and Cherry Alexander.
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20
Arctic Climate Impact Assessment
Chapter 9
Marine Systems
Lead Author
Harald Loeng
Contributing Authors
Keith Brander, Eddy Carmack, Stanislav Denisenko, Ken Drinkwater, Bogi Hansen, Kit Kovacs, Pat Livingston, Fiona McLaughlin,
Egil Sakshaug
Consulting Authors
Richard Bellerby, Howard Browman,Tore Furevik, Jacqueline M. Grebmeier, Eystein Jansen, Steingrimur Jónsson, Lis Lindal Jørgensen,
Svend-Aage Malmberg, Svein Østerhus, Geir Ottersen, Koji Shimada
Contents
9.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .454
9.2. Physical oceanography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .454
9.2.1. General features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .454
9.2.2. Sea ice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .456
9.2.2.1. Seasonal cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .456
9.2.2.2. Fast ice and polynyas . . . . . . . . . . . . . . . . . . . . . . . . . . . .457
9.2.2.3. Distribution and thickness . . . . . . . . . . . . . . . . . . . . . . . .457
9.2.2.4. Length of melt season . . . . . . . . . . . . . . . . . . . . . . . . . . .457
9.2.2.5. Sea-ice drift . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .457
9.2.3. Ocean processes of climatic importance . . . . . . . . . . . . . . . . . . .458
9.2.3.1. Freshwater and entrainment . . . . . . . . . . . . . . . . . . . . . .460
9.2.3.2. Mixed-layer depth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .460
9.2.3.3.Wind-driven transport and upwelling . . . . . . . . . . . . . . .461
9.2.3.4.Thermohaline circulation . . . . . . . . . . . . . . . . . . . . . . . . .461
9.2.3.5.What drives the Atlantic inflow to the Arctic
Mediterranean? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .465
9.2.4.Variability in hydrographic properties and currents . . . . . . . . . . .465
9.2.4.1. Seasonal variability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .466
9.2.4.2. Interannual to decadal variability . . . . . . . . . . . . . . . . . . .467
9.2.5. Anticipated changes in physical conditions . . . . . . . . . . . . . . . . .469
9.2.5.1. Atmospheric circulation . . . . . . . . . . . . . . . . . . . . . . . . . .470
9.2.5.2. Sea-ice conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .471
9.2.5.3. Ocean circulation and water properties . . . . . . . . . . . .472
9.2.5.4. Ocean fronts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .477
9.2.5.5. Possibility and consequences of altered thermohaline
circulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .477
9.3. Biota . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .478
9.3.1. General description of the community . . . . . . . . . . . . . . . . . . . .479
9.3.1.1. Phytoplankton, microalgae, and macroalgae . . . . . . . . . . .481
9.3.1.2. Microheterotrophs . . . . . . . . . . . . . . . . . . . . . . . . . . . . .481
9.3.1.3. Zooplankton . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .482
9.3.1.4. Benthos . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .482
9.3.1.5. Fish . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .484
9.3.1.6. Marine mammals and seabirds . . . . . . . . . . . . . . . . . . . . .487
9.3.2. Physical factors mediating ecological change . . . . . . . . . . . . . . . .490
9.3.2.1. Primary production . . . . . . . . . . . . . . . . . . . . . . . . . . . . .491
9.3.2.2. Secondary production . . . . . . . . . . . . . . . . . . . . . . . . . . .493
9.3.2.3. Fish . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .494
9.3.2.4. Marine mammals and seabirds . . . . . . . . . . . . . . . . . . . . .496
9.3.3. Past variability – interannual to decadal . . . . . . . . . . . . . . . . . . .497
9.3.3.1. Plankton . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .497
9.3.3.2. Benthos . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .497
9.3.3.3. Fish . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .499
9.3.3.4. Marine mammals and seabirds . . . . . . . . . . . . . . . . . . . . .504
9.3.4. Future change – processes and impacts on biota . . . . . . . . . . . .504
9.3.4.1. Primary production . . . . . . . . . . . . . . . . . . . . . . . . . . . . .505
9.3.4.2. Zooplankton production . . . . . . . . . . . . . . . . . . . . . . . . .506
9.3.4.3. Benthos . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .507
9.3.4.4. Fish production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .507
9.3.4.5. Marine mammals and seabirds . . . . . . . . . . . . . . . . . . . .509
9.4. Effects of changes in ultraviolet radiation . . . . . . . . . . . . . . .512
9.4.1. Direct effects on marine organisms . . . . . . . . . . . . . . . . . . . . . . .513
9.4.2. Indirect effects on marine organisms . . . . . . . . . . . . . . . . . . . . . .513
9.4.3. Ecosystem effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .514
9.4.3.1. Food chains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .514
9.4.3.2. Quantitative assessments . . . . . . . . . . . . . . . . . . . . . . . . .515
9.4.4. General perspectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .516
9.5.The carbon cycle and climate change . . . . . . . . . . . . . . . . . .516
9.5.1. Physical pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .516
9.5.2. Biological pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .518
9.5.3. Alkalinity pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .518
9.5.4.Terrestrial and coastal sources . . . . . . . . . . . . . . . . . . . . . . . . . . .518
9.5.5. Gas hydrates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .519
9.6. Key findings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .519
9.7. Gaps in knowledge and research needs . . . . . . . . . . . . . . . . .520
9.7.1. Gaps in knowledge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .521
9.7.2. Suggested research actions . . . . . . . . . . . . . . . . . . . . . . . . . . . . .522
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .522
454
9.1. Introduction
Approximately two-thirds of the area addressed by the
Arctic Climate Impact Assessment is ocean.This includes
the Arctic Ocean and its adjacent shelf seas, as well as
the Nordic Seas, the Labrador Sea, and the Bering Sea.
These are very important areas from a climate change
perspective since processes occurring in the Arctic affect
the rate of deep-water formation in the convective
regions of the North Atlantic, thereby influencing the
global ocean circulation. Also, climate models consistently show the Arctic to be one of the most sensitive
regions to climate change.
Many arctic life forms, including humans, are directly or
indirectly dependent on productivity from the sea.
Several physical factors combine to make arctic marine
systems unique including: a very high proportion of continental shelves and shallow water; a dramatic seasonality
and overall low level of sunlight; extremely low water
temperatures; presence of extensive areas of multi-year
and seasonal sea-ice cover; and a strong influence from
freshwater, coming from rivers and ice melt. Such factors represent harsh conditions for many types of marine
life. In geological terms, the arctic fauna is young; recent
glaciations resulted in major losses in biodiversity, and
recolonization has been slow owing to the extreme environmental conditions and low productivity of the arctic
system.This has resulted in arctic ecosystems, in a global
sense, being considered “simple”.They largely comprise
specialist species that have been able to adapt to the
extreme conditions, and overall species diversity is low.
The large seasonal pulse of summer production in the
Arctic, which occurs during the period of 24 hours
light, is particularly pronounced near the ice edge and in
shallow seas such as the Barents and Bering Seas.This
attracts seasonal migrants that travel long distances to
take advantage of the arctic summers and then return
south to overwinter.
This assessment has also considered the effects of
changes in ultraviolet (UV) radiation. However, although
UV-B radiation can result in negative impacts on marine
organisms and populations, it is only one of many environmental factors that can result in the types of mortality typically observed. It is thus important to assess the
relative importance, and hence potential impact, of
ozone depletion-related increases in solar UV-B radiation
on arctic marine ecosystems.
The Arctic Ocean has not been considered a significant
sink for carbon.This is because its extensive sea-ice
cover constrains atmosphere–ocean exchange, and
because levels of biological production under multi-year
sea ice were believed low. Under warmer climate conditions, however, the amount of carbon sequestered by
the Arctic Ocean may increase significantly. In addition,
the Arctic’s role as a source of carbon (methane and
carbon dioxide, CH4 and CO2 respectively) is poorly
understood owing to frozen reserves in permafrost and
gas hydrate layers.
Arctic Climate Impact Assessment
This chapter addresses physical features and processes
related to marine climate and their impact on the
marine ecosystem. Climate change scenarios for the
ocean are very uncertain as most models focus mainly
on changes in the atmosphere. Such models are not
definitive about changes to ocean circulation, deepwater formation, or the fate of major ocean fronts.
Therefore, the conclusions drawn in this chapter regarding likely changes in the marine ecosystem are based on
scenarios determined from the projected changes in the
atmosphere coupled with the present understanding of
how atmospheric forcing influences the ocean, as well as
the output from a few ocean models.
9.2. Physical oceanography
Climate changes impact upon the marine ecosystem
mainly through their effects on the physical oceanography.This section provides an overview of the physical
oceanography of the Arctic sufficient to enable an examination of potential impacts on the biological system.
It also addresses the feedback mechanisms between the
atmosphere and the ocean through which changes in the
oceanography of the Arctic could have global consequences for the atmosphere.
9.2.1. General features
The marine Arctic is defined within this assessment as
comprising the Arctic Ocean, including the deep
Eurasian and Canadian Basins and the surrounding continental shelf seas (Barents,White, Kara, Laptev, East
Siberian, Chukchi, and Beaufort Seas), the Canadian
Archipelago, and the transitional regions to the south
through which exchanges between temperate and arctic
waters occur.The latter includes the Bering Sea in the
Pacific Ocean and large parts of the northern North
Atlantic Ocean, including the Nordic, Iceland, and
Labrador Seas, and Baffin Bay. Also included are the
Canadian inland seas of Foxe Basin, Hudson Bay, and
Hudson Strait.Those arctic areas that receive most of the
heat input from inflowing warm Atlantic water, i.e., the
eastern parts of the Nordic Seas and the Arctic Ocean,
are collectively referred to as the Arctic Mediterranean.
A detailed description of the topography, water properties, and circulation of these areas is given in Chapter 2.
The present chapter presents a brief summary of some
of the salient features.
Sea ice is one of the dominant physical features for most
of these areas, with coverage ranging from year-round
cover in the central Arctic Ocean to seasonal cover in
most of the remaining areas. Exceptions occur over the
deep basins, which are ice-free throughout the year, e.g.,
the Nordic Seas and the Labrador Sea, and the deep
parts of the Bering Sea.
Relatively warm waters from the Atlantic flow through
the Nordic Seas into the Arctic Ocean via the Barents
Sea and through Fram Strait while the warm Pacific
waters flow across the Bering Sea and enter the Arctic
455
Chapter 9 • Marine Systems
Fig. 9.1. Surface currents in the Arctic Ocean (based on AMAP, 1998).
through the Bering Strait (Fig. 9.1). Approximately ten
to twenty times more Atlantic water than Pacific water
by volume enters the Arctic Ocean.Within the Arctic
Ocean the dominant features of the surface circulation
are the clockwise Beaufort Gyre, extending over the
Canadian Basin, and the Transpolar Drift that flows from
the Siberian coast out through Fram Strait. Both features
are strongly influenced by wind forcing.The surface currents along the coast are principally counterclockwise,
moving from Atlantic to Pacific on the Eurasian side and
from Pacific to Atlantic on the North American side.
The subsurface circulation is also counterclockwise and
influenced by the inflows from the Atlantic and Pacific
Oceans.Waters exit the Arctic Ocean primarily through
Fram Strait and the Canadian Archipelago.The arctic
waters leaving through Fram Strait are then transported
southward along East Greenland, and around the
Labrador Sea and Baffin Bay where they merge with the
arctic waters flowing out through the Canadian Archipelago before continuing southward.
The temperature and salinity levels of the various water
bodies in the marine Arctic vary considerably, reflecting
the extent of the Pacific and Atlantic influence, heat
exchange with the atmosphere, direct precipitation,
freshwater runoff, and the melting and freezing of sea
ice. In the Arctic Ocean, the surface waters are generally
near the freezing point owing to the ice cover, whereas
the salinity levels exhibit seasonal and spatial fluctuations
caused by the freezing and melting of sea ice and river
runoff. Density stratification within the Arctic Ocean is
principally due to vertical salinity differences.The layer
containing the greatest change in salinity is called the
halocline. Its characteristics vary across the Arctic Ocean
456
Arctic Climate Impact Assessment
and are largely characterized by the presence or absence
of Pacific-origin water.Waters below the halocline are
modified Atlantic waters that flowed into the Arctic
through Fram Strait and the Barents Sea.The Atlantic
and Pacific inflows carry relatively warm and saline
waters into the Arctic and their vertical density stratification is usually controlled more by temperature than
salinity differences. As these inflows move northward
they are cooled by the atmosphere and freshened by
river runoff. Mixing with ambient waters also generally
leads to cooling and freshening.The waters leaving the
Arctic Ocean also mix with ambient waters, in this case
becoming warmer and saltier.
the areal sea-ice extent due to changes in atmospheric
pressure patterns and their associated winds, continental
discharge, and influx of Atlantic and Pacific waters
(Gloersen, 1995; Mysak and Manak, 1989; Polyakov et
al., 2003; Rigor et al., 2002; Zakharov, 1994).
9.2.2.1. Seasonal cycle
At the time of maximum advance, sea ice covers the
entire Arctic Basin and the Siberian shelf seas (Fig. 9.2).
The warm inflow of Atlantic water keeps the southern
part of the Barents Sea open, but in cold years even its
shallow areas in the southeast are covered by sea ice.
Also, the west coast of Spitsbergen generally remains free
of ice. It is here that open water is found closest to the
Pole in winter, beyond 81º N in some years (Wadhams,
2000). Sea ice from the Arctic Ocean is transported out
through Fram Strait and advected southward by the East
Greenland Current to cover the entire east coast of
Greenland, although in mild winters it does not reach the
southern tip of Greenland. In cold years, the sea ice may
also extend south to the northern and eastern coasts of
Iceland. In most years there is a thin band of sea ice off
West Greenland, which is a continuation of the sea ice
from East Greenland and is known as “Storis”. Only
rarely does the Storis meet the dense sea-ice cover of
Baffin Bay and Davis Strait to completely surround
Greenland.The whole of the Canadian Archipelago, as
well as Hudson Bay and Hudson Strait are usually icecovered (Wadhams, 2000).The Labrador Shelf is also
covered by sea ice and the Labrador Current transports
this southward to Newfoundland. Further west, a complete sea-ice cover extends across the arctic coasts of
northwestern Canada and Alaska and fills the Bering Sea
as far south as the shelf break (Wadhams, 2000).
Sea-ice extent in the Arctic has a clear seasonal cycle and
is at its maximum (14–15 million km2) in March and
minimum (6–7 million km2) in September (Parkinson et
al., 1999).There is considerable interannual variability
both in the maximum and minimum coverage. In addition, there are decadal and inter-decadal fluctuations in
In March or April, the sea ice begins to retreat from its
low latitude extremes. By May the coast off northeastern Newfoundland is clear, as is much of the Bering
Sea. By June the area south of the Bering Strait is icefree and open water is found in Hudson Bay and at several arctic coastal locations. August and September are
9.2.2. Sea ice
Sea ice controls the exchange of heat and other properties between the atmosphere and ocean and, together
with snow cover, determines the penetration of light
into the sea. Sea ice also provides a surface for particle
and snow deposition, a habitat for plankton, and contributes to stratification through ice melt.The zone seaward of the ice edge is important for plankton production and planktivorous fish. For some marine mammals
sea ice provides a place for birth and also functions as a
nursery area.
This section describes features of sea ice that are important for physical oceanographic processes and the marine
ecosystem. More detailed information about sea ice is
given in Chapter 6.
(%)
100
90
80
70
No data
No data
No data
60
50
40
30
15
0
Land
Total ice cover
=
Multi-year ice
+
First-year ice
Fig. 9.2. Average sea-ice cover in winter based on data from satellite microwave sensors (Johannessen O. and Miles, 2000).
The illustration shows total sea-ice cover, plus the distribution of its two components; multi-year ice and first-year ice.
The multi-year ice represents the minimum sea-ice extent in summer.
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Chapter 9 • Marine Systems
the months of greatest retreat. At this time most of the
Barents and Kara Seas are free of sea ice as far as the
northern shelf break.The Laptev Sea and part of the
East Siberian Sea have open water along their coastline.
In East Greenland, the ice has retreated northward to
about 72–73º N, while Baffin Bay, Hudson Bay, and the
Labrador Sea become ice-free. In the Canadian Archipelago the winter fast ice usually breaks up. North of
Alaska, some open water is typically found along the
coast (Wadhams, 2000).
By October, new sea ice has formed in areas that were
open in summer, especially around the Arctic Ocean
coasts, and in November to January there is a steady
advance everywhere toward the winter peak.
9.2.2.2. Fast ice and polynyas
Fast ice grows seaward from a coast and remains in place
throughout the winter.Typically, it is stabilized by
grounded pressure ridges at its outer edge, and therefore
extends to the draft limit of such ridges, usually about
20 to 30 m. Fast ice is found along the whole Siberian
coast, the White Sea, north of Greenland, the Canadian
Archipelago, Hudson Bay, and north of Alaska.
Polynyas are semi-permanent open water regions ranging in area up to thousands of square kilometers. Flaw
leads occur at the border of fast ice when offshore winds
separate the drift ice from the fast ice. Polynyas and flaw
leads are environmentally important for several reasons
(AMAP, 1998):
• they are areas of high heat loss to the atmosphere;
• they typically form the locus of sea-ice breakup in
spring;
• they are often locations of intense biological
activity; and
• they are regions of deep-water formation.
thickness of about 3.1 m (1958–1976) to about 1.8 m
(1993–1997), or about 15% per decade (Rothrock et al.,
1999). In addition, the ice thinned at all 26 sites examined. Overall, the arctic sea ice is estimated to have lost
40% of its volume in less than three decades. However,
according to some models (Holloway and Sou, 2002;
Polyakov and Johnson, 2000), the submarine observations
may have been conducted over part of the ocean that
underwent thinning through shifting sea ice in response to
changing winds associated with a high Arctic Oscillation
(AO) index (see Chapter 2 for descriptions of the AO and
the associated North Atlantic Oscillation).Thus, the conclusion of reduced sea-ice thickness, while valid for the
domain of submarine measurements, may not necessarily
be true for the Arctic Ocean as a whole and an alternative
hypothesis that sea-ice thickness distribution changed in
response to the AO but that sea-ice volume may not have
changed needs to be carefully evaluated.
Scientific debate continues as to the cause of the areal
shrinkage of the arctic sea ice.There is some support for
the idea that it is probably part of a natural fluctuation in
polar climate (Rothrock et al., 1999), while others claim
it is another indication of the response to global warming due to increased levels of greenhouse gases (GHGs;
Vinnikov et al., 1999).
9.2.2.4. Length of melt season
Smith D. (1998) used satellite data, predominantly from
the Beaufort Sea, to estimate that the melt season
increased by about 5.3 days per decade during 1979 to
1996. Rigor et al. (2000) found an increase of about
2.6 days per decade in the length of the melt season in
the eastern Arctic but a shortening in the western Arctic
of about 0.4 days per decade.These trends parallel general observations of a 1 ºC per decade increase in air temperature in the eastern Arctic compared to a 1 ºC per
decade decrease in the western Arctic for the same time
period (Rigor et al., 2000).
9.2.2.3. Distribution and thickness
From a combination of satellite observations and historical records, the area covered by sea ice in the Arctic during the summer has been reported to have decreased by
about 3% per decade during recent decades (Cavalieri et
al., 1997). Multi-year ice is reported to have declined at
an even greater rate; 7% per decade during the last 20
years or approximately 600 000 km2 (Johannessen O. et
al., 1999). Combined, these results imply that the area
of first-year ice has been increasing. Sea-ice distribution
within subregions of the Arctic has also changed dramatically in the past. For example, warming in the Barents
Sea in the 1920s and 1930s reduced sea-ice extent there
by approximately 15%.This warming was nearly as great
as the warming observed over the last 20 years (see section 9.2.4.2, Barents Sea).
In addition to the recent general decrease in sea-ice coverage, submarine observations suggest that the sea ice
over the deep Arctic Ocean thinned from an average
9.2.2.5. Sea-ice drift
General sea-ice motion in the Arctic Ocean is organized
by the Transpolar Drift in the Eurasian Basin and by the
Beaufort Gyre in Canada Basin (Fig. 9.1). Although it has
long been recognized that large-scale ice-drift patterns in
the Arctic undergo interannual changes, it was not until
the International Arctic Buoy Programme (IABP) that
sufficient data became available to map the ice drift in
detail and thereby directly link changes in sea-ice trajectories to the AO.The IABP data from 1979 to 1998 suggest two characteristic modes of arctic sea-ice motion
(Fig. 9.3), one during a low AO index (AO-) and the
other during a high AO index (AO+) (Macdonald et al.,
2003a; Rigor et al., 2002).The ice motion revealed by
drifting buoys released onto the ice is reasonably well
simulated by models (Maslowski et al., 2000; Polyakov
and Johnson, 2000).There are two principal differences
between the two modes. First, during pronounced AOconditions (Fig. 9.3a), sea ice in the Transpolar Drift
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Arctic Climate Impact Assessment
(a) AO-
(b) AO+
Seas was displaced into the central Arctic and toward the
Canadian Archipelago. It is not clear from the IABP data
how much sea ice from the Russian shelves might be
transported into the Canadian Archipelago or the
Beaufort Gyre under AO+ conditions, but models
(Maslowski et al., 2000; Polyakov and Johnson, 2000)
suggest that such transport may be important at times.
Fram Strait is the main gateway for arctic ice export.
Satellite data, drifting buoys, numerical models, and
budgets have been used to construct estimates of the
sea-ice flux through Fram Strait (Kwok and Rothrock,
1999;Vinje et al., 1998).Widell et al. (2003) observed a
mean sea-ice thickness of 1.8 m and a monthly mean
volume flux of 200 km3 for the period 1990 to 1999.
They found no trends in ice thickness and volume flux.
The maximum sea-ice volume flux occurred in 1994/95
due to strong winds, combined with relatively thick ice.
9.2.3. Ocean processes of climatic importance
Fig. 9.3. Sea-ice drift patterns for years with (a) pronounced
AO- (anticyclonic) conditions and (b) pronounced AO+
(cyclonic) conditions (after Maslowski et al., 2000; Polyakov
and Johnson, 2000; Rigor et al., 2002).The small arrows show
the detailed ice drift trajectories based on an analysis of sea
level pressure (Rigor et al., 2002).The large arrows show the
general ice drift patterns.
tends to move directly from the Laptev Sea across the
Eurasian Basin and out into the Greenland Sea, whereas
during pronounced AO+ conditions (Fig. 9.3b), ice in the
Transpolar Drift takes a cyclonic diversion across the
Lomonosov Ridge and into Canada Basin (Mysak, 2001).
Second, during pronounced AO+ conditions (Fig. 9.3b),
the Beaufort Gyre shrinks back into the Beaufort Sea and
becomes more disconnected from the rest of the Arctic
Ocean, exporting less sea ice to the East Siberian Sea and
importing little sea ice from the region to the north of
the Canadian Archipelago that contains the Arctic’s thickest multi-year ice (Bourke and Garrett, 1987).These
changes in sea-ice drift are principally due to the different wind patterns associated with the two AO modes.
During AO- conditions the East Siberian Sea receives
much of its ice from the Beaufort Sea and there is an
efficient route to carry ice clockwise around the arctic
margin of the East Siberian Sea and out toward Fram
Strait. Under the strong AO+ conditions of the early
1990s, the Beaufort Sea ice became more isolated
whereas sea ice from the Kara, Laptev, and East Siberian
The marine Arctic plays an important role in the global
climate system (Box 9.1). A number of physical processes will be affected by the changes anticipated in global
climate during the 21st century, but this assessment
focuses on those that are expected to have strong
impacts on the climate or biology of the Arctic.These
include the effects of wind on the transport and mixing
of water, and the circulation systems generated by freshwater input and thermohaline ventilation (Fig. 9.4).
A key issue is the extent to which each of these processes contributes to driving the inflow of Atlantic water to
the Arctic. Models (Seager et al., 2002) have shown that
the heat transported by this inflow in some areas elevates
the sea surface temperature to a greater extent than the
temperature increase projected for the 21st century
(see Chapter 4). A weakening of the inflow could therefore significantly reduce warming in these areas and
might even induce regional cooling, especially in parts of
the Nordic Seas.Thus, special attention is paid to the
processes that affect the inflow, especially the thermohaline circulation (see section 9.2.3.4).
Fig. 9.4. Two types of processes create unique current systems
and conditions in the marine Arctic.The input of freshwater, its
outflow to the Atlantic, and the en-route entrainment of ambient water create an estuarine type of circulation within the
marine Arctic. In addition to this horizontal circulation system,
thermohaline ventilation creates a vertical circulation system.
Both patterns of circulation are sensitive to climate change.
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Chapter 9 • Marine Systems
Box 9.1. Role of the marine Arctic in the global climate system
The marine Arctic is an interconnected component of the global climate system whose primary role is to balance heat gain at
low latitudes and heat loss at high latitudes. At low latitudes
about half the excess heat is sent poleward as warm (and salty)
water in ocean currents (sensible heat, QS) and the other half is
sent poleward as water vapor in the atmosphere (latent heat,
QL). At low latitudes the subtropical gyres in the ocean collect
excess heat and salt, the western boundary currents carry
them poleward, and the Atlantic inflow brings them into the
marine Arctic. Heat carried by the atmosphere is released at
high latitudes by condensation, thus supplying freshwater to the
ocean through precipitation and runoff. Freshwater is stored in
the surface and halocline layers of the marine Arctic.To prevent
the build-up of salt (by evaporation) at low latitudes, freshwater
is exported from the high latitudes, thus completing the hydrological cycle by reuniting the atmospheric water content and
the salty ocean water. At high latitudes the return flows include
export by ice and transport in low-salinity boundary currents,
intermediate water (which forms and sinks along the subpolar
fronts), and deep water (which sinks on shelves and in gyres).
Export of these low-salinity waters southward couples the
Arctic to the world thermohaline circulation (THC) through
intermediate and deep-water formation.The role of intermediate water in governing THC is unclear.
Simplified view of the climate system
The marine Arctic plays an active role in the global climate
system with strong feedbacks, both positive and negative.
Arctic climate feedbacks
For example: albedo feedback, thermohaline feedback, and greenhouse gas feedback.
Albedo feedback – Ice and snow reflect most of the
solar radiation back into space. With initial warming
and sea-ice melting, more heat enters the ocean, thus
melting more sea ice and increasing warming.
Thermohaline feedback – If the export of freshwater
from the Arctic Ocean should increase, then stratification of the North Atlantic would probably increase, and
this could slow the THC. A decrease in the THC would
then draw less Atlantic water into high latitudes, leading
to a slowdown in the global overturning cell and subsequent localized cooling. (This scenario does not take
into account the formation of intermediate water.)
Greenhouse gas feedback – Vast amounts of methane
and carbon dioxide are currently trapped in the
permafrost and hydrate layers of the arctic margins
(Zimov et al., 1997). With warming, arctic coastal lakes
will act as a thermal drill to tap this greenhouse gas
source and further exacerbate warming.
460
9.2.3.1. Freshwater and entrainment
Freshwater is delivered to the marine Arctic by atmospheric transport through precipitation and by ocean
currents, and to the coastal regions through river inflows
(Lewis et al., 2000). Further net distillation of freshwater may occur within the region during the melt/
freeze cycle of sea ice, provided that the ice and rejected
brine formed by freezing in winter can be separated and
exported before they are reunited by melting and mixing the following summer (Aagaard and Carmack, 1989;
Carmack, 2000).
The freshwater has decisive influences on stratification
and water column stability as well as on ice formation.
Without the freshwater input, there would be less freezing, less ice cover, and less brine rejection (Rudels,
1989).This is also illustrated by the difference between
the temperature-stratified low latitude oceanic regime
and the salinity-stratified high latitude oceanic regime
(Carmack, 2000; Rudels, 1993).
In the Arctic Ocean, freshwater is stored within the various layers above and within the halocline, the latter serving as an extremely complex and poorly understood
reservoir.This is especially true for the Beaufort Gyre,
which represents the largest and most variable reservoir
of freshwater storage in the marine Arctic.The ultimate
sink for freshwater is its export southward into the
North Atlantic to replace the freshwater evaporating
from low latitude oceans and to close the global freshwater budget.This southward transport occurs partly
through the THC since the overflow from the Nordic
Seas into the Atlantic is less saline than the inflowing
Atlantic water.The role of the freshwater is illustrated in
Fig. 9.5.The figure shows the processes responsible for
the development of the horizontal and vertical circulation systems unique to the marine Arctic.
Most of the freshwater in the Arctic Ocean returns
southward in the surface outflows of the East Greenland
Current and through the Canadian Archipelago.These
flows carry low-salinity water as well as sea ice.They
include most of the water that enters the Arctic Ocean
Arctic Climate Impact Assessment
through the Bering Strait and water of Atlantic origin
entrained into the surface flow. Since the estimated
total volume flux of the surface outflows greatly
exceeds the combined fluxes of the Bering Strait inflow
and the freshwater input, most of the surface outflows
must derive from entrained Atlantic water.This process
therefore induces an inflow of Atlantic water to the
Arctic, which by analogy to the flows in estuaries is
usually termed “estuarine circulation”.This estuarinetype circulation is sensitive to climate change.
9.2.3.2. Mixed-layer depth
The vertical extent of the surface mixed layer is critical
to the primary production and depends on the vertical
density stratification and the energy input, especially
from the wind. Density stratification is affected by heat
and freshwater fluxes from the atmosphere or by advection from surrounding ocean areas. Some areas, for
example the Arctic Ocean, are salt-stratified whereas
other areas, such as the Nordic Seas and the Bering Sea,
are temperature-stratified. In a classic study, Morison
and Smith (1981) found that seasonal variations in
mixed-layer depth are largely controlled by buoyancy
(i.e., heat and salt) fluxes.
Winds blowing over the sea surface transfer energy to
the surface mixed layer. In ice-free areas, increased
winds would tend to deepen the surface mixed layer,
depending upon the strength of the vertical density
stratification. In the presence of sea ice, however, the
efficiency of energy transfer from wind to water is a
complex function of sea-ice roughness and internal ice
stress which, in turn, is a function of sea-ice concentration and compactness (see McPhee and Morison, 2001).
Because warming will decrease sea-ice concentrations
(and so decrease internal ice stress) and increase the
duration of “summer” conditions (i.e., earlier breakup
and later freeze-up), the efficiency of wind mixing in
summer is likely to increase.This is especially true for
late summer in the Arctic Ocean when energy input
from storms is greatest. However, owing to the poorly
understood role of air–ice–ocean coupling and the present level of salt-stratification, this increased exposure
* Vertical scale exaggerated
Fig. 9.5. The freshwater budget of the Arctic Ocean. Low salinity waters are added to the surface and halocline layers via precipitation
and runoff, Pacific inflow via the Bering Strait, and the sea-ice distillation process. Low salinity waters and sea ice are subsequently
advected through Fram Strait and the Canadian Archipelago into the convective regions of the North Atlantic.
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Chapter 9 • Marine Systems
will not necessarily lead to significant increases in
mixed-layer depth. Furthermore, the role that lateral
advection plays in establishing the underlying halocline
structure of the Arctic Ocean must also be considered.
9.2.3.3.Wind-driven transport and upwelling
A number of studies have shown the effect of wind stress
on the circulation of particular regions within the
marine Arctic (e.g., Aagaard, 1970; Isachsen et al., 2003;
Jónsson, 1991).Winds have also been shown to have a
strong influence on exchanges between regions (e.g.,
Ingvaldsen, 2002; Morison, 1991; Orvik and Skagseth,
2003; Roach et al., 1995). If winds were to change significantly, wind-driven currents and exchanges would
also change.These wind-induced changes in turn would
redistribute the water masses associated with the different currents, thereby affecting the location and strength
of the fronts separating the water masses (Maslowski et
al., 2000, 2001; Zhang J. et al., 2000).
Retraction of the multi-year ice cover seaward of the
shelf break in the Arctic Ocean may lead to windinduced upwelling at the shelf break, which is currently
not happening.This process might substantially increase
the rate of exchange between the shelf and deep basin
waters, the rate of nutrient upwelling onto the shelves,
and the rate of carbon export to the deep basin
(Carmack and Chapman, 2003).
9.2.3.4.Thermohaline circulation
Thermohaline circulation is initiated when cooling and
freezing of sea water increase the density of surface
waters to such an extent that they sink and are
exchanged with waters at greater depth.This occurs in
the Labrador Sea, in the Nordic Seas, and on the arctic
shelves.Together, these regions generate the main source
water for the North Atlantic Deep Water; the main
ingredient of the global ocean “Great Conveyor Belt”
(Broecker et al., 1985). All these arctic areas are therefore important for the global THC. More importantly
from the perspective of this assessment is the potential
impact of a changing THC on flow and conditions within
the marine Arctic. Some areas are more sensitive than
others, because the oceanic heat transport induced by
the THC varies regionally.The most sensitive areas are
those that currently receive most of the heat input from
inflowing warm Atlantic water, i.e., the eastern parts of
the Nordic Seas and the Arctic Ocean (Seager et al.,
2002), namely the Arctic Mediterranean.
The THC in the Arctic Mediterranean is often depicted
as more or less identical to open-ocean convection in the
Greenland Sea.This is a gross over-simplification since,
in reality, there are several different processes contributing to the THC and they occur in different areas.The
THC can be subdivided into four steps (Fig. 9.4).
1. Upper layer inflow of warm, saline Atlantic water
into the Arctic Ocean and the Nordic Seas.
2. Cooling and brine rejection making the incoming
waters denser.
3.Vertical transfer of near-surface waters to deeper
layers.
4.The overflow of the dense waters in the deep
layers over the Greenland–Scotland Ridge and
their return to the Atlantic.
Although these steps are linked by feedback loops that
prevent strict causal relations, the primary processes
driving the THC seem to be steps 2 and 3, which are
termed thermohaline ventilation. By the action of the
thermohaline ventilation, density and pressure fields are
generated that drive horizontal exchanges between the
Arctic Mediterranean and the Atlantic (steps 1 and 4).
Box 9.2 illustrates the basic mechanisms of the thermohaline forcing.
Thermohaline ventilation
The waters of the Arctic Ocean and the Nordic Seas are
often classified into various layers and a large number of
different water masses (Carmack, 1990; Hopkins,
1991). For the present assessment, it is only necessary
to distinguish between “surface” (or upper layer) waters
and “dense” waters, which ultimately leave the Arctic
Mediterranean as overflow into the North Atlantic.
The term “dense waters” is used to refer to deep and
intermediate waters collectively and the term “thermohaline ventilation” is used as a collective term for the
processes that convert surface waters to dense waters.
Thermohaline ventilation is a two-step process that first
requires cooling and/or brine rejection to increase the
surface density and then a variety of processes that
involve vertical transfer.
Cooling and brine rejection
Production of dense waters in the arctic Nordic Seas is
due initially to atmospheric cooling, and then to brine
rejection during sea-ice formation (Aagaard et al.,
1985).The waters flowing into the Nordic Seas from the
Atlantic exhibit a range of temperatures depending on
location and season. On average, their temperature is
close to 8 ºC, but it decreases rapidly after entering the
Nordic Seas.The temperature decrease is especially large
in the southern Norwegian Sea.The simultaneous salinity decrease indicates that some of the temperature
decrease may be due to admixture of colder and less
saline adjacent water masses. Except for relatively small
contributions of freshwater from river inflow and the
Pacific-origin waters flowing along the east coast of
Greenland, the adjacent water masses are predominantly
of Atlantic origin.Thus, atmospheric cooling in the
Nordic Seas is the main cause of the decreasing temperature of the inflowing Atlantic water.
Attempts have been made to calculate the heat loss to the
atmosphere from climatological data, but the sensitivity
of the results to different parameterizations of the heat
flux makes these estimates fairly uncertain (Simonsen and
462
Haugan, 1996). Most of the heat loss from the ocean to
the atmosphere occurs in ice-free areas of the Nordic and
Barents Seas (Simonsen and Haugan, 1996).
Brine rejection, however, is intimately associated with
sea-ice formation (Carmack, 1986).When ice forms at
the ocean surface, only a small fraction of the salt follows the freezing water into the solid phase, the remainder flowing into the underlying water. Brine also continues to drain from the recently formed ice. Both processes increase the salinity, and therefore density, of the
ambient water. In a stationary state, the salinity increase
due to brine rejection in cold periods is compensated for
Arctic Climate Impact Assessment
by freshwater input from melting ice in warm periods,
but freezing and melting often occur in different
regions. For example, on the shallow shelves surrounding the arctic basins rejected brine results in shelf waters
sufficiently dense to drain off the shelves, thus becoming
separated from the overlying ice (Anderson L. et al.,
1999).Winds can also remove newly formed ice from an
area while leaving behind the high salinity water.
Vertical transfer of water
The second step in thermohaline ventilation is the vertical descent of the surface waters made denser by cool-
Box 9.2.Thermohaline forcing of Atlantic inflow to the Arctic
The processes by which thermohaline ventilation induces Atlantic inflow to the Arctic Mediterranean can be illustrated by a simple model where the Arctic Mediterranean is separated from the Atlantic by a ridge (the Greenland–
Scotland Ridge). South of the ridge, Atlantic water (red) with uniform temperature, salinity, and density (ρ) extends
to large depths. North of the ridge, the deep layers (blue) are less saline, but they are also much colder than the
Atlantic water and therefore denser (ρ+∆ρ). Above this deep, dense layer is the inflowing Atlantic water, which is
modified by cooling and brine rejection to become increasingly similar to the deep layer as it proceeds away from
the ridge.The causal links between the processes involved can be broken into three steps.
Thermohaline ventilation – Cooling and brine rejection make the inflowing Atlantic water progressively
denser until it has reached the density of the deeper layer. At that stage, the upper-layer water sinks
and is transferred to the deeper layer.This is equivalent to raising the interface between the two layers
in the ventilation areas, which are far from the ridge.
Atlantic
Arctic Mediterranean
Overflow – When ventilation has been active for
some time, the interface will be lifted in the ventilation areas and will slope down towards the ridge.
Other things being equal, this implies that the pressure in deep water will be higher in the ventilation
areas than at the same depth close to the ridge. A horizontal internal (so-called baroclinic) pressure gradient
will therefore develop which forces the deep water towards and across the ridge. In this simple model, the
overflow is assumed to pass through a channel, sufficiently narrow to allow neglect of geostrophic effects.
If the rate at which upper-layer water is converted to deeper-layer water is constant, the interface will rise
until it can drive an overflow with a volume flux that equals the ventilation rate.
Sea-level drop – When thermohaline ventilation has initiated a steady overflow, there will be a continuous
removal of water from the Arctic Mediterranean. Without a compensating inflow, the sea level would drop
rapidly north of the ridge.Thus an uncompensated overflow of the present-day magnitude would make the
average sea level in the Arctic Mediterranean sink by more than one meter a month. As soon as the water
starts sinking north of the ridge, there will, however, develop a sea-level drop across the ridge.This sea-level
drop implies that water in the upper layer north of the ridge will experience lower pressure than water at
the same level in the Atlantic. A sea surface (so-called barotropic) pressure gradient therefore develops that
pushes water northward across the ridge.The amount of Atlantic water transported in this way increases
with the magnitude of the sea-level drop. In the steady state, the sea-level drop is just sufficient to drive an
Atlantic inflow of the same volume flux as the overflow and the ventilation rate.
When upper-layer water is converted to deeper-layer water at a certain ventilation rate (in m3/s), an overflow
and an Atlantic inflow are therefore generated which have the same volume flux on long timescales. In the
present state, these fluxes must equal the estimated overflow flux of about 6 Sv. Simple, non-frictional, models
indicate that the required interface rise is several hundred meters, as is observed, while the required sea-level
drop is only of the order of 1 cm.
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Chapter 9 • Marine Systems
ing and brine rejection. Several processes contribute to
the transfer.These include the sinking of the boundary
current as it flows around the Arctic Mediterranean,
open-ocean convection, and shelf convection as well as
other ventilation processes (Fig. 9.6).
1.The boundary current enters the Arctic
Mediterranean as pure Atlantic water with relatively high temperature (> 8 ºC) and salinity
(> 35.2). It enters mainly through the Faroe–
Shetland Channel and within the Channel joins
with part of the Iceland–Faroe Atlantic inflow.
Part of the boundary current continues as an
upper-layer flow along the continental slope to
Fram Strait.There, one branch moves toward
Greenland while the other enters the Arctic
Ocean and flows sub-surface along its slope to
join the first branch as it exits again through Fram
Strait.The flow continues as a subsurface boundary current over the slope off East Greenland all
the way to Denmark Strait with the core descending en route (Rudels et al., 2002).While circulating through the Arctic Mediterranean, boundary
current waters experience a large temperature
decrease, much of it during the initial flow along
the Norwegian shelf.While the associated density
increase is partly offset by a salinity decrease,
there is still a considerable net density increase.
After passing Fram Strait, both branches are submerged without direct contact to the atmosphere
such that temperature and salinity changes occur
mainly through isopycnal mixing with surrounding waters. Isopycnal mixing occurs between
waters of the same density but different temperatures and salinities.
2. Open-ocean convection is very different from
boundary current deepening, being essentially a
vertical process. After a pre-conditioning phase in
which the waters are cooled and mixed, further
intensive cooling events may trigger localized
intense descending plumes or eddies with horizontal scales of the order of a few kilometers or less
(Budéus et al., 1998; Gascard et al., 2002;
Marshall and Schott, 1999;Watson et al., 1999).
They have strong vertical velocities (of the order
of a few hundredths of a meter per second), but do
not represent an appreciable net volume flux since
they induce upward motion in the surrounding
water (Marshall and Schott, 1999).They do, however, exchange various properties (such as CO2)
between the deep and near-surface layers as well as
to the atmosphere.They also help maintain a high
density at depth. Open-ocean convection is
assumed to occur to mid-depths in the Iceland Sea
(Swift and Aagaard, 1981). In the Greenland Sea,
convective vortices have been observed to reach
depths of more than 2000 m (Gascard et al., 2002)
and it is assumed that convection in earlier periods
penetrated all the way to the bottom layers to produce the very cold Greenland Sea Deep Water, as
observed in 1971 (Malmberg, 1983).
3. Shelf convection results from brine rejection and
convection, and can lead to the accumulation of
high salinity water on the shelf bottom (Jones et
al., 1995; Rudels et al., 1994, 1999). Freezing of
surface waters limits the temperature decrease, but
if winds or other factors remove the sea ice while
leaving the brine-enriched water behind, prolonged cooling can produce a high salinity water
mass close to the freezing point. Eventually, gravity
results in this saline, dense water mass flowing off
the shelf and sinking into the arctic abyss. As it
sinks, it entrains ambient waters and its characteristics change (Jones et al., 1995; Quadfasel et al.,
1988; Rudels, 1986; Rudels et al., 1994). Shelf
convection is the only deep-reaching thermohaline
ventilation process presumed to enter the Arctic
Ocean and hence is responsible for local deepwater formation.
There are at least two additional sinking mechanisms (not
included in Fig. 9.6) that may transfer dense water downward; isopycnal sinking and frontal sinking. Overflow
water is often defined as water denser than σθ = 27.8
(Dickson and Brown, 1994) and such water is widely
found in the Arctic Ocean and the Nordic Seas, close to
the surface. During winter, mixing and cooling result in
surface densities up to and above this value.This water can
therefore flow over the ridge, sinking below the top of
the ridge but without crossing isopycnals.This is termed
“isopycnal sinking”. A somewhat-related mechanism has
been termed “frontal sinking”, which indicates that nearsurface water from the dense side of a front can sink in
the frontal region and flow under the less dense water.
In the Nordic Seas, this has been observed in the form of
low-salinity plumes sinking at fronts between Arctic and
Atlantic waters (Blindheim and Ådlandsvik, 1995).
Horizontal water exchange
Fig. 9.6. Three of the thermohaline ventilation processes that
occur in the Arctic Mediterranean: boundary current deepening,
open-ocean convection, and shelf convection.
The Nordic Seas and the Arctic Ocean are connected to
the rest of the World Ocean through the Canadian
Archipelago, across the Greenland–Scotland Ridge, and
through the Bering Strait, and they exchange water and
various properties with the World Ocean through these
gaps. Four exchange branches can be distinguished
464
(Fig. 9.7).The near-surface outflow from the Arctic
Ocean through the Canadian Archipelago and Denmark
Strait, and the Bering Strait inflow to the Arctic Ocean
from the Pacific are important in connection with freshwater flow through the Arctic Ocean and the Nordic
Seas. For the THC, the overflow of cold and dense water
from the Nordic Seas into the Atlantic and the inflow of
Atlantic water to the Nordic Seas and the Arctic Ocean
are the most important factors.
Overflow
The term overflow is used here to describe near-bottom
flow of cold, dense (σθ > 27.8; Dickson and Brown, 1994)
water from the Arctic Mediterranean across the
Greenland–Scotland Ridge into the Atlantic. It occurs in
several regions. In terms of volume flux, the most important overflow site is the Denmark Strait, a deep channel
between Greenland and Iceland with a sill depth of
620 m.The transport in this branch is estimated at 3 Sv,
or about half the total overflow flux (Dickson and Brown,
1994). Mauritzen C. (1996) and Rudels et al. (2002)
argue that water from the East Greenland Current forms
the major part of this flow. Other sources contribute,
however (Strass et al., 1993); some workers suggest the
Iceland Sea as the primary source for the Denmark Strait
overflow (Jónsson, 1999; Swift and Aagaard, 1981).
The Faroe Bank Channel is the deepest passage across
the Greenland–Scotland Ridge and the overflow through
the channel is estimated to be the second largest in
terms of volume flux, approximately 2 Sv (Saunders,
2001). Owing to the difference in sill depth, the deepest
water flowing through the Faroe Bank Channel is usually
colder than water flowing through the Denmark Strait
and the Faroe Bank Channel is thus the main outlet for
the densest water produced in the Arctic Mediterranean.
Overflow has also been observed to cross the Iceland–
Faroe Ridge at several sites, as well as the Wyville–
Arctic Climate Impact Assessment
Thomson Ridge, but more intermittently.The total overflow across these two ridges has been estimated at slightly above 1 Sv, but this value is fairly uncertain compared
to the more reliable estimates for the Denmark Strait
and Faroe Bank Channel overflow branches (Hansen and
Østerhus, 2000).
As the overflow waters pass over the ridge, their temperature varies from about -0.5 ºC upward. A large
proportion of the water is significantly colder than the
3 ºC value often used as a limit for the overflow
(approximately equivalent to σθ > 27.8). After crossing
the ridge, most of the overflow continues in two density-driven bottom currents that are constrained by the
effects of the earth’s rotation (i.e., the Coriolis force)
to follow the topography, although gradually descending.The bottom current waters undergo intensive mixing and entrain ambient waters from the Atlantic
Ocean, which increases the water temperature.
When the Denmark Strait and Faroe Bank Channel
overflow waters join in the region southeast of Greenland, they have been warmed to 2 to 3 ºC, typical of
the North Atlantic Deep Water.Through entrainment,
enough Atlantic water is added to approximately double
their volume transport.
Atlantic inflow
Inflow of Atlantic water to the Nordic Seas occurs across
the Greenland–Scotland Ridge along its total extent
except for the westernmost part of the Denmark Strait.
Iceland and the Faroe Islands divide this flow into three
branches (Fig. 9.7); the Iceland branch (Jónsson and
Briem, 2003), the Faroe branch (Hansen et al., 2003),
and the Shetland branch (Turrell et al., 2003).There is a
gradual change in water mass characteristics with the
most southeastern inflow being the warmest (and most
saline).There is also a difference in the volume fluxes,
with that for the Iceland branch being much less than for
the other two, which are similar in magnitude.
* Vertical scale exaggerated
Fig. 9.7. The Arctic Mediterranean has four current branches that import water into the upper layers; three from the Atlantic (the
Iceland, Faroe, and Shetland branches), and one from the Pacific.The outflow occurs partly at depth through the overflows and partly
as surface (or upper-layer) outflow through the Canadian Archipelago and the East Greenland Current.The numbers indicate volume
flux in Sverdrups (106 m3/s) rounded to half-integer values and are based on observations, with the exception of the surface outflow,
which is adjusted to balance (based on Hansen and Østerhus, 2000).
Chapter 9 • Marine Systems
The Iceland branch flows northward on the eastern side
of the Denmark Strait. North of Iceland, it turns east
and flows toward the Norwegian Sea, but the heat and
salt content of this branch are mixed with ambient
water of polar or Arctic Ocean origin and freshwater
runoff from land. By the time it reaches the east coast
of Iceland it has lost most of its Atlantic character.
The Faroe and Shetland branches flow directly into the
Norwegian Sea. On their way they exchange water, but
still appear as two separate current branches off the
coast of northern Norway.Their relative contribution to
various regions is not clarified in detail but the Barents
Sea is clearly most affected by the inner (Shetland)
branch, while the western Norwegian Sea and the
Iceland Sea receive most of their Atlantic water from
the outer (Faroe) branch.
Budgets
The horizontal exchanges between the Arctic and oceans
to the south transfer water, heat, salt, and other properties such as nutrients and CO2. Since typical temperatures, salinities, and concentrations of various properties
are known, quantifying the exchanges is mainly a question of quantifying volume fluxes.
The water budget for the Arctic Ocean and the Nordic
Seas as a whole is dominated by the Atlantic inflow and
the overflow (Fig. 9.7).The Bering Strait inflow is fairly
fresh (S < 33) and most of it can be assumed to leave the
Arctic Mediterranean in the surface outflow (Rudels,
1989).The deeper overflow is formed from Atlantic
water, which means that 75% of the Atlantic inflow is
ventilated in the Arctic Ocean and the Nordic Seas.
Errors in the flux estimates may alter this ratio somewhat, but are not likely to change the conclusion that
most of the Atlantic inflow exits via the deep overflow
rather than in the surface outflow.
The question as to how the thermohaline ventilation is
split between the Nordic Seas and the Arctic Ocean and
its shelves can be addressed in different ways. One
method is to measure the fluxes of the various current
branches that flow between these two ocean areas;
another is to estimate the amount of water produced by
shelf convection. Both methods involve large uncertainties, but generally imply that most of the ventilation
occurs in the Nordic Seas with perhaps up to 40% of the
overflow water produced in the Arctic Ocean (Rudels et
al., 1999).That most of the heat loss also appears to
occur in the Nordic and Barents Seas (Simonsen and
Haugan, 1996) highlights the importance of these areas
for the THC.
9.2.3.5.What drives the Atlantic inflow to the
Arctic Mediterranean?
The Atlantic inflow is responsible for maintaining high
temperatures in parts of the marine Arctic and potential
changes in the Atlantic inflow depend on the forces
driving the flow.The few contributions to this discus-
465
sion to be found in the literature (e.g., Hopkins, 1991)
generally cite direct forcing by wind stress, estuarine
circulation, or thermohaline circulation as being the
main driving forces.
The freshwater input combined with entrainment generates southward outflows from the Arctic Mediterranean
in the upper layers, which for continuity reasons require
an inflow (estuarine circulation). Similarly, thermohaline
ventilation generates overflows, which also require
inflow (thermohaline circulation). If inflows do not
match outflows, sea-level changes are induced, which
generate pressure gradients that tend to restore the balance (Box 9.2).To the extent that the water budget
(Fig. 9.7) is reliable, it is therefore evident that the
processes that generate the estuarine circulation can
account for 2 Sv of the Atlantic inflow, whereas thermohaline ventilation is responsible for an additional 6 Sv.
This has led some workers to claim thermohaline ventilation as the main driving force for the Atlantic inflow
(Hansen and Østerhus, 2000).
Wind affects both the estuarine and the thermohaline
circulation systems in many different ways (e.g., through
entrainment, cooling, brine rejection, flow paths).
Direct forcing by wind stress has also been shown to
affect several current branches carrying Atlantic water
(Ingvaldsen et al., 2002; Isachsen et al., 2003; Morison,
1991; Orvik and Skagseth, 2003), but there is no observational evidence for a strong direct effect of wind stress
on the total Atlantic inflow to the Nordic Seas. On the
contrary,Turrell et al. (2003) and Hansen et al. (2003)
found that seasonal variation in the volume flux for the
two main inflow branches (the Faroe Branch and
Shetland Branch on Fig. 9.7) was negligible, in contrast
to the strong seasonal variation in the wind stress.
Thermohaline ventilation is also seasonal, but its effect is
buffered by the large storage of dense water in the Arctic
Mediterranean, which explains why the total overflow
and hence also thermohaline forcing of the Atlantic
inflow has only a small seasonal variation (Dickson and
Brown, 1994; Hansen et al., 2001; Jónsson, 1999).
In a recent modeling study, Nilsen et al. (2003) found
high correlations between the North Atlantic Oscillation
(NAO) index and the volume flux of Atlantic inflow
branches, but that variations in the total inflow were
small in relation to the average value.
These studies indicate that the Atlantic inflow to the
Arctic Mediterranean is mainly driven by thermohaline
(Box 9.2) and estuarine forcing, but that fluctuations at
annual and shorter timescales are strongly affected by
wind stress.Variations in wind stress also have a large
influence on how the Atlantic water is distributed within
the Arctic Mediterranean.
9.2.4.Variability in hydrographic properties
and currents
Ocean climate changes on geological time scales in the
Arctic are briefly discussed in Box 9.3.
466
Arctic Climate Impact Assessment
Box 9.3. Arctic climate – a long-term perspective
At the start of large-scale glaciation around 3 million years ago, the Arctic was relatively warm with forests growing along the shores of the Arctic Ocean (Funder et al., 1985; Knies et al. 2002). About 2.75 million years ago a
marked phase of global cooling set in, leading to a widespread expansion of ice sheets across northern Eurasia
and North America (Jansen et al., 2000). Before this marked cooling, climates were only cold enough to sustain
glaciers on Greenland, indicating that the ocean was warmer and the sea-ice cover less than at present (Fronval
and Jansen, 1996; Larsen et al., 1994).This cooling is believed due to reduced northward heat transport to the
Arctic. After this cooling event, multi-year sea-ice cover and cold conditions probably existed throughout the
Arctic, however, less freshwater influx may have reduced surface ocean stratification and open areas and
polynyas may have prevailed. Lower sea level also left major portions of the shelf areas exposed.
The next major change occurred approximately 1 million years ago. Glacial episodes became longer, with a
distinct 100000 year periodicity and glaciation more severe.Yet between the glacial periods, warmer but short
interglacial periods persisted, due to stronger inflow of warm Atlantic waters to the Nordic Seas (Berger and
Jansen, 1994; Jansen et al., 2000).The long-term effects of sea-level change through ice sheet erosion affected
the ocean exchange with the Arctic. For example, water mass exchange could take place between the Atlantic
and the Arctic through the Barents Sea when it changed from a land area to a sea.
After the last glacial period, which ended about 11000 years ago, the marginal ice zone was farther north than at
present since the summer insolation was higher in the Northern Hemisphere than now. In the early phase of the
postglacial period (Holocene), 8000 to 6000 years ago, mollusks with affinities for ice-free waters were common
in Spitsbergen and along the east coast of Greenland. Summer temperatures over Greenland and the Canadian
Arctic were at their highest, 3 ºC above present values (Dahl-Jensen et al., 1998).The sea-ice cover expanded
southward again in the Barents and Greenland Seas 6000 to 4000 years ago, concomitant with the expansion of
glaciers in Europe.This expansion was most likely to be a response to the diminishing summer insolation.
Superimposed on these long-term trends, there is evidence of high amplitude millennial- to century-scale
climate variability.The millennial-scale events are recorded globally and shifts in temperature and precipitation
occurred with startling speed, with changes in annual mean temperature of 5 to 10 ºC over one to two
decades (Alley et al., 2003; Dansgaard et al., 1993; Haflidason et al., 1995; Koc et al., 1993).These abrupt climate
changes occurred repeatedly during glacial periods with a temporal spacing of 2000 to 10 000 years.The latest
was the Younger Dryas cooling about 12000 years ago, which was followed by two cold phases of lower amplitude, the last 8200 years ago. Cooling periods in the regions surrounding the Arctic were associated with widespread drought over Asia and Africa, as well as changes in the Pacific circulation. Mid-latitude regions were most
affected, while the amplitudes of these climate shifts were lower in the high Arctic.
The rapid climate shifts were accompanied by changes in the deep-water formation in the Arctic and the
northward protrusion of warm water towards the Arctic (Dokken and Jansen, 1999), yet it would be wrong to
say that they shut off entirely during the rapid change events. Instead they were characterized by shifts in the
strength and in the depth and location of ocean overturning.The high amplitude climate shifts are hypothesized
to be caused by, or at least amplified by, freshwater release from calving and melting of ice sheets in the Arctic.
Bond et al. (2001) identified events when icebergs originating from Greenland were more strongly advected
into the North Atlantic and proposed that changes in insolation may have been the cause. Some of these
events coincide with known climate periods, such as the Medieval Warm Period and an increase in icebergs
during the following cooling period, known as the Little Ice Age.Temperature data from the Greenland Ice
Sheet show a general warmer phase (800 to 1200 AD) and a general cold phase (1300 to 1900 AD) during
these periods, respectively (Dahl-Jensen et al., 1998). Proxy data with higher temporal resolution from the
Nordic Seas suggest similar temperature trends there, but it is clear that neither the Medieval Warm Period
nor the Little Ice Age was monotonously warm or cold (Koc and Jansen, 2002).
9.2.4.1. Seasonal variability
Upper-layer waters in the Arctic Ocean that are open or
seasonally ice-free experience seasonal fluctuations in
temperature due to the annual cycle of atmospheric
heating and cooling.The extent of the summer temperature rise depends on the amount of heat used to melt sea
ice (and hence not used for heating the water) and the
depth of the surface mixed layer. For shallow mixed layers caused by ice melt, surface temperatures can rise
substantially during the summer. Seasonal temperature
ranges in the near-surface waters generally tend to
increase southward.The melting and formation of sea
ice leads to seasonal changes in salinity. Salt is rejected
Chapter 9 • Marine Systems
from newly formed ice, which increases the salinity of
the underlying water.This water sinks as it is denser than
its surroundings. Salinity changes in some coastal regions
are governed more by the annual cycle of freshwater
runoff than by ice, e.g., along the Norwegian coast, in
the Bering Sea, and Hudson Bay. Except for areas in
which brine rejection from sea-ice formation occurs
annually, seasonal changes in temperature and salinity
below the mixed layer are usually small.
9.2.4.2. Interannual to decadal variability
Variability observed at interannual to decadal time scales
is important as a guide for predicting the possible effect
of future climate change scenarios on the physical
oceanography of the Arctic.
Arctic Ocean
Long-term oceanographic time series from the Arctic
Ocean deep basins are scarce. Data collections have been
infrequent, although there was a major increase in shipboard observations during the 1990s (Dickson et al.,
2000).These efforts identified an increased presence of
Atlantic-derived upper ocean water relative to Pacificderived water (Carmack et al., 1995; Morison et al.,
1998).Temperatures and salinities rose, especially in the
Eurasian Basin.The rise in temperature for the Atlantic
waters of the arctic basins ranged from 0.5 to 2 ºC.
The major cause of the warming is attributed to increased
transport of Atlantic waters in the early 1990s and to the
higher temperatures of the inflowing Atlantic water
(Dickson et al., 2000; Grotefendt et al., 1998). At the
same time, the front between the Atlantic- and Pacificcharacter waters moved 600 km closer to the Pacific from
the Lomonosov Ridge to the Alpha-Mendeleyev Ridge
(Carmack et al., 1995; McLaughlin et al., 1996; Morison
et al., 1998).This represented an approximate 20%
increase in the extent of the Atlantic-derived surface
waters in the Arctic Ocean. In addition, the Atlantic
Halocline Layer, which insulates the Atlantic waters from
the near-surface polar waters, became thinner (Morison et
al., 2000; Steele and Boyd, 1998). As the Atlantic-derived
waters increased their dominance in the Arctic Ocean,
there was an observed shrinking of the Beaufort Gyre and
a weakening and eastward deflection of the Transpolar
Drift (Kwok, 2000; Morison et al., 2000).These were
shown to be a direct response to changes in the wind forcing over the Arctic associated with variability in the AO
(Maslowski et al., 2000, 2001; Zhang et al., 2000).
467
2003).The Shetland Branch of the Atlantic inflow
(Fig. 9.7; also known as the Norwegian Atlantic Current)
is a major contributor to the inflow to the Barents Sea.
It is strongly correlated with the North Atlantic wind
stress curl with the current lagging the wind stress curl
by 15 months (Orvik and Skagseth, 2003).
Variability in both the volume and temperature of the
incoming Atlantic water to the Barents Sea strongly
affects sea temperatures. A series of hydrographic stations along a line north of the Kola Peninsula in northwest Russia has been monitored for over 100 years.
Annual mean temperatures for this section show relatively warm conditions since the 1990s. It was also
warm between 1930 and 1960, but generally cold prior
to the 1930s and through much of the period between
1960 and 1990 (Fig. 9.8). Since the mid-1970s there has
been a trend of increasing temperature, although the
warmest decade during the last century was the 1930s
(Ingvaldsen et al., 2003). Also evident are the strong
near-decadal oscillations since the 1960s and prior to the
1950s. Annual ocean temperatures in the Barents Sea are
correlated with the NAO; higher temperatures are generally associated with the positive phase of the NAO
(Ingvaldsen et al., 2003; Ottersen and Stenseth, 2001).
The correlation is higher after the early 1970s, which is
attributed to an eastward shift in the Icelandic Low
(Dickson et al., 2000; Ottersen et al., 2003).
Willem Barentsz was the first to provide information on
sea ice conditions in the northern Barents Sea when he
discovered Spitsbergen in 1596 (de Veer, 1609). Observations became more frequent when whaling and sealing
started early in the 17th century (Vinje, 2001) and since
1740 there have been almost annual observations of seaice conditions.Typically, interannual variation in the
position of the monthly mean ice edges is about 3 to 4
degrees of latitude.Variations on decadal and centennial
scales are also observed. In all probability, the extreme
northern position of the ice edge in summer coincides
with an increased influx of Atlantic water entering the
Arctic Ocean north of Svalbard. Complete disintegration
of the sea ice in the Barents Sea proper (south of 80º N)
was reported between 1660 and 1750. A similar north-
Barents Sea
Inflow to the Arctic via the Barents Sea undergoes large
variability on interannual to decadal time scales (Ingvaldsen et al., 1999, 2003; Loeng et al., 1997).The inflows
change in response to varying atmospheric pressure patterns, both local (Ådlandsvik and Loeng, 1991) and
large-scale, as represented by the NAO, with a larger
transport associated with a higher index (Dickson et al.,
2000; Dippner and Ottersen, 2001; Ingvaldsen et al.,
Fig. 9.8. Annual and five-year running means in sea temperature
(at 50–200 m) from a series of hydrographic stations along a
line north of the Kola Peninsula in northwest Russia (based on
data supplied by the Knipovich Polar Research Institute of
Marine Fisheries and Oceanography, Russia).
468
ern retreat of the sea ice was seen again in recent
decades (after 1937). In contrast, sea ice completely
covered the Barents Sea, as well as the Greenland and
Iceland Seas, and the northern part of the Norwegian
Sea, during 1881.This coincided with the lowest mean
winter air temperature on record.
Northern North Atlantic
In the 1910s and 1920s, a major and rapid atmospheric
warming took place over the North Atlantic and Arctic,
with the greatest changes occurring north of 60º N
(Fig. 9.9; Johannessen O. et al., 2004; Rogers, 1985).
Warm conditions generally continued through to the
1950s and 1960s. Sea ice thinned and the maximum
extent of the seasonal ice edge retracted northward
(Ahlmann, 1949). Increases in surface temperature
were reported over the northern North Atlantic (Smed,
1949) and throughout the water column over the shelf
off West Greenland (Jensen, 1939). Higher temperatures between the 1930s and 1960s were also observed
in the Barents Sea along the Kola Section (Fig. 9.8).
The cause of this warming is uncertain although a
recent hypothesis suggests that it was due to an increase
in the transport of the North Atlantic Current into the
Arctic (Johannessen O. et al., 2004).
At the end of this warm period, water temperatures
declined rapidly. For example, at a monitoring site off
northern Iceland, temperatures (at 50 m) suddenly
declined in 1964 by 1 to 2 ºC (Malmberg and Blindheim, 1994).This was caused by the replacement of the
warm Atlantic inflow by the cold waters of the East
Greenland Current. Also, the front to the east of
Iceland between the warm Atlantic waters and the cold
arctic water moved southward.These observations signified that the cooling had coincided with large-scale
changes in circulation.
In the Labrador Sea, temperatures reached maximum
values in the 1960s and did not decline substantially
until the early 1970s. Shelf temperatures on the
western Grand Banks at a site 10 km off St. John’s,
Newfoundland have been monitored since the late
1940s. Low-frequency subsurface temperature trends
at this site are representative of the Grand Banks to
southern Labrador (Petrie et al., 1992).Temperatures
Fig. 9.9. Observed time–latitude variability in surface air temperature anomalies north of 30° N (Johannessen O. et al., 2004).
Arctic Climate Impact Assessment
continued a general decline superimposed upon by
quasi-decadal oscillations until the mid-1990s.
Temperature minima were observed near the mid1970s, mid-1980s, and mid-1990s that correspond to
peaks in the NAO index (Colbourne and Anderson,
2003). After the mid-1990s, temperatures rose.
Winter temperatures off Newfoundland are negatively
correlated with those in the Barents Sea (Fig. 9.10) and
linked through their opposite responses to the NAO.
The Barents Sea and Newfoundland temperatures however have only been closely linked to the NAO since the
1960s (Ottersen et al., 2003).
During the 1970s, an upper-layer surface salinity minimum was observed in different regions of the North
Atlantic (e.g., Dickson and Blindheim, 1984; Dooley et
al., 1984; Malmberg, 1984). The generally accepted
explanation for this observation was given by Dickson
et al. (1988). During the 1960s, an intense and persistent high-pressure anomaly became established over
Greenland. As the northerly winds increased through to
a peak in the late 1960s, there was a pulse of sea ice
and freshwater out of the Arctic via Fram Strait with
the result that the waters in the East Greenland
Current and the East Icelandic Current became colder
and fresher. In addition, convective overturning north
of Iceland and in the Labrador Sea was minimal, preserving the fresh characteristics of the upper layer.
Beginning in the Greenland Sea in 1968, significant
quantities of freshwater were advected via Denmark
Strait into the Subpolar Gyre. The low salinity waters
(called the Great Salinity Anomaly) were tracked
around the Labrador Sea, across the Atlantic, and
around the Nordic Sea before returning to the Greenland Sea by 1981–1982. Similar transport of low salinity features around the Subpolar Gyre was suggested to
have occurred in the early 1900s (Dickson et al., 1988)
and in the mid-1980s (Belkin et al., 1998). Belkin et al.
(1998) proposed that the source of the mid-1980s
salinity anomaly originated in Baffin Bay.
Fig. 9.10. Five-year average winter temperature anomalies
(relative to the mean for 1971 to 2000) for the Barents Sea
(the Kola Section off northwestern Russia, 0–200 m mean) and
the Labrador Sea (Station 27 on the western Grand Bank off
Newfoundland, near bottom at 175 m).
469
Chapter 9 • Marine Systems
The deep water of the Norwegian Sea has for a long
time been considered to have a relatively stable temperature. However, since the mid-1980s there has been a
steady increase of more than 0.05 ºC for the waters
between 1200 m and 2000 m, and even the deepest
water has shown a small temperature increase (Østerhus
and Gammelsrød, 1999). In the surface layer there has
been a steady decrease in salinity. In the deep, southflowing waters of the Greenland Sea there has been a
40-year trend toward decreasing salinity and this trend
toward decreasing salinity has spread throughout much
of the northern North Atlantic (Dickson et al., 2002).
Dickson et al. (2003) suggest this may correspond to a
general freshening of the whole Atlantic.
Interannual variability in the depth of convection in the
Greenland Sea (Budéus et al., 1998; Meincke et al.,
1992) and Labrador Sea (Lazier, 1980, 1995) depends
upon wind, air temperature, upper layer salinity and
temperature, and the pre-winter density structure.
Dickson et al. (1996) and Dickson (1997) found the
convective activity in the two areas to be of opposite
phase, linked to shifting atmospheric circulation as
reflected in the NAO index. In the late 1960s when the
NAO index was low, there was intense convection in
the Greenland Sea and little convection in the Labrador
Sea owing to reduced winds and freshwater accumulation at the surface. In contrast, in the late 1990s when
the NAO index was high, the reverse occurred with
deep convection in the Labrador Sea and minimal convection in the Greenland Sea. Deep-reaching convection
in the Greenland Sea contributes to overflow waters but
Hansen et al. (2001) did not observe any NAO-like
variations in their 50-year time series of Faroe Bank
Channel overflow. However, deep convection is only
one of several ventilation processes affecting the overflow (see section 9.2.3.4, vertical transfer of water).
Hansen et al. (2001) did however find a general
decreasing trend in the overflow, as was observed for
the overflows across the southern part of the Iceland–
Faroe Ridge and the Wyville–Thompson Ridge (Hansen
et al., 2003). In the 1990s, higher temperatures offset
the corresponding reduced Atlantic inflow to the
Nordic Seas such that there was no net change in the
heat flux but Turrell et al. (2003) suggested that a
reduced salt flux may account for some of the freshening observed in large parts of the Nordic Seas.
Hudson Bay and Hudson Strait
The timing of the sea-ice advance and retreat in Hudson
Bay and Hudson Strait varies between years by up to a
month from their long-term means.This sea-ice variability has been linked to dominant large-scale atmospheric modes, in particular the NAO and the El Niño–
Southern Oscillation (ENSO; Mysak et al., 1996;Wang
J. et al., 1994). In years of high positive NAO and
ENSO indices, heavy ice conditions occur in Hudson
Bay as well as in Baffin Bay and the Labrador Sea.
This increase in sea ice is attributed to cold air masses
and stronger northwesterly winds over the region.
Between 1981 and the late 1990s air temperatures over
Hudson Bay and Hudson Strait increased.This led to an
earlier breakup of sea ice (Stirling et al., 1999) and an
earlier spring runoff of river discharge into Hudson Bay
(Gagnon and Gough, 2001).
Bering Sea
At decadal and longer timescales, the Bering Sea
responds to two dominant climate patterns: the Pacific
Decadal Oscillation (PDO) and the AO (see Chapter 2
for a detailed discussion).The PDO is strongly coupled
to the sea level pressure pattern with stronger winds in
the Aleutian low-pressure system during its positive
phase (Mantua et al., 1997). It has a major impact on the
southern Bering Sea.Thus the 40- to 50-year oscillation
in the PDO led to higher sea surface temperatures in the
North Pacific from 1925 to 1947 and 1977 to 1998, and
cold conditions in 1899 to 1924 and 1948 to 1976.
The AO had major shifts around 1977 and 1989 and
there has been a long-term strengthening from the 1960s
through the 1990s. Heavy sea-ice years in the Bering Sea
generally coincide with negative values of the PDO, such
as occurred in the early 1970s.The late 1970s and 1980
were warm years with reduced sea-ice cover. Heavy sea
ice was again observed in the 1990s, but was not as
extensive as in the early 1970s. In the 1990s, there was a
shift toward warmer spring temperatures that resulted in
sea ice in the Bering Sea melting one week earlier than in
the 1980s, and the snow melting up to two weeks earlier
(Stabeno and Overland, 2001).
9.2.5. Anticipated changes in physical
conditions
During the 1990s it became apparent that global warming would occur more rapidly and with greater impact in
the high latitudes (Morison et al., 2000; SEARCH,
2001). Observations showed substantial variability in the
arctic water column, atmosphere, ice cover, and export
to the North Atlantic (e.g., Belkin et al., 1998; Carmack
et al., 1995; Morison et al., 1998; Rothrock et al.,
1999;Walsh J.E. et al., 1996).This variability spans temporal scales that include interannual fluctuations, interdecadal patterns, and long-term trends.The first challenge is to define the temporal scales and magnitudes of
arctic variability, for example to distinguish recurrent
modes from trends and to separate natural from anthropogenic climate forcing.The second challenge is to
understand and predict the impact of changes in the
physical environment on the biota.
This section links the various sub-components of the
physical system (e.g., land/ocean exchanges, shelf/basin
interactions, inter-basin fronts, and the transport of ice
and water properties) to climate-scale forcing at seasonal and decadal timescales. The assessment is based
on the outcome of Chapter 4, plus the most recent
results from the Intergovernmental Panel on Climate
Change (IPCC, 2001) and information from the peerreviewed literature.
470
Arctic Climate Impact Assessment
9.2.5.1. Atmospheric circulation
General features of projected changes in the arctic atmosphere relevant to marine processes are summarized in
Table 9.1. Air temperatures are very likely to increase by
4 to 5 ºC over most of the Arctic by 2080. As air temperatures are very likely to increase more in winter than
in summer there is very likely to be an associated
decrease in the amplitude of the seasonal cycle.The
IPCC (2001) reported that some studies have shown
increasingly positive trends in the indices of the NAO/
AO in simulations with increased concentrations of
GHGs.The magnitude and character of the changes vary
for the different models. In general, the intensity of
winter storms and the zonal temperature gradient are
likely to decrease. However, in some regions (e.g., the
Labrador, Nordic, Bering, and Beaufort Seas) an increase
in storm activity is likely. Storm tracks are likely to shift
northward under stronger AO and NAO conditions.
Christensen and Christensen (2003) projected that the
atmosphere will contain more water under a warmer
climate, making more water available for precipitation.
Model scenarios project an increase in precipitation of
10% by 2080 and an increase in cloud cover of 8%.
Paeth et al. (1999) assessed changes in the mean and
variance of the NAO at decadal scales.They predicted
that the mean value will increase, while the variance will
decrease, suggesting that the NAO will stabilize in the
positive phase.The consequences of such a scenario are
likely to be more westerly winds and milder weather
over Europe during winter, while the Labrador Sea
would be likely to experience more northwesterly winds
and colder conditions. Shindell et al. (1999) and Fyfe et
al. (1999) also predicted a positive trend in the NAO
index. Ulbrich and Chrisroph (1999) concluded that
there will be a northeastward shift of the NAO’s northern variability center from a position close to the east
coast of Greenland to the Norwegian Sea while Shindell
(2003) stated that if the dynamic strengthening of the
arctic vortex continues the Northern Hemisphere is
likely to continue to warm up rapidly during winter.
Despite present uncertainties, it can be concluded that
if the NAO increased, it would be likely to lead to
increased westerly winds over the North Atlantic and
more frequent storm patterns. Any trend toward positive AO conditions would be very likely to result in a
weakening of the Beaufort High and increased cyclonicity over Canada Basin, as noted by Proshutinsky and
Johnson (1997).Winds over the Bering/Chukchi Seas
would probably also weaken. Changes in atmospheric
forcing will impact upon most of the features discussed
in the following sections; sea-ice conditions, ocean cir-
Table 9.1. Changes in surface and boundary forcing based on model projections and/or extrapolation of observed trends. Unless
otherwise specified these projected changes are very likely to happen.
Air temperature
annual meana
2020
2050
2080
1–1.5 ºC increase
2–3 ºC increase
4–5 ºC increase
winter
2.5 ºC increase
4 ºC increase
6 ºC increase in the central Arctic
summer
0.5 ºC increase
0.5–1.0 ºC increase
1 ºC increase
seasonality
interannual variability
Reduced seasonality (warmer winters compared to summer)
No change
No change
No change
Wind
means
storm frequency
While changes in winds are expected, there is at present no consistent agreement from general
circulation models as to the magnitude of the changes in either speed or direction
Possible increase in storm intensity regionally (Labrador, Beaufort, Nordic Seas); in general, winter
storms will decrease slightly in intensity because the pole to equator temperature gradient decreases
storm tracks
regional issues
Precipitation/runoff
meanb
seasonality
snow on ice
Probable northward shift in storm tracks
In areas of sea-ice retreat, there will be an increase in wind-driven effects (currents, waves) because
of longer fetch and higher air–sea exchange
2% increase
6% increase
10% increase
Decreased seasonality in runoff related to earlier snow melt. Seasonality in precipitation unclear
1–2% increase
3–5% increase
6–8% increase
5 cm rise
15 cm rise
25 cm rise
3% increase
5% increase
8% increase
spring, autumn
4–5% increase
5–7% increase
8–12% increase
winter, summer
1–2% increase
3–5% increase
4–8% increase
Not available
Not available
Not available
Sea level
Cloud cover
general
Cloud albedo
aThese
numbers are averages and should be higher in the central Arctic and lower over southern regions; bbased on the estimates of precipitation minus evaporation in
Chapter 6.
471
Chapter 9 • Marine Systems
for the period 1978 to 2002 (Fig. 9.11, see also Serreze et
al., 2003). Substantial changes in sea-ice conditions are
evident in Canada Basin north of the Chukchi Sea, and in
the sea-ice extent in Fram Strait and north of Svalbard.
(a)
Land
Coast
No Data
Weather
Ocean
16-21 %
22-28
29-35
36-42
43-49
50-56
57-63
64-70
71-77
78-84
85-91
92-98
99+
(b)
Projected changes in sea-ice conditions for the 21st century are summarized in Chapter 6 based on output from
the five ACIA-designated global climate models.Tables
9.2 and 9.3 show the maximum and minimum values for
sea-ice extent projected by these five models, respectively.The values shown are the adjusted model values,
meaning that the data have been “normalized” by forcing
a fit to the 1981–2000 baseline observations.The projections vary widely, especially for the summer.The
CSM_1.4 (National Center for Atmospheric Research)
model consistently projects the greatest sea-ice extent
and the least amount of change, while the CGCM2
(Canadian Centre for Climate Modelling and Analysis)
model consistently projects the least sea ice and the
greatest amount of change. However, all five ACIAdesignated models agree in projecting that sea-ice coverage will decrease both in summer and winter.
Areal ice extent
Under scenarios of climate warming, sea-ice cover is
expected to “retreat” further into the Arctic Basin, to
breakup earlier and freeze-up later, and to become thinner
and more mobile. For example, substantial differences in
sea-ice conditions were observed in summer 2002 compared to the climatology of sea-ice conditions in summer
Increases in the AO index are likely to result in the
Transpolar Drift taking a strongly cyclonic diversion
across the Lomonosov Ridge and into Canada Basin and
the Beaufort Gyre shrinking back into the Beaufort Sea
(section 9.2.2.5; Fig. 9.3).This is very likely to alter the
advective pathways and basin residence times of sea ice
formed in winter on the Eurasian shelves. Furthermore,
the ice extent in early autumn is also likely to be
reduced, due to expected changes in wind forcing and
winter air temperature in the eastern Russian Arctic
(Rigor et al., 2002). By 2050, the CGCM2 model,
which results in the greatest rate of sea-ice melt, projects that the entire marine Arctic may be sea-ice free in
summer (Table 9.3).The other four models agree in
projecting the presence of summer sea ice, at least until
the end of the 21st century, but disagree in their projections of the extent of areal coverage.While the changes
in winter sea-ice coverage are generally projected to be
much smaller than in summer (Table 9.2), it is likely
that the Barents Sea and most of the Bering Sea may be
totally ice free by 2050 (see Chapter 6).
Table 9.2. Sea-ice extent in March (106 km2) as projected by
the five ACIA-designated models.
Table 9.3. Sea-ice extent in September (106 km2) as projected
by the five ACIA-designated models.
Fig. 9.11. Sea-ice concentration based on NOAA AVHRR
data, comparing (a) climatology of sea-ice conditions in
summer (September; 1978–2002) and (b) conditions in
September 2002.
culation and water properties, ocean fronts, and
thermohaline circulation.
9.2.5.2. Sea-ice conditions
Model
1981–2000 2011–2030 2041–2060 2071–2090
Model
1981–2000 2011–2030 2041–2060 2071–2090
13.26
CGCM2
14.16
14.01
CSM_1.4
7.22
7.00
6.72
6.59
14.97
14.38
ECHAM4/
OPYC3
7.02
6.03
4.06
2.68
15.60
14.86
14.52
GFDLR30_c
7.28
5.91
4.33
2.91
15.53
14.87
13.74
HadCM3
7.41
6.22
5.12
3.22
CGCM2
16.14
15.14
13.94
CSM_1.4
16.32
15.00
ECHAM4/
OPYC3
16.19
15.62
GFDLR30_c
16.17
HadCM3
16.32
CGCM2: Canadian Centre for Climate Modelling and Analysis; CSM_1.4: National
Center for Atmospheric Research; ECHAM4/OPYC3: Max-Planck Institute for
Meteorology; GFDL-R30_c: Geophysical Fluid Dynamics Laboratory; HadCM3:
Hadley Centre for Climate Prediction and Research.
7.28
3.33
0.55
0.05
CGCM2: Canadian Centre for Climate Modelling and Analysis; CSM_1.4: National
Center for Atmospheric Research; ECHAM4/OPYC3: Max-Planck Institute for
Meteorology; GFDL-R30_c: Geophysical Fluid Dynamics Laboratory; HadCM3:
Hadley Centre for Climate Prediction and Research.
472
Arctic Climate Impact Assessment
(a)
(b)
Fig. 9.12. Changes in the areal coverage of the seasonal sea-ice
zone over the 21st century as projected by the five ACIA-designated
models.The illustration is based on the values in Tables 9.2 and 9.3.
Seasonal sea-ice zone
Every year around 7 to 9 million km2 of sea ice freezes
and melts in the Arctic (Parkinson et al., 1999). Four of
the five ACIA-designated models project that the seasonal sea-ice zone is likely to increase in the future
because sea-ice coverage will decrease more during
summer than winter (Fig. 9.12).This suggests that seaice thickness is also likely to decrease because a single
winter of sea-ice growth is an insufficient period to
reach equilibrium thickness.There is very likely to be a
shorter period of sea-ice cover due to earlier breakup
and later freeze-up. Longer ice-free periods will significantly increase sub-surface light availability. (At present,
sea ice lingers in the Arctic Ocean through May and
June, months of high levels of insolation.) A delayed
freeze-up will also expose more open water to forcing
by autumn storms. Retreat of the seasonal sea-ice zone
northward into the central arctic basins will affect
nutrient and light availability on the continental shelves
during summer and autumn by increasing the areas of
open water, wind mixing, and upwelling.
Fast ice is not explicitly included in climate model
scenarios. Although reductions in the extent, thickness,
and stability of fast ice are likely to occur, the implications of climate change for fast ice is recognized as a gap
in knowledge.
9.2.5.3. Ocean circulation and water
properties
Changes in the surface and boundary forcing (Table 9.1)
will probably result in changes in ocean circulation,
water mass properties, and ocean processes (section
9.2.3). Sea surface temperatures are likely to increase
by approximately the same amount as air temperatures
in areas that are sea-ice free, but are very likely to
remain the same (i.e., near freezing) in ice-covered
waters. By 2020 the upper water layer of all arctic
shelves is very likely to exhibit stronger seasonality in
(c)
Fig. 9.13. The annual pattern of (a) incoming solar radiation,
(b) wind speed, and (c) incremental changes in incoming solar
radiation (∆L) and wind energy (∆W) to the water column
from earlier breakup and delayed freeze-up. Earlier breakup
allows a disproportionate amount of solar energy into the
water column, while delayed freeze-up exposes the water
column to autumn storms.
terms of sea-ice cover, and by 2080, 50 to 100% of the
Arctic Ocean is likely to undergo such variability.
Whether or not there is a concurrent increase in
mixed-layer depth in summer depends on the relative
coupling of wind and ocean in the presence or absence
of sea ice, which in turn depends on the magnitude of
internal ice stress (Wadhams, 2000). McPhee and
Morison (2001) argue that, away from coastal areas, in
summer most of the wind momentum transferred to
the sea ice is subsequently passed on to the water and
that sea ice may even serve to enhance the coupling of
wind to water. Mixed-layer deepening is also very likely
to be influenced by increased river discharge. Sub-sea
light levels will increase in areas where sea ice is absent,
but are very likely to decrease where sea ice remains
due to increased snow.
General circulation models project a strengthening of
the AO leading to increased atmospheric cyclonicity over
the Arctic Ocean during the 21st century (Fyfe et al.,
473
Chapter 9 • Marine Systems
1999).This, in turn, is very likely to affect the sea-ice
drift and surface currents in the Arctic Basin.With
increased cyclonicity the Transpolar Drift is very likely
to shift eastward to favor drift directly toward Fram
Strait (Rigor et al., 2002).The Beaufort Gyre is very
likely to weaken and retreat into Canada Basin, following
the “cyclonic mode” discussed by Proshutinsky and
Johnson (1997) and Polyakov and Johnson (2000). In
turn, changes in the Beaufort Gyre are very likely to
affect the storage and release of freshwater in Canada
Basin (Proshutinsky et al., 2002). Under this scenario
the position of the Atlantic/Pacific Front will tend to
align with the Alpha-Mendeleyev Ridge rather than the
Lomonosov Ridge (McLaughlin et al., 1996; Morison et
al., 1998) and perhaps retreat further into Canada Basin.
Modeling studies by Zhang and Hunke (2001) and
Maslowski et al. (2000) are in general agreement.
Relatively small changes in the timing of sea-ice
breakup and freeze-up (of the order of a few weeks) are
very likely to have a disproportionate effect on the
physical forcing of arctic waters (Fig. 9.13). For example, under present-day conditions, much of the incoming solar radiation during the long summer days is
reflected back by the ice and snow and so does not
reach the water column to warm it. A later freeze-up
will mean that the ocean surface is exposed to wind
forcing by autumn storms for a longer period of time.
Combined with prolonged exposure of the shelf break
to wind forcing, this is very likely to enhance vertical
mixing and the shelf–basin exchange of heat, salt,
nutrients, and carbon.
Thresholds for change in the Arctic Ocean
Three potential thresholds for substantial changes in
ocean circulation and water mass properties are
described in this section (also see Box 9.4).
1. If and when the seasonal sea-ice zone retreats
annually beyond the shelf break.
2. If and when the Arctic Ocean becomes sea-ice
free in summer.
3. If and when parts of the deep arctic basins
(e.g., the western Nansen Basin and western
Canada Basin) remain sea-ice free in winter.
The seasonal retreat of sea ice from shelf domains to
the deep Arctic Basin, anticipated as soon as 2020
(Tables 9.2 and 9.3, and Chapter 6), will expose the
shelf-break region to upwelling- and downwellingfavorable winds, both for longer and more often.
The coupling of wind and water in the presence of sea
ice is not straightforward and can be of greater significance than in sea-ice free waters if internal ice stress
(a function of ice concentration and compactness) is
sufficiently small (McPhee and Morison, 2001). It is
thus likely that a zone of maximum coupling exists in
the transition from full sea-ice cover to open water,
and that if this zone were located over the shelf break,
then shelf–basin exchange would also increase
(Carmack and Chapman, 2003). Such exchange would
draw more Pacific- and Atlantic-origin waters onto the
shelves, with an associated increase in the delivery of
salt, heat, and nutrients.
Box 9.4. Effects of climate change in the Arctic on global ocean circulation and climate
The Arctic plays a key role in the global climate through its production of North Atlantic Deep Water (NADW).
North Atlantic Deep Water is formed by the mixture of waters produced by thermohaline ventilation in the
Arctic Mediterranean, entrained Atlantic water, and water convected in the Labrador Sea. Once formed the
NADW flows southward through the Atlantic Ocean and, together with the denser Antarctic Bottom Water
(AABW), forms the source of all the deep and bottom waters of the World Ocean. NADW is of considerable
significance for the global thermohaline circulation (THC).
If climate change should result in reduced thermohaline ventilation in the Arctic, there is considerable – although
not unambiguous – evidence for a reduced NADW–THC through the Atlantic (Ganachaud and Wunsch, 2000;
Munk and Wunsch, 1998; Rahmstorf and England, 1997;Toggweiler and Samuels, 1995). A proper understanding of
this scenario requires an understanding of the relative magnitudes of the NADW and the AABW contributions to
the global THC.Traditional estimates of NADW production (e.g., Schmitz and McCartney, 1993) are of the order
of 15 Sv and this is supported by modern estimates based on the WOCE (World Ocean Circulation Experiment)
data set (Ganachaud and Wunsch, 2000). Estimates of AABW production are less consistent, but even the highest
estimates (Broecker et al., 1999) indicate that AABW production is currently significantly less than NADW production.The NADW is therefore considered to account for more than half the deep-water production of the World
Ocean at present.The latest IPCC assessment (IPCC, 2001) concludes that most models show a weakening of the
Northern Hemisphere THC, which contributes to a reduction in surface warming in the northern North Atlantic.
The more extreme scenario of a complete shutdown of the THC would have a dramatic impact on the climate of
the North Atlantic region, on the north–south distribution of warming and precipitation, on sea-level rise, and on
biogeochemical cycles (IPCC, 2001).The IPCC concluded this to be a less likely, but not impossible, scenario.
More reliable estimates of its likelihood and consequences require more reliable coupled ocean–atmosphere
models than are presently available (see section 9.7).
474
Arctic Climate Impact Assessment
Box 9.5.The Chukchi albedo feedback loop: An Achilles Heel in the sea-ice cover of the
western Arctic?
Attention has long focused on the role of Atlantic inflow waters in the transport
of heat within the Arctic Basin, and its potential to impact upon the overlying
sea ice should the arctic halocline weaken or break down.This box highlights the potential for Pacific inflow waters to impact upon the overlying sea ice, and the potential for this inflow to amplify locally the
well-known albedo feedback mechanism.
Pacific inflow waters are warmed in summer as they travel
northward across the seasonally ice-free parts of the Bering
and Chukchi Seas. On reaching the shelf break, these waters
subduct below the polar mixed layer and enter the arctic
halocline, forming Pacific Summer Water (PSW), identified
by a shallow temperature maximum at depths 40 to 60 m
and salinities near 31.5.The water at the temperature
maximum may be higher in years with extensive open
waters over the Bering and Chukchi Seas. Summer climatological data (see panel,Timokhov and Tanis, 1998;
Shimada et al., 2001) demonstrates the accumulation of
such water within the Beaufort Gyre over the eastern
flank of the Northwind Ridge.
One possibility for the fate of this stored heat within the
PSW in the southwestern Canada Basin is that it acts to
retard the growth of sea ice during the subsequent winter.
Therefore, the amount of summer melting (freshwater addition) and winter freezing (freshwater removal) are not balanced, and ice floes drifting over the “warm patch” will be thinner than in surrounding waters.The thin sea ice observed east
of the Northwind Ridge, also noted by Bourke and Garrett
(1987), is evidence of local PSW influence. When winter sea-ice
growth falls below a critical (and unknown) value at the start of the
melt season, the thickness and concentration of sea ice over the region
would be sufficient to reduce albedo and initiate further sea-ice reduction,
thus initiating a feedback. An alternate explanation for the record low sea-ice concentrations in summer 2002 is given by Serreze et al. (2003).
The disappearance of sea-ice cover in the Arctic in summer, as projected by the CGCM2 model by 2050, will
have far reaching effects on upper-layer circulation and
water properties. Direct exposure of surface waters to
wind will enhance wind-driven circulation. Also, it is
probable that wind-driven vertical mixing will increase
the depth of the surface mixed layer, depending upon the
strength of local stratification. For example, wind-driven
deepening of the mixed layer is very likely to be more
pronounced in the more weakly stratified Nansen Basin
than in Canada Basin with its strong Pacific influence.
Concurrently, the seasonal sea-ice zone is very likely to
increase (perhaps by 10 million km2) owing to projections
that the rate of decrease in sea-ice cover for summer will
be greater than for winter (Fig. 9.12;Tables 9.2 and 9.3).
Some model scenarios project that by 2080 the formation of sea ice in winter will no longer completely cover
the Arctic Basin. If this does occur, two parts of the
Arctic Basin are potential sites for sea-ice free or at least
decreased ice concentrations in winter: the western
Nansen Basin and western Canada Basin.
The first site is the weakly stratified western Nansen Basin
adjacent to the inflow and subduction of Atlantic waters
(Martinson and Steele, 2001). Here the incoming waters
are warmest and the overlying halocline is weakest.
At present, this region has the deepest winter mixed layer
in the central Arctic Ocean. Under the extreme climate
change scenario in which sea ice in winter no longer
completely covers the Arctic Basin, the Nansen Basin is
likely to become a region of strong convection and deepwater formation. However, the dynamics are more likely
to resemble the present day Nordic Sea system, i.e., with
deeper mixed-layer ventilation or convection (see
Muench et al., 1992 and Rudels et al., 2000 for a discussion of water masses). However, this argument supposes
an increased transport of warmer Atlantic water into the
Arctic whereas some models (e.g., Rahmsdorf, 1999)
suggest a weakening or southward shift of the THC.
(ºC)
-1.1
-1.2
-1.3
-1.4
-1.5
-1.6
-1.7
-1.8
475
Chapter 9 • Marine Systems
The second site is located in the western Canada Basin
immediately north of the Chukchi Sea and above the
Northwind Ridge (Box 9.5).This area is adjacent to the
inflow of shallow and relatively warm summer water
through the Bering Strait and across the Chukchi Sea.
The spread of this relatively warm water takes place
within the Beaufort Gyre at depths of 40 to 60 m, and is
thus within the limits of winter haline convection
(Shimada et al., 2001).
At both sites, it is their proximity to warm inflows from
the Atlantic and Pacific that establishes conditions that
may reduce winter sea-ice cover. It is not clear, however,
if release of heat from subsurface sources would serve to
melt the sea ice, or merely keep new ice from forming.
In either case ecosystems currently located in the Nordic
and Bering Seas are very likely to shift northward.
Changes in the Nordic and the Barents Seas
An 80-year CMIP2 integration (1% per year increase in
the atmospheric CO2 concentration) with the Bergen
Climate Model (BCM) was used to estimate changes in
the Nordic and Barents Seas (Furevik et al., 2003).
This model has a relatively high spatial resolution in
these areas and is believed to give as reliable projections
for these areas as can be obtained at present. However,
in common with other such models, its predictive capability is limited and the results presented should be seen
as possible, rather than likely outcomes.
The evolution of the winter sea surface temperature
field is shown in Fig. 9.14. From the present to 2020 a
minor cooling is projected over most of the area.
The greatest decrease is projected to occur along the
marginal ice zone in the Barents Sea and off the East
Greenland coast, with a maximum decrease of more
than 1 ºC projected in Denmark Strait. Some of this
cooling is likely to be associated with the weaker westerlies projected for this period (Furevik et al., 2002).
In the central Nordic Seas a warming of 0.5 ºC is projected. By 2050, the entire Nordic Seas are projected to
become warmer with the exception of a small area in
Denmark Strait.The largest warming is projected to
occur in the northeastern Barents Sea and to the south
of Iceland.With the doubling of the atmospheric CO2
concentration assumed by 2070, surface temperatures in
the Nordic Seas are projected to increase by 1 to 2 ºC,
with the highest values in the Barents Sea. Minimum
warming (< 0.5 ºC) is projected in the Denmark Strait.
(a)
(b)
2016–2024
2016–2024
2046–2054
2046–2054
2072–2076
2072–2076
Fig. 9.14. Evolution of the sea surface temperatures and the sea-ice edge (heavy black line) in the BCM CMIP2 integration; (a) shows
the March sea surface temperatures and sea-ice distribution around the years 2020, 2050, and 2075, (b) shows projected changes from
2000 to 2020, 2050, and 2075, respectively (Furevik et al., 2002).
476
Arctic Climate Impact Assessment
Projected salinity changes in the Nordic Seas are generally small, except for areas influenced by coastal runoff
and the melting of sea ice. By 2020, there is projected to
be a freshening (a salinity decrease of 0.1 to 0.3) in the
southeast Barents Sea and the Kara Sea, and a weak
freshening along the East Greenland coast.The freshening continues to the 2050s, with salinity reductions
north of Siberia in the range 0.1 to 0.5. A significant
freshening is also projected in the Arctic Ocean (a salinity decrease of 0.3 to 0.5), which is advected southward
with the East Greenland Current into the Denmark
Strait and East Icelandic Current.The arctic waters are
projected to become slightly more saline, but not
exceeding a salinity increase of 0.1. By the 2070s, the
model output suggests 0.1 to 0.2 more saline water
south of the inflow area, and less than 0.1 more saline
arctic waters in the Nordic Seas. North of Siberia and in
the Arctic Ocean, salinities are projected to decrease by
0.5 to 1.0, and a tongue of fresher water is projected
along the East Greenland Coast.
In terms of volume flow, from 2000 to 2020 the Bergen
Climate Model projects a small (< 10%) increase in the
net Atlantic inflow through the Iceland–Scotland Gap,
mainly near Iceland, and a corresponding increase in the
Denmark Strait outflow.There is generally a weakening
by a few percent of the cyclonic gyre in the Nordic Seas.
By 2050, the Nordic Seas gyre is projected to have
weakened by a further 10%. A greater inflow of arctic
waters is projected via the eastern branch (east of the
Faroe Islands), and less via the western. No significant
changes are projected for the Barents Sea.Toward 2070 a
further reduction in the internal cyclonic flow in the
Nordic Seas is projected.There is also a strengthening
(~ 0.25 Sv, ~ 12%) in the transport of arctic waters
through the Barents Sea with a compensating reduction
through Fram Strait (Furevik et al., 2002).
Seas of the North American Arctic
Projections of change in the Bering, Chukchi, and
Beaufort Seas, the Canadian Archipelago, Baffin and
Hudson Bays, and the Labrador Sea are highly uncertain
as many important aspects of these regions (e.g., the
presence of fast ice, strong seasonality, complex water
mass structure, through flow) are not included in the
current global climate models.The following discussion
is thus highly speculative.
These seas are expected to experience the general
changes in sea ice, sea surface temperature, mixed-layer
depth, currents, fronts, nutrient and light levels, air
temperature, winds, precipitation and runoff, sea level,
and cloud cover summarized in Tables 9.1 and 9.4, but
owing to their more southerly latitude and contact with
terrestrial systems, the changes may be greater and perhaps faster. Because the Bering/Chukchi shelf is very
shallow the effects of the albedo feedback mechanism
Table 9.4. Summary of changes projected in ocean conditions according to the five ACIA-designated models relative to baseline
conditions. Unless otherwise specified these projected changes are very likely to happen.
2020
2050
2080
Shorter by 10 days
Shorter by 15–20 days
Shorter by 20–30 days
6–10% reduction
15–20% reduction
Sea ice
duration
winter extent
summer extent
export to North Atlantic
type
landfast ice
Shelves likely to be ice free
Probable open areas in high
Arctic (Barents Sea and
possibly Nansen Basin)
30–50% reduction from present 50–100% reduction from present
No change
Reduction beginning
Strongly reduced
Some reduction in multi-year
ice, especially on shelves
Possible thinning and a retreat
in southern regions
Significant loss of multi-year ice,
with no multi-year ice on shelves
Probable thinning and further
retreat in southern regions
Little or no multi-year ice
Possible thinning and
reduction in extent in all
arctic marine areas
Sea surface temperature
winter/summer (outside THC
regions and depending upon
stratification and advection)
seasonality
Mixed-layer depth
Currents
Ocean fronts
Light exposure
Nutrient levels
An increase by about the same amount as the air temperatures in ice-free regions.
No change in ice-covered regions
All shelf seas to undergo
seasonal changes
30–50% of Arctic Ocean to
undergo seasonal changes
50–100% of Arctic Ocean to
undergo seasonal changes
Increase during summer in areas with reduced ice cover and increased wind
In regions affected by THC, modifications to the THC will change the strength of the currents
Fronts are often tied to topography but with altered current flows, may rapidly shift their position
With decreasing ice duration and areal extent, more areas to be exposed to direct sunlight
Substantial increases over
the shelf regions due to retreat
of the sea ice beyond the shelf
break
High levels on shelves and in deep arctic basins;
higher levels due to deeper mixed layer in areas of
reduced ice cover
Chapter 9 • Marine Systems
477
are likely to be amplified as water moves across ice-free
parts of the shelves. Preconditioning of Pacific inflow
waters during their transport across the shelf supplies a
reservoir of heat at shallow depths within the offshore
halocline, which may affect conditions to the east on the
Beaufort Shelf (Box 9.5). Such heat could potentially
retard sea-ice growth the following winter.
The Canadian Archipelago is a large (~ 2.9 million km2,
including Foxe Basin and Hudson Strait) and complex
shelf domain for which it is particularly difficult to
draw conclusions regarding global warming (Melling,
2000). Sea ice remains landfast for more than half the
year there, but the presence of fast ice is not included in
the global climate models.The general trends projected
by the ACIA-designated models and summarized in
Table 9.1 are likely to be representative for this region.
Two additional features of the Canadian Archipelago are
(1) that it serves as a passageway for water masses moving from the Arctic Ocean to the North Atlantic via
Baffin Bay and the Labrador Sea, and (2) that its sea-ice
domain is a variable mixture of local growth and floes
imported from the Arctic Basin, and that transport
through the Canadian Archipelago is governed in the
present climate by ice bridges across connecting channels (Melling, 2002).
Large uncertainties exist in the changes projected for
the Labrador Sea. If the NAO increases as some models
project, then there are likely to be stronger northwesterly winds and colder air masses over this region.
This would lead to increased sea-ice cover, colder water
temperatures, and increased deep convection. Conversely, general atmospheric warming would lead to
warmer water temperatures, decreased sea-ice cover,
and decreased convection.The slight increase in precipitation may possibly lower salinities over the Labrador
Sea, with the largest decline occurring over the shelves
due to the accumulation of river discharges.Temperatures in the region are also likely to be greatly influenced by the relatively warm Irminger Current inflow
but given the poor understanding of future wind fields,
changes in its strength are highly uncertain. Polynyas,
such as the North Water Polynya in northern Baffin Bay,
owe their existence, at least in part, to winds that move
sea ice from the area of its formation southward, so
maintaining the area as open water even in the middle
of winter. If the winds change, the number and size of
polynyas are also likely to change.
9.2.5.4. Ocean fronts
Open ocean fronts generally separate water masses, are
associated with strong current flows, and act as barriers
for marine organisms. It is difficult, however, to provide
reliable estimates of how fronts will respond to climate
change since few models provide such information.
Most of the deep ocean fronts are linked to bottom
topography and so it is likely that these will maintain
their present positions, e.g., along the Mohn Ridge in
the Greenland Sea and around the Svalbard Bank in the
Fig. 9.15. Infrared satellite image showing the position of the
Subarctic Front (also called the Iceland–Faroe Front in this
region) between Iceland and Scotland on 18 May 1980.
Dark areas indicate warm water, and light areas indicate cold
water, except where cloud cover occurs (satellite image
supplied by University of Dundee, UK).
Barents Sea. However, where topographic steering is
weak, fronts may disappear or be displaced.The eastern
part of the Polar Front in the Barents Sea is very likely
to disappear as a result of climate change (Loeng,
2001). In the Norwegian Sea, the front to the east of
Iceland is likely to move northeastward to the position
it occupied during the warm period at Iceland between
1920 and 1964.
The reduced inflow of Atlantic water projected by some
models would be very likely to shift ocean fronts toward
the continental slope region. For example, in the Norwegian Sea the Subarctic Front separates Atlantic and
arctic waters, typically lies a few hundred kilometers
north of the Faroe Islands (Fig. 9.15), and reduced inflow
would be likely to move the front closer to or even onto
the Faroe Shelf. If such a shift takes place a cooling of the
order of 5 ºC would possibly occur in the areas affected.
Assessing the likelihood of its occurrence is, however, far
beyond the capability of present-day models.
9.2.5.5. Possibility and consequences of altered
thermohaline circulation
A major uncertainty in projecting the extent of climate
change in the Arctic concerns the response of the THC
to altered freshwater flux. In turn, the THC of the Arctic
is an integral part of the global THC (see Boxes 9.2 and
9.4). At present, climate models do not generate unambiguous results. Some project a significant weakening, or
even collapse, of the THC, while others project a stable
THC. An alternative view is that the THC will not weaken or shut down, but that the sites of ventilation will
relocate north or south within the system (Aagaard and
Carmack, 1994; Ganopolski and Rahmstorf, 2001).
478
Several coupled atmosphere–ocean general circulation
models have been used to simulate the effects of
increased GHG emissions on the North Atlantic THC.
Rahmstorf (1999) summarized the outcome of six such
simulations, all of which projected a weakening of the
Atlantic overturning. Latif et al. (2000), however, did not
find weakening of the overturning in their model.
The models tend to agree that global climate change is
very likely to include increased freshwater input to the
Arctic Mediterranean, but tend to disagree on the associated consequences. Much of the uncertainty involves the
response of the Atlantic inflow and the positive feedback
mechanism that it can induce through salt advection.
In the simulation by Latif et al. (2000), the feedback
mechanism was counteracted by the increased salinity of
the Atlantic inflow to the Arctic Mediterranean.
The salinity increase in their model was explained by
increased freshwater transport from the Atlantic to the
Pacific in the tropical atmosphere. Latif (2001) used the
observed salinity increase at Bermuda to support their
conclusions. In the Nordic Seas, observations indicate the
opposite with a general freshening in the upper layers
(Blindheim et al., 1999;Verduin and Quadfasel, 1999).
Most of the general circulation models that project a
weakening of the THC project a reduction of no more
than 50% for the 21st century (IPCC, 2001). Some,
however, project instabilities and the possibility of a
more or less total collapse of the THC when the intensity of the circulation falls below a certain threshold
(Tziperman, 2000). Although such results may explain
the instabilities reported for the glacial climate state,
their applicability to a GHG-warming scenario cannot
be assessed objectively at present.
Observations of the salinity of overflow water in the
Atlantic confirm a long-term decrease (Dickson et al.,
2002). However, observational evidence for or against a
reduction in the THC itself is uncertain.While many
observations indicate a reduction in deep convection in
the Greenland Sea since 1970, deep convection to
depths below the sill level of the Greenland–Scotland
Ridge is still occurring (Budéus et al., 1998; Gascard et
al., 2002; Meincke et al., 1997) and there are also
Arctic Climate Impact Assessment
other sources of dense water. Observations of the Faroe
Bank Channel overflow (Fig. 9.16) indicate significant
decreases in volume flux during the latter half of the
20th century, especially since 1970 (Hansen et al.,
2001). A lack of similar data for the Denmark Strait
overflow leaves open the question as to whether the
change in the Faroe Bank Channel overflow is representative of the total overflow flux.
A significantly weakened THC in the Nordic Seas is thus a
possible scenario. Reduced ventilation implies reduced
renewal rates for deep water in some of the basins, and
this seems to be happening in the Norwegian Basin
(Østerhus and Gammelsrød, 1999).These changes are
slow, however.The magnitude of the inflow weakening
and its spatial extent will possibly be influenced by
changes in the wind field (Blindheim et al., 1999).The
waters most likely to be affected in this scenario are those
to the north of Iceland and the Faroe Islands, those in the
southern Norwegian Sea, and those in the Barents Sea.
The situation in the waters to the north of Iceland,
where the present-day climate is associated with a highly
variable Atlantic inflow, can be used to illustrate a potential impact of climate change. Hydrographic investigations show clear seasonal variation in this inflow, with a
maximum inflow in summer.There are, however, pronounced interannual differences in the variability of the
inflow that affect the temperature, salinity, and stability
of the water column (Ástthórsson and Vilhjálmsson,
2002;Thordardóttir, 1977). Most of the Atlantic inflow
(80–90%, see Fig. 9.7) enters the Arctic Mediterranean
through the Norwegian Sea.This region is characterized
by abnormally high sea surface temperatures (up to
almost 10 ºC) compared to zonal averages (Rahmstorf
and Ganopolski, 1999). Much of this elevation is due to
the heat flux from the inflowing Atlantic water.The temperature decrease in some areas, especially in winter,
resulting from a severely weakened Atlantic inflow
would thus be much larger than the projected warming
(Chapter 4) by the end of the 21st century according to
certain models (Seager et al., 2002).Thus, there is the
possibility that some areas of the Arctic Ocean will
experience significant regional cooling rather than warming, but present models can assess neither the probability
of this occurring, nor its extent and magnitude.
According to Rahmstorf (2003) the extent to which
Europe’s mild winters depend on the transport of heat
by the North Atlantic Current is presently unknown.
9.3. Biota
Fig. 9.16. Temporal variability in the intensity of the overflow
through the Faroe Bank Channel.The lavender line shows the
five-year running mean for the depth of the 28.0 density surface
(γθ = 28.0 kg/m3) at Ocean Weather Ship M (OWS-M).This surface is considered the upper limit of the dense overflow water
and its height (H) above the sill level of the Faroe Bank Channel
(FBC) is used as an indicator for overflow intensity. A deepening
trend in the density surface implies a decreasing overflow intensity through this channel (Hansen et al., 2001).
Following a general introduction to the biota of the
marine Arctic, this section reviews the dominant
species and, where possible, presents relevant life
history and ecological information. The section then
addresses the influence of physical factors on the biota
and discusses variations in abundance and distribution
observed in response to past climate fluctuations.
The section concludes by presenting possible future
changes in the arctic biota induced by the projected
479
Chapter 9 • Marine Systems
changes in the atmospheric forcing functions and
potential future sea-ice conditions discussed in Chapter
6. Salmon ecology and response to climate change are
addressed in Chapters 8 and 13.
9.3.1. General description of the community
Table 9.5. Average carbon biomass and annual carbon
productivity for different trophic levels within the Barents Sea,
compared with that for human populations in Norway and
Japan. Data recalculated from Sakshaug et al. (1994).
Biomass
(mg C/m2)
Bacteria
Productivity
(mg C/m2/yr)
400
60000
2000
90000
>3000
9500
Biological production in the oceans is based primarily on
phytoplankton or planktonic algae.These are microscopic unicellular plants that mostly reside within the
water column but in the Arctic are also found in and on
the sea ice.Through photosynthesis, they reduce CO2
while releasing oxygen and producing carbohydrates.
The carbohydrates are converted, according to the needs
of the algae, into essential compounds such as proteins
and nucleic acids by incorporating nitrogen, phosphorus,
sulfur, and other elements.
Phytoplankton
The organic matter produced by the algae is primarily
consumed by herbivorous (i.e., plant-eating) animals,
mainly zooplankton, which in turn may be eaten by fish.
The fish are then consumed by seabirds and mammals,
including humans. Each segment of the food web within
which organisms take in food in the same manner is
called a trophic level.Thus phytoplankton are considered
the first tropic level, zooplankton the second, etc.The
loss of organic matter between one trophic level and the
next is about 75 to 80%.The main losses are associated
with respiration (i.e., the burning of food) within the
organisms themselves, consumption by bacteria (i.e.,
microbial degradation) of dissolved organic matter, and
sinking cellular remains and fecal pellets (i.e., the body’s
waste).These processes all result in the release of CO2
or nutrients. Only a small fraction of the organic matter
reaches the seabed – the deeper the water column, the
smaller this fraction (Box 9.6).
Seabirds
2.5
0.4
Polar bears
0.25
0.027
Zooplankton
(copepods and krill)
Zoobenthosa
5160
1550
Capelinb
600
300
Codc
300
100
Minke whales
110
2.6
30
0.5
Seals
People, Norway
People, Japan
107
2200
1.5
22
aInterannual
biomass variation, 3000–7350 mg C/m2 (Denisenko and Titov, 2003);
biomass variation, 30–700 mg C/m2; cInterannual biomass variation,
150–700 mg C/m2.
bInterannual
Pelagic ecosystems are those which occur within the
water column of the open ocean away from the ocean
floor. Arctic pelagic ecosystems, like pelagic ecosystems
elsewhere and in contrast to terrestrial ecosystems, are
dominated by animal biomass. In the Barents Sea, for
example, the mean annual plant biomass is 2 g C/m2
whereas the mean annual animal biomass is at least four
times more. Globally, annual marine primary production is about 40 Pg C (i.e., 1015 grams) or 40% of the
Box 9.6. Organisms in the food web
Population abundance, whether for algae, fish, or polar bears (Ursus maritimus), is dependent on the population
growth and death rates. Given a growth rate higher than the death rate, the population size will increase, and vice
versa. If the two rates are equal, the population is in steady state. Another variable is population migration; stocks
may arrive in or leave a given ecosystem. Essentially, a change in any environmental variable, including those affected by climate change, has a direct impact on one or more processes by changing their rate, which in turn causes a
change in population biomass.Thus, while the population growth rate is determined by light or nutrient levels
(algae), or food availability (animals), the loss rate represents the sum of losses due to natural death, pollution,
sedimentation, and being eaten, fished, or hunted.
Populations can be arranged hierarchically within a food web on the basis of what they eat, with the lowest
trophic level comprising photosynthetic organisms. Animals can move up the food-web hierarchy as they grow, by
becoming able to eat larger prey. Because most of the food intake is spent on maintaining life, reproduction,
movements, etc., only 15 to 25% contributes to population growth, which during steady state represents food for
the next trophic level. Consequently, marine food chains are short, with a maximum of five trophic levels.
In models, population growth is described by exponential functions in which growth and mortality rates themselves are functions of environmental change, including changes caused by the evolution of the ecosystem itself
(feedback). Ideally, ecosystem models should include all trophic levels, including major species as separate entities;
however, coupling plankton and fish is difficult, as is the coupling of fish and higher animals.
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Arctic Climate Impact Assessment
Box 9.7. Sea-ice communities
Sympagic organisms are those that live in close association with sea ice, either within channels in the ice itself,
on the underside of the ice, or at the interface with the water immediately below the ice.The organisms that
inhabit this environment are highly specialized, but cover a wide taxonomic range, from bacteria and simple
algae, to vertebrate fauna. Some species, particularly microorganisms, become incorporated into the sea ice as
the ice crystals grow. While it may seem an inhospitable environment, the sea ice is actually quite a stable and
organically-enriched environment for those organisms that can tolerate its extreme conditions. While some
organisms occupy the sea ice as it forms, others actively or passively migrate into the ice ecosystems. Organisms that live within the interstitial spaces of sea ice include microfauna such as protists, and larger organisms
such as ciliates, nematodes, rotatorians, turbellarians, and copepods. Multi-year sea ice has the most complex
communities and often serves as a platform for colonizers to young ice. In addition, the abundance and biomass of the multi-year sea ice organisms can be very high. For example, copepods may easily exceed densities
of 150 individuals per square meter. Given the correct conditions vast algal mats can form on the under-surface
of sea ice, including both microalgae and macroalgae such as sea-tangle (Fucus distichus), and their associated
epiphytic organisms such as Pylaiella littoralis. In comparison, seasonal sea ice normally has lower densities and
lower biomasses and tends to support more simple communities.
The spatial distribution of sea-ice fauna is generally patchy, even within single ice fields, because the origin, history, size, snow thickness, and the thickness of the sea ice itself can vary dramatically. Interannual variability within
a community is also high. In areas such as the Barents Sea, the size of the Atlantic Water inflow varies from year
to year, causing dramatic changes in the sympagic community. Nevertheless, sympagic communities are characterized by fauna that can withstand high levels of variation in food availability and low temperatures. Generally,
the older the sea ice, the more complex and established the sympagic community. Ice-living invertebrates tend
to have low basal metabolic rates, concomitant slow growth, and long life cycles. For example, some arctic ice
amphipods live for five or six years, while their more temperate counterparts, or amphipods in other arctic
habitats, have average life spans of two to three years. Large, lipid-rich ice-dwelling amphipods are prime prey
for the circumpolar polar cod (Boreogadus saida).This small, arctic fish is an opportunistic feeder that can live
pelagically, or in association with sea-ice communities. In ice-filled waters its diet largely comprises Themisto
libellula and Apherusa glacialis.The fish capture these small “lipid packages” and convert them into prey that is
substantial enough to support higher vertebrates such as seabirds and marine mammals. Some seabirds and
marine mammals also eat large invertebrate ice-dwellers directly. Black guillemots (Cepphus grylle) and thickbilled murres (Uria lomvia) feed on the amphipod Gammarus wilkitzkii. Little auks (Alle alle) and ivory gulls
(Pagophila eburnea) also eat sympagic amphipods. First-year harp seal (Phoca groenlandica) feed extensively on
sympagic amphipods when they start to self-feed. However, the preferred prey within the sympagic community
is polar cod for most marine mammals.
Thinning, and reduced coverage of arctic sea ice will have dramatic impacts on the entire sympagic ecosystem,
particularly on interstitial organisms as these do not have alternate habitats in which to live. Also, given that the
sympagic community is important in providing pelagic and benthic communities with food, particularly during
the summer when the sea ice melts, changes in this highly specialized environment are likely to have repercussions throughout the arctic marine community as a whole.
global total (marine plus terrestrial) production.
Macroalgal biomass (i.e., large plants such as kelp and
sea-tangle) in the Arctic is believed to be small due to
habitat restrictions caused by freezing, ice scouring by
small icebergs, and local freshwater input. In some
areas, however, macroalgal biomass can be large as kelp
forests do occur in the Arctic.
Generally, the higher the trophic level, the smaller the
production. In the Barents Sea, major pelagic fish species
represent a few hundred milligrams of carbon biomass
per square meter and seabirds and polar bears, only 2.5
and 0.25 mg C/m2, respectively (Table 9.5).The table
shows the inverted biomass pyramid which is typical for
phytoplankton and zooplankton in the marine pelagic
food web. On the Bering Shelf, the annual primary pro-
duction is higher than in the Barents Sea. In the shallow
areas of the Bering Sea (40 to 100 m depth), the “rain”
of organic particles from the upper layers to the benthic
(bottom-dwelling) animals can be higher than the fraction grazed by pelagic animals (Walsh J.J. et al., 1989).
This input is also much higher than in the Barents Sea,
which has an average depth of 230 m. Benthic biomass
and production are lowest in the deep Arctic Ocean.
Box 9.7 reviews the highly specialized communities
associated with seasonal and multi-year sea ice.
Although phytoplankton generally grow more slowly in
the Arctic than in warmer areas, near-freezing temperatures would not delay the onset of the initial phytoplankton bloom (i.e., period of very high production) by
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Chapter 9 • Marine Systems
more than two to three days compared to that at 5 to
10 ºC. Light- and nutrient-limitation is more important
than temperature. Arctic zooplankton, certainly the predominant copepods, have adapted to cold conditions by
having life cycles that are two to ten times longer than
corresponding species in temperate conditions.
The Arctic Ocean as a whole is not particularly productive yet seasonal productivity in patches of the Barents
and Chukchi Seas, and on the Bering Shelf, is among the
highest of anywhere in the world (Rysgaard et al., 2001;
Sakshaug, 2003; Sakshaug et al., 1994; Springer et al.,
1996;Walsh, 1989). In these areas, the primary production supports large populations of migratory seabirds, a
large community of various mammals, and some of the
world’s richest fisheries.
Many seabirds and some marine mammal species either
migrate into the Arctic during the summer pulse of productivity or can cope with the long periods when food
supplies are limited. Many of the permanent residents
store large quantities of reserve energy in the form of
lipids (oils) during periods of abundant food supply
while others survive winter in a dormant stage.
9.3.1.1. Phytoplankton, microalgae, and
macroalgae
Phytoplankton are often classified according to size.
Nanoplankton (2–20 µm) are the most abundant yet
several microplankton species (> 20 µm; some reaching
500–750 µm) can produce intense blooms given sufficient light, nutrients, and stratification. Microalgae can
join together and then sink to form thick mats on the
bottom in shallow coastal waters (Glud et al., 2002).
Among the approximately 300 species of marine phytoplankton known in high northern latitudes, diatoms and
dinoflagellates comprise around 160 and 35 species,
respectively (Sukhanova et al., 1999). Diatoms have
non-growing siliceous shells and thus need silicate for
growth while dinoflagellates move by the action of taillike projections called flagella. Diatoms are responsible
for most of the primary production in arctic pelagic
ecosystems.Within the Arctic, the Arctic Ocean has the
lowest number of different species and the western
Barents Sea the most (Horner, 1984; Loughlin et al.,
1999; Melnikov, 1997).
Prymnesiophytes (another group of swimming flagellates) include the two bloom-forming species; Phaeocystis
pouchetii and Emiliania huxleyi (the latter being an exception among prymnesiophytes by lacking flagella and having a cover of calcite platelets, and as such are highly relevant to the carbon cycle). Phaeocystis pouchetii is common throughout the Arctic except in the deep Arctic
Ocean (Hasle and Heimdal, 1998; Sukhanova et al.,
1999). Emiliania blooms have been observed south of
Iceland (Holligan et al., 1993), in the Norwegian and
Bering seas (Paasche, 1960; Sakshaug et al., 1981;
Sukhanova et al., 1999), and in Norwegian fjords
(Berge, 1962; Johnsen and Sakshaug, 2000). Emiliania
huxleyi blooms were first recorded on the southeastern
Bering Shelf in 1997 during an extremely bright summer (Napp and Hunt, 2001) and in the Barents Sea in
2000 (Fossum et al., 2002). Emiliania huxleyi continues
to bloom in both areas.
Dinoflagellates, chrysophytes, cryptophytes, and green
flagellates are common in arctic waters. Cyanobacteria
(formerly called blue-green algae), common in temperate and tropical waters, are abundant in the deep reaches of the Bering Sea (Sukhanova et al., 1999).They are
also transported into the Barents Sea by the Atlantic
inflow. Dinoflagellates are particularly important in
multi-year ice, and a variety of flagellates thrive in melt
ponds on top of the sea ice in summer (Braarud, 1935;
Gosselin et al., 1997).
The major species of diatom and prymnesiophyte possess the water-soluble reserve carbohydrate ß-1,3 glucan
(chrysolaminarin), which is by far the most important
carbon source for marine bacteria. Although in most
phytoplankton species lipids comprise < 10% of dry
weight, a large proportion comprises essential polyunsaturated fatty acids that are distributed throughout the
ecosystem (Falk-Petersen et al., 1998; Henderson et al.,
1998). Healthy phytoplankton cells are protein-rich,
with proteins comprising up to 50% of dry weight
(Myklestad and Haug, 1972; Sakshaug et al., 1983).
Locally, the hard-bottom intertidal zone in the Arctic
Ocean supports beds of sea-tangle (Fucus distichus) and in
the littoral and sublittoral regions (down to about
40 m in clear water) are kelp forests of Alaria esculenta,
Laminaria saccharina, L. digitata, and L. solidungula (Borum
et al., 2002; Hop et al., 2002; Zenkevich, 1963).
Laminaria saccharina, L. digitata, and the red alga Ahnfeltia
plicata are commercially important in the northern
coastal areas of Russia (Korennikov and Shoshina, 1980).
9.3.1.2. Microheterotrophs
Microheterotrophs are non-photosynthetic microorganisms.Their role is not well documented in the Arctic,
but bacterial production is generally thought to be high,
albeit somewhat reduced due to the low temperatures
(Pomeroy et al., 1990). Rates of bacterial production are
mainly determined by the amount of decaying organic
matter available, although limitation by mineral nutrients
cannot be excluded in some cases (Rich et al., 1997).
There are upward of 1011 to 1012 bacteria cells per cubic
meter in the water column (Steward et al., 1996).
Phages, a group of highly species-specific viruses, which
are even more abundant than bacteria, attack and kill
bacteria and phytoplankton, thus regulating their abundance (Bratbak et al., 1995). A well-developed community of heterotrophic flagellates grazes on the bacteria.
These in turn are eaten by a variety of protozoans such
as ciliates, which are in turn eaten by copepods.Thus the
ciliates form an important link between the microbial
(i.e., bacteria-based) and grazing food webs.
482
Excluding bacteria, the microheterotrophs in sea ice and
ice-filled waters comprise 60 to 80 species of flagellate
and about 30 species of protozoan, especially ciliates
(Ikävalko and Gradinger, 1997). In contrast to first-year
ice, multi-year ice has a well-developed microbial community.The abundance of microheterotrophs is particularly high during and immediately after phytoplankton
maxima (Booth and Horner, 1997).
9.3.1.3. Zooplankton
Mesozooplankton play a major role in pelagic ecosystems including those of the Arctic, where a diverse array
of planktonic animals comprise, on average more than
50% of the total pelagic biomass (Sakshaug et al., 1994).
Marine mesozooplankton comprises ~ 260 species in the
Arctic, ranging from less than 40 species in the East
Siberian Sea to more than 130 species in the Barents Sea
(Zenkevich, 1963).
Herbivorous mesozooplankton belonging to the family
Calanoidae in the crustacean order Copepoda are predominant in terms of species richness, abundance, and
biomass. Large herbivorous copepods (2–5 mm adult
size) can make up 70 to 90% of the mesozooplankton
biomass in the arctic seas. The most important are
Calanus finmarchicus, C. hyperboreus, and C. glacialis in
Atlantic and Arctic Water, and C. marshallae, Eucalanus
bungii, Neocalanus spp., Metridia longa, and M. pacifica in
the North Pacific and the Bering Sea. Calanus finmarchicus predominates in Atlantic Water, C. hyperboreus is
found in both Atlantic and Arctic Water, and C. glacialis
is found almost exclusively in Arctic Water. Variations
in the distribution and abundance of Calanus species
are considered early indicators of climate-induced
change in the North Atlantic system (Beaugrand et al.,
2002) with major consequences for the recruitment of
fish species such as cod, which depend on them
(Beaugrand et al., 2003).
The large copepods in the Arctic represent, as elsewhere, important links between primary production and
the upper levels of the food web because they store large
amounts of lipid for overwintering and reproduction
(e.g., Scott et al., 2000). Calanoid copepods overwinter
at depths of several hundred meters and then ascend to
surface waters in spring to reproduce. Adults and the
late copepodite stage V feed on phytoplankton in the
surface waters storing lipids through the spring and
summer (e.g., Dawson, 1978; Hargrave et al., 1989).
Daily vertical migrations, common in most seas, have
not been observed in the Arctic, not even under sea ice
(Fortier et al., 2002). Many small copepods, < 2 mm
adult size, are known to be herbivorous while some are
carnivorous (Loughlin et al., 1999; Smith and SchnackSchiel, 1990; Stockwell et al., 2001).
Krill (euphausiids) are swarming shrimp-like crustaceans that are common on the Atlantic side of the
Arctic Ocean and in the Bering Sea but are not common in the central Arctic Ocean.They can make up to
Arctic Climate Impact Assessment
45% of mesozooplankton catches by weight (Dalpadado
and Skjoldal, 1991, 1996) but are generally less abundant in the Arctic than in some areas of the Southern
Ocean (Dalpadado and Skjoldal, 1996; Loughlin et al.,
1999; Smith, 1991). Some species, for example
Thysanoessa inermis, are herbivorous whereas others are
omnivorous or even carnivorous, for example T. raschii,
T. longipes, T. longicauda, and Euphausia pacifica.
Most graze diatoms and Phaeocystis pouchetii efficiently
(Båmstedt and Karlson, 1998; Falk-Petersen et al.,
2000; Hamm et al., 2001; Loughlin et al., 1999;
Mackas and Tsuda, 1999; Smith, 1991).
Amphipods, another crustacean group, are represented
in the Arctic by Apherusa glacialis, Onisimus spp.,
Gammarus wilkitzkii, and Themisto libellula, all of which
are associated with sea ice or ice-influenced waters.
Except for the latter, they live in the interstitial cavities
(brine channels) in the ice and on the underside of the
pack ice, where G. wilkitzkii constitutes > 90% of the
amphipod biomass at times. Apherusa is common in firstyear ice, and Onisimus in fast ice (Hop et al., 2000).
Themisto libellula lives in ice-filled waters but is not
dependent on sea ice. It is an important food source for
the upper trophic levels and is itself carnivorous, feeding
on herbivorous copepods and other ice-associated zooplankton. It appears to fill the same niche as krill where
these are absent (Dunbar, 1957).The largest of the ice
amphipods, Gammarus wilkitzkii, can reach 3 to 4 cm in
length. Apherusa glacialis and G. wilkitzkii, which are
closely associated with multi-year ice, have a high
fecundity (Melnikov, 1997; Poltermann et al., 2000).
Although copepods, amphipods, and euphausiids are
predominant in terms of mesozooplankton biomass in
the arctic seas, virtually all major marine zooplankton
groups are represented, namely, hydrozoans, ctenophores, polychaetes, decapods, mysids, cumaceans,
appendicularians, chaetognaths, and gastropods (Hop et
al., 2002; Murray, 1998). Pteropods (planktonic snails)
such as Limacina helicina occur in vast swarms some years
(Grainger, 1989; Kobayashi, 1974).
9.3.1.4. Benthos
The benthic fauna differs substantially between the continental shelves and the abyssal areas of the Arctic due
to differences in hydrography, with warmer and more
saline water in the deeper areas (Curtis, 1975).
The benthos of the Bering Sea and the Canadian
Archipelago between the New Siberian Islands and
Bathurst Island is primarily Pacific (Dunton, 1992).
The Atlantic fauna are carried into the Barents Sea by
the Atlantic inflow and into the central Arctic by strong
boundary currents.The fauna of the shallow Kara,
Laptev, and Pechora Seas has to contend with large
seasonally fluctuating physical conditions and massive
amounts of freshwater from the Russian rivers.The littoral (i.e., near-coastal) zone varies from the rocky
shore of exposed coasts, to sand and mud in sheltered
Chapter 9 • Marine Systems
areas of fjords and bays, and is influenced to varying
degrees by ice cover and scouring. Despite the formative studies by Russian workers in the first decades of
the twentieth century (summarized by Zenkevich,
1963) detailed quantitative information on the distribution of the benthos and the structure of benthic communities in the Eurasian Arctic (especially in coastal and
estuarine areas) is limited. Since around 1980, extensive
regions of the North American arctic shelf and fjord
areas have been sampled and their communities
described and related to environmental influences, see
for example studies by Stewart et al. (1985), Aitken and
Fournier (1993), Grebmeier et al. (1989), and Feder et
al. (1994).The greatest numbers of benthic species are
found in areas of mixing between cold polar waters and
temperate waters, for example between the Barents Sea
and the Bering Sea, and off West Greenland and Iceland.
The total number of benthic invertebrate species in the
Barents Sea has been estimated at around 1600, but in
the western parts of the Bering Sea alone the total
number may exceed 2000 (Zenkevich, 1963). In the
shallow waters of the Laptev Sea there are 365 benthic
species (Zenkevich, 1963) and even fewer in the
Beaufort Sea owing to the cold, unproductive arctic
water masses, and to the brackish conditions (Curtis,
1975). In the deep Arctic Ocean, the number of benthic
macrofauna species varies from 0 to 11 (Kröncke,
1994).The number of species in the intertidal zone of
Svalbard (Weslawski et al., 1993), Bjørnøya (Weslawski
et al., 1997), Baffin Island (Ellis, 1955), and Greenland
(Madsen, 1936) varies between 30 and 50.The low
number of benthic macrofauna species in the arctic
intertidal zone is usually attributed to ice scouring
(Ellis, 1955), a combination of tidal height and ice
thickness (Ellis and Wilce, 1961), or heavy wave action
(Weslawski et al., 1997).
Most recent benthic research has focused on specific patterns and processes resulting in biological hot spots such
as below predictable leads in the sea ice, polynyas,
oceanographic fronts, areas of intense mixing, and the
marginal ice zone (Dayton et al., 1994).
Fig. 9.17. Levels of benthic faunal biomass
in the northern regions of the Bering,
Chukchi, East Siberian, and Beaufort Seas
(Dunton et al., 2003).
483
Because a relatively large proportion of the primary
production in highly productive water columns can
potentially reach the bottom, primary and benthic production tends to be coupled.The fraction of sinking
matter that reaches the bottom is related to bottom
depth; the shallower the water body, the greater the
amount of material reaching the bottom. In shallow arctic waters, the benthic food web plays a greater role
than in the deep seas or at lower latitudes (Cooper et
al., 2002; Grebmeier and Barry, 1991).The Bering
Shelf and the southern Chukchi Sea exhibit some of the
highest levels of faunal biomass in the world’s oceans
(Fig. 9.17), supporting a rich fauna of bottom-feeding
fish, whales, seals, walruses, and sea ducks (Grebmeier
et al., 1995; Hood and Calder, 1981; Joiris et al., 1996;
Welch et al., 1992). Other rich benthic communities in
the Arctic occur in Lancaster Sound and the shallow
parts of the Barents Sea.
The benthic fauna varies with depth and habitat.
For example, off Svalbard the most common species in
the steep rocky littoral zone include the macroalgae
Fucus spp., sessile (i.e., non-mobile) barnacles (Balanus
balanoides), and motile (i.e., mobile) gastropods
(Littorina saxatilis) and amphipods (Gammarus setosus and
G. oceanicus).The tidal flats are inhabited by a rich and
diverse non-permanent fauna due to sediment freezing
for six to eight months each year (Weslawski et al.,
1999).The sediment fauna is dominated by small polychaetes (Scoloplos armiger, Spio filicornis, Chaetozone setosa)
and oligochaetes (Weslawski et al., 1993). Sublittoral
organisms include the barnacle Balanus balanus that contributes a large proportion of the biomass of sessile
species (Jørgensen and Gulliksen, 2001). Other conspicuous, sessile species are the bivalve Hiatella arctica,
actinarians Urticina eques and Hormathia nodosa, bryozoans, and Ophiopholis aculeata. Many, small, motile
amphipods (Calliopidae sp.), isopods (Munna sp. and
Janira maculosa), snails (Alvania sp.) and barnacles
(Tonicella sp.), are observed together with infaunal
polychaetes, nematodes, bivalves (Thyasira sp.), and
amphipods (Harpinia spp.).The infauna occur in pockets
of sediment on the rocky wall. At depths between 100
and 300 m in soft bottom areas of the northern Barents
Sea (Cochrane et al., 1998), the polychaetes Maldane
sarsi, Spiochaetopterus typicus, and Chone paucibranchiata
are among the dominant species.
Some crustaceans occur or have occurred in the arctic
regions at densities sufficient for commercial interest.
These include the deepwater prawns Pandalus borealis
(Aschan and Sunnanå, 1997) and Pandalopsis dispar, and
several crab species: red king crab (Paralithodes camtschatica, Hjelset et al., 2002; Jewett and Feder, 1982),
Lithodes aequispina,Tanner and snow crab (Chionoecetes
spp.), and Dungeness crab (Cancer magister, Orensanz et
al., 1998). Commercially harvested arctic mollusks
include clams (Mya truncata, M. arenaria), blue mussel
(Mytilus edulis), and Iceland scallop (Chlamys islandica).
Commercial fisheries and aquaculture are addressed in
detail in Chapter 13.
484
9.3.1.5. Fish
Arctic or Arctic-influenced waters are inhabited by
more than 150 species of fish (Murray, 1998). Few are
endemic to the Arctic, unlike the situation in the
Southern Ocean where endemic species predominate.
Most fish species found in the Arctic also live in boreal
(northern) and even temperate regions. Arctic fish communities are dominated by a small number of species.
The most abundant being Greenland halibut (Reinhardtius hippoglossoides), polar cod, Atlantic and Pacific
cod (Gadus morhua and G. macrocephalus), Greenland cod
(G. ogac), walleye pollock (Theragra chalcogramma),
capelin (Mallotus villosus), long rough dab, also known as
American plaice (Hippoglossoides platesoides), yellowfin
sole (Pleuronectes asper), Atlantic and Pacific herring
(Clupea harengus and C. pallasi), and redfish (Sebastes spp.
e.g., S. mentella, S. marinus).
Greenland halibut, polar cod, and capelin have a circumpolar distribution. Greenland cod is a predominantly
arctic species that is restricted to Greenland waters.
The other species principally occur in waters to the
south of the Arctic Ocean, except for parts of the
Barents and Chukchi Seas.
Capelin
Capelin is a small circumpolar pelagic fish (Fig. 9.18).
It is planktivorous (i.e., eats plankton), feeding mainly
on copepods, followed by krill and amphipods. It is
particularly abundant in the North Atlantic and the
Barents Sea (Gjøsæter, 1995, 1998), and around
Iceland (Vilhjálmsson, 1994). In the eastern Bering
Sea, capelin tend to occur in cooler or more northerly
areas. Capelin populations are subject to extreme fluctuations (e.g., Gjøsæter and Loeng, 1987; Sakshaug et
al., 1994) in their distribution and abundance. Capelin
is heavily exploited in the Atlantic but not the Pacific
sector of the Arctic.
Arctic Climate Impact Assessment
Table 9.6. Annual productivity and food requirement of higher
trophic levels: average for the whole Barents Sea over several
years. Data recalculated from Sakshaug et al. (1994) by Sakshaug
and Walsh (2000).
Annual production
(mg C/m2)
Capelin
Cod
Food requirement
(mg C/m2)
280
90
550
Whales
3.6
360
Seals
0.8
95
Seabirds
0.5
78
Capelin fishery
Total
200
375
1280
Capelin is important in the diet of other fishes, marine
mammals, and seabirds (e.g., Haug et al., 1995; Lawson
and Stensen, 1997; Mehlum and Gabrielsen, 1995) and
is thus regarded as a key prey species. Capelin can provide more than 20% of the food required by seabirds,
higher predators, and the capelin fishery collectively in
an average year (Table 9.6).
Fluctuations in the abundance of capelin have a big impact
on their predators, particularly cod, seals, and seabirds.
The growth rate of cod and their somatic and liver condition, for example, are correlated with capelin population
abundance (Carscadden and Vilhjálmsson, 2002;
Vilhjálmsson, 1994, 2002;Yaragina and Marshall, 2000).
Herring
Atlantic herring is generally restricted to waters south of
the Polar Front, for example in the Nordic Seas and the
Barents Sea (Vilhjálmsson, 1994). Like capelin, Atlantic
herring is planktivorous, feeding in highly productive
frontal areas of the open sea. Larval herring are important prey for seabirds. Adult herring is an important
food item for larger fish and marine mammals.
The principal population of Atlantic herring in the Arctic
is the Norwegian spring-spawning stock; one of the
largest fish stocks in the world and with a spawning
biomass that exceeded ten million tonnes for much of
the 20th century.This population, together with the
Icelandic spring- and summer-spawning herring make up
the Atlanto-Scandian herring group.The migration route
from nursery areas to feeding areas to overwintering
areas to spawning areas takes the Norwegian springspawning herring around the Norwegian Sea (Box 9.8),
over a distance of several thousand kilometers, and even
into the Icelandic Sea during certain climatic warm periods (see Fig. 9.19 and section 9.3.3.3).
Fig. 9.18. Distribution of capelin (green) (based on
Vilhjálmsson, 1994).
Spawning occurs at many sites along the Norwegian
coast between 58º and 70º N.The spawning grounds
comprise five main areas, but their relative importance,
the time of arrival on the spawning grounds, and the
spawning time have often changed (Slotte, 1998).
These changes are not solely due to varying environmen-
485
Chapter 9 • Marine Systems
tal conditions, but are also affected by population structure, and the optimum life history strategy for individual
fish under varying levels of food supply. Flexibility in
spawning behavior offers an adaptive advantage to the
population during changing climates.
Pacific herring are common in the Bering Sea shelf
regions (NRC, 1996).This species is, however, of relatively minor importance for seabirds and marine mammals in that region (Livingston, 1993).
Polar cod
Polar cod is a key species in many
arctic food chains and forms a
major link in the transfer of
energy from zooplankton to
top carnivores (Fig. 9.20).
Large polar cod (23–27 cm)
consume mainly fish and are
themselves eaten by a variety
(a)
(b)
of large fish as well as by many seabird species and most
arctic marine mammals (e.g., Dahl T. et al., 2000;
Hobson and Welch, 1992; Holst M. et al., 2001; Lawson
and Stenson, 1997; Lowry and Frost, 1981; Mehlum et
al., 1999; Nilssen et al., 1995; Orr and Bowering, 1997;
Rowe et al., 2000;Wathne et al., 2000). Polar cod spend
much of their time associated with sea ice and stay in
arctic waters throughout their life cycle.This species is
broadly distributed, from inshore surface waters to very
deep waters (Falk-Petersen et al., 1986; Jarvela and
Thorsteinson, 1999; Pedersen and Kanneworff, 1995;
Walters V., 1955). Polar cod occur in large schools
(Crawford and Jorgenson, 1996;Welch et al., 1993)
Box 9.8. Effects of climate on Norwegian spring-spawning
herring
In the Icelandic area, herring was the fish species most affected by the environmental adversities of the 1960s (Dragesund et al., 1980; Jakobsson, 1980;
Jakobsson and Østvedt, 1999).This is not surprising since herring are plankton
feeders and in Icelandic waters are near their northern limit of distribution.
Thus, the traditional feeding migrations of the Norwegian spring-spawning herring stock to the waters off northern Iceland (Fig. 9.19a) stopped completely
when the Atlantic plankton community collapsed. In 1965–1966, the oldest
herring were instead forced to search for food in the Norwegian Sea near the
eastern boundary of the East Icelandic Current, i.e., around 150 to 200 nautical miles farther east than previously (Fig. 9.19b). In 1967–1968, the stock
migrated north to feed west of Svalbard during summer (Fig. 9.19c).This was
also the case in 1969 when the overwintering grounds also shifted from 50 to
80 nautical miles east of Iceland to the west coast of Norway (Fig. 9.19d).The
Norwegian spring-spawning herring stock collapsed in the latter half of the
1960s (Dragesund et al., 1980) and the feeding migrations to the west into
the Norwegian Sea ceased altogether (Fig. 9.19e).
The abundance of the Norwegian spring-spawning herring stock increased
dramatically in the 1990s.This process has, however, taken about twenty-five
years despite a ban on commercial fishing in the period 1973 to 1983. It was
not until the mid-1990s that these herring resumed some semblance of their
previous feeding pattern.The Norwegian spring-spawning herring still overwinter in fjords in the Lofoten area on the northwest coast of Norway.
When and if they will revert completely to the traditional distribution and
migration pattern cannot be predicted.
(c)
(d)
(e)
Fig. 9.19. Changes in the migration routes, and feeding and wintering areas of Norwegian springspawning herring during the latter half of the twentieth century.The plots show (a) the normal migration
pattern during the warm period before 1965, (b and c) the pattern following the Great Salinity Anomaly
until the stock collapsed in 1968, (d) during years of low stock abundance, and (e) the present migration
pattern (based on Vilhjálmsson, 1997).
Spawning areas
Juvenile areas
Main feeding areas
Spawning migrations
Feeding migrations
Over-wintering area
486
Arctic Climate Impact Assessment
collapse of this cod population during the 20th century
is described in section 9.3.3.3.The cod population off
Newfoundland and Labrador also collapsed during the
1990s, owing to high fishing mortality combined with
adverse environmental changes (Drinkwater, 2002).
Pacific cod is a mixed feeder that consumes a wide
variety of fish (primarily walleye pollock), shellfish,
and invertebrates in the eastern Bering Sea (Livingston
et al., 1986).
Walleye pollock
Fig. 9.20. Distribution of polar cod (red) (based on
Ponomarenko, 1968).
mostly north of 60º N in the eastern Bering Sea or in the
cold pool of the mid-shelf region (Wyllie-Echeverria and
Wooster, 1998).The importance of this species is likely
to have been underestimated in the past, in part owing
to its patchy distribution. Polar cod displays a variety of
physiological and biochemical adaptations to life in cold
waters, including bioenergetic adjustment to low temperature (Hop et al., 1997; Ingebrigtsen et al., 2000;
Steffensen et al., 1994).
Cod
Cod species found in the Arctic include Atlantic cod,
Pacific cod (Bergstad et al., 1987), Pacific tomcod
(Microgadus proximus), which occurs as far north as the
Bering Sea, Greenland cod, and Arctic cod (Arctogadus
glacialis) that resides in the Arctic Ocean, but about
which little is known (Mikhail and Welch, 1989; Morin
et al., 1991; Sufke et al., 1998).The majority of these
species appear regularly in the diet of marine mammals
(e.g., Holst M. et al., 2001;Welch et al., 1992).
Atlantic cod is the most abundant gadoid species in the
northern North Atlantic. Like Atlantic herring it
occurs mainly to the south of the Polar Front, yet can
live in temperatures below 0 ºC by producing
antifreeze proteins.
Four large cod populations occurred in the arctic areas
of the North Atlantic during the 20th century.The
Northeast Arctic cod spawns along the Norwegian coast,
with more than 50% of this occurring in the Lofoten
area. Cod from Iceland spawn around the coast with
more than 50% of this occurring off the southwest corner.The cod off Greenland have inshore and offshore
spawning components, and an immigrant contribution
from Icelandic waters.The history of the increase and
Walleye pollock is the single most abundant fish species
in the Bering Sea, comprising the bulk of the commercial catch in this area (Akira et al., 2001; Livingston and
Jurado-Molina, 2000;Wespestad et al., 2000). It is
mainly semi-pelagic, dominating the outer shelf
regions.Walleye pollock is primarily planktivorous,
feeding on copepods and euphausiids but adults become
cannibalistic, feeding on juveniles seasonally (Dwyer et
al., 1987). Juvenile pollock is an important prey item
for other fish species, marine mammals, and seabirds
(Springer, 1992).
Redfish
Several redfish species are broadly distributed and common in arctic deep waters (100 to > 500 m).They are
slow-growing and long-lived species.The three common
species which are exploited in the northern North
Atlantic are Sebastes marinus, S. mentella, and S. viviparus,
but the latter, which is the smallest of the three, is not
caught in significant amounts (Frimodt and Dore, 1995;
Hureau and Litvinenko, 1986; Muus and Nielsen, 1999).
There are two distinct populations of S. mentella.
These vary in their habitat and fishery and are commonly
known as deep-sea redfish and oceanic redfish, respectively.The relationship between the two forms and the
extent to which the populations are separated spatially is
not clear (ICES, 2003).
Oceanic redfish are caught in the Irminger Sea during
the summer at depths of 100 to 200 m and water temperatures of 5 to 6 ºC. Mature fish feed on krill and
small fish such as capelin and herring and undertake
extensive feeding migrations.They mate in early winter
and the female carries the sperm and eggs, and later
larvae, which are born in April/May (Wourms, 1991).
The juveniles stay near the bottom, along the edge of the
continental shelf.
Greenland halibut
Greenland halibut is commercially important in the
North Atlantic and the Pacific, and is an important food
item for deep-feeding marine mammals (e.g., narwhal
and hooded seals) and sharks feeding on benthos such as
the Greenland shark (Somniosus macrocephalus). During
their first four to five years as immature fish in the eastern Bering Sea, the Greenland halibut inhabit depths to
487
Chapter 9 • Marine Systems
200 m. On the Atlantic side, immature fish occur mainly
between 200 and 400 m depth. Adults mainly occupy
slope waters between 200 and 1000 m or more (Alton
et al., 1988).Walleye pollock and squid are the main
prey items for Greenland halibut in the eastern Bering
Sea (Yang and Livingston, 1988).
Other flatfish
Other arctic flatfish include the long rough dab, which is
an abundant bottom-dweller in some parts of the Arctic
seas, including the Barents Sea (Albert et al., 1994).
On the Pacific side in the eastern Bering Sea, yellowfin
sole, flathead sole (Hippoglossoides elassodon), rock sole
(Pleuronectes bilineatus), Alaska plaice (Pleuronectes
quadrituberculatus), and arrowtooth flounder (Atheresthes
stomias) are important members of the groundfish community (Livingston, 1993).Yellowfin sole, Alaska plaice,
and rock sole consume mostly infaunal prey such as
polychaetes, clams, and echiuran worms.These fish are
distributed at depths generally less than 50 m.The highly
piscivorous (i.e., fish-eating) arrowtooth flounder is
found mostly on the outer shelf area, as is flathead sole,
which mainly consumes brittle stars.
9.3.1.6. Marine mammals and seabirds
Arctic marine mammals to a large extent escaped the
mass extinctions that affected their terrestrial counterparts at the end of the Pleistocene (Anderson, 2001).
Like fish, mammals and birds have the advantage of having great mobility and hence are good colonizers.Thus,
it is not surprising that these groups dominate the arctic
marine megafauna, represented both by resident and
migratory species.Their high abundance was a major
attractant for people to this region historically, becoming the mainstay of the diet of coastal communities
throughout the Arctic (Chapter 12) and later the subject
of extreme levels of commercial exploitation.The massive harvests of marine mammals and seabirds that
began in the 1600s and lasted for several hundred years
decimated many arctic populations. Bowhead whales
(Balaena mysticetus) and sea otters (Enhydra lutris) were
almost driven to extinction throughout the Arctic
(Burns et al., 1993; Kenyon, 1982), while the great auk
(Pinguinus impennis) and Steller sea cow (Hydrodamalis
gigas) did become extinct.Walruses (Odobenus rosmarus)
were all but extirpated in some arctic regions (Gjertz
and Wiig, 1994, 1995). Polar bears, all the great
whales, white whales (Dephinapterus leucas), and many
species of colonially nesting seabird were dramatically
reduced. Harvesting of marine mammals and seabirds is
now undertaken in accordance with management
schemes based on sustainability in most Arctic countries, although overexploitation of some species is still
occurring (CAFF, 2001).
Marine mammals are the top predators in the Arctic
other than humans.Virtually all large-scale taxonomic
groupings of marine mammals have arctic representatives (Perrin et al., 2002).
Polar bear
The polar bear, the pinnacle predator, has a circumpolar
distribution and is dependent on sea ice to provide for
most of its needs (Ferguson et al., 2000a,b; Mauritzen
M. et al., 2001; Stirling et al., 1993). Polar bears feed
almost exclusively on ice-associated seals (e.g., Lønø,
1970; Stirling and Archibald, 1977; Smith T., 1980).
Adult bears can swim quite long distances if required,
but mothers with cubs depend on ice corridors to move
young cubs from terrestrial denning areas to prime
hunting areas on the sea ice (Larsen T., 1985, 1986).
Pregnant females dig snow dens in the early winter and
give birth several months later.This requires a significant
depth of snow, thus females return year after year to
land sites that accumulate sufficient snow early in the
season. A mother that emerges from the den with her
young has not eaten for five to seven months (Ramsay
and Stirling, 1988).Therefore, successful spring hunting
is essential for the family’s survival and largely dictates
condition, reproductive success, and survival for all
polar bears (e.g., Stirling and Archibald, 1977). Factors
that influence the distribution, movement, duration, and
structure of sea ice profoundly affect the population
ecology of polar bears, not least due to their influence
on the principal prey species, ringed seal (Phoca hispida)
(Stirling and Øritsland, 1995; Stirling et al., 1999).
The global polar bear population is estimated at 22000
to 27 000 (IUCN, 1998).
Walrus
Walruses, like polar bears, are circumpolar, but with a
more disjointed distribution. Two sub-species are recognized: the Pacific walrus (Odobenus rosmarus divergens)
and the Atlantic walrus (O. r. rosmarus) (Fay, 1981,
1982). The global walrus population is estimated at
about 250 000, of which 200 000 belong to the Pacific
sub-species. The Atlantic walrus is distributed from the
central and eastern Canadian Arctic eastward to the
Kara Sea (Fay, 1981; Zyryanov and Vorontsov, 1999),
including several more or less well-defined sub-
Fig. 9.21.Walrus routinely use sea ice as a haul-out platform in
shallow areas where they feed on benthic fauna (photo supplied
by Kit Kovacs & Christian Lydersen, Norwegian Polar Institute).
488
populations (Andersen L. et al., 1998; Buchanan et al.,
1998; Outridge and Stewart, 1999).Walruses haul-out
on pack ice most months of the year (Fig. 9.21), using
land-based sites only during summer when sufficient sea
ice is unavailable.Walruses have a narrow ecological
niche, depending on the availability of shallow water
(< 80 m) with bottom substrates that support a high
production of bivalves (e.g., Born et al., 2003; Fisher
and Stewart, 1997;Wiig et al., 1993).
Seals
Ringed seals represent the “classical” arctic ice seal,
being uniquely able to maintain breathing holes in thick
sea ice.Thus, they can occupy areas far from sea-ice
edges, unreachable by other seal species.They are distributed throughout the Arctic, even at the North Pole
(Reeves, 1998).They number in the millions and this is
by far the most abundant seal species in the Arctic.
This species exclusively uses the sea ice for breeding,
molting, and resting (haul-out), and rarely, if ever,
moves onto land. Although quite small, ringed seals survive the thermal challenges posed by the arctic winter
by building lairs in the snow on top of sea ice, where
they rest in inclement weather and where they house
their new-born pups (e.g., Lydersen and Kovacs, 1999;
Smith T. and Stirling, 1975). Ice amphipods and fish
constitute much of their diet (e.g., Gjertz and
Lydersen, 1986;Weslawski et al., 1994).
The bearded seal (Erignathus barbatus) has a patchy
circumpolar Arctic distribution (Burns, 1981a).
This species breeds on drifting sea ice (Kovacs et al.,
1996) but occasionally hauls out on land during the summer.These animals are mostly benthic feeders, eating a
wide variety of fish, mollusks, and other invertebrates in
shallow areas. Some bearded seal populations are
thought to be resident throughout the year, while others
follow the retreating pack ice in summer, and then move
southward again in the late autumn and winter (Burns,
1967; Gjertz et al., 2000).The global population has not
been assessed but is thought to number in the hundreds
of thousands in the Arctic (Kovacs, 2002a).
Harbour seals (Phoca vitulina) have one of the broadest
distributions of the pinnipeds, from temperate areas as
far south as southern California to arctic waters of the
North Atlantic and into the Bering Sea in the Pacific
(Bigg, 1969; Rice, 1998).They are coastal, nonmigratory, and aggregate in small numbers on rocky
outcrops, beaches, or inter-tidal areas (Grellier et al.,
1996; Pitcher and McAllister, 1981).They are opportunistic feeders that eat a wide variety of fish species
and some cephalopods and crustaceans (Bowen and
Harrison, 1996). Harbour seals are not numerous in the
Arctic and several of the populations that live north of
the Arctic Circle are very small (Boveng et al., 2003;
Henriksen et al., 1996).
In the Atlantic sector of the Arctic, there are three additional phocid (i.e., true) seal species: harp seals, hooded
Arctic Climate Impact Assessment
seals (Cystophora cristata), and grey seals (Halichoerus
grypus). Harp seals are highly gregarious and migratory,
moving southward to three traditional breeding sites
(off the east coast of Canada, in the White Sea, and
between Jan Mayen and Svalbard) for the birthing period on pack ice in March (Lavigne and Kovacs, 1988).
Following the breeding season, harp seals from each
population move northward into molting sites before
dispersing into the Arctic for the rest of the year (e.g.,
Folkow and Blix, 1992). Adult harp seals feed mainly on
small marine fish such as capelin, herring, sculpins
(Cottidae), sand lance (Ammodytes americanus), and polar
cod (e.g., Lawson and Stenson, 1997; Lawsen et al.,
1995; Nilssen, 1995), and then on krill and amphipods.
The global population is thought to exceed seven million animals (Lavigne, 2002).
The hooded seal is a large, pack-ice breeding northern
phocid that ranges through a large sector of the North
Atlantic. In spring the adults gather to breed in two
main groups; one off the east coast of Canada and the
other either in Davis Strait or off East Greenland
depending on conditions (Lavigne and Kovacs, 1988).
Some weeks after breeding, the animals move northward into traditional molting areas before dispersing for
the summer and autumn, preferring the outer edges of
pack ice (Folkow and Blix, 1995).They feed on a variety of deep-water fishes including Greenland halibut
and a range of redfish species, as well as squid (Folkow
and Blix, 1999).The global population is very difficult
to estimate because hooded seals are difficult to survey,
but is certainly in excess of half a million animals
(Kovacs, 2002b).
Grey seals were historically abundant in Icelandic waters
and along the coastal regions of northern Norway and
northeastern Russia (Collett, 1912).They have been
depleted through hunting and government culling programs (Wiig, 1987) and in some areas have been extirpated (Haug et al., 1994). A crude estimate of the population of grey seals inhabiting northern Norway and the
Murman coast of Russia is 4500 (Haug et al., 1994).
Two additional ice-breeding seals that occur in the
Bering Sea are the spotted seal (Phoca largha) and the
ribbon seal (Phoca fasciata).The spotted seal breeds in
eight largely discrete birthing areas (Rice, 1998).
They have a coastal distribution during the summer and
early autumn, but migrate offshore to the edge of the ice
pack for the rest of the year (Lowry et al., 1998).
Spotted seals eat a wide variety of prey, including fish,
crustaceans, and cephalopods (Bukhtiyarov et al., 1984;
Lowry and Frost, 1981; Lowry et al., 1982).There are
no recent, reliable population estimates for this species
(Burns J., 2002). Ribbon seals are poorly known, packice breeders that congregate loosely in suitable areas of
thick pack ice in the North Pacific during the breeding
season (Rice, 1998).They do not haul out on land and
are assumed to be either pelagic or northern pack-ice
dwellers in summer (Burns J., 1981b).They are reported to eat crustaceans, fish, and cephalopods (Frost K.
Chapter 9 • Marine Systems
and Lowry, 1980; Shustov, 1965). Current data on population size are not available, but counts in the 1970s
revealed 100000 to 200 000 animals (Burns J., 1981b).
Northern fur seals (Callorhinus ursinus), Steller sea lions
(Eumetopias jubatus), and sea otters all breed terrestrially
on the Pribilof, Aleutian, Commander, and Kurile
Islands in the North Pacific.The latter two species breed
as far south as the Californian coast.
Whales
White whales, narwhal (Monodon monoceros), and bowhead whales live only in the high Arctic (see Perrin et
al., 2002) and are commonly found in ice-covered
waters where they use edges, leads, and polynyas to surface for breathing. Narwhal mainly occur within the
Atlantic region, while the others have patchy circumpolar ranges (Rice, 1998). All three migrate seasonally,
largely in relation to the northward retraction and
southward expansion of the seasonal sea ice.They prey
on small fishes, especially polar cod, although narwhal
also eat large quantities of cephalopods, and bowhead
whales consume a greater proportion of planktonic crustaceans than either of the other two species.
Other cetaceans also frequent arctic waters in summer,
but these remain in relatively ice-free waters and spend
most of the year elsewhere.These include white-beaked
dolphin (Lagenorhynchus albirostris) in the North Atlantic/
Barents/Greenland Sea and Dahl’s porpoise (Phocoenoides
dalli), right whales (Eubalaena glacialis), and grey whales
(Eschrichtius robustus) in the North Pacific/Bering Sea.
Harbour porpoise (Phocoena phocoena) and killer whales
(Orcinus orca) are among the toothed whales, and blue
whales (Balaenoptera musculus), fin whales (B. physalus),
minke whales (B. acutorostrata), humpback whales
(Megaptera novaeangliae), and sei whales (B. borealis) are
some of the baleen whales that are regular summer residents in arctic waters. Many of the great whales inhabit
the Bering Sea in summer.
Seabirds
Some of the largest seabird populations in the world
occur in the Arctic (e.g., Anker-Nilssen et al., 2000;
Boertmann et al., 1996; Gaston and Jones, 1998;
Norderhaug et al., 1977). Over 60 seabird species
frequent the Arctic, and over 40 breed there (Murray,
1998). Many species take advantage of the summer peak
in productivity and then overwinter elsewhere. In the
extreme, the red phalarope (Phalaropus fulicarius), the
northern phalarope (P. lobatus), and the Arctic tern
(Sterna paradisaea) spend the summer in the high Arctic
and overwinter in the southern hemisphere off Peru or
West Africa. In contrast, the spectacled eider (Somateria
fisheri), black guillemot (Cepphus grylle), ivory gull, and
northern fulmar (Fulmaris glacialis) stay in the Arctic all
year round, using the southern edges of the sea ice or
open water areas for feeding in winter. Polynyas are
extremely important winter habitats for these species
489
(Brown and Nettleship, 1981; Stirling, 1997). Most of
the global population of the threatened spectacled eider
overwinters in single-species flocks in a few polynyas in
a restricted area of the Bering Sea (Petersen et al.,
1999). In the rare instance that such polynyas freeze for
longer than a few days, mass mortalities can occur, altering population growth and affecting the species for
decades (Ainley and Tynan, 2003).
Most arctic seabird species nest in large colonies on
cliffs, which offers some protection from terrestrial
predators such as the Arctic fox (Alopex lagopus).
Other species, such as Sabine’s gull (Xema sabini), nest
on the ground on isolated islands, while others use
burrows either on sloping ground (e.g., little auk) or in
rock crevices (e.g., black guillemot). Several of the auk
species are among the most abundant nesting arctic
seabirds, including the little auk, thick-billed murre,
common murre (Uria aalge), and the Atlantic puffin
(Fratercula arctica). The blacked-legged kittiwake (Rissa
tridactyla) is the most numerous Arctic gull, but glaucous gulls (Larus hyperboreus) are also common. Arctic
terns are abundant in some regions, as are common
eider (Somateria mollissima). The Pribilof Islands, in the
eastern Bering Sea, are breeding sites for large numbers of piscivorous seabirds including black-legged and
red-legged kittiwake (R. brevirostris), and common and
thick-billed murre.
The foraging ecology and energetics of seabirds have
been studied quite extensively in many arctic areas
(e.g., Barrett et al., 2002; Bogstad et al., 2000; Croxall,
1987; Montevecchi, 1993) and despite species differences, some basic patterns are evident. Most arctic
seabirds forage on small fish and large copepods, primarily in the upper and mid-water column (e.g., Garthe,
1997; Montevecchi and Myers, 1996). Foraging is often
concentrated in frontal areas or at ice edges, where
convergences can concentrate marine zooplankton
(Hunt et al., 1999). Eiders are the exception, foraging
in shallow water for benthic animals, particularly echinoderms and mollusks. Polar cod is an extremely important prey item for most arctic seabirds, but other small
school-forming species (such as capelin and herring in
the Barents Sea) are extremely important regionally.
Surface feeders (e.g., kittiwakes and fulmars) forage onthe-wing, dipping into the water to capture prey, or
feed while sitting on the water surface when prey concentrations are high and available within the top few
centimeters.The alcids and related species dive to considerable depths (Schreer and Kovacs, 1997) in search
of prey.They also travel considerable distances and can
stay underwater for relatively extended periods, allowing them to take advantage of fish and invertebrates that
reside under the sea ice, e.g., euphausiids, amphipods,
and polar cod (Bradstreet, 1980). As foragers, most
seabird species are generalists responding to changing
spatial and temporal prey availability (e.g., Montevecchi
and Myers, 1995, 1996). However, the little auk and
the Bering Sea least auklet (Aethia pusilla), which specialize on calanoid copepods, have a narrow foraging
490
niche (Karnovsky et al., 2003). Ivory gulls are one of
the most specialized of the arctic seabirds, living in
association with pack ice for most of their lives and
breeding on exposed mountain peaks in glaciated areas
of the high Arctic. One of their favorite foods is the
blubber of marine mammals, acquired by scavenging on
carcasses.Yet, similar to many arctic seabirds, a large
part of their diet comprises polar cod and other small
fish and invertebrates.The small fish and invertebrates
are usually taken after being washed onto the surface of
ice floes and edges (Haney and MacDonald, 1995;
Hunt et al., 2002). Ross’ gulls (Rhodostethia rosea) also
perform this type of foraging behavior.
In addition to seabirds that are strictly marine feeders,
skuas, a host of arctic shorebirds, and some ducks
(beside the marine feeding eiders), geese, and divers also
spend time at sea.
9.3.2. Physical factors mediating ecological
change
There are a variety of means by which climate can affect
marine biota.These can be direct or indirect. Examples
of the former include temperature, which affects the
metabolism and distribution of organisms; wind-driven
currents, which transport planktonic organisms; sea ice,
which provides higher predators with a platform for
birthing or foraging; and snow, which allows for the
construction of overwintering lairs. An indirect means
by which climate can affect biota is through those climate processes that affect nutrient levels and surface
mixed layer depth, which in turn influence primary and
secondary productivity, and ultimately food availability
to the upper trophic levels. Figure 9.22 illustrates those
Fig. 9.22. Those climate
parameters that may impact
upon the marine food chain, both
directly and indirectly (based on Stenseth
et al., 2002).
Arctic Climate Impact Assessment
climatic factors that can influence the Barents Sea
ecosystem, both directly and indirectly. Similar interactions are also valid for other marine areas.The timing of
sea-ice formation and melt-back, as well as temperature, can influence the timing, location, and intensity of
biological production.
Of the main factors mediating ecological change in the
Arctic, the distribution of sea ice is most important.
Sea ice, together with its snow cover, can reduce light
levels at the water surface to those observed at 40 m or
more in an ice-free water column. Primary production
in the water column below the sea ice is thus severely
light-limited. However, the sea ice is of major importance as a habitat for marine mammals and the location
of ice edges is extremely important to seabirds.
Moreover, the melting of sea ice in spring results in a
stratification of the upper water column that promotes
primary production.
The flow of warm water into the Arctic and the mixing
and stratification of the water column are also important.The flow of warm water into the Arctic is important for the northward transport of zooplankton populations, such as the transport of Calanus finmarchicus
from the Norwegian Sea to the Barents Sea.The mixing
and stratification of the water column is determined by
the opposing forces of wind and freshwater supply
(Sakshaug and Slagstad, 1992).
Generally, sea surface temperatures in the Arctic are
low, but true ectotherms (previously called “coldblooded organisms”, i.e., their body temperatures vary
with the temperature of their surroundings) can grow
at the freezing point of seawater. In principle, organisms
491
Chapter 9 • Marine Systems
grow faster the higher the temperature up to an optimum range, which can be from 8 to 15 ºC for species
living in the Arctic. A temperature increase of 10 ºC
would roughly double the biochemical rates, and thus
the growth rate.
9.3.2.1. Primary production
The effect of temperature on primary production is
largely indirect, through its effect on sea-ice cover and
the mixing characteristics of the water column.The
direct effect of rising temperature, through its effect on
growth rate, would primarily shorten the spring bloom
by two to five days, and perhaps slightly increase regenerative production. New production would be likely to
increase because it is primarily regulated by the vertical
nutrient supply.
Limiting factors
Potentially limiting nutrients in the Arctic are nitrogen
or phosphorus, and for diatoms, also silicate. Iron controls primary production by retarding nitrate uptake in
the Northeast Pacific and the deep regions of the eastern Bering Sea (Frost and Kishi, 1999). It has also been
observed to limit temporarily spring bloom production
in the Trondheimsfjord (Õzturk et al., 2002). Silicate,
which like nitrogen is also affected by iron control,
limits diatom growth in some areas of the Barents Sea
(Nielsen and Hansen, 1995;Wassmann et al., 1999).
Because arctic rivers are rich in nitrogen and silicate but
poor in phosphate, phosphorus limitation is likely in and
around some estuaries.
Most microalgae are probably not limited by CO2
because they contain the enzyme carbonic acid anhydrase, which can furnish CO2 from bicarbonate (Anning
et al., 1996; Goldman, 1999; Reinfelder et al., 2000;
Sültemeyer, 1998). Production of the coccoliths that
cover coccolithophorids also furnishes CO2.
In nature, an increase in the supply of the limiting
nutrient typically causes a predominance of largecelled species. A sufficient supply of iron and silicate
favors large bloom-forming diatoms that enhance the
sedimentation rate.
Nutrient status in winter differs strongly between arctic
regions, reflecting the nutrient concentration of the
deep or intermediate waters that supply nutrients to
the upper layers.This is related to the increasing age of
the intermediate and deep waters along their THC
route.Thus, Atlantic water (which is relatively young)
exhibits the lowest concentrations and the deep Bering
Sea water (which is older) the highest (Table 9.7).
However, because mixing between surface and intermediate water in the Bering Sea is low owing to the high
stability of the water column, surface water concentrations in the Bering Sea are actually lower than in the
Southern Ocean.
Owing to the high winter nutrient concentrations on
the Bering Shelf and in the southern Chukchi Sea, productivity in these regions can be two to four times higher than in the Barents Sea (Coachman et al., 1999;
Grahl et al., 1999; Olsen et al., 2003; Schlosser et al.,
2001; Shiomoto, 1999;Walsh J.J. and Dieterle, 1994).
Because of its distance from shelf-break upwelling,
however, the northeast coastal Alaskan Shelf exhibits
low nutrient levels, on a par with those of the Atlantic
sector (Coachman and Walsh, 1981).
North of 85º N, severe light limitation restricts primary
production in the water column to a six-week growth
season, which is initiated by the melting of the snow on
top of the sea ice in July (English, 1961; Kawamura,
1967; Usachev, 1961). In multi-year ice, the dense biomass on the underside of the sea ice is also strongly
light-limited, but in melt ponds, intense small-scale
production can occur (Booth and Horner, 1997;
Gosselin et al., 1997; Sherr et al., 1997). Productivity
in the multi-year ice in the shelf seas is an order of magnitude greater than in first-year ice, presumably because
of a greater nutrient supply, however, the latter generally has very low levels of primary production (Andersen
O., 1989; Gradinger, 1996; Juterzenka and Knickmeier
(1999). In polynyas, early melting of sea ice can prolong
the growth season by three months (Smith et al., 1997;
Suzuki et al., 1997).
Timing
In seasonally ice-covered areas, the onset of the phytoplankton bloom is usually determined by the timing of
the breakup of the sea ice (Alexander and Niebauer,
1981; Braarud, 1935; Gran, 1931; Head et al., 2000;
Stabeno et al., 2001;Wassmann et al., 1999).Typically,
an ice-edge bloom unfolds in a 20 to 100 km wide belt
south of the northward-retreating ice edge.The bloom
develops rapidly because water from the melting sea ice
establishes a shallow wind-mixed layer of 15 to 35 m
depth.The ice-edge bloom generally begins in mid-
Table 9.7. Winter nutrient levels (mmol/m3) in the Barents Sea, the Bering Sea (surface and at depths >300 m), and the Southern
Ocean (the Ross and Scotia Seas) (Sakshaug, 2003).
Barents Sea
(Atlantic Water)
Bering Sea
(surface water)
Bering Sea
(deep water)
Ross Sea
(surface water)
Scotia Sea
(surface water)
10–12
10–30
45
25
30
Phosphate
0.85
1.0–2.0
3.5
2
2
Silicate
6–8
25–60
100–300
50–60
100
Nitrate
492
Arctic Climate Impact Assessment
plies from upwelling or strong tidal mixing can maintain
high levels of production, as observed in both the
Barents and Bering Seas.
Fig. 9.23. The relative timing of the sea-ice retreat and the
spring bloom in the Bering Sea (Hunt et al., 2002).
April to early May at the southernmost fringes of the
first-year ice, both in the Barents and Bering Seas and in
the Labrador/Newfoundland region (Alexander and
Niebauer, 1981). In the Bering Sea, years with early
sea-ice retreat (i.e., starting in winter) have delayed
blooms as the blooms cannot begin until light levels and
stratification are sufficient to support them.Thus, in the
Bering Sea, early ice retreat implies a late bloom, while
late ice retreat implies an early bloom (Fig. 9.23). In the
Barents Sea, however, very cold winters that result in a
more southern distribution of the ice edge (with sea ice
forming over Atlantic water to the south of the Polar
Front) can have very early blooms because once melting
starts the sea ice melts rapidly from below. Near multiyear ice in the Arctic Ocean, melting is delayed until
July, resulting in a short growing season (Strass and
Nöthig, 1996), and in the ice-filled regions of the
Greenland Sea, late melting can delay the ice-edge
bloom until late May as far south as the Denmark Strait
(Braarud, 1935).
Impact of physical and chemical forcing
After the ice-edge bloom, primary production becomes
very low in the strongly stratified waters, with nutrients
near the limit of detection (Fujishima et al., 2001;
Taniguchi, 1999;Whitledge and Luchin, 1999). In ironcontrolled waters, however, there are still high nitrate
concentrations in the water column. Near the pycnocline (i.e., the region of strongest vertical density gradient) in arctic waters, a restricted vertical supply of
nutrients enables the development of a 3 to 10 m thick
chlorophyll maximum layer that is strongly light-limited
(Heiskanen and Keck, 1996; Luchetta et al., 2000;
Nielsen and Hansen, 1995).
In ice-free waters, it is the onset of thermally-derived
stratification that determines the timing of the spring
bloom.The blooms deplete the upper layer nutrient
concentrations. In the Norwegian Sea and the Atlantic
(southwest) part of the Barents Sea, thermally-derived
water-column stability is established in late May to early
June (Halldal, 1953; Olsen et al., 2003; Paasche, 1960;
Steemann-Nielsen, 1935). In ice-free estuaries and
fjords, and waters surrounding Iceland, freshwaterinduced stability triggers a bloom in late March to late
April (Gislason and Ástthórsson, 1998; Braarud 1935;
Sakshaug, 1972). On continental shelves, nutrient sup-
Pulsed (wind-driven) nutrient supplies associated with
passing atmospheric low pressure systems often result
in small blooms, however, in arctic waters, the pycnocline is usually too strong to allow a temporary deepening of the surface mixed layer and so bring in nutrients
from sub-pycnocline waters (Overland et al., 1999b;
Sakshaug and Slagstad, 1992). In the Bering Sea,
storms, especially those in mid- to late May, lead to a
large nutrient supply and prolonged primary production, whereas a weakening of the summer winds lowers
the nutrient supply for continuing summer blooms
(Stabeno et al., 2001).
Wind-driven nutrient supply supports about 50% of the
annual primary production in the southern Barents Sea
influenced by the Atlantic inflow and this supply exhibits
no clear temporal trend. In the northern Barents Sea,
however, primary production clearly follows variations
in the NAO index, being high following NAO+ years –
which correspond to years with relatively warm winters
and little sea ice (Slagstad and Støle Hansen, 1991).
The higher production is a result of the reduced sea-ice
cover allowing a larger area of the northern Barents Sea
exposure to the strong light levels.
For the outer and mid-shelf domains of the Bering Shelf,
the wind-driven nutrient supply supports 30 to 50% of
the annual primary production, depending on the frequency and intensity of summer storms. Interdecadal
trends in chlorophyll-a (Chl-a) concentration were
observed by Sugimoto and Tadokoro (1997) in eastern
Bering Sea regions deeper than 150 m but it is not
known if these resulted in changes in either the spring or
overall annual primary production levels.The few available data suggest that the summer contribution to annual
new production may have decreased in recent years with
the advent of calmer, sunnier summers. Coastal domain
production is not thought to vary much between years.
On the northern shelf, variability in phytoplankton biomass and production has been linked to variability in the
transport of the Bering Slope Current that leads to the
Anadyr Stream (Springer et al., 1996).
Distribution of primary production
The distribution of primary production in the Arctic
provides a good illustration of the effects of physical and
chemical forcing (Table 9.8). Annual primary production
in the deep Arctic Ocean, the lowest known for any sea,
reflects the high incidence of multi-year sea ice with
snow, and thus the short growing season (Cota et al.,
1996; Gosselin et al., 1997). Nevertheless, present estimates are far higher than the pre-1990 estimates, which
ignored production within the multi-year ice.
Due to the inflow of Atlantic and Bering Sea water, the
Barents Sea and a patch of the Chukchi Sea, respectively,
493
Chapter 9 • Marine Systems
have enhanced annual production (Hegseth, 1998; Noji
et al., 2000; Sakshaug and Slagstad, 1992; Smith et al.,
1997;Walsh J.J. and Dieterle, 1994). In the other
Siberian shelf areas, annual production is low due to
multi-year ice hindering wind-driven upwelling of
nutrient-rich deep water along the shelf break, leaving
re-mixing of nutrient-poor shelf water and phosphoruspoor river water as the main nutrient sources.
upwelling of extremely nutrient-rich water along the shelf
break and the Anadyr Current (Hansell et al., 1993;
Nihoul et al., 1993; Springer et al.1996;Walsh J.J. et al.,
1989). In the deep eastern Bering Sea, annual primary productivity is similar to, or slightly higher than that in the
Barents Sea (Maita et al., 1999; Springer et al., 1996).
In Atlantic water, annual primary production is high, in
part due to wind-driven episodic upwelling in summer
(Fig. 9.24) (Olsen et al., 2003; Sakshaug and Slagstad,
1992).The most productive area is the Bering Shelf where
a highly productive “greenbelt” is associated with the
Although the zooplankton database is small, it suggests
that growth rates of calanoid copepods and other crustaceans are dependent on temperature such that the time
from hatching to the next adult generation is shorter in
warmer water.The growth rate, however, is also very
9.3.2.2. Secondary production
Table 9.8. Estimated levels of primary production, defined as the integrated net photosynthesis (corrected for respiration) over at
least 24 hours, plus the grazing rate of mesozooplankton (compiled by Sakshaug (2003) on the basis of data from several authors).
Area
(103 km2)
Central Deep Arctic
4489
Arctic shelves
5052
Barents Sea
1512
Barents north slope
Total primary
production
(g C/m2)
>11
New primary
production
(g C/m2)
<1
Grazing rate of
zooplankton
(g C/m2)
-
Total primary
production
(Tg C)
>50
32
<20 –200a
8
10
279
<8 –100
15 –50
136
-
35
16
-
-
90
25
6
-
2
Kara Sea
926
30 –50
7 –12
-
37
Laptev Sea
498
25 –40
6 –10
-
16
East Siberian Sea
987
25 –40
6 –10
-
30
Chukchi Sea
620
20 –>400
5 –>160
Beaufort Sea
178
30 –70
7 –17
-
8
White Sea
Lincoln Sea
7 –>90
42
64
20 –40
5 –10
-
3
Other (Canadian Arctic)
182
20 –40
5 –10
-
5
Northeast Water Polynya
<50
20 –50
13 –32
-
-
-
150
70
-
-
Total Arctic Ocean
North Water Polynya
9541
>26
<5
-
>329
Atlantic sector
5000
97
50
-
483
Baffin Bay
690
60 –120
25 –50
-
62
Hudson Bay
820
50 –70
25 –35
-
49
Greenland Sea
600
70
40
-
42
Labrador Sea
1090
100
45
-
110
Norwegian Sea
1400
80 –150
100 –200b
35 –65
-
160
45 –90
-
60
120
55
-
>300
Icelandic Sea
West Spitsbergen
Bering Shelf
Alaskan coastal
400
1300
>230
-
-
-
50 –75
<20
32 –50
-
Siberian coastal
-
>400
>160
>90
-
Middle, outer shelf
-
150 –175
30 –50
35 –70
-
Shelf Break
-
450 –900
170 –360
-
-
Bering oceanic
1000
60 –180
-
-
155
Okhotsk Sea
1600
100 –200
-
-
Global, ocean
362 000
110
-
-
240
40000c
Global, land
148 000
405
-
-
60 000
aHighest
values occur where topography and currents cause continuous nutrient supply in Atlantic sector, lowest values in northernmost part; bproduction to the south
and east of Iceland (i.e., in Atlantic water) is four times that to the north and east; cplus 5000 Tg benthic (seaweed) carbon production and 4000 to 7000 Tg of dissolved
organic carbon.
494
Arctic Climate Impact Assessment
nutrients.Thus, sedimentation rates are lower when
there is a match between phytoplankton and zooplankton. Grazing and sedimentation are thus competing
processes and both are strongly dependent on largecelled new production.
Fig. 9.24. Estimated (a) primary production and (b) wind
speed for the Atlantic water of the Barents Sea in summer
1998 (wind data and hind-cast model data from the Norwegian
Meteorological Institute; production model by D. Slagstad,
Norwegian University of Science and Technology).
dependent on food supply. More specifically, the growth
rate depends on the extent to which the fat-storage organs
of the zooplankton are filled to capacity, which in turn is
highly dependent on phytoplankton availability (Hygum et
al., 2000). Nauplii (early-stage larvae) and early-stage
copepodite stages can be food-limited at < 0.5 to 0.7 mg
Chl-a/m3 (Campbell et al., 2001).This level of concentration is common in waters which receive a low supply of
new nutrients due to strong stratification and are therefore dominated by low levels of regenerative primary production (Båmstedt et al., 1991; Booth et al., 1993; Hirche
and Kwasniewski, 1997; Irigoien et al., 1998).
In Atlantic water, late development of copepodite stages
of Calanus finmarchicus is a good match with the late and
relatively long-lasting phytoplankton blooms that occur
in mid-May to June (Dalpadado and Skjoldal, 1991;
Skjoldal et al., 1987). But it is mismatched with the timing of the initial blooms, which is presumably one of the
main reasons why C. finmarchicus is allochthonous in the
Barents Sea (Melle and Skjoldal, 1998).The mismatch is
greatest in very cold winters when sea ice covers
Atlantic water and the blooms are typically four to six
weeks earlier than usual (Olsen et al., 2003).The reason
that the blooms are earlier than usual in such winters is
because once melting starts the sea ice over the Atlantic
water melts rapidly from below.This can result in the
phytoplankton bloom being too early for the zooplankton, thus causing a mismatch in timing with the peak in
zooplankton (Olsen et al., 2003; Skjoldal and Rey,
1989). Such years can have very low levels of secondary
production. Although not strongly correlated, a match
seems likely to occur in Atlantic water with mixing
depths greater than 40 m, while a mismatch seems likely
with mixing depths less than 40 m.
In the generally ice-free Norwegian fjords, the major
phytoplankton blooms occur from February to early
April, depending on latitude and the extent of freshwater-induced stability. As the major zooplankton peak
does not occur until April or May, the zooplankton must
feed on the secondary summer and autumn blooms
(Wassmann, 1991). Owing to the extreme mismatch,
almost all of the early spring bloom sinks to the bottom
of the fjord.
Match versus mismatch
The concept of match and mismatch is very important in
food-web energy transfer. A match implies that the predators are located in the same space and time as their prey
and a mismatch when they are not. In principle, grazing
by zooplankton is efficient when a large and growing
population of zooplankton coincides with a phytoplankton bloom. Production of mesozooplankton is small in
areas characterized by a mismatch.This is a highly nonlinear event because phytoplankton blooms and zooplankton swarms are episodic.To ensure a match higher in the
food web, fish and zooplankton populations also need to
coincide in time and space. Physical oceanographic conditions, such as temperature, salinity, stratification, mixing,
and currents can influence the timing and location of the
plankton production and biomass as well as the eggs and
larvae of fish and invertebrates. In this sense, oceanographic conditions play a large role in determining the
extent of a match or mismatch between trophic levels.
Non-grazed phytoplankton sink except for most of the
(nanoplankton) fraction that is based on regenerated
9.3.2.3. Fish
Climate fluctuations affect fish directly, as well as by causing changes in their biological environment (i.e., in relation to predators, prey, species interactions, and disease).
Direct physiological effects include changes in metabolic
and reproductive processes. Climate variability may influence fish population abundance, principally through
effects on recruitment.Variability in the physical environment may also affect feeding rates and competition by
favoring one species relative to another, as well as by
causing changes in the abundance, quality, size, timing,
spatial distribution, and concentration of prey.Variability
in the physical environment also affects predation
through influences on the abundance and distribution of
predators. Fish diseases leading to a weakened state or
even death may also be environmentally triggered.
Particular temperature ranges may, for instance, be more
conducive to allowing disease outbreaks.While water
temperature is typically the main source of environmental impact on fish, salinity and oxygen conditions, and
ocean mixing and transport processes are also important.
Chapter 9 • Marine Systems
Reproduction, recruitment, and growth
The physical environment affects the reproductive cycle
of fish. For example, ambient temperatures may determine the age at sexual maturity. Atlantic cod off
Labrador and the northern Grand Banks mature at 7 yr,
while in the warmer waters off southwest Nova Scotia
and on Georges Bank they mature at 3.5 and 2 yr,
respectively (Drinkwater, 1999). Reproduction is typically temperature-dependent with gonad development
occurring more quickly under warm conditions.
Thus, temperature determines the time of spawning.
Examples of low temperatures resulting in delayed
spawning have been observed off Newfoundland, both
in capelin (Nakashima, 1996) and Atlantic cod
(Hutchings and Myers, 1994).
Understanding variability in recruitment (the number of
young surviving long enough to potentially enter the
fishery) has long been a prime issue in fisheries science.
Evidence of changes in fish abundance in the absence of
fishing suggests environmental causes. Following spawning, cod eggs and later young stages are generally distributed within the upper water column before they settle toward the bottom as half-year olds.The strength of a
year-class is to a large degree determined during the
first six months of life (Helle et al., 2000; Hjort, 1914;
Myers and Cadigan, 1993; Sundby et al., 1989); life
stages during which ocean climate may have a decisive
effect (Cushing, 1966; De Young and Rose, 1993;
Dickson and Brander, 1993; Ellertsen et al., 1989;
Ottersen and Sundby, 1995; Sætersdal and Loeng,
1987).The effects of temperature on recruitment of
Atlantic cod across its entire distribution range were
examined by Ottersen (1996) and Planque and Fredou
(1999). Populations inhabiting areas at the lower end of
the overall temperature range of the species (i.e.,West
Greenland, Labrador, Newfoundland, and the Barents
Sea) had higher than average recruitment when temperature anomalies were positive, while recruitment to populations occupying the warmer areas (e.g., the Irish and
North Seas) seemed better with negative temperature
anomalies. For populations inhabiting regions with midrange temperatures the results were inconclusive.
The recruitment of Norwegian spring-spawning herring
is also linked to variability in water temperature
(Toresen and Østvedt, 2000; see section 9.3.3.3).
The pelagic ecosystem in the southeastern Bering Sea
may, according to the recently published Oscillating
Control Hypothesis, alternate between primarily
bottom-up control in cold regimes and primarily topdown control in warm regimes (Hunt and Stabeno,
2002; Hunt et al., 2002).The timing of spring primary
production in the southeastern Bering Sea is determined
predominately by the timing of sea-ice retreat. Late
retreat leads to an early, ice-associated bloom in cold
water, whereas no ice, or early retreat, leads to an openwater bloom in warm water. In years when the spring
bloom occurs in cold water, low temperatures limit the
production of zooplankton, and the survival of larval and
495
juvenile fish, and their recruitment into the populations
of large piscivorous fish, such as walleye pollock, Pacific
cod, and arrowtooth flounder. Continued over decadal
scales, this will lead to bottom-up limitation and a
decreased biomass of piscivorous fish. Alternatively, in
periods when the bloom occurs in warm water, zooplankton populations should grow rapidly, providing
plentiful prey for larval and juvenile fish. Abundant zooplankton will support strong recruitment of fish and will
lead to abundant predatory fish that control forage fish,
including in the case of walleye pollock, their own juveniles (Hunt and Stabeno, 2002; Hunt et al., 2002).
Because fish are ectothermic, temperature is the key
environmental factor. Individual growth is the result of a
series of physiological processes (i.e., feeding, assimilation, metabolism, transformation, and excretion) whose
rates are all controlled by temperature (Brett, 1979;
Michalsen et al., 1998). Brander (1994, 1995) examined
17 North Atlantic cod populations and showed that
mean bottom temperature accounted for 90% of the
observed (ten-fold) difference in growth rates between
populations. Higher temperatures led to faster growth
rates over the temperature range experienced by these
populations. Growth rate decreases at higher temperatures and the temperature for maximum growth
decreases as a function of size (Björnsson, 2001).
The biomass of zooplankton, the main food for larval
and juvenile fish, is generally greater when temperature
is high in the Norwegian and Barents Seas (Nesterova,
1990). High food availability for the young fish results
in higher growth rates and greater survival through the
vulnerable stages that determine year-class strength.
Temperature also affects the development rate of fish
larvae directly and, thus, the duration of the highmortality and vulnerable stages decreases with higher
temperature (Blood, 2002; Coyle and Pinchuk, 2002;
Ottersen and Loeng, 2000; Ottersen and Sundby,
1995). Also, in the Barents Sea, mean body size as halfyear olds fluctuates in synchrony for herring, haddock,
and Northeast Arctic cod and the length of all three is
positively correlated with water temperature.This indicates that these species, having similar spawning and
nursery grounds, respond in a similar manner to largescale climate fluctuations (Loeng et al., 1995; Ottersen
and Loeng, 2000). For Barents Sea cod, mean lengthsat-age for ages 1 to 7 are greater in warm periods
(Dementyeva and Mankevich, 1965; Michalsen et al.,
1998; Nakken and Raknes, 1987).
For 2- and 3-year old Barents Sea capelin, Gjøsæter and
Loeng (1987) found positive correlations between temperature and growth for different geographical regions
and for different years. Changes in water temperature
through altered climate patterns may also affect
predator–prey interactions. In the Barents Sea, the
increase in basic metabolic rates of Northeast Arctic cod,
associated with higher temperatures, can result in a rise
in the consumption of capelin by 100 000 tonnes per
degree centigrade (Bogstad and Gjøsæter, 1994).
496
Distribution and migration
Temperature is one of the main factors, together with
food availability and suitable spawning grounds, which
determines the large-scale distribution pattern of fish.
Because most fish species (and stocks) tend to prefer a
specific temperature range (Coutant, 1977; Scott J.,
1982), long-term changes in temperature can lead to
expansion or contraction of the distribution range of a
species.These changes are generally most evident near
the northern or southern boundaries of the species
range; warming results in a northward shift and cooling
draws species southward. For example, in the Barents
Sea, temperature-related displacement of Northeast
Arctic cod has been reported on interannual time scales
as well as at both small and large spatial scales. In warm
periods, cod distribution is extended eastward and
northward compared to colder periods when the fish
tend to concentrate in the southwestern part of the
Barents Sea (Ottersen et al., 1998). Capelin distribution
also responds to changes in water temperature both in
the Barents Sea (Sakshaug et al., 1992) and off
Newfoundland and Labrador.
The relatively high interannual stability of residual
currents, which prevail in most regions, maintains the
main features of larval drift patterns from spawning
area to bottom settlement area for each population, and
consolidates differences between populations. Interannual variation is introduced through changes in largeand regional-scale atmospheric pressure conditions.
These affect winds and upper ocean currents, which in
turn modify drift patterns of fish larvae and introduce
variability in water temperature and the availability of
prey items.While a long and unrestricted larval drift is
important for some cod populations, such as those in
the Barents Sea and the Icelandic component at West
Greenland, recruitment to populations residing in small
and open systems depends on larval retainment and the
avoidance of massive advective losses (Ottersen, 1996;
Sinclair M., 1988).
Many species that undertake seasonal migrations appear
to use environmental conditions as cues. For example,
April sea surface temperatures and sea-ice conditions in
the southern Gulf of St. Lawrence determine the average arrival time of Atlantic herring on their spawning
grounds (Lauzier and Tibbo, 1965; Messieh, 1986).
Sea-ice conditions also appear to control the arrival
time in spring of Atlantic cod onto the Magdalen
Shallows into the Gulf of St. Lawrence (Sinclair A. and
Currie, 1994). Atlantic salmon arrive earlier along the
Newfoundland and Labrador coasts during warmer
years (Narayanan et al., 1995).
The Norwegian spring-spawning herring stock, inhabiting the Norwegian and Icelandic Seas, is highly migratory. Larvae and fry drift into the Barents Sea, while adults
undergo substantial feeding and spawning migrations
(Holst J. et al., 2002). Since around 1950, biomass and
migration patterns have fluctuated dramatically.While
Arctic Climate Impact Assessment
these shifting migration patterns may be dominated by
density-dependence, environmental conditions are also
likely to have been important (Holst J. et al., 2002).
In the Bering Sea, warmer bottom temperatures lead to
the distribution of adult walleye pollock, Greenland turbot, yellow Irish lord (Hemilepidotus jordani), and thorny
sculpin (Icelus spiniger) being more widespread on the
shelf, while Arctic cod are restricted to the cold pool
(Wyllie-Echeverria and Wooster, 1998).
The combination of environmentally influenced distribution patterns and politically restricted fisheries patterns
can have pronounced impacts on the availability of fish
to fishers. For instance, most of the Barents Sea is under
either Norwegian or Russian jurisdiction, but there is a
small, disputed region of international waters in the center.This area is aptly named the “Loophole” and at times
it is the site of extensive fishing activity by the international fishing fleets. Most fishing occurs in the southern
part of the Loophole, where in warmer years several
species of all sizes are found throughout the year.
However, in colder years there may be hardly any fish in
the area for prolonged periods.The reason for this pattern is that the southern part of the Loophole lies to the
south of the Polar Front so that even relatively small
east–west movements of the water masses may result in
large temperature changes. In cold years, the Polar Front
is displaced farther south and west than the Loophole.
The fish move in order to remain within the warmer
water, thereby making them unavailable to the international fishing fleets (Aure, 1998).The movement of the
Polar Front is most pronounced between warm and cold
years in the Barents Sea as a whole, but movements may
also occur on time scales of weeks.
9.3.2.4. Marine mammals and seabirds
Some important predator–prey match–mismatch issues
also occur with higher predators.The timing of reproduction in many seal species is thought to match the
availability of large zooplankton and small fishes at the
time when pups are weaned and when polar bear den
emergence occurs during the peak reproductive period
of their favorite prey, ringed seal. Likewise, invertebrate
or fish species must be available in the upper parts of
the water column when seabird young commence selffeeding. Higher predators might not easily track shifts in
the production of zooplankton and fish, which are more
directly influenced by temperature.
Factors that influence the distribution and annual duration of sea ice or snow availability in the spring can
potentially have profound influences on the population
ecology of some arctic marine mammals. Sea ice is the
breeding habitat for all pagophilic (i.e., ice-loving) seal
species and it is the primary hunting platform for polar
bear. Changes in the time of formation or disappearance
of seasonal sea ice, in the quality of the sea ice, and in
the extent of total coverage of both seasonal and multiyear ice could all affect ice-dependent species. Snow
497
Chapter 9 • Marine Systems
cover is very important for polar bears and ringed seals
and changes in average snow depth or duration of the
snow season could affect their breeding success.
Walruses appear to follow an annual migratory pattern,
moving with the advance and retreat of the sea ice in
most parts of their range (Fay, 1981, 1982;Wiig et al.,
1996). However, this may be due to the sea ice blocking
access to shallow-water feeding areas, rather than to it
serving as an essential habitat element.
The primary requirement for seabirds in the Arctic is
suitable breeding cliffs near abundant prey sources.
If ice edges or frontal regions shift such that the distance
between these highly productive areas and the nesting
areas becomes too great, the mismatch would have serious consequences for seabirds.
9.3.3. Past variability – interannual to
decadal
Previous data collections combined with present-day
models shows that climate variability is very likely to
have influenced population parameters of marine organisms, especially fish (section 9.3.2.3).Water temperature undoubtedly affects species composition in different
areas, as well as the recruitment, growth, distribution,
and migration of different fish species. However, most of
the relationships between water temperature and population variables are qualitative and few of those discussed
here can be quantified.
9.3.3.1. Plankton
There are few long time series for phytoplankton in the
Arctic. Exceptions include (1) datasets covering 20 years
or more for Icelandic waters (Thordardóttir, 1984) and
Norway (Oslofjord,Trondheimsfjord; Johnsen et al.,
1997); (2) a program undertaken during the 1990s to
monitor harmful algae along the Norwegian coast (Dahl
E. et al., 1998, 2001); and (3) zooplankton data provided by the Continuous Plankton Recorder, which has
been used in much of the North Atlantic between 50º
and 65º N for over fifty years (Johns et al., 2001).This
has generated one of the most detailed records of seasonal, interannual, and decadal variability in zooplankton
to date. Sampling in the Northwest Atlantic is less complete but extends across the Labrador Sea to the Grand
Banks, the Scotia Shelf, and the Gulf of Maine.
The copepod Calanus finmarchicus contributes > 50% of
the biomass of sampled plankton in the North Atlantic.
Its population has declined substantially in the Northeast
Atlantic since the early 1960s (Fig. 9.25), apparently as a
function of variation in the NAO (Planque and Batten,
2000). Also, recent and persistent declines seem to be
related to a low-frequency change in the volume of
Norwegian Sea Deep Water, where Calanus finmarchicus
overwinters (Heath et al., 1999). Figure 9.26 shows
that, in contrast, the arctic species Calanus glacialis
extended its range in the Northwest Atlantic during the
1990s as a consequence of the extension of cold
Labrador Slope Water (Johns et al., 2001).
Historical time series of zooplankton biomass suggest a
decrease in biomass between 1954 and 1995 in the
oceanic and outer shelf regions of the eastern Bering Sea
(Sugimoto and Tadokoro, 1998). However, when the data
are separated by shelf region, such a trend is not apparent
(Napp et al., 2002). Inshore sampling of Calanus marshallae indicates a much higher biomass in the late 1990s
compared to the early 1980s.Water temperature is the
most important factor influencing zooplankton growth
rates and may be responsible for the observed interannual
variability in mid-shelf zooplankton biomass (Coyle and
Pinchuk, 2002; Napp et al., 2000). During cold springs
when the spring bloom is dominated by ice-edge blooms,
reduced coupling between the mesozooplankton and phytoplankton means more phytoplankton will be ungrazed
and sink to the bottom, so enhancing the benthic food
web. Stronger coupling between mesozooplankton and
phytoplankton in warmer springs may result in a stronger
pelagic production.
The population of the jellyfish Chrysaora melamaster
increased at least ten-fold during the 1990s (Brodeur et
al., 1999b).These large jellyfish compete for food with
young walleye pollock (consuming an estimated 5% of
the annual crop of zooplankton) and also feed upon
them (consuming an estimated 3% of newborn walleye
pollock). Jellyfish have very low energy requirements
compared with fish (20 times less) and mammals
(200 times less than whales) on a per unit weight basis.
Their increased abundance may be due to reduced
nutrients and a lower-energy plankton regime.
9.3.3.2. Benthos
Data are available for sedentary and long-lived macrozoobenthos, which are relevant indicators of multi-year
environmental fluctuations between the late 1700s and
the present. Biogeographical boundaries in the Barents
Sea have shifted as a result of temperature fluctuations
(Blacker, 1965). Based on analyses using temperature
paleo-reconstructions, it appears that high arctic
species tend to survive only when temperatures remain
between -1.8 and 6 ºC, whereas adults of boreal species
can survive temperatures of -1 to 25 ºC. Also, biogeographical changes in the bottom fauna appear to occur
faster and are more easily detected during warm periods than cold periods.
The zoobenthos of the Russian Arctic seas has been most
intensively studied in the Barents Sea. Deryugin (1924)
detected several unusual species in Kola Bay in 1908 and
1909 and related this to fluctuations in water temperature. Some boreal species in the Barents Sea have
responded to environmental change by shifting their
biogeographical borders (Fig. 9.27; Chemerisina, 1948;
Nesis, 1960).This reflects variations in population size at
habitat boundaries, not changes in the size and shape of
the habitats themselves (Galkin, 1998).
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Arctic Climate Impact Assessment
1960–1969
1960–1969
1970–1979
1970–1979
1980–1989
1980–1989
1990–1999
1990–1999
Abundance
Abundance
(log10 (x+1))
(log10 (x+1))
1.2
0.10
1.0
0.08
0.8
0.06
0.6
0.4
0.2
0
Fig. 9.25. Long-term changes in the abundance of
Calanus finmarchicus during Continuous Plankton
Recorder surveys (Johns, 2001).
0.04
0.02
0
Fig. 9.26. Long-term changes in the abundance of
Calanus glacialis during Continuous Plankton
Recorder surveys (Johns, 2001).
499
Chapter 9 • Marine Systems
In years following warming, the polychaete
Spiochaetopterus typicus predominates along the Kola
Section in the Barents Sea. Following cold years, the polychaete Maldane sarsi predominates. Spiochaetopterus typicus
is thus an indicator of warming or warm conditions.
Estimating natural fluctuations in zoobenthos biomass in
the Barents Sea is difficult owing to the impact of commercial bottom trawling (Denisenko, 2001). In the
Pechora Sea, where there is no traditional demersal fishery, changes in zoobenthos biomass in 1924, 1958 to
1959, 1968 to 1970, and 1992 to 1995 show a negative
correlation between zoobenthos biomass and temperature (Denisenko, pers. comm., Zoological Institute
RAS, St. Petersburg, 2003).
In the Bering Sea, long-term change in zoobenthos
communities is known for the eastern regions as a
result of Soviet and American investigations in 1958 to
1959 and 1975 to 1976. In the 1950s, maximum biomass occurred in the northwestern part of the eastern
Bering Sea in the mid-shelf region at bottom depths
between 50 and 150 m. In the early 1970s, the highest
biomasses occurred in the mid-shelf area, southeast of
the Pribilof Islands. Because the early 1970s were cold
compared to the late 1950s, it may be that the difference in zoobenthos biomass related to changes in the
southern limit of the ice edge and thus to the amount of
ice-edge primary production that fell to the benthos,
ungrazed by pelagic zooplankton.
Recent studies indicate ongoing change in the benthic
communities of the Bering and Chukchi Seas (Francis et
al., 1998; Grebmeier and Cooper, 1995; Sirenko and
Koltun, 1992).The region just north of the Bering Strait
is a settling basin for organic carbon, which results in a
high benthic standing stock and high oxygen uptake rates
(Grebmeier, 1993; Grebmeier et al., 1988, 1989).
Benthic productivity in this region near 67º30' N,
169º W has historically maintained the highest benthic
faunal biomass of the entire Bering/Chukchi system
(Grebmeier, 1993; Grebmeier and Cooper, 1994;
Grebmeier et al., 1995; Stoker, 1978, 1981). Although
benthic biomass remains high in the area, regional
changes in the dominant benthic species have occurred.
This is likely to indicate changing hydrographic conditions (Grebmeier, 1993; Grebmeier et al., 1995).
In the St. Lawrence Island polynya region, changes in
regional oceanography due to the position or size of the
Gulf of Anadyr gyre are ultimately related to the northward transport of water through the Bering Strait, and
to the geostrophic balance within the Arctic Ocean
basin.The latter, which is related to variations in the
NAO/AO index, drives the northward current system in
the northern Bering Sea (Walsh et al., 1989). Roach et
al. (1995) found little flow through the Bering Strait
into the Arctic Ocean during the NAO-positive period
of the early 1990s, and a large increase in flow when the
NAO became negative in 1996. Small flow into the
Arctic Ocean is coincident with reduced northward
transport of water south of St. Lawrence Island.
The Gulf of Anadyr “cold pool” is maintained by sea-ice
production and brine formation in the St. Lawrence
Island polynya. Reduced sea-ice production to the south
of the polynya resulting in a decreased supply of nutrients for early-season primary production would limit
benthic populations (Grebmeier and Cooper, 1995).
However, it is possible that an enhanced and more energetic polynya could result from warming.This could
maintain a chemostat-type bloom system, as to the
north of St. Lawrence Island (Walsh J.J. et al., 1989),
allowing a longer growing season and greater production and thus transport.
The three species of crab that inhabit the eastern Bering
Sea shelf (red king crab,Tanner crab, and snow crab)
exhibit highly periodic patterns in abundance. Rosenkranz et al. (2001) found that anomalously cold bottom
temperatures in Bristol Bay may adversely affect the
reproductive cycle of Tanner crab and that northeasterly
winds may promote coastal upwelling, which advects
larvae to regions of fine sediments favorable for survival
upon settling. Incze and Paul (1983) linked low densities
of copepods within the 70 m isobath in Bristol Bay with
low abundance of Tanner crab larvae. Recruitment patterns for red king crab in Bristol Bay show the populations to be negatively correlated with the deepening of
the Aleutian Low and warmer water temperatures
(Zheng and Kruse, 2000). Red king crabs were commercially exploited during the late 1970s, which has also
contributed to the population decline.
Fig. 9.27. Biogeographical boundaries in the Barents Sea
during the 20th century. I maximal western extent of arctic
species in cold periods; II line of 50% average relation
between boreal and arctic species; III maximal eastern extent
of boreal species in warm periods; IV transition zone.
9.3.3.3. Fish
There are few records of marine biota showing interannual and longer-term variability in the Arctic Ocean, but
records of the abundance of commercial fish species for
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Arctic Climate Impact Assessment
the Labrador, Greenland, Iceland, Norwegian, and
Barents Sea go back to the start of the twentieth century
and even earlier in some cases.Within these areas
capelin, cod, and herring populations have undergone
very large fluctuations in biomass and distribution.
The period of warming from the mid-1920s to the mid1960s, which affected Greenland and Iceland in particular (see section 9.2.4.2), had a profound effect on the
major commercial fish species and also on most other
marine life. A number of species, which had been rare in
offshore areas west of Greenland, became abundant at
this time and population biomass increased by several
orders of magnitude.These changes were not related to
fishing and are clearly due to climate variability.
Boreal species such as cod are likely to respond strongly
to temperature variability and so show greater variability
in recruitment at the extremes of their range (Brander,
2000; Ottersen and Stenseth, 2001). However, for the
period over which records are available most populations
have been reduced to low levels as a result of fishing
pressure and may therefore show high variability
throughout their distribution.
The warming period of the 1920s
The warming period of the 1920s caused a poleward
extension in the range of distribution for many fish and
other marine and terrestrial species from Greenland to
Iceland and eastward to the Kara Sea. Records of
changes in species distribution during the 1920s
provide some of the most convincing evidence of the
pervasive effects of a change in climate on the marine
ecosystem as a whole. Jensen (1939) published a
comprehensive review of the effects of the climate
change in the Arctic and subarctic regions during this
period, which presents much of this information.
Some of the salient points concerning fish species are
summarized in Table 9.9.
The marine shelf ecosystem off West Greenland is
affected by cold polar water masses and temperate
Atlantic water. Changes in the distribution of these
water masses, under the influence of the NAO, affect
the distribution and abundance of fish species and hence
fisheries yields (Pedersen and Rice, 2002; Pedersen and
Smidt, 2000; Schopka, 1994).
The distribution of cod extended poleward by about
1000 km between 1920 and 1930 and can be followed in
some detail, because fishing stations were established
progressively further north as directed coastal fisheries
were established by the Greenland Administration.
The international offshore fishery for cod off West
Greenland reached a peak of over 400000 tonnes in the
early 1960s before collapsing.The decline was due to a
combination of fishing pressure and reduced water temperature, and probably to a lack of recruitment from
Iceland.The relationship between water temperature
and recruitment level is clear for this area (Brander,
2000; Buch et al., 1994), with poor recruitment occurring at temperatures below about 1.5 ºC (measured on
Fylla Bank, 64º N, in June).The warming of the North
Atlantic that has taken place since about the early 1990s
has also affected Greenland but temperatures remained
below 1.5 ºC until 1996.Thus it is too early to expect a
recovery of the cod population; cod take about seven
years to reach maturity and may be adversely affected by
the trawl fishery for shrimps which is now the mainstay
of the Greenland fisheries.
One of the principal changes which took place off
Iceland during the 1920s warming period occurred
within the major pelagic populations – those of herring
and capelin (Table 9.9). Prior to 1920, the capelin
spawned regularly on the south and southwest coasts of
Iceland, but from 1928 to 1935 very few capelin were
taken in these areas. In contrast, herring extended their
spawning areas from the south and southwest coast to
the east, northwest, and north coasts in this period
(Saemundsson, 1937).
Similar changes are also recorded for Jan Mayen, the
Barents Sea, the Murman Coast, the White Sea, Novaya
Zemlya, and the Kara Sea, where cod and herring
extended their ranges and became more abundant.
Table 9.9. Changes in the distribution and abundance of fish species off West Greenland and Iceland during the period of warming
from 1920 onwards. Prepared by Brander (2003) based on Saemundsson (1937) and Jensen (1939).
West Greenland
Iceland
Species previously absent, but which
appeared from 1920 onwards
Haddock (Melanogrammus
aeglefinus),tusk (Brosme brosme),
ling (Molva molva)
Bluntnose sixgill shark (Notidanus griseus), swordfish
(Xiphias gladius), horse mackerel (Trachurus trachurus)
Rare species which became more
common and extended their ranges
Coal fish (Pollachius virens; new
records of spawning fish),
Atlantic salmon (Salmo salar),
spurdog (Squalus acanthias)
Witch (Glyptocephalus cynoglossus), turbot (Psetta maxima),
basking shark (Cetorhinus maximus), northern bluefin tuna
(Thunnus thynnus), mackerel (Scomber scombrus),Atlantic
saury (Scomberesox saurus), ocean sunfish (Mola mola)
Species which became abundant and
extended their ranges poleward
Atlantic cod, Atlantic herring
(new records of spawning fish)
Atlantic cod, Atlantic herring (both extended their
spawning distribution)
Arctic species which no longer
occurred in southern areas, and
extended their northern limits
Capelin, Greenland cod,
Greenland halibut (became
much less common)
Capelin
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Chapter 9 • Marine Systems
Climate effects on fish in the Barents Sea
Understanding of the processes underlying major
fluctuations in the fish ecosystem of the Barents Sea is
considerably better than for most other areas of the
northern North Atlantic (Rødseth, 1998).The main
species involved are Atlantic cod, capelin, and Atlantic
herring.These species are closely linked through the
food web. Cod is highly dependent on capelin as its
main prey. One- to two-year old herring prey heavily
on the larvae of capelin, whose mortality increases
greatly in years with a large biomass of young herring.
Interactions between these species are strongly affected
by the highly variable oceanographic conditions of the
Barents Sea (Hamre, 1994).
The early years of the twentieth century, particularly
1902, were extremely cold in the Barents Sea, with
extensive sea-ice cover.This resulted in a crisis for the
Norwegian fisheries, with low catches of small
Northeast Arctic cod in very poor condition. Large
numbers of seals, primarily harp seals, moved down the
Norwegian coast from the Barents Sea. A similar
sequence of events occurred during the cold period in
the 1980s, when the capelin population collapsed; the
cod were small and in poor condition and harp seals
again invaded the northern coast of Norway.
For cod in particular, the consequences of variability in
water temperature, transport, and food during early life
stages have been studied closely (Michalsen et al., 1998;
Ottersen and Loeng, 2000; Ottersen et al., 1998;
Sætersdal and Loeng, 1987). Growth and survival rates
of larvae and juveniles are higher in warm years and the
large year-classes of cod spread further east into the
Barents Sea, where they encounter cooler water and their
growth rate slows as a result (Ottersen et al., 2002).
Norwegian spring-spawning herring
The biomass of Norwegian spring-spawning herring
increased almost ten-fold between 1920 and 1930, when
the Norwegian Sea and much of the North Atlantic went
through a period of rapid warming (Toresen and
Østvedt, 2000).The herring population declined rapidly
from the late 1950s and by 1970 had decreased by more
than four orders of magnitude.The decline was coincident with a period of cooling (Fig. 9.28). Although this
cooling may have been a contributing factor, it is likely
that heavy fishing pressure was the primary cause of the
collapse of the population.
The collapse of the Norwegian spring-spawning herring
population coincided with a retraction of the summer
feeding distribution due to the southward and eastward
shift in the location of the Polar Front.The Polar Front
was to the north of Iceland prior to 1965 but has since
stayed west of Iceland (see Box 9.8). Despite a complete
recovery of the herring spawning stock and a rise in
water temperature north of Iceland in 2000 to levels
similar to those of the mid-1960s (Malmberg and
Valdimarsson, 2003), the herring have not returned to
their earlier feeding areas.
The rapid cooling during the mid- and late 1960s also
resulted in reduced growth and recruitment of the
Norwegian spring-spawning herring (Toresen and
Østvedt, 2000).The same happened with the Icelandic
summer spawning herring (Jakobsson et al., 1993).
Temperature-mediated habitat changes in
Canadian capelin
Capelin off Newfoundland and Labrador spread southward as far as the Bay of Fundy when water temperatures declined south of Newfoundland in the mid-1960s
and retracted northward as water temperatures rose in
the 1970s (Colton, 1972; Frank et al., 1996;Tibbo and
Humphreys, 1966). During cooling in the latter half of
the 1980s and into the 1990s, capelin again extended
their range, eastward to Flemish Cap and southward
onto the northeastern Scotia Shelf off Nova Scotia
(Frank et al., 1996; Nakashima, 1996). For example,
small quantities of capelin began to appear in the
groundfish trawl surveys on the Scotia Shelf in the mid1980s and since then numbers have increased dramatically (Frank et al., 1996). Initially, only adult capelin
were caught, but juveniles later appeared, suggesting
capelin were successfully spawning.
This shift appears to have been part of a larger-scale
ecosystem change.While capelin were spreading onto
the Scotia Shelf, polar cod, whose primary grounds have
traditionally been the Labrador Shelf stretching southward to northern Newfoundland, were moving southward. In the late 1980s and early 1990s, as water temperatures decreased, polar cod pushed southward onto
the Grand Banks and into the Gulf of St. Lawrence in
large numbers (Gomes et al., 1995; Lilly et al., 1994).
Historical climate and fish in the Bering Sea
Fig. 9.28. Relationship between water temperature and the
biomass of the Norwegian spring-spawning herring stock
(Toresen and Østvedt, 2000).
The direct effects of atmospheric forcing resulting from
climate variations are very important to the physical
502
oceanographic conditions of the Bering Sea. Since the
eastern Bering Sea shelf has a characteristically sluggish
mean flow and is separated from any direct oceanographic connection to the North Pacific Ocean by the
Alaska Peninsula, linkages between the eastern Bering
Sea and the climate system are primarily a result of the
ocean–atmosphere interaction (Stabeno et al., 2001).
Climate variations in this region are directly linked to
the location and intensity of the Aleutian Low pressure
center, which affects winds, surface heat fluxes, and the
formation of sea ice (Hollowed and Wooster, 1995).
The pressure index has experienced eight statistically
significant shifts on roughly decadal time scales that
alternated between cool and warm periods (Overland
et al., 1999a). A well-documented shift (Trenberth,
1990 among others) from a cool to a warm period
occurred between 1977 and 1989, which coincided
with the start of fishery-independent sampling programs and fishery catch monitoring of major groundfish
Arctic Climate Impact Assessment
species. Information from the contrast between this
period and the previous and subsequent cool periods
(1960 to 1976 and 1989 to 2000) forms the basis of the
following discussion.
Changes in atmospheric climate are primarily transmitted through the Bering Sea to the biota via the mechanisms of wind stress (Francis et al., 1998) and the
annual variation in sea ice extent (Stabeno et al., 2001).
These mechanisms directly alter the timing and abundance of primary and secondary production by changing
the salinity, mixed-layer depth, nutrient supply, and vertical mixing in the ocean system.
The extent and timing of the sea ice also determines
the area where cold bottom water temperatures will
persist throughout the following spring and summer.
This eastern Bering Sea area of cold water, known as
the cold pool, varies with the annual extent and dura-
(a)
(b)
(c)
Arctic Oscillation Index Values
Fig. 9.29. Winter spawning flatfish (a) recruitment and (b) predicted wind-driven larval drift patterns relative to (c) decadal-scale
atmospheric forcing in the eastern Bering Sea (Wilderbuer et al., 2002).
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Chapter 9 • Marine Systems
Box 9.9. Effect of atmospheric forcing in the Bering Sea
Recruitment responses of many Bering Sea fish and crab species are linked to decadal scale patterns of climate
variability (Francis et al., 1998; Hare and Mantua, 2000; Hollowed et al., 2001; Wilderbuer et al., 2002; Zheng and
Kruse, 2000). Decadal changes in the recruitment of some flatfish species in the eastern Bering Sea appear to be
related to patterns in atmospheric forcing (see Fig. 9.29).The AO index, which tracks the variability in atmospheric
pressure at polar and mid-latitudes, tends to vary between negative and positive phases on a decadal scale.
The negative phase brings higher-than-normal pressure over the polar region and the positive phase does the
opposite, steering ocean storms farther north.These patterns in atmospheric forcing in winter may influence surface wind patterns that advect fish larvae onto or off the shelf. When the index was in its negative phase in the
1980s, southwesterly winds tended to dominate, which is likely to have resulted in the transport of flatfish larvae
to favorable nursery grounds.The positive phase in the 1990s showed winds to be more southeasterly, which
would tend to advect larvae off the shelf.The relative recruitment of three species of winter spawning flatfish in
the Bering Sea – arrowtooth flounder, rock sole, and flathead sole – was high in 1977 to 1988 and low in 1988 to
1998, indicating a link between surface wind advection patterns during the larval stage and flatfish survival.
However, periods of strong Aleutian Lows are associated with weak recruitment for some Bering Sea crab species
and are unrelated to others (Zheng and Kruse, 2000) depending on species-specific life history traits. Winds from
the northeast favor retention of crab larvae in offshore mud habitats that serve as suitable nursery areas for
young Tanner crabs since they bury themselves for protection (Rosenkranz et al., 2001). However, southwesterly
winds promote inshore advection of crab larvae to coarse, shallow water habitats in inner Bristol Bay that serve
as nursery areas for red king crabs who find refuge among biogenic structures (Tyler and Kruse, 1998).Timing and
composition of the plankton blooms may also be important, as red king crab larvae prefer to consume
Thalassiosira spp. diatoms, whereas Tanner crab larvae prefer copepod nauplii. Some species, such as Bering Sea
herring, walleye pollock, and Pacific cod, show interannual variability in recruitment that appears more related to
ENSO-driven climate variability (Hollowed et al., 2001; Williams and Quinn, 2000).Years of strong onshore transport, typical of warm years in the Bering Sea, correspond to strong recruitment of walleye pollock, possibly due
to separation of young fish from cannibalistic adults (Wespestad et al., 2000). Alaskan salmon also exhibit decadal
scale patterns of production, which are inversely related to the pattern of west coast salmon production (Hare
and Mantua, 2000). Including environmental variables such as sea surface temperature and air temperature significantly improved the results of productivity models for Bristol Bay sockeye salmon (Oncorhynchus nerka) compared
to models containing density-dependent effects only (Adkison et al., 1996).
tion of the ice pack and can influence fish distributions.
Pollock have shown a preference for warmer water, and
exhibit an avoidance of the cold pool (WyllieEcheverria, 1995). In cold years they utilize a smaller
portion of the shelf waters, in contrast to warm years
when they have been observed as far north as the
Bering Strait and the Chukchi Sea. Strong year-classes
of pollock have been found to occur synchronously
throughout the Bering Sea (Bulatov, 1995) and to coincide with above-normal air and bottom water temperatures and reduced sea-ice cover (Decker et al., 1995;
Quinn and Niebauer, 1995). These favorable years of
production are the result of good juvenile survival and
are related to how much cold water habitat is present
(Ohtani and Azumaya, 1995), the distribution of juveniles relative to the adult population which influences
the level of predation (Wespestad et al., 2000), and
enhanced rates of embryonic development in warmer
water (Blood, 2002; Haynes and Ignell, 1983).
The distributions of forage fishes including Pacific herring, capelin, eulachon (Thaleichthys pacificus), and juvenile Pacific cod and pollock indicate temperature-related
differences (Brodeur et al., 1999a). Capelin exhibits an
expanded range in years with a larger cold pool and contracts in years of reduced sea-ice cover. Although the
productivity of capelin populations in relation to water
temperature is not known, Bering Sea herring populations exhibited improved recruitment during warm
years (Williams and Quinn, 2000), similar to other herring populations where the timing of spawning is also
temperature-related (Zebdi and Collie, 1995).
Recruitment and stock biomass have been examined for
evidence that climatic shifts induce responses in the production of groundfish species in the Bering Sea and North
Pacific Ocean (Hollowed and Wooster, 1995; Hollowed et
al., 2001). Even though results from these studies are
highly variable, strong autocorrelation in recruitment
associated with the significant change in climate in 1977
was observed for many salmonids and some winterspawning flatfish species such as eastern Bering Sea arrowtooth flounder and Greenland halibut.The two latter
species showed opposite changes post-1977 (increasing
biomass for arrowtooth flounder and decreasing biomass
for Greenland halibut). Substantial increases in the abundance of Pacific cod, skates, flatfish such as rock sole, and
non-crab benthic invertebrates also took place on the
Bering Shelf in the 1980s (Conners et al., 2002).
The decadal-scale patterns in recruitment success for
winter-spawning flatfish (Fig. 9.29) may be associated with
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Arctic Climate Impact Assessment
decadal shifts in the Aleutian low pressure system that
affects cross-shelf advection patterns of larvae to favorable
nursery areas rather than with water temperature
(Wilderbuer et al., 2002). Box 9.9 describes the effects of
atmospheric forcing in the Bering Sea in more detail.
9.3.3.4. Marine mammals and seabirds
Although fragmented, there is a lot of evidence to suggest that climate variations have profound effects on
marine mammals and seabirds.The capelin collapse in
the Barents Sea in 1987 had a devastating effect on
seabirds breeding on Bjørnøya. Repeated years (1967,
1981, 2000, 2001, and 2002) with little or no sea ice in
the Gulf of St. Lawrence resulted in years with almost
zero production of seal pups, compared to hundreds of
thousands in good sea-ice years.
Vibe (1967) explored the relationship between climate
fluctuations and the abundance and distribution of
animals, including marine mammals and seabirds, in
Greenland. During the cold, dry, and stable “drift-ice
stagnation” phase in West Greenland (approximately
1810 to 1860), marine mammals and seabirds concentrated at central West Greenland because the sea ice did
not advance far north into Davis Strait. During the
“drift-ice pulsation stage” (1860 to 1910), when the sea
ice of the Arctic Ocean drifted into the Atlantic Ocean
in larger amounts than before, marine mammal and
seabird populations decreased in the unstable and wet
climate of West Greenland because the East Greenland
Current and the East Greenland sea ice advanced far
north into Davis Strait in summer. In the same period,
the Greenland right whale (Balaena mysticetus) population
“stagnated” in the Atlantic region. During the “drift-ice
melting stage” (1910 to 1960) the East Greenland sea ice
decreased in Davis Strait and populations of marine
mammals and seabirds increased in northern West
Greenland. Cod were abundant along the coast of West
Greenland and multiplied in Greenland waters.
The condition of adult male and female polar bears has
declined in Hudson Bay since the early 1980s, as have
birth rates and the proportion of first-year cubs in the
population. Stirling et al. (1999) suggest that the proximate cause of these changes in physical and reproductive
parameters is a trend toward earlier breakup of the sea
ice, which has resulted in the bears coming ashore in
poorer condition.
9.3.4. Future change – processes and
impacts on biota
Table 9.4 summarizes the potential physical oceanographic changes in the Arctic based on the projected
changes in the atmospheric forcing functions (Table 9.1)
Table 9.10. Potential long-term ecological trends due to climate warming. Unless otherwise specified these projected changes are
very likely to happen.
Phytoplankton
Zooplankton
Benthos
Fish
Marine mammals and seabirds
Distribution
Increased spatial
extent of areas
of high primary
production in
the central
Arctic Ocean.
Southern limit
of distribution
for colder
water species
to move
northward.
Distribution of
more southerly
species to move
northward.
Southern limit of
distribution for colder
water species to move
northward.
Distribution of more
southerly species to
move northward.
Southern limit of distri- Poleward shift in species
bution for colder water distributions.
species to move northward. Distribution of
more southerly species
to move northward.
Timing and location of
spawning and feeding
migrations to alter.
Production
Increased production in central
Arctic Ocean,
and Barents and
Bering Sea
shelves.
Difficult to
predict, will
depend on the
timing of
phytoplankton
production and
seawater
temperatures.
Difficult to predict, will
partly depend on the
degree of match/
mismatch between
phytoplankton/zooplankton production
and on water temperature. Production by
shrimp and crab
species may decline.
Wind-driven advection
patterns of larvae may
be critical as well as a
match/mismatch in the
timing of zooplankton
production and fish
larval production.
Dramatic declines in production by ice-associated marine
mammals and increases by
more temperate species.
Seabird production likely
to be mediated through
forage availability, which is
unpredictable.
Species
composition/
diversity
Dependent on
mixing depth:
shallow mixing
favors diatoms,
intermediate
depth mixing
favors Phaeocystis,
deep mixing may
favor nanoflagellates.
Adaptable arctic
copepods, such
as Calanus
glacialis, may be
favored.
Cold-water species
may decline in abundance along with some
clams and crustaceans,
while warm water
polychaetes, blue
mussel (Mytilus edulis),
and other types of
benthos may increase.
Cod, herring, walleye
pollock, and some
flatfish are likely to
move northward and
become more abundant, while capelin,
polar cod, and
Greenland halibut
will have a restricted
range and decline in
abundance.
Declines in polar bear, and in
ringed, harp, hooded, spotted,
ribbon, and possibly bearded
seals. Increased distribution
of harbour seals and grey
seals. Possible declines in
bowhead, narwhal, grey, and
beluga whales. Ivory gulls and
several small auk species are
likely to decline while other
changes in bird populations
are unpredictable.
Chapter 9 • Marine Systems
and potential future sea-ice conditions discussed in
Chapter 6.Table 9.10 summarizes the potential longterm ecological changes in the marine system that are
considered likely to arise as a result of these physical
changes.The time frames for these changes to the biological system are addressed in this section by trophic
level and by region where appropriate.The most pronounced physical changes are likely to include a substantial loss of sea ice, an increase in air and sea surface
temperature, and changes in the patterns of wind and
moisture transport.
Changes in the distribution of many species, ranging from
phytoplankton to whales, are very likely to occur.The main
habitat changes affecting marine mammals and seabirds
include a reduction in sea ice, changes in snow cover, and a
rise in sea level. Phenological changes, species replacements, and changes at lower trophic levels are also likely to
have a strong influence on upper trophic level species.
9.3.4.1. Primary production
Changes in sea ice, water temperature, freshwater input,
and wind stress will affect the rate of nutrient supply
through their effect on vertical mixing and upwelling.
Changes in vertical mixing and upwelling will affect the
timing, location, and species composition of phytoplankton blooms, which will in turn affect the zooplankton
community and the productivity of fish.
Changes in the timing of the primary production will
determine whether this production is utilized by the
pelagic community or is exported and utilized by the
benthos (Box 9.10).The retention to export ratio also
depends upon the advection and temperature preferences
of grazing zooplankton, which together determine the
505
degree of match or mismatch between primary and secondary production.The projected disappearance of seasonal sea ice from the Barents and Bering Seas (and thus
elimination of ice-edge blooms) implies that these areas
would have blooms resembling those of more southerly
seas.The timing of these open ocean blooms in the
Barents and Bering Seas will then be determined by the
onset of seasonal stratification, again with consequences
for a match/mismatch in timing with zooplankton.
Removal of light limitation in areas presently covered
by multi-year sea ice is likely to result in a two- to fivefold increase in primary production, provided wind
mixing is sufficient to ensure adequate nutrient supply.
Moreover, earlier melting in the seasonal sea-ice zone is
likely to enhance annual primary production by extending the growing season.The actual outcome in terms of
annual production, however, is highly dependent upon
regional and local changes in upwelling, wind-driven
vertical mixing, and freshwater supply from sea ice and
rivers. Note, for example, that it takes only a small
increase in salt stratification (i.e., a decrease in surface
salinity) to offset the effect of increased winds on vertical mixing. Regional cooling, as projected by some of
the ACIA-designated models, would result in the opposite effects to those of the warming scenarios described
in the rest of this section.
The disappearance of sea ice from the Barents Sea is likely to result in a more than doubling of the present levels
of primary production, especially in the northernmost
part.This is a consequence of a deeper wind-mixed layer
and an increased vertical supply of nutrients from the
underlying Atlantic water. Predicting changes in the timing of the spring bloom requires a better understanding
of, and capability of modeling, the combined effects of
Box 9.10. Effects of a variable ice edge on key biological processes affecting carbon flux on an
arctic shelf
Primary production (PP) occurs in the euphotic zone when light and nutrient conditions allow.This primary production may be retained by recycling within the euphotic zone or exported to deeper waters and be available
for the benthos.The efficiency of retention is strongly determined by the occurrence of a match (where zooplankton are available to graze and recycle the primary production) or mismatch (where zooplankton are not
present in sufficient numbers and primary production sinks out of the euphotic zone to be grazed by the benthos). Zooplankton densities may be affected by
advection in certain shelf locations such as the
Barents and Chukchi Seas. Additional concerns
involve sequestration of carbon in shelf, slope, and
basin sediments, and exchange processes that act
to move carbon from one regime to another (red
arrows).The location of the ice edge, where much
primary production occurs, relative to topography
(e.g., the shelf break and slope) strongly impact
upon all of these processes. Under climate change
scenarios, the ice edge will retreat further and
faster into the basin, thus increasing the export of
PP first to the slope and then to the abyssal ocean
(E.C. Carmack, pers. comm. 2004).
506
ice-edge retreat and stability in the position of the Polar
Front.To the south of the Polar Front, the absence of sea
ice will reduce stratification thereby delaying the spring
bloom until the onset of thermal stratification and the
development of the seasonal surface mixed layer. North
of the Polar Front, however, the timing of the spring
bloom is strictly tied to light availability. At present, the
spring bloom in the northern Barents Sea must await the
retreat of the marginal ice zone for adequate light levels.
In the absence of sea ice, the spring bloom is likely to
occur earlier, and is very likely to occur earlier than in
the region to the south of the Polar Front.
Primary production on the Bering Shelf is also likely to
be enhanced if it becomes permanently ice-free, primarily due to an extended growing season and continuous
upwelling of nutrient-rich water along the highly productive zone associated with the Bering Shelf break.
More intense wind and more arid conditions at and near
the Gobi and Takla Makan deserts in northeast Asia will
possibly lessen the impact of iron control in the
Northeast Pacific and the eastern Bering Sea.
In the shelf seas of the Arctic Ocean (e.g., the Kara,
Laptev, East Siberian, and Beaufort Seas), a significant
increase in nutrient supply is very likely to happen when
the edge of the permanent ice pack retreats beyond the
shelf break.This is very likely to trigger the onset of
shelf-break upwelling and the delivery of nutrient-rich
offshore waters to shallow shelf regions, perhaps more
than doubling present levels of productivity.
In the central Arctic Ocean, two additional conditions of
sea-ice retreat are important to primary production: the
disappearance of sea-ice cover in summer and the
regional appearance of open water areas in winter
(e.g., north of Svalbard and northeast of the Chukchi
Sea). In open water areas during summer, productivity is
likely to increase due to increased wind mixing and
nutrient re-supply.Within areas regionally open in winter, additional nutrients are likely to be supplied through
the combined effects of wind stress and convective
mixed layer deepening. It is possible that these two types
of area will be as productive as is currently the case in
their southern counterparts (the Greenland and deep
Bering Seas, respectively). Before the development of
these two distinctive conditions, areal primary production is likely to increase as the number and size of leads
in the multi-year ice increase.
Surface mixed-layer depth is likely to have a strong
impact on phytoplankton community structure, particularly in the Nordic Seas. Regions where the seabed or
the depth of mixing (due to ice melt or river inflow) is
less than about 40 m are likely to favor diatom blooms.
Deeper mixing, to about 80 m, is likely to favor
Phaeocystis.Thus, unless there is an increase in freshwater
input, stronger winds are likely to result in Phaeocystis
becoming more common than at present.This is possible
in Atlantic water to the south of the Polar Front. If the
surface mixed layer in the Atlantic water extends beyond
Arctic Climate Impact Assessment
about 80 m, it is possible that a low-productive community dominated by nanoflagellates would be favored, as
currently occurs in the off-shelf parts of the Southern
Ocean (Hewes et al., 1990).This implies little transfer
of carbon to herbivores and sediments because the grazers would be largely ciliates (Sakshaug and Walsh, 2000).
9.3.4.2. Zooplankton production
Any northward extension of warm water inflows is
likely to carry with it temperate zooplankton, for
instance into the Siberian Shelf Seas and the Bering
Shelf (Brodeur and Ware, 1992; Overland et al., 1994;
Skjoldal et al., 1987). Such inflows are likely to include
gelatinous plankton in summer and autumn (Brodeur et
al., 2002). Ice fauna such as the large amphipods will
suffer massive loss of habitat if multi-year ice disappears.The possibility of increased transport of cold
water on the western side of the North Atlantic could
bring cold-loving zooplankton species farther south.
Correspondingly, the southern limit of distribution of
northern species may shift northward on the eastern
side of the North Atlantic and southward on the western side, as indicated by zooplankton studies over the
last 40 years (Beaugrand et al., 2002).
If the Siberian Shelf Seas become warmer in the future,
it is possible that Calanus finmarchicus will thrive and
multiply throughout the area as a whole, rather than
being restricted to the Siberian Shelf water as currently
occurs.There is, however, risk of a mismatch with phytoplankton blooms in that earlier melting will cause earlier stratification and, thus, an earlier bloom. However, if
sea ice is absent during summer and autumn, there will
be deeper vertical mixing, making the system more like
that of the southern Barents Sea, with later blooms,
albeit dependent on stratification caused by freshwater
inputs from rivers. If water temperatures in the Siberian
Shelf Seas stay lower than presently occur in the southern Barents Sea, the development of C. finmarchicus is
likely to be retarded.
Grazing versus sedimentation
If a mismatch occurs in the timing of phytoplankton and
zooplankton production due to early phytoplankton
blooms, the food web will be highly inefficient in terms
of food supply to fish and export production (Hansen et
al., 1996). Export production and protozoan biomass
are likely to increase.
A match with phytoplankton blooms can be achieved by
arctic copepods, such as C. glacialis, which can adjust its
egg production to the development of the phytoplankton
bloom whether early or late in the season.This may also
pertain to other important copepods in arctic waters.
If so, actively grazing zooplankton “for all seasons” are
very likely to exist for any realistic climate change and
thus future ratios of grazed to exported phytoplankton
biomass in the Arctic Ocean are unlikely to be much
different to those at present.
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Chapter 9 • Marine Systems
Fish versus zooplankton
The crucial issue concerning the effects of climate
change on zooplankton production is likely to be related
to the match versus mismatch between herbivorous zooplankton and fish.The extent to which commercially
valuable fish will migrate northward and the extent to
which they will be able to utilize early developing
populations of C. glacialis along the Siberian Shelf are
unknown. A worst-case scenario would be a mismatch
resulting in starving and, ultimately, dying fish in a summer ecosystem characterized by protozoans and unsuccessful, inflexible copepods such as C. finmarchicus.
9.3.4.3. Benthos
Future fluctuations in zoobenthic communities are very
likely to be related to the temperature tolerance of the
animals and to future water temperatures.While the
majority of boreal forms have planktonic larvae that
require a fairly long period to develop to maturity, arctic species do not (Thorson, 1950).Thus, boreal species
should be quick to spread in warm currents in periods
of warming, while the more stenothermal arctic species
(i.e., those able to live within a narrow temperature
range only) will perish quickly. In periods of cooling,
the arctic species, with their absence of pelagic stages
are very likely to slowly follow the warmer waters as
they recede. Boreal species that can survive in nearfreezing water could remain within the cooler areas.
From the prevailing direction of warm currents in the
Barents Sea, shifts in the geographical distribution of
the fauna should be quicker and more noticeable
during periods of warming than periods of cooling.
Any change in the abundance or biomass of benthic
communities is most likely to result from the impact
of temperature on the life cycle and growth rate of the
various species. If warming occurs within the Barents
Sea over the next hundred years, thermophilic species
(i.e., those capable of living within a wide temperature
range) will become more frequent. This is likely to
force changes in the zoobenthic community structure
and, to a lesser extent, in its functional characteristics,
especially in coastal areas.
The highly productive region to the north of the Bering
Strait is likely to undergo changing hydrographic conditions, which in turn are likely to result in changes to
the dominant species (Grebmeier, 1993; Grebmeier et
al., 1995).The hydrography of the St. Lawrence Island
polynya region and the Anadyr region is ultimately
related to the northward transport of water through the
Bering Strait. Because the latter is related to variations
in the AO, the future of the northern Bering Shelf is
very likely to be closely related to variations in these
oscillations (Walsh J.J. et al., 1989). If AO+ conditions
predominate in the future, it is likely that the flow of
Bering Water into the Arctic Ocean will be small,
resulting in a reduction in northward transport of water
south of St Lawrence Island.
Because the Gulf of Anadyr “cold pool” is maintained by
sea-ice production/brine formation in the St Lawrence
Island polynya, an enhanced and more energetic polynya
resulting from warming is likely to maintain a chemostattype bloom system (Walsh J.J. et al., 1989), allowing a
longer growing season and higher levels of production.
9.3.4.4. Fish production
Understanding how climate variability affects individual
fish populations and fisheries and how the effects differ
between species is extremely important when projecting
the potential impacts of climate change. Projections of
the response of local marine organisms to climate
change scenarios have a high level of uncertainty.
However, by using observations of changes in fish populations due to past climate variability it is possible to
predict some general responses.
Climate change can affect fish production through a
variety of means. Direct effects of temperature on the
metabolism, growth, and distribution of fish could
occur. Food web effects could also occur, through
changes in lower trophic level production or in the
abundance of top-level predators, but such effects are
difficult to predict. However, it is expected that generalist predators are more adaptable to change than specialists. Fish recruitment patterns are strongly influenced by oceanographic processes such as local wind
patterns and mixing and by prey availability during
early life stages, which are also difficult to predict.
Recruitment success could be affected by changes in the
time of spawning, fecundity rates, survival rate of larvae, and food availability.
General trends in distribution and production
Poleward extensions of the distribution range for many
fish species are very likely under the projected climate
change scenarios (see Fig. 9.30 and Box 9.11). Some of
the more abundant fish species that would be very likely
to move northward under the projected warming
include Atlantic and Pacific herring and cod, walleye
pollock in the Bering Sea, and some of the flatfishes that
might presently be limited by bottom temperatures in
the northern areas of the marginal arctic seas.The southern limit of colder-water fishes such as polar cod and
capelin would be very likely to move northward.The
Greenland halibut is also likely either to shift its southern boundary northward or restrict its distribution more
to continental slope regions. Salmon, which show high
fidelity of return to natal streams, might possibly be
affected in unknown ways that relate more to conditions
in natal streams, early marine life, or feeding areas that
might be outside the Arctic.
Fish production patterns are also very likely to be
affected, although there are large uncertainties regarding the timing and location of zooplankton and benthic
production that serve as prey resources for fish growth,
and the wind advection patterns and direction that favor
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Box 9.11. Climate impact on the distribution of fish in the Norwegian and Barents Seas
An increase in water temperature of 1 to 2 ºC in the Atlantic part of the Norwegian and Barents Sea is very
likely to result in a change in distribution for several species of fish. However, in both seas there are fronts
between the warm Atlantic water and the cold arctic water masses, whose position is partly determined by
bottom topography. How these fronts may move in future is addressed in section 9.2.5.4.
Previous experience of how fish react to changes in water temperature in the Barents Sea may be used to
speculate about future changes.The most likely impact of an increase in water temperature on some commercial
fish species in shown in Fig. 9.30. Capelin is very likely to extend its feeding area north and northeastward.
During summer it might feed in the Arctic Basin and migrate to the Kara Sea. Whether the capelin maintain their
spawning ground along the coast of northern Norway and the Kola Peninsula is unknown.They may possibly
move eastward, and may even spawn along the west coast of Novaya Zemlya. Cod is also likely to expand its
feeding area eastward, especially as capelin is its main food source. As cod is demersal (i.e., a near-bottom fish),
it is not likely to migrate north of the Barents Sea and into the deep Arctic Basin. Haddock will probably follow
the same track as cod, but as at present is likely to remain further south than cod.
In the Norwegian Sea, herring is likely to return to the feeding and overwintering area used before 1964 (see Box
9.8), but is likely to maintain the same spawning areas along the Norwegian coast. Mackerel (Scomber scombrus)
and blue whiting (Micromesistius poutassou) are likely to migrate northeast to the Barents Sea.The mackerel and
blue whiting will then compete with the other pelagic species in the Barents Sea for a limited supply of food. It is
also likely that new species may enter the Norwegian Sea.
survival of some fish species relative to others.This is an
active area of research, presently being addressed by
GLOBEC (Global Ocean Ecosystem Dynamics)
research programs around the world. Given historical
recruitment patterns, it seems likely that herring, cod,
and walleye pollock recruitment would be increased
under future climate warming scenarios. Benthicfeeding flatfish, such as rock sole in the eastern Bering
Sea, would be likely to have higher average recruitment
in a warmer Bering Sea. Greenland halibut, capelin, and
polar cod would be likely to decline in abundance.The
Fig. 9.30. Likely extension of the feeding area for some
of the main fish populations if sea temperature increases.
For herring, see also Box 9.8 (modified after Blindheim et
al., 2001).
greatest variability in recruitment would occur for all
species at the extremes of their ranges.
Migration patterns are very likely to shift, causing
changes in arrival times along the migration route.
The timing of the spring migration of cod into the Gulf
of St. Lawrence appears to be related to the timing of
ice melt. In winter, cod appear to congregate at the edge
of the sea ice but do not pass beneath it (Fréchet, 1990).
The spring migration appeared to be delayed by as much
as 20 days in 1992, when ice melt was particularly late
in the southern region of the Gulf. Change in sea ice
distribution is one of the expected effects of climate
change that is likely to have pronounced impacts on
many fish species. Growth rates are very likely to vary,
with the amplitude and direction being species dependent.While cod growth rates in the southern areas of the
Arctic are very likely to increase with a rise in water
temperature (Brander, 1995; Michalsen et al., 1998),
this may not be the case for Arctic Ocean species.
Qualitative predictions of the consequences of climate
change on fish resources require good regional atmospheric and oceanic models of the response of the ocean
to climate change. Dynamically or statistically downscaled
output from global circulation models, which are only
recently becoming available, could be very useful. Greater
understanding is needed concerning the life histories for
those species for which predictions are required, and concerning the role of the environment, species interactions,
and fishing in determining the variability of growth,
reproduction, distribution, and abundance of fish populations.The multi-forcing and numerous past examples of
“failed” predictions of environment–fish relationships indicate the difficulties faced by fisheries scientists in providing reliable predictions of the response to climate change.
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Chapter 9 • Marine Systems
9.3.4.5. Marine mammals and seabirds
The impacts of climate change scenarios on marine mammals and seabirds in the Arctic are likely to be profound,
but the precise form these impacts will take is not easy to
determine (Jarvis, 1993; Shugart, 1990). Patterns of
change are non-uniform (Parkinson, 1992) and highly
complex. Oscillations occurring at a variety of scales
(e.g., Mysak et al., 1990) complicate regional predictions
of long-term trends. Also, species responses will vary
dramatically (e.g., Kitaysky and Golubova, 2000). Mesoscale environmental features, e.g., frontal zones and
eddies, that are associated with enhanced productivity are
important to apex predators, but future changes in these
features are not represented well at the present spatial
resolution of circulation models (Tynan and DeMaster,
1997). Regional, small-scale coupled air–sea–ice models
are needed in order to make reliable projections of
change in mesoscale environmental features.
Given the most likely scenarios for changes in oceanographic conditions within the ACIA region by 2020
(Table 9.4), changes in seabird and marine mammal
communities are very likely to be within the range(s)
observed over the last 100 years. If, however, the
increase in water temperature and the sea-ice retreat
continue as projected until 2050 and 2080, marine
ecosystems will change in ways not seen in recent history. One of the first changes expected is a poleward shift
in species (and broader assemblages). However, there is
a limit to how far north arctic species can shift following the sea ice. Once seasonal sea-ice cover retreats
beyond the shelf regions, the oceanographic conditions
will change dramatically and become unsuitable for
many species. If the loss of sea ice is as dramatic temporally and spatially as has been projected by the ACIAdesignated models, negative consequences are very likely within the next few decades for arctic animals that
depend on sea ice for breeding or foraging (Brown,
1991; Burns, 2001; Stirling and Derocher, 1993;Tynan
and DeMaster, 1997).The worst-case scenarios in terms
of reduced sea-ice extent, duration, thickness, and concentration by 2080 are very likely to threaten the existence of whole populations and, depending on their
ability to adapt to change, are very likely to result in the
extinction of some species. Prospects for long-term
abundance projections for populations of large marine
predators are not good (e.g., Jenkins, 2003).
Climate change also poses risks to marine mammals and
seabirds in the Arctic in terms of increased risk of disease for arctic-adapted vertebrates owing to improved
growing conditions for the disease vectors and from
introductions via contact with non-indigenous species
(Harvell et al., 1999); increased pollution loads via
increased precipitation bringing more river borne pollution northward (Macdonald et al., 2003b); increased
competition from northward temperate species expansion; and impacts via increased human traffic and development in previously inaccessible, ice-covered areas.
Alterations to the density, distribution, or abundance of
keystone species at various trophic levels, such as polar
bears and polar cod, are very likely to have significant
and rapid effects on the structure of the ecosystems they
currently occupy.
Although many climate change scenarios focus on negative consequences for ecosystems, climate change will
provide opportunities for some species.The ability to
adapt to new climate regimes is often vast, and this
potential should not be underestimated; many higher
marine vertebrates in the Arctic are adapted to dealing
with patchy food resources and high variability in the
abundance of food resources.
Marine mammals
Changes in the extent and type of sea ice will affect the
distribution and foraging success of polar bears.The earliest impact of warming had been considered most likely
to occur at the southern limits of their distribution, such
as James and Hudson Bays (Stirling and Derocher,
1993), and this has now been documented (Stirling et
al., 1999). Late sea-ice formation and early breakup
means a longer period of annual fasting for polar bears.
Reproductive success is strongly linked to their fat
stores; females in poor condition have smaller litters and
smaller cubs, which are less likely to survive, than
females in good condition.There are also concerns that
direct mortality rates are likely to increase with the climate change scenarios projected by the ACIA-designated
models. For example, increased frequency or intensity of
spring rain could cause dens to collapse resulting in the
death of the female as well as the cubs. Earlier spring
breakup of ice could separate traditional den sites from
spring feeding areas, and young cubs forced to swim
long distances from breeding areas to feeding areas
would probably have a lower survival rate. It is difficult
to envisage the survival of polar bears as a species given
a zero summer sea-ice scenario.Their only option would
be a terrestrial summer lifestyle similar to that of brown
bears, from which they evolved. In such a case, competition, risk of hybridization with brown bears and grizzly
bears, and increased interactions with people would then
number among the threats to polar bears.
Ice-living seals are particularly vulnerable to the
changes in the extent and character of arctic sea ice
projected by the ACIA-designated models because they
depend on the sea ice as a pupping, molting, and resting platform, and some species forage on many iceassociated prey species (DeMaster and Davis, 1995).
Of the high arctic pinnipeds ringed seals are likely to be
most affected because many aspects of their life history
and distribution are linked to sea ice (Finley et al.,
1983; Smith T. et al., 1991;Wiig et al., 1999). They are
the only arctic seal species that can create and maintain
holes in thick sea ice and hence their distribution
extends further north than that of all other pinnipeds.
Ringed seals require sufficient snow cover to construct
their lairs and the sea ice must be sufficiently stable in
spring to rear young successfully (Fig. 9.31) (Lydersen
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Arctic Climate Impact Assessment
in the last two decades when ice did not form in the
Canadian Gulf of St. Lawrence breeding area implies
severe consequences for harp and hooded seals if spring
sea-ice conditions continue to follow current and projected trends.The range and relative abundance of these
species is linked to sea-ice cover and climatic conditions
(Vibe, 1967) and it is not known whether natal site
fidelity is maintained for life, regardless of reproductive
outcome.Thus, it is difficult to predict whether harp and
hooded seals will adjust the location of their breeding
and molting activities if spring sea-ice distribution
changes dramatically over a relatively short period.
Fig. 9.31. A ringed seal pup outfitted with a radio-transmitter
that was deployed as part of a haul-out behavior study in
Svalbard, spring 2003 (photo by Kit Kovacs & Christian
Lydersen, Norwegian Polar Institute).
and Kovacs, 1999). Premature breakup of the sea ice
could result in premature separation of mother–pup
pairs and hence high neonatal mortality. Ringed seals
do not normally haul out on land and to do this would
represent a dramatic change in behavior. Land breeding
would expose the pups to much higher predation rates,
even in a best-case scenario.
Bearded seals use regions of thin, broken sea ice over
shallow areas with appropriate benthic prey communities (Burns J., 1981a).Their distribution, density, and
reproductive success are dependent on the maintenance
of suitable sea-ice conditions in these shallow, often
coastal, areas.Walruses, another predominantly benthic
feeder, also have quite specific sea-ice requirements.
They overwinter in areas of pack ice where the ice is
sufficiently thin that they can break through and maintain breathing holes (Stirling et al., 1981), but is sufficiently thick to support the weight of groups of these
highly gregarious animals. Ice retreat may result in much
of the remaining arctic sea ice being located over water
that is too deep for these benthic foragers. Also, there is
a more general concern that the likely decline in the
community of plants, invertebrates, and fishes that live
in close association with the underside of sea ice are very
likely to result in a dramatic decrease in the flux of carbon to the benthic community, upon which bearded
seals, walruses, and other animals such as grey whales
depend (Tynan and DeMaster, 1997).
Harp seals are flexible about the nature of their summer
sea-ice habitat, but during breeding travel to traditional
sites in southern waters where they form large herds on
extensive areas of pack ice. Massive pup mortality
occurs during poor ice years. Hooded seals also breed in
traditional areas, but select thicker sea ice than harp
seals, and prefer areas where individual floes are large.
Females move away from ice edges, presumably to
reduce harassment from males (Kovacs, 1990). Pup
mortality is also high for hooded seals during poor ice
years.The situation which occurred during three years
Spotted seals require sea ice over waters of specific
depth and so, like bearded seals in the Atlantic, are very
likely to be strongly affected by reduced sea-ice extent.
The ecological requirements of ribbon seals are so poorly known that the effects of changes in sea-ice conditions
are impossible to predict.Their flexibility in shifting
from traditional breeding and foraging sites is unknown.
Poor seasonal sea-ice conditions will result in a decimation of year-classes in the short term, but in the longer
term, herds may form at more northerly sites that meet
their needs.Those species that haul out on land when sea
ice is not available, such as walrus and spotted seal, may
be less affected by changes in sea-ice conditions than the
other ice-associated seals.
In contrast, harbour seals and grey seals are likely to
expand their distribution in an Arctic with less sea ice.
They are for the most part temperate species that have a
broad enough niche that they can occupy warm spots in
the current Arctic. Other pinnipeds that breed on land in
the Arctic are otariid seals.These are likely to be profoundly affected by changes in their food base, as is
thought to be happening in the present regime shift in the
North Pacific.They could also be affected by heat stress,
but Steller sea lions have a present distribution that
includes the Californian coast, implying a considerable
tolerance for warm conditions given access to the ocean.
Sea otters, like Steller sea lion, have a broad distribution
at present and are likely to be most affected by changes at
lower trophic levels which affect their food availability.
The impact of climate-induced perturbations on
cetaceans is less certain than for ice-breeding pinnipeds
and polar bears (Tynan and DeMaster, 1997), although
Burns (2001) suggests grave implications for cetaceans
in the Arctic.The uncertainty arises because the link
between arctic cetaceans and sea ice is largely via prey
availability rather than the sea ice itself (Moore, 2000;
Moore et al., 2000). All the northern whales exhibit
habitat selection, with sea-ice cover, depth, bathymetric
structure, for example, of varying importance (Moore,
2000; Moore et al., 2000). Bowhead whales, beluga
whales (Delphinapterus leucas), narwhals, and minke
whales can all break young sea ice with their backs in
order to breathe in ice-covered areas, but their distribution is generally restricted to areas containing leads or
polynyas and open-water areas at the periphery of the
pack-ice zone. Bowhead whales are considered the most
Chapter 9 • Marine Systems
ice-adapted cetacean.They feed largely on high arctic
copepods and euphausiids (Lowry, 1993), and the distribution of these prey species determines their movements and distribution. Bowhead whales have evolved as
ice whales, with elevated rostrums (i.e., beaks) and
blow holes that allow them to breathe more easily in sea
ice; it is not known whether they could adjust to icefree waters (Tynan and DeMaster, 1997). Bowhead
whales are presently an endangered species despite
decades of protection from commercial hunting.They
consume Calanus spp. and euphausiids and changes in
sea-ice conditions are likely to have a major impact on
their foraging (Finley, 2001).
Narwhal and beluga are known to forage at ice edges and
cracks (Bradstreet, 1982; Crawford and Jorgenson,
1990), but are highly migratory and range well south of
summer edges in the arctic pack ice (Rice, 1998), foraging along the fronts of glaciers (Lydersen et al., 2001) or
even in areas of open water (Reeves, 1990). A small,
threatened, population of belugas is resident in the
Canadian Gulf of St. Lawrence, well south of the Arctic
Circle, which has been affected by industrial pollution
and habitat disturbance.Tynan and DeMaster (1997) predicted that arctic belugas might alter the timing and spatial patterns of seasonal migration given a retreat of the
southern ice edge, particularly in the Canadian Archipelago.Vibe (1967) reported that the historical beluga
distributions are linked to sea ice, wind, and current conditions along the Greenland coast (see section 9.3.3.4).
The changes projected for arctic sea ice over the coming
decades may promote genetic exchange between populations that are currently isolated due to the barrier
formed by the southern ice edge. Narwhal utilize coastal
habitats in summer, but in winter move offshore to deepwater areas with complex bathymetry.These areas are
completely ice-covered except for shifting leads and
cracks. Narwhal are thought to feed on cephalopods at
this time (Dietz et al., 2001), thus the effects of climate
change on narwhal are likely to be via sea-ice distribution
patterns and effects on key prey species.
All other cetacean species that frequent the Arctic avoid
ice-covered areas.Their distributions are predominantly
determined by prey availability (Ridgway and Harrison,
1981-1999) and so the impact of climate change will
occur indirectly via changes to their potential prey base.
Grey whales are unusual in that they are benthic feeders,
and so are very likely to be affected by climate change in
ways more similar to walruses and bearded seals than
other cetaceans.
Seabirds
The effects of climate change on seabird populations,
both direct and indirect through effects on the oceans,
are likely to be detected first near the limits of the
species range and near the margins of their oceanographic range (Barrett and Krasnov, 1996; Montevecchi and
Myers, 1997). Brown (1991) suggests that the southern
limits for many arctic seabird species will move north-
511
ward, as will their breeding ranges. Changes in patterns
of distribution, breeding phenology, and periods of residency in the Arctic are likely to be some of the first
responses to climate change observed in arctic seabird
populations.This is partly because these are more easily
detected than subtle or complex changes such as changes
in population size and ecosystem function (Furness et
al., 1993; Montevecchi, 1993). Because arctic seabirds
are long-lived, have generally low fertility, and live in a
highly variable environment, effects of climate change on
population size, even if quite significant, may take several years to show (Thompson and Ollason, 2001).
Seabirds are likely to be influenced most by indirect
changes in prey availability (Brown, 1991; IPCC, 1998;
Schreiber E., 2001). Seabirds respond to anything that
affects food availability and so are often good indicators
of a system’s productivity (Bailey et al., 1991; Hunt et
al., 1991; Montevecchi, 1993). Several studies have
shown that climate-induced changes in oceanographic
conditions can have large-scale and pervasive effects on
vertebrate trophic interactions, affecting seabird population size and reproductive success (Duffy, 1990;
Montevecchi and Myers, 1997; Schreiber R. and
Schreiber, 1984). Species with narrow food or habitat
requirements are likely to be the most sensitive (Jarvis,
1993;Vader et al., 1990). As warmer (or colder) water
would affect the distribution of prey, the distribution of
individual seabird species is likely to change in accordance with changes in the distribution of macrozooplankton and fish populations. Brown (1991) suggests
that improved foraging conditions will result in range
expansions northward for many species.This is because
the retreating pack ice will open up more feeding areas
in spring and will provide phytoplankton with earlier
exposure to daylight, thereby increasing productivity
throughout the Arctic. However, from analyses of probable changes in food availability in subantarctic waters,
Croxall (1992) concluded that it was not possible to be
certain whether a change in the amount of sea ice would
mean more or less prey for seabirds. Many of these
uncertainties are also relevant to arctic areas.
Changes in water temperature are very likely to have
significant consequences for pelagic fish species (see section 9.3.4.4 and Chapter 13). Most fish species are sensitive to changes in water temperature (e.g., Gjøsæter,
1998), and only slight changes in the thermal regime
can induce changes in their temporal and spatial (both
vertical and horizontal) distributions (Blindheim et al.,
2001; Loeng, 2001; Methven and Piatt, 1991; Shackell
et al., 1994). For example, increases in air temperature
will probably lead to a greater inflow of warm Atlantic
water into the Barents Sea, caused by complex interactions between different water masses, ocean currents,
and wind systems in the north Atlantic.This inflow is
very likely to displace the Polar Front north- and eastward, especially in the eastern Barents Sea.The ice edge
would then be located further north in winter, with a
consequent reduction in the phytoplankton bloom
which normally follows the receding ice edge during
512
spring and summer. It is likely that the distribution of
the Barents Sea capelin would be displaced northeastward, from the central to the northeastern Barents Sea.
Important life-cycle changes are likely to include
changes in the timing of spawning, with a consequent
shift in the timing of migration and a displacement of
migration routes (Loeng, 2001). Such changes to capelin
alone could have profound consequences for many arctic
seabirds in the Barents Sea.
Extreme changes in the spatial and temporal availability
of food can have dramatic effects on the survival of adult
seabirds (Baduini et al., 2001; Piatt and van Pelt, 1997).
However, seabirds are able to travel great distances and
so are insulated to some extent from environmental variability.They are able to exploit locally and ephemerally
favorable conditions during much of the year quite freely.
However, during the breeding season when they are constrained to return to a land-based breeding site but are
dependant on marine resources for foraging, less extreme
reductions in prey availability can affect reproductive success. Most Northern Hemisphere seabirds forage within
200 km of their colonies (Hunt et al., 1999). Because
seabirds generally lay only one egg they cannot alter
clutch size to compensate for low food availability in a
given season. Instead, they reduce the extent of their
parental care contribution when resources are in short
supply in order to protect their own long-term survival
(Øyan and Anker-Nilssen, 1996;Weimerskirch, 2001).
Because they are long-lived, have delayed sexual maturity,
and have conservative reproductive output, even dramatic
reductions in fledgling survival may not be apparent in
terms of overall population size for several years.
If climate change induces long-term shifts in the spatial
distribution of macrozooplankton (predominantly crustaceans) and small schooling pelagic fish, seabird breeding distribution patterns are likely to alter.These prey
species are usually concentrated in frontal or upwelling
areas, which provide a spatially and temporally predictable food supply for seabirds (Hunt, 1990; Hunt et
al., 1999; Mehlum et al., 1998a,b; Schneider, 1990;
Watanuki et al., 2001). If changing environmental conditions cause these oceanographic features to relocate,
then prey distributions are very likely to change. If new
breeding sites become available in close proximity to the
new feeding areas, little change is likely. However, if
suitable breeding areas are not available near the relocated fronts or upwelling, the seabirds may not be able to
take advantage of available food at its new location during the reproductive season, resulting in reproductive
failure.The impacts of future climate change on seabirds
are likely to be extremely variable in a spatial context.
Temporal changes in prey availability can also change the
timing of breeding in seabirds (Schreiber E., 2001), and
potentially result in a mismatch between the timing of
reproduction and the time of food abundance (Visser et
al., 1998). Such a mismatch may have profound impacts
on reproductive success (Brinkhof et al., 1997).The timing of breeding is especially critical for birds breeding in
Arctic Climate Impact Assessment
arctic areas; low temperatures and a restricted period of
prey availability create a narrow temporal window in
which the nesting period sits (Hamer et al., 2001).
The ivory gull is an exception to many of these general
patterns.This species is closely associated with sea ice
throughout most of its life cycle. Changes in sea-ice
extent and concomitant changes in the distribution of
ice-associated seals and polar bears are very likely to
result in changes in ivory gull distribution and potentially
negative effects on abundance.There is concern that
major reductions in ivory gull populations have already
occurred (Krajick, 2001; Mallory et al., 2003).There is
also concern that little auks, specialist feeders on arctic
copepods during the summer, would be negatively affected by the changes predicted in the “Calanus complex” in
the Barents Sea and other parts of the North Atlantic.
Changes in sea level may restrict breeding at existing
sites, but may increase the suitability of other sites
that are not currently usable owing to, for example,
predator access.
Direct evidence of negative effects of environmental conditions (weather) for seabirds is rare, although wind is
thought to be important for foraging energetics. Healthy
arctic seabirds have little difficulty coping with extreme
cold; they are insulated by feathers and subcutaneous fat.
However, owing to these adaptations they may have difficulty keeping cool.Warmer temperatures in the Arctic
are very likely therefore to set southern limits to seabird
distributions that are unrelated to the availability of prey
or breeding sites (Brown, 1991). Extreme weather can
result in direct mortality of chicks or even adults, but it
is most likely that the greatest effect of inclement weather would be to restrict the opportunity for seabirds to
forage (Harris and Wanless, 1984). Heavy rain could
flood the nests of burrowing species such as little auks or
puffins (Rodway et al., 1998; Schreiber E., 2001) and
freezing rain could affect the thermal balance of exposed
chicks leading to mortality (Burger and Gochfeld, 1990).
Changes to the normal patterns of wind speed and direction could alter the cost of flight, particularly during
migration (Furness and Bryant, 1996; Gabrielsen et al.,
1987), but it is the nature and extent of the change that
determine whether the consequences are negative (or
positive) for individual seabird species.
9.4. Effects of changes in ultraviolet
radiation
This section assesses the potential impacts of ozone
depletion-related increases in solar ultraviolet-B radiation
(280–315 nm = UV-B) on arctic marine ecosystems.
For a comprehensive review of the extensive and rapidly
growing technical literature on this subject, readers are
referred to several recent books (DeMora et al., 2000;
Häder, 1997; Helbling and Zagarese, 2003), and particularly to Hessen (2001) with its focus on the Arctic. UV-B
optics in marine waters and ozone layer depletion and
solar ultraviolet radiation are described in Chapter 5.
513
Chapter 9 • Marine Systems
The exponential relationship between the capacity of
ozone to filter ultraviolet light – lower wavelengths are
much more strongly filtered – means that small reductions in stratospheric ozone levels result in large
increases in UV-B radiation at the earth’s surface
(e.g., Kerr and McElroy, 1993; Madronich et al., 1995).
Since ozone layer depletion is expected to continue for
many more years, albeit at a slower rate (Shindell et al.,
1998; Staehelin et al., 2001;Taalas et al., 2000), the
possible impacts of solar UV-B radiation on marine
organisms and ecosystems are currently being investigated (Browman, 2003; Browman et al., 2000; De
Mora et al., 2000; Häder, 1997; Häder et al., 2003;
Helbling and Zagarese, 2003; Hessen, 2001). A growing
number of studies have found that current levels of UVB radiation are harmful to aquatic organisms and may, in
some extreme instances, reduce the productivity of
marine ecosystems (De Mora et al., 2000; Häder, 1997;
Häder et al., 2003; Helbling and Zagarese, 2003;
Hessen, 2001). Reductions in productivity induced by
UV-B radiation have been reported for phytoplankton,
heterotrophic organisms, and zooplankton; the key
intermediary levels of marine food chains (De Mora et
al., 2000; Häder, 1997; Häder et al., 2003; Helbling
and Zagarese, 2003; Hessen, 2001). Similar studies on
planktonic fish eggs and larvae indicated that exposure
to levels of UV-B radiation currently incident at the
earth’s surface results in higher mortality and may lead
to reduced recruitment success (Hunter et al., 1981,
1982; Lesser et al., 2001; Pommeranz, 1974;Walters
C. and Ward, 1998;Williamson et al., 1997; Zagarese
and Williamson, 2000, 2001).
Ultraviolet radiation also appears to affect biogeochemical cycling within the marine environment and in a manner that could affect overall ecosystem productivity and
dynamics (Zepp et al., 2003).
9.4.1. Direct effects on marine organisms
The majority of UV-B radiation research examines direct
effects on specific organisms. Some marine copepods are
negatively affected by current levels of UV-B radiation
(Häder et al., 2003). UV-B-induced mortality in the
early life stages, reduced survival and fecundity in
females, and changes in sex ratios have all been reported
(Chalker-Scott, 1995; Karanas et al., 1979, 1981;
Lacuna and Uye, 2001; Naganuma et al., 1997;
Tartarotti et al., 2000). UV-B-induced damage to the
DNA of crustacean zooplankton has also been detected
in samples collected up to 20 m deep (Malloy et al.,
1997). Eggs of Calanus finmarchicus – a prominent member of the mesozooplankton community throughout the
North Atlantic – incubated under UV-B radiation exhibited a lower percentage hatch rate than those protected
from UV-B radiation (Alonso Rodriguez et al., 2000).
This indicates that Calanus finmarchicus may be sensitive
to variation in incident UV-B radiation. Results for the
few other species that have been studied are highly variable with some showing strong negative impacts, while
others are resistant (Damkaer, 1982; Dey et al., 1988;
Thomson, 1986; Zagarese and Williamson, 2000).The
factors determining this susceptibility are many and
complex, but include seasonality and location of spawning, vertical distribution, presence of UV-B-screening
compounds, and the ability to repair UV-B-induced
damage to tissues and DNA (Williamson et al., 2001).
The work of Marinaro and Bernard (1966), Pommeranz
(1974), and Hunter et al. (1979, 1981, 1982) provided
clear evidence of the detrimental effect of UV-B radiation on the planktonic early life stages of marine fish.
Hunter et al. (1979), working with northern anchovy
(Engraulis mordax) and Pacific mackerel (Scomber japonicus) embryos and larvae, reported that exposure to surface levels of UV-B radiation could be lethal. Significant
sub-lethal effects were also reported: lesions in the
brain and retina, and reduced growth rate.The study
concluded that, under some conditions, 13% of the
annual production of northern anchovy larvae could be
lost as a result of UV-B-related mortality (Hunter et al.,
1981, 1982). Atlantic cod eggs were negatively affected
by exposure to UV-B radiation in very shallow water;
50 cm deep or less (Béland et al., 1999; Browman and
Vetter, 2001).With the exception of a small (but rapidly growing) number of recent studies, little additional
information is available on the effects of UV-B radiation
on the early life stages of fish. However, as for copepods, the early life stages of fish will vary in their susceptibility to UV-B radiation and for the same reasons.
Thus, some studies conclude that the effects of UV-B
radiation will be significant (e.g., Battini et al., 2000;
Lesser et al., 2001;Williamson et al., 1997), while others conclude that they will not (e.g., Dethlefsen et al.,
2001; Kuhn et al., 2000; Steeger et al., 2001).
9.4.2. Indirect effects on marine organisms
Exposure to UV radiation, especially UV-B radiation,
has many harmful effects on health.These may result in
poorer performance, or even death, despite not being
directly induced by exposure to UV-B radiation. UV-B
radiation suppresses systemic and local immune
responses to a variety of antigens, including microorganisms (Garssen et al., 1998; Hurks et al., 1994).
In addition to suppressing T-cell-mediated immune reactions, UV-B radiation also affects nonspecific cellular
immune defenses. Recent studies demonstrate disturbed
immunological responses in UV-B-irradiated roach
(Rutilus rutilus): the function of isolated head kidney
neutrophils and macrophages (immuno-responsive cells)
were significantly altered after a single dose of UV-B
radiation (Salo et al., 1998). Natural cytotoxicity,
assumed to be an important defense mechanism in
viral, neoplastic, and parasitic diseases, was also
reduced. A single dose of UV-B radiation exposure
decreased the ability of fish lymphocytes to respond to
activators, and this was still apparent 14 days later
(Jokinen et al., 2001).This indicates altered regulation
of lymphocyte-dependent immune functions. Finally,
exposure to UV-B radiation induces a strong systemic
stress response which is manifested in fish blood by an
514
increased number of circulating phagocytes and elevated
plasma cortisol levels (Salo et al., 2000a). Exposure to
UV-A (315–400 nm) radiation induced some of the
same negative effects on the immune system (Salo et
al., 2000b). Since high cortisol levels induce immunosuppression in fish (Bonga, 1997) the effect of exposure
to UV-B radiation on the immune system clearly has
both direct and indirect components.Taken together,
these findings indicate that the immune system of fish is
significantly affected by exposure to a single, moderatelevel dose of UV-B radiation. At the population level, a
reduction in immune response might be manifested as
lowered resistance to pathogens and increased susceptibility to disease.The ability of the fish immune system
to accommodate increases in solar UV-B radiation is not
known. Also, the immune system of young fish is likely
to be highly vulnerable to UV-B radiation because lymphoid organs are rapidly developing and because critical
phases of cell proliferation, differentiation, and maturation are occurring (Botham and Manning, 1981;
Chilmonczyk, 1992; Grace and Manning, 1980). It is
also possible that exposure to ambient UV-B radiation
impedes the development of the thymus or other lymphoid organs resulting in compromised immune defense
later in life.The effect of UV-B radiation on the
immune function of fish embryos and larvae, and on the
development of the immune system, is unknown.
Other indirect effects of UV-B radiation are also possible. For example, UV-B radiation may affect sperm quality for species that spawn in the surface layer (Don and
Avtalion, 1993;Valcarcel et al., 1994) and so affect fertilization rate and/or genome transfer.
Studies on the impact of UV-B radiation have almost all
examined the effects of short-term exposure on biological
end-points such as skin injury (sunburn), DNA damage,
development and growth rates, immune function, or outright mortality. Few have examined the potential effects of
longer-term (low-level) exposure (but see Fidhiany and
Winckler, 1999). All these indirect (and/or longer-term)
effects of UV-B radiation have yet to be investigated.
Arctic Climate Impact Assessment
The few studies that have investigated the indirect
effects of UV-B radiation on specific organisms conclude that UV-B-induced changes in food-chain interactions can be far more significant than direct effects on
individual organisms at any single trophic level
(Bothwell et al., 1994; Hessen et al., 1997; Williamson
et al., 1999). Recent investigations indicate the possibility of food-chain effects in both the marine and
freshwater environment: exposure to UV-B radiation
(even at low dose rates) reduces the total lipid content
of some microalgae (Arts and Rai, 1997; Arts et al.,
2000; Plante and Arts, 1998) and this includes the
polyunsaturated fatty acids (PUFAs) (Goes et al., 1994;
Hessen et al., 1997; Wang K. and Chai, 1994). For
zooplankton and fish larvae, the only source of PUFAs
is the diet – they cannot be synthesized and so must be
obtained from prey organisms (Goulden and Place,
1990; Rainuzzo et al., 1997; Reitan et al., 1997;
Sargent et al., 1997). Dietary deficiencies are manifested in many ways. For example, in the freshwater cladoceran Daphnia spp., growth rates are correlated with
the concentration of eicosapentaenoic acid in the water
column (De Lange and Van Donk, 1997; MüllerNavarra, 1995a,b; Scott C. et al., 1999). In Atlantic
herring, dietary deficiencies of essential fatty acids, in
particular docosahexaenoic acid, reduce the number of
rods in the eyes (Bell M. and Dick, 1993) and negatively affect feeding at low light levels (Bell M. et al.,
1995; Masuda et al., 1998). Other negative consequences of essential fatty acid deficits have also been
reported (Bell J. et al., 1998; Kanazawa, 1997;
Rainuzzo et al., 1997). A UV-B-induced reduction in
the PUFA content of microalgae will be transferred to
the herbivorous zooplankton that graze on them, thereby decreasing the availability of this essential fatty acid
to fish larvae. Since fish larvae (and their prey) require
these essential fatty acids for proper development and
growth, a reduction in the nutritional quality of the
food base has potentially widespread and significant
implications for the overall productivity and health of
aquatic ecosystems.
9.4.3.2. Quantitative assessments
9.4.3. Ecosystem effects
9.4.3.1. Food chains
Although the effects of UV-B radiation are strongly
species-specific, marine bacterioplankton and phytoplankton can be negatively affected (De Mora et al., 2000;
Hessen, 2001). Severe exposure to UV-B radiation can,
therefore, decrease productivity at the base of marine
food chains.The importance of this decrease is highly
speculative, but decreases in carbon fixation of 20 to 30%
have been proposed (Helbling and Villafañe, 2001). Arctic
phytoplankton appear more susceptible than antarctic
species, possibly owing to deeper surface mixed layers in
the Arctic (Helbling and Villafañe, 2001). Also, if UV-B
radiation reduces the productivity of protozoans and
crustacean zooplankton there will be less prey available
for fish larvae and other organisms that feed upon them.
Quantitative assessments of the effects of UV-B radiation on marine organisms at the population level are
scarce. However, several studies are currently underway
using mathematical simulation models. Neale et al.
(1998, 2001) estimated that a 50% seasonal reduction
in stratospheric ozone levels could reduce total levels of
primary production – integrated throughout the water
column – by up to 8.5%. Kuhn et al. (2000) developed
a model that incorporates physical and biological information and were able to generate an absolute estimate
of mortality under different meteorological and hydrographic conditions. As a result, they were able to evaluate the relative impacts of different combinations of
environmental conditions – for example, a typical clear
sky versus a typical overcast sky; a typical clear water
column versus a typical opaque coastal water column;
current ambient ozone levels versus a realistically
Chapter 9 • Marine Systems
515
thinned ozone layer. For Calanus finmarchicus eggs in the
estuary and Gulf of St. Lawrence, UV-B-induced mortality for all model scenarios ranged from < 1% to 51%,
with a mean of 10.05% and an uncertainty of ± 11.9%
(based on 1 standard deviation and 48 modeled scenarios). For Atlantic cod, none of the scenarios gave a
UV-B-induced mortality greater than 1.2%, and the
mean was 1.0± 0.63% (72 modeled scenarios).
In both assessments (Kuhn et al., 2000; Neale et al.,
1998, 2001), the most important determinant of UV-Brelated effects was water column transparency (see Fig.
9.32): even when ozone layer depletions of 50% were
modeled, the effect on mortality remained far lower
than that resulting from either thick cloud cover or
opacity of the water column.This demonstrates that
variability in cloud cover, water quality, and vertical distribution and displacement within the surface mixed
layer have a greater effect on the flux of UV-B radiation
to which planktonic marine organisms are exposed than
ozone layer depletion. In contrast, Huot et al. (2000)
showed that ozone thickness could in some instances be
the single most important determinant of DNA damage
in bacterioplankton.
Since the concentrations of dissolved organic carbon
(DOC) and Chl-a are strongly correlated with the transparency of the water column to UV-B radiation, it follows that their concentrations are an overriding factor
affecting UV-B-induced mortality.The Kuhn et al. (2000)
model supports this contention. DOC levels in eutrophic
coastal zones are often greater than 3 to 4 mg/L; the diffuse attenuation coefficients for UV-B radiation at such
levels essentially protect Calanus finmarchicus and cod eggs
from UV-B-induced mortality (Fig. 9.33).Thus, DOC
can be considered as a sunscreen for organisms inhabiting
eutrophic coastal zone waters. DOC concentrations in
arctic waters are typically < 1 mg/L (Aas et al., 2001).
At these levels, DOC is not as effective at protecting
planktonic marine organisms from UV-B-related damage
(Fig. 9.33).
Although these model-based predictions are useful, there
are limited data to parameterize the models, and it will
be some time before similar predictions can be made for
the many species inhabiting the full range of conditions
within the world’s ocean, including those of the Arctic.
9.4.4. General perspectives
Although UV-B radiation can have negative impacts
(direct effects) on marine organisms and populations,
it is only one of many environmental factors (e.g., bacterial and/or viral pathogens, predation, toxic algae)
that result in the mortality typically observed in these
organisms. Recent assessments indicate that UV-B radiation is generally only a minor source of direct mortality (or decreases in productivity) for populations, particularly in “DOC-protected” coastal zones. However,
for those species whose early life stages occur near the
surface, there may be circumstances (albeit rare) –
Fig. 9.32. Output of a mathematical simulation model (Kuhn et
al., 2000) illustrating the relative effects of selected variables on
UV-induced mortality in Calanus finmarchicus embryos (modified
from Browman et al., 2000).The plots illustrate the effects on
irradiance of (a) clear versus cloudy sky, (b) clear versus an
opaque water column, (c) 50% thinning of ozone versus ambient
ozone, while (d) compares the relative impacts of all three on
mortality.This graphic illustrates that water column transparency is the single most important determinant of UV exposure –
of considerably more importance than ozone layer depletion.
516
such as a cloudless sky, thin ozone layer, lack of wind,
calm seas, low nutrient loading – under which the contribution of UV-B radiation to the productivity and/or
mortality of a population could be far more significant.
The impact of indirect effects has not as yet been adequately evaluated.
Arctic Climate Impact Assessment
9.5.The carbon cycle and climate change
The Arctic Ocean has not been considered a significant
carbon sink; first, because extensive sea-ice cover constrains atmosphere–ocean exchange, and second,
because levels of biological production under perennial
sea ice were considered low (English, 1961). Under
warmer conditions, however, the amount of carbon
sequestered by the Arctic Ocean is very likely to increase
significantly.The role of the Arctic as a potential carbon
source, in the form of CH4 and CO2, is unclear owing to
limited information on the likely impact of climate
change on the substantial frozen reserves in permafrost
and gas hydrate layers.
The ocean carbon cycle comprises a physical pump, a
biological pump, and an alkalinity or anion pump.
The physical pump is driven by physical and chemical
processes, which affect the solubility of CO2 and the
transport of water from the surface mixed layer to depth.
The biological pump is driven by primary production,
consuming dissolved CO2 through photosynthesis and
producing particulate organic carbon (POC) and DOC.
The alkalinity pump concerns the removal of carbon by
calcification in the upper waters and the release of carbon
when calcium carbonate is dissolved at depth.The alkalinity pump is not affected by temperature itself, but is
affected indirectly through shifts in biological speciation.
9.5.1. Physical pump
The presence of sea ice strongly affects the physical
pump, which regulates the exchange of CO2 between the
atmosphere and the ocean.This exchange is primarily
determined by the difference in partial pressure of CO2
(pCO2) over the air–sea interface. Physical factors, such
as wind mixing, temperature, and salinity, are also important in this exchange. Dissolved inorganic carbon (DIC) is
the largest component of the marine carbon pool.
Fig. 9.33. Level of protection from UV damage afforded by the
organic matter content of the water column. (a) diffuse attenuation coefficient (Kd) at 305 nm versus modeled survival of Atlantic
cod embryos exposed to UV radiation in a mixed water column;
(b) Kd at 305 nm versus modeled survival of Calanus finmarchicus
embryos exposed to UV radiation in a mixed water column;
(c) dissolved organic carbon (DOC) versus Kd at 305 nm from
field measurements in temperate marine coastal waters (the estuary and Gulf of St. Lawrence, Canada).The straight line is the
regression; the curved lines the 95% confidence intervals
(modified from Browman, 2002).
Multi-year ice restricts air–sea exchange over the central
Arctic Ocean and seasonal sea ice restricts air–sea
exchange over shelf regions to ice-free periods. Because
the solubility of CO2 in seawater increases with decreasing temperature, the largest uptake of atmospheric CO2
occurs primarily in the ice-free Nordic Seas (~ 86 x 1012
g C/yr; Anderson L. and Katlin, 2001) where northward
flowing Atlantic waters are rapidly cooled. Similarly, the
Barents and Bering/Chukchi Seas, where inflowing
Atlantic and Pacific waters undergo cooling, are also
important uptake regions: uptake in the Barents Sea is
~ 9 x 1012 g C/yr (Fransson et al., 2001) and in the
Bering/Chukchi Seas is ~ 22 x 1012 g C/yr (Katlin and
Anderson, 2005). Uptake in the Bering/Chukchi Seas is
higher than in the Barents Sea for reasons discussed in
greater detail in section 9.5.2; namely, a higher potential
for new production owing to a greater supply of nutrients, and a larger area of retreating ice edge along which
much of the primary production occurs. Carbon uptake
in the ice-covered Arctic Ocean and interior shelf seas is
~ 31 x 1012 g C/yr (Katlin and Anderson, 2005).
Chapter 9 • Marine Systems
Although these fluxes are not large on a global scale
(~ 2000 x 1012 g C/yr), the air–sea CO2 flux is very
likely to increase regionally under scenarios of climate
warming. For example, the ACIA-designated models
project the Barents Sea and the northern Bering Sea to
be totally ice-free by 2050 (see section 9.2.5.2). Such
changes in ice cover and longer periods of open water
will result in more regions that resemble the Greenland
Sea, where the physical pump is strong due to low
surface water temperatures and high wind speeds
(Johannessen T. et al., 2002). Atmospheric exchange
will also increase as the areal coverage of the permanent
ice pack is reduced and more leads and polynyas are
formed. Here, the combination of increased atmospheric exchange (driven by winds) and ventilation
(driven by sea-ice formation and convection) transport
CO2 from the atmosphere into the halocline and potentially deeper, eventually entering the deep North
Atlantic Ocean and the THC.Ventilation of Arctic
Ocean intermediate waters has been estimated to
sequester ~ 0.026 Gt C/yr, nearly an order of magnitude more than the sink due to convection in the
Greenland Sea (Anderson L. et al., 1998) and this is
very likely to increase, possibly significantly.
Seasonally ice-covered shelf regions are also important
dense water formation areas. Brine release during seaice formation increases the density of surface waters
which then sink and are advected from the shelf to
basin interiors, transporting CO2 into the halocline and
deeper waters. Under warming conditions, ice formation on shelves will occur later and ice melt will occur
earlier, thereby increasing the time available for air–sea
Fig. 9.34. Profiles of the fugacity (partial pressure corrected for
the fact that the gas is not ideal) of CO2 in Canada Basin and
the Eurasian Basin. Data to the left of the dotted line are undersaturated and to the right are over-saturated.
517
interaction/equilibration and CO2 uptake. The coincidence of open water with late summer storms will also
increase air–sea exchange and CO2 uptake.
Changes in dense water production and the THC will
affect the ocean carbon reservoir (Hopkins, 2001).
The global ocean stores approximately fifty times more
carbon than the atmosphere, mostly in the deep waters of
the Pacific Ocean owing to their volume and long residence time. Slowing or stopping the THC would make the
Atlantic circulation more like that of the Pacific, increasing its carbon storage and thus weakening the greenhouse
effect and cooling the atmosphere – a negative feedback.
In contrast however, if sites of deep ventilation were to
move northward into the Arctic Basin (Aagaard and
Carmack, 1994), the resulting overturn may result in a
positive feedback due to CO2 release to the atmosphere.
Changes in ice cover extent also affect the uptake of
atmospheric CO2 by altering the equilibrium concentrations in the water column. Anderson L. and Katlin
(2001), using the Roy et al. (1993) solubility equations, calculated that melting 2 to 3 m of sea ice and
mixing the resulting freshwater into the top 100 m of
the water column would increase CO2 uptake and
could remove ~ 3 g C/m2. But, where warming is sufficient to increase surface water temperatures by 1 ºC,
~ 8 g C/m2 could be released due to the decrease in
solubility. At high latitudes, surface waters are often
undersaturated because heat is lost to the atmosphere
more quickly than CO2 can dissolve. If ice cover
retreated and the contact period with the atmosphere
increased, this undersaturation would result in atmospheric CO2 uptake. Anderson L. and Katlin (2001),
using data for the Eurasian Basin where Atlantic waters
dominate the upper water column, calculated that surface waters in the St. Anna Trough, the Eurasian Basin,
and the Makarov Shelf slope have a potential carbon
uptake of 35, 48, and 7 g C/m2, respectively, when ice
cover conditions allow saturation.
Regionally, the effects of upwelling of halocline waters
onto the shelf must also be considered. For example, a
profile of the fugacity (partial pressure corrected for
the fact that the gas is not ideal) of CO2 (f CO2) shows
that Pacific-origin waters below 50 m in Canada Basin
are oversaturated due to their origin in the productive
Bering/Chukchi Seas (see Fig. 9.34). If upwelling
brought these oversaturated waters onto the shelf and
they mixed with surface waters CO2 would be released.
Upwelling of waters with salinity ~ 33 (near 150 m in
the Canada Basin) has been observed on the Alaskan and
Beaufort shelves (Aagaard et al., 1981; Melling, 1993;
Melling and Moore, 1995). Upwelling is also expected
to increase when the ice edge retreats beyond the shelf
break (Carmack and Chapman, 2003). In contrast, the
f CO2 profile of Atlantic-origin waters shows that
waters below 50 m in the Eurasian Basin are undersaturated and will take up atmospheric CO2 if moved onto
the shelf by upwelling (Anderson L. and Katlin, 2001).
Hence, the recent shift in the Makarov Basin from a
518
Pacific- to an Atlantic-origin halocline has modified
shelves on the perimeter from a potential source to a
potential sink of atmospheric CO2.
9.5.2. Biological pump
The DOC concentrations in the deep arctic regions are
comparable to those in the rest of the world’s oceans
(Agatova et al., 1999; Borsheim et al., 1999; Bussmann
and Kattner, 2000; Gradinger, 1999;Wheeler et al.,
1997).Within the Arctic Ocean, shelves are regions of
high biological production, especially those within the
Bering, Chukchi, and Barents Seas. Here, CO2 uptake is
increased because CO2 fixation during photosynthesis
affects the physical pump by reducing pCO2.
Levels of primary production are high on shelves due
to increased light levels during ice-free periods and the
supply of new nutrients by advection or vertical mixing. Although phytoplankton blooms are patchy, they
are strongly associated with the retreating ice edge and
the position of the ice edge in relation to the shelf
break. In the northern Bering and southern Chukchi
Seas, primary production occurs over a shallow shelf
(50 to 200 m) and as the zooplankton and bacterioplankton cannot fully deplete this carbon source, it is
either transferred to the benthos or advected downstream (Shuert and Walsh, 1993). On the southeast
Bering Sea shelf, which is deeper at ~ 200 m, there is
potential for a match/mismatch of primary production
and zooplankton grazing due to water temperature
(Box 9.10). An early bloom in cold melt water means
most of the primary production goes to the benthos.
A shift from an ice-associated bloom to a water-column
bloom in the central and northern Bering Sea shelf as a
result of ice retreat provides the potential for development of the plankton community at the expense of the
benthic community (Hunt et al., 2002). Under climate
warming, the benthic community is very likely to be
most affected if this carbon is transferred to the deep
basin instead of the shelf. Under these circumstances,
carbon is disconnected from the food web and can be
buried. In contrast, the Barents Sea shelf is much deeper (300 m) and primary production supports a large
pelagic community that is unlikely to be affected.
Nevertheless, a larger quantity of carbon is likely to be
buried in future as deposition shifts from the shelf
region to the deeper slope and basin region due to the
northward movement of the ice edge.
Projections that the Arctic Ocean will be ice-free in
summer (see section 9.2.5.2) imply that production
will increase in waters where it was previously limited
by ice cover. Based on nutrient availability, Anderson L.
et al. (2003) estimated that the biological carbon sink
would increase by 20 x 1012 g C/yr under ice-free conditions. However, mesocosm studies on the effect of
high initial ambient CO2 (750 µatm) on coccolithophore assemblages have shown an increase in POC
production (Zondervan et al., 2002).This would be a
negative response to atmospheric CO2 increase.
Arctic Climate Impact Assessment
9.5.3. Alkalinity pump
Removal of carbonate ions during the formation of calcareous shells and the subsequent sinking of these shells
is important in the transfer of inorganic carbon to deeper waters and eventually the sediments. Carbonate shell
sinking is also an efficient means of removing organic
carbon from the euphotic zone (see section 9.5.2).
Together, these processes will provide a negative feedback. However, calcification results in an increase in
oceanic pCO2 through the redistribution of carbonate
species, which represents a positive feedback. Partial
equilibrium with the atmospheric CO2 will result in an
increase in pH that may reduce calcification (Riebesell
et al., 2000).
9.5.4.Terrestrial and coastal sources
The Arctic Ocean accounts for 20% of the world’s continental shelves and these receive, transport, and store terrestrial organic carbon (primarily from rivers and coastal
erosion sources) to an extent significant at the global
scale (Rachold et al., 2004). Olsson and Anderson (1997)
estimated that 33 to 39 x 1012 g of inorganic carbon are
delivered to the Arctic Ocean each year by rivers.
Although the amount of total organic carbon is more
difficult to estimate because more than 90% is deposited
in deltas (Rachold et al., 1996), it may be similar. An
increase in precipitation due to climate warming will not
necessarily increase carbon burial, however, as the geological composition of the drainage basin and the amount
of flow are both controlling factors. For example, the
Mackenzie and Yukon are both erosional rivers, while the
Siberian rivers are depositional, especially the Ob for
which the drainage basin includes marsh lowlands
(Pocklington, 1987).Thus, increased precipitation is likely to lead to increased DIC delivery in the first case but
not the second, and depends on the timing and intensity
of the freshwater flow into the sea. Burial will occur on
the shelf, and in adjacent ocean basins if transported offshore by sea ice, ocean currents, or turbidity currents.
Regional transport of terrestrial organic carbon to the
marine system also results from coastal erosion. For
example, the near-shore zone of the Laptev and East
Siberian Seas is the most climatically sensitive area in the
Arctic and has the highest rates of coastal retreat (Are,
1999; Grigoriev and Kunitsky, 2000). Biodegradation of
this coastal material is a regional source of high pCO2 in
surface waters of the Laptev and East Siberian Seas
(Semiletov, 1999a). Longer ice-free conditions and latesummer storms may accelerate the release of terrestrial
carbon frozen during the last glaciation. Pleistocene
permafrost soils contain huge ice wedges (up to 60 to
70% by volume) and are enriched by organic carbon (~ 1
to 20% by weight; Are, 1999, Romanovsky et al., 2000).
The amount of organic carbon stored in permafrost is
large (~ 450 Gt C), similar to the quantity of dissolved
carbon stored in the Arctic Ocean (Semiletov, 1999b),
and its release to the atmosphere depends on sediment
burial rates and competing consumption by biota.
519
Chapter 9 • Marine Systems
The rate of coastal erosion in the Arctic appears to have
increased from a few meters per year to tens of meters
per year (Are, 1999;Tomirdiaro, 1990).The highest
rates of coastal retreat have been observed at capes;
regions important as hunting locations. Bottom erosion
is also evident.The bottom depth in the near-shore zone
of the Northern Sea Route has increased by ~ 0.8 m over
the past 14 years (Tomirdiaro, 1990). Many climaterelated factors affect coastal retreat in the Arctic: permafrost ice content, air temperature, wind speed and direction, duration of open water, hydrology, and sea-ice conditions. In addition to the direct effects of climate
change, rates of coastal retreat might also increase
indirectly due to wave fetch and storm surge activity.
Sea-level rise (~ 15 cm per 100 years, Proshutinsky et
al., 2001) will further accelerate coastal erosion.
9.5.5. Gas hydrates
The release of CH4 and CO2 trapped in vast gas-hydrate
reservoirs in permafrost is very likely to play a key but
largely overlooked role in global climate, particularly as
CH4 is 60 times more efficient as a GHG (on a molar
basis) than CO2. For example, Semiletov (1999a) estimated that the upper 100 m layer of permafrost contains
at least 100 000 Gt of organic carbon in the form of CH4
and CO2. Although CH4 is one of the most important
GHGs, there are currently only ~ 4 Gt of CH4 carbon in
the atmosphere. If a small percentage of CH4 from the
gas-hydrate reservoir were released to the atmosphere, it
could result in an abrupt and significant increase in global temperature through positive feedback effects (Bell P.,
1982; Nisbet, 1990; Paull et al., 1991; Revelle, 1983).
The marine Arctic is a particularly important source
region for CH4. Following glacial melting and sea-level
rise during the Holocene, relatively warm (0 ºC) Arctic
Ocean waters flooded the relatively cold (-12 ºC)
Arctic permafrost domain (Denton and Hughes, 1981).
As a result, permafrost sediments underlying the arctic
shelf regions are still undergoing a dramatic thermal
regime change as this heat is conducted downward as a
thermal pulse. Subsurface temperatures within the sediment may have risen to the point that both gas hydrate
and permafrost may have begun to thaw. In this case
CH4 would undergo a phase change, from a stable gas
hydrate to a gas, and therefore rise through the sediment. Little is known about the fate of CH4 released in
this manner. Depending on the structure and ice
matrix of surrounding sediments, CH4 can be either
consumed by anaerobic CH4 oxidation or released
upward through conduits into the overlying seawater.
Evidence of elevated CH4 concentrations in seawater
has been observed in the Beaufort Sea (Macdonald,
1976) and along the North Slope of Alaska
(Kvenvolden, 1991; Kvenvolden et al., 1981).
Kvenvolden et al. (1993) noted that CH4 concentrations under sea ice in the Beaufort Sea were 3 to 28
times higher in winter than summer, suggesting that
CH4 accumulates under the sea ice in winter and is
rapidly released into the atmosphere when the sea ice
retreats. The timing and release of these under-ice
accumulations will change with changes in ice cover.
9.6. Key findings
This section summarizes the conclusions from sections
9.2.5, 9.3.4, 9.4, and 9.5.
The Arctic is a major component of the global climate
system; it both impacts and is impacted upon by the
larger global system.This interaction is illustrated in the
bulleted list of key findings, respectively labeled A > G
and G > A.There are also forcing mechanisms and
responses that remain internal to the Arctic (A > A). Any
change in atmospheric forcing (wind, temperature, and
precipitation) is of great importance for the ocean circulation and ocean processes (G > A).
• Large uncertainties in the response of the arctic
climate system to climate change arise through
poorly quantified feedbacks and thresholds associated with the albedo, the THC, and the uptake of
GHGs by the ocean. Since climate models differ in
their projections of future change in the pressure
fields and hence their associated winds, much
uncertainty remains in terms of potential changes
in stratification, mixing, and ocean circulation.
• The Arctic THC is a critical component of the
Atlantic THC.The latest assessment by the
Intergovernmental Panel on Climate Change
(IPCC, 2001) considered a reduction in the
Atlantic THC likely, while a complete shutdown is
considered unlikely but not impossible. If the
Arctic THC is reduced, it will affect the global
THC and thus the long-term development of the
global climate system (A > G). Reduction in the
global THC may also result in a lower oceanic heat
flux to the Arctic (G > A). If the THC is reduced,
local regions of the Arctic are likely to undergo
cooling rather than warming, and the location of
ocean fronts may change (A > A).The five ACIAdesignated models cannot assess the likelihood of
these occurrences.
• Most of the present ice-covered arctic areas are
very likely to experience reductions in sea-ice
extent and thickness, especially in summer.
Equally important, it is very likely that there will
be earlier sea-ice melt and later freeze-up (G > A).
This is likely to lead to an opening of navigation
routes through the Northwest and Northeast
Passages for greater periods of the year and thus
to increased exploration for reserves of oil and
gas, and minerals.
• Decreased sea-ice cover will reduce the overall
albedo of the region, which is very likely to result
in a positive feedback for global warming (A > G).
• Upper water column temperatures are very likely
to increase, especially in areas with reduced seaice cover.
• The amount of carbon that can be sequestered in the
Arctic Ocean is likely to increase significantly under
520
scenarios of decreased sea-ice cover, through surface
uptake and increased biological production (A > G).
• Greenhouse gases (CO2 and CH4) stored in
permafrost may be released from marine sediments to the atmosphere subsequent to warming,
thus initiating a strong positive feedback (A > G).
• In areas of reduced sea-ice cover, primary production is very likely to increase, which in turn is likely to increase zooplankton and possibly fish production. Increased cloud cover is likely to have the
opposite effect on primary production in areas that
are currently ice free (G > A).
• The area occupied by benthic communities of
Atlantic and Pacific origin is very likely to increase,
while areas occupied by colder-water species are
very likely to decrease. Arctic species with a narrow
range of temperature preferences, especially longlived species with late reproduction, are very likely
to be the first to disappear. A northward retreat for
the arctic benthic fauna may be delayed for the benthic brooders (the reproductive strategy for many
dominant polar species), while species producing
pelagic larvae are likely to be the first to colonize
new areas in the Arctic (G > A).
• A reduction in sea-ice extent is very likely to
decrease the natural habitat for polar bears, ringed
seals, and other ice-dependent species, which is
very likely to lead to reductions in the survival of
these species. However, increased areas and periods of open water are likely to be favorable for
some whale species and the distribution of these
species is very likely to move northward (G > A).
• Some species of seabird such as little auk and
ivory gull are very likely to be negatively affected
by the changes predicted to occur within the arctic communities upon which they depend under
climate warming, while it is possible that other
species will prosper in a warmer Arctic, as long as
the populations of small fish and large zooplankton are abundant (G > A).
• Increased water temperatures are very likely to
lead to a northward shift in the distribution of
many species of fish, to changes in the timing of
their migration, to a possible extension of their
feeding areas, and to increased growth rates.
Increased water temperatures are also likely to
lead to the introduction of new species to the
Arctic but are unlikely to lead to the extinction of
any of the present arctic fish species. Changes in
the timing of biological processes are likely to
affect the overlap of spawning for predators and
their prey (match/mismatch; Box 9.10) (G > A).
• Stratification in the upper water column is likely to
increase the extent of the present ice-free areas of
the Arctic, assuming no marked increase in wind
strength (G > A).
• There are strong correlations between DOC,
Chl-a, and the attenuation of UV radiation in
marine waters.This is particularly significant within the context of possible UV-B attenuation in
marine coastal systems, since DOC and Chl-a are
Arctic Climate Impact Assessment
usually more highly concentrated in ice-free waters
than ice-covered waters.
• Present assessments indicate that UV-B radiation
generally represents only a minor source of direct
mortality (or decreased productivity) for populations, particularly in DOC-protected coastal
zones. However, for those species whose early life
stages occur near the surface, it is possible that
under some circumstances – a cloudless sky, thin
ozone layer, lack of wind, calm seas, low nutrient
loading – the contribution of UV-B radiation to the
productivity and/or mortality of a population
could be far more significant.Thus, it is likely that
UV-B radiation can have negative impacts (direct
and/or indirect effects) on marine organisms and
populations. However, UV-B radiation is only one
of many environmental factors responsible for the
mortality typically observed in these organisms.
9.7. Gaps in knowledge and research needs
Many aspects of the interaction between the atmosphere
and the ocean, and between climate and the marine
ecosystem require a better understanding before the high
levels of uncertainty associated with the predicted
responses to climate change can be reduced.This can only
be achieved through monitoring and research, some areas
requiring long-term effort. For some processes, the ocean
responds more or less passively to atmospheric change,
while for others, changes in the ocean themselves drive
atmospheric change.The ocean clearly has a very important role in climate change and variability. Large, longlived arctic species are generally conservative in their lifehistory strategies, so changes, even dramatic changes, in
juvenile survival may not be detected for long periods.
Zooplankton, on the other hand, can respond within a
year, while microorganisms generally exhibit large and
rapid (within days or weeks) variations in population size,
which can make it difficult to detect long-term trends in
abundance. Long data series are thus essential for monitoring climate-induced change in arctic populations.
Although the ACIA-designated models all project that
global climate change will occur, they are highly variable
in their projections.This illustrates the great uncertainty
underlying attempts to predict the impact of climate
change on ecosystems.The models do not agree in terms
of changes projected to wind fields, upon which ocean
circulation and mixing processes depend.Thus, conclusions drawn in this chapter regarding future changes to
marine systems are to a large extent based on extrapolations from the response of the ocean to past changes in
atmospheric circulation.This is also the case for predictions regarding the effects of climate change on marine
ecosystems.The present assessment has been able to
provide some qualitative answers to questions raised
regarding climate change, but has rarely been able to
account for non-linear effects or multi-species interactions. Consequentially, reliable quantitative information
on the response of the marine ecosystem to climate
change is lacking.
521
Chapter 9 • Marine Systems
9.7.1. Gaps in knowledge
This section highlights some of the most important gaps
in knowledge.These require urgent attention in order to
make significant progress toward predicting and understanding the impacts of climate change on the marine
environment. Each item includes an explanation as to
why it is considered important.
Thermohaline circulation
Global circulation models provide an ambiguous assessment of potential changes to the THC. Most project a
decrease in the strength of the THC; however, some
recent models project little or no change.The THC is
extremely important for the thermal budget of the
Arctic Ocean and the North Atlantic.
Vertical stratification
Present climate models are unable to project future
wind conditions, or to project how increased air temperatures, ice melt, and freshwater runoff will influence
the vertical stability of the water column.The amount
of vertical mixing that will occur is thus uncertain. Such
information is required in order to project the effects of
climate change on vertical heat and nutrient fluxes.
Ocean currents and transport pathways
It is necessary to understand the forces driving ocean
circulation (wind, freshwater runoff, sea-ice freezing/
melting) and their variability. Ocean circulation is fundamental to the distribution of water masses and thus
the distribution and mixture of species within the
marine ecosystem.
Fronts
Open ocean fronts act as barriers to many marine organisms and are important feeding areas for higher trophic
organisms.The relative importance of production at
frontal regions compared to that at non-frontal regions
has not been assessed for the Arctic, nor has the importance of fronts in terms of recruitment success for fish.
Few climate models provide information on fronts and
their variability, and even less have an adequate spatial
resolution with which to address this issue.
Release of greenhouse gases and sequestration
of carbon
Changes in the balance of GHGs (i.e., sources relative to
sinks) are known to impact upon climate yet little is
known about the arctic reservoir.This is made all the
more important through positive feedback mechanisms.
Carbon can be sequestered by physical and biological
processes, and can be released during ocean mixing
events and the thawing of permafrost; estimates of the
rates and reservoir sizes need refining before they can be
used in global circulation models. Changes in the extent
and timing of sea-ice cover may affect trophic structure
and thus the delivery of carbon to the sediment.
Species sensitivity to climate change
Little is known about the response times of species to
climate change. For example, the rapid disappearance of
sea ice may not allow for adaptive change by many arctic
specialists and may possibly result in the disappearance
of ice-dependent species. Microorganisms, zooplankton,
and fish are all expected to exhibit shifts in distribution
but the rates at which this will occur cannot be predicted at present.
Match/mismatch between predators and prey
The timing of reproduction for many species is related
to that of their prey. How the timing and location of the
production or spawning of most species might alter in
response to climate change is unclear and so therefore is
the extent of a potential match/mismatch between predators and their prey. Potentially, this could impact upon
the whole arctic ecosystem.
Indirect and non-linear effects on biological
processes
Biota are indirectly affected by atmospheric climate
change through effects on their surrounding environment and on the food web.While the response of a
species to change in one particular variable can often be
surmised, although generally not quantified, its
response to a collection of direct and indirect effects
occurring simultaneously is considerably more difficult
to address.This is further complicated by the nonlinearity of many processes.
Competition when/if new species are
introduced into the ecosystem
Many arctic specialists have relatively narrow habitat and
other niche requirements.Their likely response to a possible increase in competition from more opportunistic/
generalist species in a warmer Arctic is unclear.
Gelatinous zooplankton
The abundance and variability of gelatinous zooplankton
such as jellyfish has not been determined for most arctic
regions. Although gelatinous zooplankton are known to
be important as both predators and prey, and that they
can represent a significant component of the biomass at
times, their actual role within the ecosystem is unclear.
UV-B radiation exposure
Almost all existing evaluations of the effects of UV radiation are based on short-term studies. Studies are lacking on longer-term sub-lethal exposure to UV radiation,
on both individual species and the overall productivity of
marine ecosystems. UV-induced reductions in the nutri-
522
tional quality of the food base could possibly pass
through the food chain to fish, potentially reducing their
growth rates as well as their nutritional condition.
9.7.2. Suggested research actions
This section lists possible actions that could be undertaken to improve the knowledge and understanding of
important processes related to climate change.To reduce
the uncertainties in the predicted responses to climate
change it is necessary for work to proceed on several
fronts simultaneously. Research actions that are considered to be of highest priority are identified by an H.
Observational technologies
• Increase the application of recently developed technologies.
Recent developments range from current meters, to
satellite sensors, to monitors for marine mammals.
• Develop Remote Underwater Vehicles (RUVs) capable of
working reliably under the sea ice for extended periods.
This will reduce sampling costs and enable data collection in regions difficult to access using conventional sampling methods. Instrumentation on the
RUVs should include means to sample the biota.
Surveying and monitoring
• Undertake surveys in those areas of the marine Arctic
that are poorly mapped and whose resident biota have
not been surveyed (H).These include surveys under
the permanent ice cap in winter (perhaps using
RUVs), and surveys to quantify the CH4 and
carbon reserves in the arctic marine sediments.
• Continue and expand existing monitoring programs (H),
both spatially and in breadth of measurement. New
monitoring activities should be established in areas
where they are presently lacking and these should
be designed to address the effects of climate
change. Issues to be addressed include the timing
and amount of primary and secondary production,
larval fish community composition, and reproductive success in marine mammals and seabirds.
Key ecosystem components, including noncommercial species, must be included.
• Evaluate monitoring data through data analysis and
modeling to determine their representativeness in
space and time.
Data analysis and reconstruction
• Reconstruct the twentieth-century forcing fields over the
arctic regions. Present reconstructions only extend
back to around 1950.These reconstructions would
help to model past climates.
• Establish an arctic database that contains all available
physical and biological data.There should be open
access to the database.
• Recover past physical and biological data from the Arctic.
There are many data that are not presently available but could be recovered.
Arctic Climate Impact Assessment
• Undertake analysis of past climate events to better
understand the physical and biological responses to
climate forcing. An example is the dramatic air
temperature warming that took place from the
1920s to 1960 in the Arctic.
Field programs
• Undertake field studies to quantify climate-related
processes (H). Examples of particular processes that
require attention are: open ocean and shelf convection; forces driving the THC; physical and biological processes related to oceanic fronts; sequestrating of carbon in the ocean, including a quantification of air–ice–ocean exchange; long-term effects
of UV-B radiation on biota; and, interactions
between benthic, ice, and pelagic fauna.
Modelling
• Improved modeling of the ocean and sea ice in global
circulation models (H). For example, how will the
THC change? What are the consequences of
change in the THC for the position and strength of
ocean fronts, ocean current patterns, and vertical
stratification?
• Development of reliable regional models for the Arctic
(H).These are essential for determining impacts
on the physics and biology of the marine Arctic.
• Strengthen the bio-physical modeling of the Arctic.
Increased emphasis is required on coupling biological models with physical models in order to
improve predictive capabilities.
Approaches
• Prioritize ecosystem-based research (H). Previous biological research programs were often targeted on
single species.While these data are essential for
input to larger-scale programs, the approach must
be complemented by a more holistic ecosystembased approach. Alternative concepts, methods,
and modeling approaches should be explored.
More effort should be placed on integrating multiple ecosystem components into modeling efforts
concerning climate effects. Research on microbial
communities, which may play a future role in a
warmer Arctic, must be included.
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Chapter 10
Principles of Conserving the Arctic’s Biodiversity
Lead Author
Michael B. Usher
Contributing Authors
Terry V. Callaghan, Grant Gilchrist, Bill Heal, Glenn P. Juday, Harald Loeng, Magdalena A. K. Muir, Pål Prestrud
Contents
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .540
10.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .540
10.2. Conservation of arctic ecosystems and species . . . . . . . . . .543
10.2.1. Marine environments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .544
10.2.2. Freshwater environments . . . . . . . . . . . . . . . . . . . . . . . . . . . .546
10.2.3. Environments north of the treeline . . . . . . . . . . . . . . . . . . . . .548
10.2.4. Boreal forest environments . . . . . . . . . . . . . . . . . . . . . . . . . . .551
10.2.5. Human-modified habitats . . . . . . . . . . . . . . . . . . . . . . . . . . . . .554
10.2.6. Conservation of arctic species . . . . . . . . . . . . . . . . . . . . . . . .556
10.2.7. Incorporating traditional knowledge . . . . . . . . . . . . . . . . . . . .558
10.2.8. Implications for biodiversity conservation . . . . . . . . . . . . . . .559
10.3. Human impacts on the biodiversity of the Arctic . . . . . . . .560
10.3.1. Exploitation of populations . . . . . . . . . . . . . . . . . . . . . . . . . . .560
10.3.2. Management of land and water . . . . . . . . . . . . . . . . . . . . . . . .562
10.3.3. Pollution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .564
10.3.4. Development pressures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .566
10.4. Effects of climate change on the biodiversity of the Arctic . .567
10.4.1. Changes in distribution ranges . . . . . . . . . . . . . . . . . . . . . . . .568
10.4.2. Changes in the extent of arctic habitats . . . . . . . . . . . . . . . . .570
10.4.3. Changes in the abundance of arctic species . . . . . . . . . . . . . .571
10.4.4. Changes in genetic diversity . . . . . . . . . . . . . . . . . . . . . . . . . . .572
10.4.5. Effects on migratory species and their management . . . . . . .574
10.4.6. Effects caused by non-native species and their management .575
10.4.7. Effects on the management of protected areas . . . . . . . . . . .577
10.4.8. Conserving the Arctic’s changing biodiversity . . . . . . . . . . . . .579
10.5. Managing biodiversity conservation in a changing
environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .579
10.5.1. Documenting the current biodiversity . . . . . . . . . . . . . . . . . .580
10.5.2. Identifying changes in the Arctic’s biodiversity . . . . . . . . . . . .583
10.5.3. Recording the Arctic’s changing biodiversity . . . . . . . . . . . . . .585
10.5.4. Managing the Arctic’s biodiversity . . . . . . . . . . . . . . . . . . . . . .589
10.5.5. Concluding remarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .590
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .591
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .591
540
Arctic Climate Impact Assessment
Summary
10.1. Introduction
Biodiversity is fundamental to the livelihoods of arctic
people.The Convention on Biological Diversity defines
biodiversity as “the variability among living organisms
from all sources including, inter alia, terrestrial, marine
and other aquatic ecosystems and the ecological complexes of which they are a part: this includes diversity
within species, between species and of ecosystems”.
A changing climate can affect all three levels of biodiversity.There are many predicted influences of climate change on the Arctic’s biodiversity.These include
(1) changes in the distribution ranges of species and
habitats; (2) changes in the extent of many habitats;
(3) changes in the abundance of species; (4) changes in
genetic diversity; (5) changes in the behavior of migratory species; (6) some non-native species becoming
problematic; and (7) the need for protected areas to be
managed in different ways.
Arctic peoples obtain their primary source of food and
many of the materials used in clothing and building from
the plant and animal species indigenous to the Arctic.
These species range from mammals, fish, and birds, to
berries and trees. However, the relationship between
arctic people and those arctic species upon which they
depend is not simple since each of these species is in
turn dependent on a range of other arctic species and on
the ecological processes operating within the arctic
ecosystems.The biological diversity of the arctic environment is thus fundamental to the livelihoods of arctic
peoples. Relevant information from indigenous peoples
on arctic biodiversity is given in Chapter 3.
What should be done now before the anticipated
changes occur? First, it is important to document the
current state of the Arctic’s biodiversity. Local inventories of biodiversity have generally not been carried out,
although the inventory for Svalbard is a striking exception, recording both native and non-native species in
both terrestrial and marine environments. Such work
requires trained ecologists, trained taxonomists, circumpolar knowledge, and a focus on all three levels of biodiversity (genes, species, and ecosystems). Second, the
changes that take place in the Arctic’s biodiversity need
to be identified. Management of the Arctic’s biodiversity,
in the sea, in freshwater, or on land, must work with
ecological succession and not against it. Considerably
more effort needs to be invested in developing predictive models that can explore changes in biodiversity
under the various scenarios of climate change.Third,
changes in the Arctic’s biodiversity need to be recorded
and the data shared. In a situation where so much uncertainty surrounds the conservation of biodiversity, knowledge of what has changed, where it has changed, and
how quickly it has changed becomes critically important. Monitoring biodiversity, especially on a circumpolar basis, must be a goal, and a circumpolar monitoring network needs to be fully implemented so as to
determine how the state of biodiversity is changing,
what the drivers of change are, and how other species
and people respond. Finally, new approaches to managing the Arctic’s biodiversity need to be explored. Best
practice guidelines should be available on a circumpolar
basis.The Circumpolar Protected Area Network needs
to be completed and reviewed so as to ensure that it
does actually cover the full range of the Arctic’s present
biodiversity. An assessment needs to be made, for each
protected area, of the likely effects of climate change,
and in the light of this assessment the methods of management for the future.This poses questions of resources
and priorities, but it is essential that the Arctic’s ecosystems continue to exist and function in a way that such
services as photosynthesis, decomposition, and purification of pollutants continue in a sustained manner.
The two major processes operating within ecosystems
are photosynthesis and decomposition. Photosynthesis is
the biochemical process whereby radiant energy from
the sun is used to synthesize carbohydrates from carbon
dioxide (CO2) and water in the presence of chlorophyll.
The energy fixed during photosynthesis is transferred
from the primary producers through successive trophic
levels by feeding and thus starts the food chains and food
webs upon which all animal life depends.The organisms
responsible are green plants – predominantly vascular
plants in the terrestrial environment and algae in the
freshwater and marine environments.The vascular
plants, which include all flowering plants and ferns, are
relatively well-known taxonomically and feature in most
books on the terrestrial environment of the Arctic
(e.g., CAFF, 2001; Sage, 1986).The non-vascular plants
such as the mosses, liverworts, and lichens are less wellknown taxonomically.The algae are taxonomically the
least well-known plants of the Arctic; most are singlecelled and many have a wide distribution range within
the northern hemisphere (John et al., 2002).
Decomposition is the process whereby dead plant and
animal material is broken down into simple organic and
inorganic compounds, with a consequent release of
energy. The carbon is released back into the atmosphere
as CO2, and nutrients such as nitrogen, phosphorus,
and potassium are available for recycling. Decomposition processes are undertaken by an enormous range of
organisms in soils and in aquatic sediments. These
organisms include bacteria, actinomycetes, fungi,
protozoa, nematodes, worms (especially enchytraeid
worms), mollusks, insects (especially collembolans –
springtails, and dipteran larvae – flies), crustaceans,
and arachnids (especially mites). Species richness can
be outstanding, with up to 2000 species within a square
meter of grassland soil (Usher, 1996), which has led to
soil being considered “the poor man’s tropical rain
forest”. However, many of the species in soils and sediments are unknown and undescribed, and their roles in
the soil or sediment ecosystem, and in the processes of
decomposition, are very poorly understood. This means
that, within a changing climate, there are many questions about the decomposition process that need
addressing (Heal, 1999).
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Chapter 10 • Principles of Conserving the Arctic’s Biodiversity
In addition to photosynthesis and decomposition, there
are many other important ecological processes operating
within arctic ecosystems, for example: pollutant breakdown and detoxification, the purification of water, the
release of oxygen, and nutrient recycling.
visitors) depend, and whether the Arctic exacerbates
climate change by releasing greater quantities of CO2 to
the atmosphere or helps to control climate change by
acting as a sink for atmospheric CO2. Biodiversity is
therefore both affected by and affects climate change.
The major ecosystems of the Arctic, and their biological
diversity, are addressed in detail in other chapters:
Chapter 7 addresses the terrestrial environment, focusing on the tundra and polar desert ecosystems; Chapter
8 addresses freshwater ecosystems; and Chapter 9
addresses marine systems.This chapter focuses on the
principles of conserving biodiversity, exploring the
ecosystems, species, and genes in the Arctic, and the
threats faced in a changing environment.The starting
point for this discussion is the Convention on Biological
Diversity (SCBD, 2000), which states that its objectives
are “... the conservation of biological diversity, the sustainable use of its components and the fair and equitable
sharing of the benefits arising out of the utilization of
genetic resources...” (Article 1).
The first two lines of approach to biodiversity conservation are often the development of lists of species and
habitats to be given special protection (usually through
legislation, and often on the basis of “Red Lists”), and
the designation of protected areas where biodiversity
conservation takes primacy over other forms of water
and land use. By 1990, there had been significant
achievements (IUCN, 1991) in establishing protected
areas in the Arctic. Norway, Sweden, and Finland, for
example, all had strict nature reserves (IUCN management category I), national parks (IUCN category II),
and/or other nature reserves (IUCN category IV) within their arctic territories. In fact, the extent of these
protected arctic areas is often considerably greater than
the extent of equivalent protected areas further south.
In Sweden, four of the seven national parks located
within the Arctic are each larger than the total area of
the 18 national parks south of the Arctic (Table 10.1).
One of these, Abisko, has as its aim “to preserve the
high Nordic mountain landscape in its natural state”
(Naturvårdverket, 1988), while others have similar aims
to preserve landscapes and, by implication, the biodiversity that those landscapes contain.
The Convention on Biological Diversity defines “biological diversity” (often shortened to “biodiversity”) as
“the variability among living organisms from all sources
including, inter alia, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which
they are a part; this includes diversity within species,
between species and of ecosystems” (Article 2).
This definition clearly implies that biodiversity, and
both its conservation and utilization, must be viewed at
three levels – the level of the gene, the species, and the
ecosystem (or habitat).
A changing climate can affect all three levels of biodiversity, and Chapters 7, 8, and 9 address such issues.What
the human population wishes to conserve, and the way
that biodiversity conservation is practiced, will also be
affected by a changing climate.The exploitation of the
Arctic’s biodiversity resources, and the potential for
their exploitation in the future, will equally be affected,
and these topics are considered in greater detail in
Chapter 11 (wildlife conservation and management), 12
(hunting, herding, fishing, and gathering by indigenous
peoples), 13 (marine fisheries and aquaculture), and 14
(forests and agriculture).The present chapter deals primarily with the first two tenets of the Convention on
Biological Diversity, namely the conservation of biodiversity and its sustainable use by the peoples of the
Arctic.The first involves all aspects of the Arctic’s
wildlife, from the smallest organisms (viruses, bacteria,
and protozoa) to the largest plants and animals.The latter invokes the concept of stewardship: stewardship
implies a sustainable form of management rather than
the preservation of species and ecosystems without
change. Climate change will result in changes in the productivity of ecosystems through photosynthesis and
changes in the rates of decomposition.The balance
between these two major processes will, to a large
extent, determine the future nature of the arctic environment, the resources upon which arctic peoples (and
In 1996, Conservation of Arctic Flora and Fauna (CAFF)
developed a strategy, with an associated action plan, for
a Circumpolar Protected Area Network. CAFF’s efforts,
jointly with other international governmental and nongovernmental organizations, and a range of local, regional, and national bodies, led to the establishment of nearly
400 protected areas (each greater than 10 km2) by 2000
(CAFF, 2001).The selection process for potential protected areas has been studied in many parts of the world
and tends to be a blend of science (what is most desirable to protect?) and pragmatism (what is possible to
Table 10.1. Details of the 25 national parks in Sweden
(Hanneberg and Löfgren, 1998).
Extent (ha)
National parks in the Arctic
Abisko
Muddus
7700
50350
Padjelanta
198400
Pieljekaise
15340
Sarek
197000
Stora Sjöfallet
127800
Vadvetjåkka
2630
Average extent of the seven national parks
in the Arctic
85603
Average extent of the 18 national parks south
of the Arctic (range: 27 to 10440 ha)
2446
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Arctic Climate Impact Assessment
protect?), and is not always easy even with a broad measure of agreement between the public and government.
Internationally, many criteria have been proposed as a
basis for selecting sites for protection and designation as
nature reserves and national parks.These were reviewed
by Margules and Usher (1981) and further developed by
Usher (1986) into a “popularity poll” reflecting frequency of use (Table 10.2).Whereas some of these may be
inappropriate in the Arctic (being better suited to the
more fragmented environments of industrialized
regions), the criteria ranked highest are all relevant to
northern ecosystems. However, one of the difficulties of
applying such criteria is that comprehensive habitat and
species inventories may not exist, and so it is impossible
to make meaningful comparisons or to determine the
areas of greatest priority (see also section 10.5.1).
Table 10.2 essentially contains “scientific” criteria,
without the socio-economic criteria necessary for
assessing existing and proposed land and water use
plans. So although it might be possible to establish a
Table 10.2. Criteria used for selecting areas of land or water
for protection and designation as nature reserves and national
parks (Usher, 1986).The 26 criteria are ranked from those most
frequently used (1) to those used only once in the review of 17
published sets of criteria (19=).
Rank
Criterion or criteria
1=
• Diversity of species
• Diversity of habitats
3=
• Naturalness
• Rarity of species
• Rarity of habitats
6
• Extent of habitat
7
• Threat of human interference or disturbance
8=
• Educational value
• Representativeness
• Amenity value for local human population
11
• Scientific value
12
• Recorded history
13=
• Size of population of species of conservation concern
• Typicalness
15=
• Uniqueness
• Potential value
• Ecological fragility
• Position in an ecological or geographical unit
19=
• Archaeological interest
• Availability
• Importance for migratory wildfowl
• Ease of management
• Replaceability
• Silvicultural gene bank
• Successional stage
• Wildlife reservoir potential
range of assessments based on the scientific criteria
listed in Table 10.2, to gain a balanced perspective it
is also important to establish plans for land and water
use and the aspirations of people living in the area.
Local economies depend on the biodiversity resources,
and in balancing the various criteria it is essential to
include long-term views and to ensure that demands
for short-term gains do not predominate. The possible
effects of climate change on biodiversity also need to
be included in assessments, especially effects that will
be experienced over the longer term.
Thus, there are many competing pressures on the ability
of an individual, group, organization, or nation to conserve the biodiversity of the Arctic.These can be summarized in six points:
• all species native to the Arctic need to be conserved (i.e., neither allowed to become extinct nor
driven to extinction by human activity);
• the genetic variation within these species needs to
be conserved because this ensures the greatest
chance of species’ adaptation to a changing environment and hence their long-term survival under
a changing climate;
• the habitats of these species need to be conserved
because each species is an integral part of a food
web, being itself dependent on a set of other
species and with a different set of species dependent upon it;
• human populations living in the Arctic are themselves an integral part of the Arctic’s biodiversity
and food webs;
• non-native species and external human pressures
may present challenges to arctic genes, species,
and ecosystems, and hence risk assessments are a
vital factor in managing new pressures on the
arctic environment; and
• protected areas are not a universal panacea for the
conservation of the Arctic’s biodiversity, but should
be viewed as land and water managed for the primacy of nature in a broader geographical area where
other land- and water-uses may have primacy.
CAFF (2002a) summarized these points by stating that
“The overall goal of Arctic nature conservation is to
ensure that Arctic ecosystems and their biodiversity
remain viable and vigorous for generations to come and,
therefore, able to sustain human socio-economic and
cultural needs”. Balancing this duality of biodiversity
conservation and sustainable use, CAFF developed five
strategic issues (see Table 10.3) and these are further
developed throughout this chapter.
This chapter comprises four main sections. Section 10.2
provides a brief introduction to the special features of
arctic ecosystems and arctic species that justify conservation attention; possible threats to the Arctic’s biodiversity are considered in section 10.3. Eight issues are then
addressed in relation to the management and conservation of the Arctic’s biodiversity (section 10.4).The chap-
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Chapter 10 • Principles of Conserving the Arctic’s Biodiversity
Table 10.3. The five key strategic issues facing nature conservation in the Arctic (as quoted from CAFF, 2002a).
Strategic issue
Overall goal
Conserving arctic species
... to maintain vigorous populations of Arctic plant and animal species
Conserving arctic ecosystems
and habitats
... to maintain and enhance ecosystem integrity in the Arctic and to avoid habitat fragmentation and
degradation
Assessing and monitoring
arctic biodiversity
... to monitor status and trends in Arctic biodiversity as an integral part of assessing the overall state of the
Arctic environment
Global issues
... to understand and minimize the impacts of global changes and activities on Arctic biodiversity
Engaging society
... to promote circumpolar and global awareness of Arctic biodiversity issues
ter concludes with an exploration of some general
principles concerning the conservation of the Arctic’s
biodiversity, some of the implications, and a series of
recommendations (section 10.5).
10.2. Conservation of arctic ecosystems
and species
Earlier chapters focused on the terrestrial, freshwater,
and marine environments of the Arctic, and their component species. Several physical characteristics distinguish polar environments from the environments of
other regions: limited daylight for much of the year,
low temperatures, and low levels of precipitation.
Collectively, these limit biological productivity over a
large part of the year because photosynthesis and
decomposition are severely constrained. In contrast,
the brief arctic summer, which experiences continuous
daylight and warmer temperatures, generates a large
pulse of primary productivity.These dramatic seasonal
changes strongly influence the Arctic’s biodiversity. For
example, productivity in summer is sufficient to attract
migratory species of birds and mammals to the region.
Recent glaciations have resulted in major losses of the
resident arctic fauna and recolonization has been slow
(particularly in the terrestrial and freshwater environments), owing to both the extreme environmental conditions and the low overall productivity of arctic ecosystems.This has resulted in the arctic ecosystems, in a global sense, being considered “simple”, i.e., having relatively
few species.The species that they do contain are mainly
“specialists” in the sense that they have been able to adapt
to the extreme conditions.Thus, there are few species at
any particular trophic level, and overall species diversity
in terrestrial, freshwater, and marine habitats is low.
The seasonal constraints result in similar life-history
traits in many arctic plant and animal species. Compared
to species living in temperate regions, species living in
the Arctic throughout the year are typically long-lived,
slow-growing, and have low rates of annual reproduction.These factors appear to be adaptive to environments that can vary greatly from year to year, and where
productivity is constrained to a short period of time,
even in a favorable year (MacArthur and Wilson, 1967;
Pianka, 1970). Specifically, these life-history traits are
suitable for plant and animal species living in environments where reproductive attempts within a single year
may need to be abandoned to ensure adult survival
(Trathan et al., 1996;Weimerskirch, 2002).
Several of these traits may limit the capacity of species
to respond to rapid environmental change. High adult
survival rates, coupled with low rates of reproduction,
make populations slow to recover from catastrophic
events (Danchin et al., 1995; Jenouvrier et al., 2003).
Also, the adaptations unique to species living in polar
environments also limit their ability to respond to
warming conditions or to the greater environmental
variability projected to result from climate change
scenarios for the Arctic (Laxon et al., 2003; Parkinson,
2000; Parkinson et al., 1999;Vinnikov et al., 1999).
The rest of section 10.2 considers the special features
of arctic habitats that make their biological diversity
vulnerable to climate change. In their analysis of the
European Arctic, Hallanaro and Pylvänäinen (2002) recognized nine broad habitat types. Six of these have not
been significantly affected by human activities: habitats
above and beyond (i.e., north of) the treeline; forests;
wetlands; lakes and rivers; coasts and shores; and the
sea.The other three have been strongly affected: farmland; urban areas; and mosaic landscapes.
In this chapter the Arctic is considered in terms of five
broad habitat groupings, including marine environments;
freshwater environments; environments north of the
treeline; boreal forests; and habitats intensively modified
by people.The term wildlife was defined in Anon (2001a)
as “in a more scientific sense…wildlife refers to all nondomesticated organisms. It includes mammals, birds,
fish, amphibians, and reptiles, as well as vascular plants,
algae, fungi, bacteria, and all other wild living organisms”. Anon (2001a) defined habitats as “all the elements
of the Earth that are used by wildlife species to sustain
themselves throughout their life cycles.This includes
the spaces (i.e., terrestrial and aquatic) that they require
as well as the properties of those places (e.g., biota,
climate, soils, ecological processes and relationships).
Habitats function in providing such needs as food, shelter, and a home place. Habitats can be thought of as
distinctive places or ecosystems…”.These broad definitions are used in this chapter.
Although it might seem simple to identify terrestrial,
freshwater, and marine habitats, as well as the wildlife
that occurs in each, in practice it is not because each
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Arctic Climate Impact Assessment
habitat merges into another. For example, catchments or
watersheds on land are terrestrially defined, but water
percolating through the soil or running off the soil surface eventually enters streams and rivers. So where do
terrestrial habitats end and freshwater habitats begin?
Similarly, rivers enter estuaries where they are subject to
tides, and species characteristic of rivers meet species
characteristic of the sea.Where do freshwater habitats
end and marine habitats begin? Along the shore the sea
and the land interact, and there may be no clear demarcation between terrestrial and marine habitats.The situation is further complicated by anadromous species, such
as Atlantic salmon (Salmo salar).These spawn in rivers,
and the young pass through the estuaries on their way to
the sea where they mature before returning several years
later to their natal rivers to begin the cycle again.
The reverse occurs with catadromous species, such as
the eel (Anguilla anguilla), which spawns at sea.There
are thus gradients, rather than clear boundaries between
the wildlife of terrestrial, freshwater, and marine environments, and a pragmatic approach to allocating species
and habitats to these broad groupings is taken within
sections 10.2.1 to 10.2.4.
export ratio also depends on the advection of plankton
and nutrients within the water body (Shuert and
Walsh, 1993) and on the temperature preferences of
the grazing zooplankton; these both determine the
degree of match or mismatch between primary and
secondary production (see Chapter 9).
10.2.1. Marine environments
Future fluctuations in zoobenthic communities will be
related to the temperature tolerance of the animals and
to the future temperature of the seawater.Whereas most
boreal species have planktonic larvae that need a fairly
long period to develop to maturity, arctic species do not
(Thorson, 1950). Consequently, boreal species should be
quick to spread with warm currents during periods of
warming, while the more stenothermal arctic species
(i.e., those only able to tolerate a small temperature
range) will quickly perish. Shifts in the distribution of
the fauna are likely to be quicker and more noticeable
during periods of warming than periods of cooling.
Change in the abundance or biomass of benthic communities is most likely to result primarily from the impact
of temperature on the life cycles and growth rates of the
species concerned. If warming occurs, thermophilic
species (i.e., those tolerating a wide temperature range)
will become more frequent (see Chapter 9).This will
force changes to the zoobenthic community structure
and, to a lesser extent, to its functional characteristics,
especially in coastal areas.
The arctic marine environment covers about 13 million
km2 (CAFF et al., 2000), of which about 45% is a permanent ice cap that covers part of the Arctic Ocean.
Seasonal sea ice forms during winter, and recedes during
the short arctic summer, exposing large areas of open
water.The marine environment is thus dominated by sea
ice (CAFF, 2001) and by the dynamics of that ice and
especially the location of the ice edge.The transition
zone between the sea ice and the open water has intense
algal growth in spring and summer, and it is the primary
production by these phytoplankton that supports the
arctic marine food webs. Only in exceptional cases can
the energy that drives the marine food webs be obtained
from other sources. CAFF (2001) recorded the recent
discoveries of “hot vents” and “cold seeps” in the Arctic.
At these sites, bacteria are capable of deriving energy
from methane (CH4) or hydrogen sulfide (H2S) gases
that emerge as bubbles or in solution from the vents and
seeps.These bacteria are then fed on by other organisms
and so form the basis of some very specialized and localized food webs. Research on marine biodiversity is usually expensive, which is probably why comparatively less
is known about marine biodiversity than terrestrial biodiversity (Anon, 2001a).
Projected changes in sea ice, temperature, freshwater,
and wind will affect nutrient supply rates through their
effects on vertical mixing and upwelling. These will in
turn result in changes in the timing, location, and
species composition of phytoplankton blooms and,
subsequently, in the zooplankton community and the
productivity of fishes. Changes in the timing of primary production can affect its input to the pelagic
community as well as the amount exported to and
taken up by the benthic community. The retention:
The projected disappearance of seasonal sea ice from
the Barents and Bering Seas, and so the elimination of
ice-edge blooms, would result in these areas having
blooms resembling those presently occurring in more
southerly seas (Alexander and Niebauer, 1981).The
timing of such blooms will be determined by the onset
of seasonal stratification, again with consequences for a
match or mismatch between phytoplankton and zooplankton production. If a mismatch occurs, due to early
phytoplankton blooms, the food webs will be highly
inefficient in terms of food supply to fish (Hansen B.
and Østerhus, 2000). Both export production and
protozoan biomass is likely to increase. However, both
the areal extent of export production and grazing by
copepods are projected to increase slightly because of
the larger ice-free area (see Chapter 9).
Climate change affects fish production through direct
and indirect pathways. Direct effects include the effects
of temperature on metabolism, growth, and distribution. Food web effects could also occur, through changes
in lower trophic level production or in the abundance of
top-level predators, but the effects of these changes on
fish are difficult to predict. However, generalist predators are likely to be more adaptable to changed conditions than specialist predators (see Chapter 9). Fish
recruitment patterns are strongly influenced by oceanographic processes such as local wind patterns, mixing,
and prey availability during early life stages; these are
also difficult to predict. Recruitment success could be
affected by changes in the timing of spawning, fecundity
rates, larval survival rates, and food availability.
Chapter 10 • Principles of Conserving the Arctic’s Biodiversity
Poleward extensions of the range of many fish species
are very likely under the projected climate change scenarios discussed in Chapter 4. Some of the more abundant species that are likely to move northward under the
projected warming include Atlantic and Pacific herring
(Clupea harengus and C. pallasi respectively), Atlantic and
Pacific cod (Gadus morhua and G. macrocephalus respectively), walleye pollock (Theragra chalcogramma) in the
Bering Sea (Blindheim et al., 2001), and some of the
flatfishes that might presently be limited by bottom temperatures in the northern areas of the marginal arctic
seas.The southern limit of colder-water fish species,
such as polar cod (Boreogadus saida) and capelin (Mallotus
villosus), are likely to move northward. Greenland halibut (Reinhardtius hippoglossoides) might possibly shift its
southern boundary northward or restrict its distribution
more to continental slope regions (see Chapter 9).
Migration patterns are very likely to shift, causing
changes in arrival times along the migration route
(Holst et al., 2002). Qualitative predictions of the consequences of climate change on fish resources require
good regional atmospheric and ocean models of the
response of the ocean to climate change.There is considerable uncertainty about the effects of non-native species
moving into a region in terms of their effects on the
“balance” within an ecosystem.
The impacts of the projected climate change scenarios
on marine mammals and seabirds in the Arctic are likely
to be profound (Vibe, 1967), but are difficult to predict
in precise terms. Patterns of change are non-uniform
and highly complex.The worst-case scenarios for reductions in sea-ice extent, duration, thickness, and concentration by 2080 threaten the existence of entire populations of marine mammals and, depending on their ability
to adapt, could result in the extinction of some species
(Jenkins, 2003).
Climate change also poses risks to marine mammals
and seabirds in the Arctic beyond the loss of habitat and
forage bases.These include increased risk of disease for
arctic-adapted vertebrates owing to improved growing
conditions for the disease vectors and to contact with
non-native species moving into the Arctic (Harvell et
al., 1999); increased pollution loads resulting from an
increase in precipitation bringing more river borne
pollution northward (Macdonald R. et al., 2003);
increased competition from the northward expansion of
temperate species; and impacts via increased human
traffic and development in previously inaccessible, icecovered areas. Complexity arising from alterations to
the density, distribution, or abundance of keystone
species at various trophic levels, such as polar bears
(Ursus maritimus) and polar cod, could have significant
and rapid consequences for the structure of the ecosystems in which they currently occur.
Although many climate change scenarios focus on the
potentially negative consequences for ecosystems,
environmental change can also bring opportunities.
The ability of some species to adapt to new climate
545
regimes is often considerable, and should not be
underestimated. Many marine vertebrates in the
Arctic, especially mammals and birds, are adapted to
dealing with patchy food resources and to a high
degree of variability in its abundance.
Ice-living seals are particularly vulnerable to changes in
the extent and character of the sea ice because they use
it as a pupping, molting, and resting platform, and some
species also forage on ice-associated prey. Of the arctic
pinnipeds, ringed seals (Phoca hispida) are likely to be
the most affected because so many aspects of their life
history and distribution are tied to sea ice (Smith and
Stirling, 1975).They require sufficient snow cover to
construct lairs and the ice must be sufficiently stable in
spring for them to rear young successfully. Early breakup of the sea ice could result in premature separation of
mother–pup pairs and hence increased neonatal mortality. Ringed seals do not normally haul out on land and
to do this would be a very dramatic change in their
behavior. Land breeding would expose ringed seal pups
to much higher predation rates.
Changes in the extent and type of sea ice affect the distribution and foraging success of polar bears (Ferguson
et al., 2000a,b; Mauritzen et al., 2001; Stirling et al.,
1993).The earliest impacts of warming will occur at
their southern limits of distribution, such as at James
and Hudson Bays; and this has already been documented
by Stirling et al. (1999). Late sea-ice formation and early
break-up also mean a longer period of annual fasting.
Reproductive success in polar bears is closely linked to
their fat stores. Females in poor condition have smaller
litters, as well as smaller cubs that are less likely to survive.There are also concerns that direct mortality rates
might increase. For example, increased frequency or
intensity of spring rains could cause dens to collapse,
resulting in the death of the female as well as the cubs.
Earlier spring break-up of sea ice could separate traditional den sites from spring feeding areas, and if young
cubs were forced to swim long distances between breeding areas and feeding areas this could decrease their survival rate.The survival of polar bears as a species is difficult to envisage under conditions of zero summer sea-ice
cover.Their only option would be to adopt a terrestrial
summer lifestyle similar to brown bears (Ursus major),
from which they evolved. But competition, risk of
hybridization with brown and grizzly bears (both U.
major), and an increase in human interactions, would also
pose a threat to their long-term survival.
The effects of climate change on seabird populations,
both direct and indirect, are very likely to be detected
first near the limits of the species range and the margins
of their oceanographic range (Barrett and Krasnov, 1996;
Montevecchi and Myers, 1997).The southern limits of
many arctic seabirds are likely to retract northward, also
causing breeding ranges to shift northward (Brown,
1991). Changes in patterns of distribution, breeding phenology, and periods of residency in the Arctic are likely
to be some of the first observed responses to climate
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Arctic Climate Impact Assessment
change. Seabirds will also be affected by changes in prey
availability and so can serve as indicators of ecosystem
productivity. Since warmer (or colder) water would
affect the distribution of prey species, the distribution of
individual seabird species is likely to reflect changes in
the distribution of macrozooplankton and fish populations. Changes in sea level may restrict the use of current
breeding sites, but may increase the suitability of other
sites that are not currently used owing to predator access
or for other reasons.
ter to enable the recycling of nutrients. It is the totality
of the biodiversity of the marine habitats and ecosystems
of the Arctic that support the sustainable production of
the biological resources upon which the indigenous peoples, and others, depend.This holistic approach is underlined in the final sections of Chapter 9 which discuss the
effects of climate change on phytoplankton; zooplankton
production; benthic organisms; fish production; marine
mammal distribution, especially in relation to sea-ice
cover; and seabird distribution and prey availability.
With climate change already underway, planning for
the conservation of marine biodiversity is an imperative. Series of actions are being proposed (CAFF et al.,
2000; Anon, 2001a). These can be grouped into five
key issues, namely:
Although there are many unknowns, it is likely that many
of the vertebrate animals will move northward, with
many of these species likely to become less abundant.
However, for the phytoplankton, it is the extent of the
mixing of the ocean layers that will determine the increases and decreases for the various taxonomic groups.
• the implementation of an inventory of the
Arctic’s biodiversity and of schemes for monitoring trends in the biodiversity resource, including
appropriate indicators;
• the completion of a circumpolar network of
marine and maritime protected areas;
• the development of circumpolar guidelines for
managing arctic biodiversity in a sensitive manner,
bearing in mind the needs of local communities
and the fact that “controlled neglect” may be an
appropriate means of management;
• the establishment of fora for developing integrated
management schemes for coasts and seas; and
• the review of marine regulatory instruments,
with recommendations for further actions
where necessary.
Conservation is unlikely to be easy (CAFF, 2001), but as
many as possible of these five key issues should be developed on a circumpolar basis.This is particularly the case
for the marine environment because many of the species
tend not to be localized, but to be widely distributed
throughout the Arctic Ocean as a whole. Indeed, some
species have regular, seasonal patterns of migration.
Satellite tracking has shown that walrus (Odobenus
rosmarus) and narwhal (Monodon monoceros) can move
great distances within the Arctic Ocean in relatively
short periods of time (Anon, 2001b). Similarly, polar
bears, ringed seals, and beluga whales (Delphinapterus
leucas) have been shown to exhibit extensive and rapid
circumpolar movements.
The main requirement for the conservation of marine
biodiversity is the need to take a holistic approach.
The majority of national parks and reserves are predicated primarily upon the protection of coastal birds and
mammals (Bernes, 1993).This needs to be expanded to
include the ecosystems upon which these birds and
mammals depend, and upon which the commerciallyexploited fish populations also depend. It is not just the
vertebrate animals that are important, but the whole
range of biodiversity, and especially those small and
often unknown organisms that are either trapping solar
energy by photosynthesis or decomposing organic mat-
10.2.2. Freshwater environments
The Arctic has many types of freshwater habitat.
There is a wide range of wetlands, including mires,
marshes, sedge and reed beds, floodplain “grasslands”,
salt marshes, and coastal lagoons, as well as a large
number of rivers, streams, and lakes. In fact, excluding
the freshwater locked up in permanent ice in the
Antarctic, a large proportion of the earth’s liquid
freshwater resources occur in the Arctic.
There is no universally accepted definition of a “wetland”. Hallanaro and Pylvänäinen (2002) described a
wetland as “areas where the water table lies near the surface for much of the year. Shallow water bodies can also
be considered as wetlands if they are mainly covered by
vegetation. In wetlands at least half of all of the plants
should be hydrophytes, which can withstand or may
even depend on high water levels”.With such a loose
definition, there can be many gradients from a wetland
to some other sort of habitat. For example, as wetlands
border onto colder areas, permafrost could become
common, whereas near the coast the influence of sea ice
will be greater, and toward the taiga there will be an
assortment of wet woodland habitats.
Lakes and rivers are abundant in the Arctic. Norway is
estimated to have in excess of 200000 lakes with a surface area greater than 0.01 km2 but less than 1 km2, and
2457 lakes larger than this. Sweden is estimated to have
2908 rivers and the Republic of Karelia 1210 rivers.The
18 largest lakes in Europe are all in northern Europe,
although some are located outside the Arctic (located
between 60º and 66º N). Such statistics demonstrate the
extent of the liquid freshwater resource in the Arctic.
Thus, there is a great range in the type and extent of
arctic freshwater environments (see Chapter 8 for further details), and this extent is perhaps proportionally
greater than in other geographical areas. For example,
the rivers, lakes, and wetlands of Siberia are mainly fed
by thaw and summer rains, which account for up to
80% of total annual flow (Zhulidov et al., 1997) and
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Chapter 10 • Principles of Conserving the Arctic’s Biodiversity
which do not usually penetrate the impermeable
permafrost barrier. Rivers in eastern Siberia typically
freeze over in winter, flowing mainly, if not solely, in
summer.The larger rivers in western Siberia have
greater flows, controlled by discharges from their substantial catchments that extend into more southerly latitudes.The Rivers Ob and Yenisey provide significant
contributions to the total freshwater discharge from
Asia to the Arctic Ocean. Another example, is the
Mackenzie Delta in North America, which is the second
largest delta in the Arctic and subarctic (Lewis, 1991),
being 200 km long and 65 km wide (Prowse, 1990).
The delta has about 50% lake coverage (Mackay, 1963)
and extensive wetlands.The small coastal rivers in the
western Mackenzie Delta freeze over in winter.The
spring break-up in the upstream parts of the Mackenzie
River catchment causes rapid increases in water and
suspended sediment discharges into the delta.These
flood low-lying land and can recharge delta lakes.
These examples illustrate two of the special features of
arctic freshwater environments. First, that the ecosystems can be frozen for much of the year, meaning water
is available for relatively short periods of time. Second,
that there is considerable variability, both within and
between years, in terms of flooding, drying out, freezing, freeze–thaw cycles, and the periods of time over
which these occur.
The dynamics of many of the lotic (river) and lentic
(lake) environments in the Arctic are related to permafrost, and freezing can reduce or even halt the flow of
rivers.The relationships between river flow, lake depth,
and the onset or cessation of freezing conditions are also
features of the arctic environment. Sources of water
during the summer include, in addition to rain, late or
perennial snow patches, glaciers, thawing of permafrost,
and groundwater discharges (Rydén, 1981; van Everdingen, 1990).The projected increases in temperature
are likely to result in these water sources becoming
greater contributors to the annual water budgets of
freshwater ecosystems. Many of the lentic environments
are relatively shallow, and so the species within them
have to be able to withstand considerable environmental
variability, especially when the water bodies freeze.
Arctic freshwater ecosystems are species-poor compared to similar ecosystems in temperate and tropical
areas (Bazely and Jefferies, 1997). This makes them
particularly suitable for trophic studies, as for example
the research by Kling et al. (1992) using isotopes of
nitrogen and carbon. As Bazely and Jefferies (1997)
reported, aquatic food chains in the Arctic are long,
which is unusual given the low overall productivity per
unit area. This paradox may reflect the pulse-regulated
nature of the ecosystems, whereby seasonal resource
acquisition and population growth are restricted to
short periods. During unfavorable periods for growth
and reproduction, low maintenance costs (or migration) enable populations to survive. It is postulated that
this “idling” survival strategy allows extended food
chains to occur because high-energy demands by
organisms do not occur year-round.
A crucial feature of the biodiversity of the Arctic’s freshwater environment is the fish, generally occurring at
high trophic levels and providing an important resource
for the human population. Given the slow growth rates
and low overall productivity, these fish populations can
easily be over-exploited. Chapter 8 outlines the possible
effects of climate change on a number of fish stocks,
both those resident in freshwater and those that are
diadromous (migrating between freshwater and sea
water). Anadromous behavior (migrating from salt to
freshwater, as in the case of a fish moving from the sea
into a river to spawn) is most prevalent in northern latitudes (McDowall, 1987) because the ocean is more productive than the freshwater environments.
Climate change will affect arctic freshwater habitats by
causing local extinctions and by changing the distribution ranges of species (see Chapter 8). Changes in the
amount of precipitation and the length of snow lie will
be important.The effects of increased precipitation for
freshwater habitats will be primarily geomorphological,
especially in the increased sediment loads in rivers and
the increased deposition of sediments in lakes, at hydroelectric dams, and in estuaries. Such changes will affect
habitats and the species they support, and so are likely to
impact adversely on the biodiversity of the Arctic.
The effects of decreased precipitation could be even
more severe, resulting in the drying of wetlands, oxidation of organic compounds in sediments, and so a further release of CO2 to the atmosphere. Changes in temperature are likely to affect the physiology of individuals,
altering population dynamics and interactions between
species.Temperature effects are very likely to be most
pronounced in relation to fish, potentially opening up
arctic freshwater ecosystems to fish species that currently have a more southern distribution.
Conservation of the biodiversity of freshwater habitats
in the Arctic has been hampered by the lack of a common classification of habitats, especially for the wetlands.With each country using different definitions, it is
difficult to determine trans-Arctic trends and to compare differences between regions. Classification schemes
can be contentious, but it is vital that schemes are
adopted as soon as possible (Naiman et al., 1992).
For conservation, classification of habitats or species
provides a framework for communication, management
and, where necessary, legislation or regulation.This is
important because of the many threats to arctic freshwater biodiversity. An analysis of environmental trends
in the Nordic countries viewed threats to the freshwater
environment from a two-dimensional perspective
(Fig. 10.1).The vertical axis shows the area over which
the threat operates and the horizontal axis represents
the perceived seriousness of the threat.The illustration
includes 14 current threats to biodiversity and ten longterm threats to the natural resources of the Nordic
countries.The position of the ellipses on each diagram
548
is therefore analogous to a risk assessment for that particular threat.The diagram does not show how these
threats will change as the climate changes, but it is likely that many of the ellipses will move to the right.
Such predictions contain many uncertainties. Nevertheless, Chapter 8 concludes with a series of nine predictions about the effects of climate change on freshwater
environments and their biodiversity:
• microbial decomposition rates are likely to increase;
• increased production is very likely to result from a
greater supply of organic matter and nutrients;
• shifts in invertebrate species’ ranges and community compositions are likely to occur;
• shifts in fish species’ ranges, composition, and
trophic relations will very probably occur;
Arctic Climate Impact Assessment
• spawning grounds for cold-water fish species are
likely to diminish;
• an increased incidence of mortality and decreased
growth and productivity from disease/parasites are
likely to occur in fish species, and will possibly
occur in aquatic mammals and waterfowl;
• subsistence, sport, and commercial fisheries will
possibly be negatively affected;
• probable changes in habitat are likely to result in
altered migration routes and timing of migration
for aquatic mammals and waterfowl; and
• probable changes in timing of habitat availability,
quality, and suitability are very likely to alter
reproductive success in aquatic mammals and
waterfowl.
These issues pose many challenges, and neither traditional knowledge nor scientific knowledge are able to
meet these challenges completely. In addition to the
need for more research, the development of generic
models is essential if research in one area, on one
species, or on one habitat, is to be applied to other
areas, to other species, or to other habitats.
10.2.3. Environments north of the treeline
Arctic organisms must either survive or avoid the long,
cold winters. Adaptations range from avoidance behavior
(long-distance migration, migration from tundra to forest, migration down the soil profile) to specific physiological, morphological, and life history traits in both
plants and animals. Species with specific adaptations to
cold conditions often lack the flexibility to adapt to new
conditions, particularly interactions with immigrant,
competitive species from the south. For example the
displacement of Arctic fox (Alopex lagopus) by red fox
(Vulpes vulpes), and many arctic plant species that are
shade intolerant (see Chapter 7).
Fig. 10.1. A representation of the impacts of various threats to
the freshwater environment of the Nordic nations.The vertical
axis is a logarithmic representation of the extent, ranging from
100 to 100 000 km2.The horizontal axis represents the perceived severity of the threat.Thus in each diagram threats to
the lower left are of least concern, while those to the upper
right are of greatest concern. (a) current threats to biodiversity,
(b) long-term threats to natural resources. (Based on Bernes,
1993; reproduced with permission from The Nordic Council of
Ministers, Denmark).
In addition to the constraints of low temperatures on
biodiversity, the contrast between summer and winter
conditions is also important.The photoperiod is likely to
constrain budburst, frost hardening, and reproduction in
some potentially immigrant shrubs and trees. It is also
likely to affect the endocrinology of mammals leading to
constraints on reproduction and the onset of appetite.
Short growing seasons select for plants that are perennials and have long development periods, for example
three to four years from flower bud initiation to seed
set. Marked temperature differences between summer
and winter conditions currently select for plants that
accumulate and store resources: up to 98% of biomass
can be below ground. Such storage organs are likely to
become a respiratory burden with warmer winters, and
slow-growing plant species with multi-year development
are eventually likely to be displaced by faster growing
species, including annuals.
Overall, species richness in the Arctic north of the treeline is low (see Chapter 7). About 3% of the species
making up the global flora occur in the Arctic. However,
Chapter 10 • Principles of Conserving the Arctic’s Biodiversity
lower taxonomic groups are better represented than
higher orders: only 0.7% of the flowering plant species
occur in the Arctic compared with 1.6% of the conebearing plants. At a scale of 100 m2, however, the diversity of the flora of some arctic communities can equal
that of temperate or boreal latitudes owing to the generally small size of arctic plants.Within the Arctic, the
diversity of animals (about 6000 species) is twice that of
plants. Again, with lower taxonomic groups better represented. Springtails, at 6% of the global total, are better represented than advanced invertebrate groups such
as beetles with 0.1% of the global total. Climatic warming is very likely to increase the total number of species
in the Arctic as species with more southern ranges shift
northward, but the overall composition of the flora and
fauna is vulnerable to the loss of arctic species at lower
taxonomic orders (Cornelissen et al., 2001). Some taxonomic groups are particularly species rich in a global
context: any impact of climate warming on such species,
for example, willows (Salix spp.), sawflies, stoneflies,
wading birds, and salmonid fish, is likely to affect their
diversity at the global level.
An important consequence of the decline in numbers
of species with increasing latitude is a corresponding
increase in dominance. For example, one species of
collembolan, Folsomia regularis, may constitute 60% of
the total collembolan density in polar deserts (Babenko
and Bulavintsev, 1997). Examples for plants include the
cotton-grass Eriophorum vaginatum, and Dryas species.
These “super-dominants” are generally highly adaptable, occupy a wide range of habitats, and have significant effects on ecosystem processes. Lemmings
(Lemmus spp. and Dicrostonyx spp.) are super-dominant
species during peak years in their population cycles
(Stenseth and Ims, 1993).
Trophic structure is less complex in the Arctic than further south. In all taxonomic groups, the Arctic has an
unusually large proportion of carnivorous species and a
low proportion of herbivores (Chernov, 1995). As herbivores are strongly dependent on the response of vegetation to climate variability, warming is likely to alter the
trophic structure substantially as well as the dynamics of
arctic ecosystems.The herbivore-based system in most
tundra habitats is dominated by one or two lemming
species (Batzli et al., 1980; Oksanen et al., 1997;
Wiklund et al., 1999), while the abundance of phytophagous (plant-eating) insects relative to plant biomass is
small on arctic tundra (Strathdee and Bale, 1998). Large
predators such as wolves, wolverines, and bears are less
numerous in the tundra than the boreal forest (Chernov
and Matveyeva, 1997) and predation impacts on tundra
ungulates are usually low.Thus, the dynamics and assemblages of vertebrate predators in arctic tundra are almost
entirely based on lemmings and other small rodent
species (Microtus spp. and Clethrionomys spp.) (Batzli,
1975;Wiklund et al., 1999), while lemmings and small
rodents consume more plant biomass than other herbivores. Climate has direct and indirect impacts on the
interactions among trophic levels, but there is greater
549
uncertainty about the responses to climate change of
animals at higher trophic levels.
Mechanical disturbance to plants and soils (animals can
avoid or respond to such problems) occurs at various
scales. Large-scale slope failures, such as active layer
detachment, destroy plant communities but open niches
for colonization by new generations of existing species
or immigrant species with ruderal characteristics (fast
growth, short life span, large reproductive capacity, and
widespread dispersal of seeds). Such disturbances can
also lead to recruitment of old genotypes of species
producing long-lived seed that has been buried for hundreds of years (Vavrek et al., 1991). Sorting of stones
and sediments in the active layer from daily to seasonal
freeze–thaw cycles causes patterning of the ground and
the creation of a mosaic of habitats at the landscape scale
and a range of niches at the centimeter to meter scale
(Matveyeva and Chernov, 2000). Such sorting, together
with longer term permafrost degradation, movement of
soils on slopes, and displacement by moving compacted
snow and ice, exerts strong forces on plant roots. Above
ground, wind-blasted ice crystals can erode plant tissues
that extend above the protective snow cover. Mechanical
impacts in the soil select for species without roots
(mosses, lichens, algae), species with very shallow and
simple root systems (e.g., Pinguicula spp.), and species
with mechanically elastic roots (e.g., Phippsia algida and
Tofieldia pusilla) (Jonasson and Callaghan, 1992). Amelioration of the mechanical impacts is likely to lead to displacement of specialized species by more competitive
neighboring species.
Super-dominant species such as lemmings have large
effects on ecosystem processes (Batzli et al., 1980;
Laine and Henttonen, 1983; Stenseth and Ims, 1993).
Lemming peak densities exceed 200 individuals per
hectare in the most productive Lemmus habitats of
Siberia and North America (Batzli, 1981) and the standing crop may approach 2.6 kg dry weight per hectare.
Lemmings have a high metabolic rate and Lemmus spp. in
particular has low digestive efficiency (about 30%, compared to 50% in other small rodents). Consequently,
their consumption rate and impact on the vegetation
exceeds that of all other herbivores combined (with the
exception of the local effects of geese near breeding
colonies). Also, lemmings destroy more vegetation than
they ingest and after population peaks typically 50% of
the above-ground biomass has been removed by the
time of snow melt (Turchin and Batzli, 2001). In unproductive snowbeds, which are favored winter habitats of
the lemming Lemmus lemmus (Kalela, 1961), between 90
and 100% of the moss and graminoids present during
winter may have been removed (Koskina, 1961).
In forest near the treeline, insect defoliators can have
devastating impacts on the ecosystem.The autumnal
moth (Epirrita autumnata) shows cyclicity in its populations and outbreak proportions occur approximately
every 10 to 11 years (Tenow, 1972, 1996). Many thousands of hectares of forests are defoliated in outbreak
550
years and defoliated forests require about 70 years to
attain their former leaf area. However, insect outbreaks
in sub-arctic Finland, followed by heavy reindeer browsing of regenerating birch shoots, have led to more or less
permanent tundra (Kallio and Lehtonen, 1973;
Lehtonen and Heikkinen, 1995).
These outbreaks are important for predators, such as
snowy owl (Nyctea scandiaca) and arctic fox, which both
prey on lemmings, and parasitoids such as the wasp
Cotesia sp., which lays its eggs in caterpillars of the
autumn moth. Changes to the populations and population trends of species such as lemmings and forest insect
pests are very likely to have far reaching consequences
for the biodiversity of the vegetation they consume, and
for their predators and parasitoids, as well as for ecosystem processes like nutrient cycling.
The geography of the Arctic forces a range of constraints
on the ability of vegetation zones and species to shift
northward. In mainland Fennoscandia and many parts of
the Russian Arctic, apart from Taymir and the western
Siberian lowland, the strip of tundra between the boreal
forest and the ocean is relatively narrow.Trees already
occur close to the Arctic Ocean at Prudhoe Bay and
Khatanga. Any northward movement of the forest will
completely displace the tundra zone, and hence its biodiversity, from these areas. On the western Siberian
plain, extensive bog ecosystems limit the northward
expansion of forest and in arctic Canada, the high Arctic
archipelago presents a natural barrier to dispersal of
plants and range extensions of animals, while the barrens
(polar desert and prostrate dwarf shrub tundra with less
than 50% of the ground covered by vegetation) consist
of soils that will constrain forest development for perhaps hundreds of years.
Continuous and discontinuous permafrost are characteristic of the Arctic. Permafrost, particularly its effect
on the thickness of the active layer, limits the depth and
volume of biologically available soil and reduces summer soil temperatures.These constraints limit plant
rooting, the activity of soil flora, fauna, and microbes,
and ecosystem process such as decomposition. Soil
movements associated with permafrost dynamics are
discussed in Chapter 7.Thawing of permafrost can have
dramatic effects on biodiversity, depending upon
drainage, precipitation changes, and, consequently, soil
moisture. Permafrost thawing associated with waterlogging can prevent the northward advance of the treeline and even initiate a southward retreat (Crawford et
al., 2003). In other areas, such as the North Slope of
Alaska, where precipitation is only about 125 mm/yr,
permafrost thawing is likely to lead to drying and in
some areas novel communities, reminiscent of the
tundra-steppe, could form.
In addition to the effects of permafrost on biodiversity,
biodiversity can also affect permafrost. A complete
cover of vegetation, particularly highly insulative
mosses, buffers soil temperatures from climate warm-
Arctic Climate Impact Assessment
ing. In extreme cases, vegetation can lead to permafrost growth and a thinning of the active layer.
Arctic terrestrial ecosystems have the same types of
feedback to the climate system as many other ecosystems, but the magnitude of these feedbacks is greater
than most others. Per square meter, the tundra stores
about half as much carbon as the boreal forests (about
9750 g/m2 and 20 500 g/m2, respectively, 15 900 g/m2
at the interface between tundra and boreal forest
according to McGuire et al., 1997). However, most of
the carbon in the tundra occurs in the soil (about
94%), whereas about half (46%) of the carbon in the
boreal forest occurs in the vegetation. The carbon
stored in the tundra (about 102 Pg) is about 40% of
that stored in the boreal forests (excluding the boreal
woodlands). The tundra, boreal forest, and boreal
woodlands together store 461 Pg of carbon; this is
equivalent to about 71 years of annual global carbon
emissions (based on emission data for the 1960s) of
CO2 from fossil fuels (about 6.5 Pg of carbon per
year). In contrast to the boreal forest, tundra has a high
albedo and reflects about 80% of incoming radiation
and this can lead to local cooling. Displacement of tundra vegetation by shrubs increases winter soil temperatures by 2 ºC (Sturm et al., 2001).
Feedbacks that change the rate of climate change
(although probably not the direction) will affect the
rates of changes in biodiversity. For example, the effect
of shrubs on soil temperatures is expected to increase
decomposition rates and nutrient cycling, and so further shrub expansion. Also, it is possible that glacial
dynamics (as well as more generally the dynamics of
frozen ground) will have an effect (Chernov, 1985).
Glaciers have expanded and contracted in response to
climatic variations. For example, in Iceland the maximum extent of the glaciers in historical times occurred
in 1890.The majority of the glaciers contracted during
the first half of the 20th century, particularly during the
warm 1930s.Then from about 1940 the climate cooled,
slowing the retreat of the glaciers, and some even started to advance again (Jóhannesson and Sigur0sson,
1998).This dynamic behavior of glaciers can have a
marked effect on the biodiversity of nunataks (hills or
mountains completely surrounded by glacial ice), which
often contain a large proportion of the regional biodiversity. For example, there are over 100 species of
vascular plants growing on Esjufjöll, a 9 km long
nunatak within the glacier Vatnajökull, which is more
than 20% of Iceland’s total vascular plant flora
(Einarsson, 1968).
Glacial dynamics are not entirely related to temperature. In Norway, there is some evidence that inland glaciers are currently retreating while coastal glaciers are
advancing in response to greater quantities of snowfall.
This indicates the difficulties of predicting the effects of
climate change on glaciers.The different rates of warming at different seasons of the year, as well as changes in
seasonal precipitation patterns, especially for snow, will
Chapter 10 • Principles of Conserving the Arctic’s Biodiversity
Fig. 10.2. Pine (Pinus sylvestris) forest in the Arctic.This area
of almost natural forest is on an island in Inarijärvi, Europe’s
eighth largest lake, near Inari in Finland (68º 55' N). (Photo:
M.B. Usher, July 1999).
551
Fig. 10.3. The mosaic structure of northern boreal forest; pine and
birch forest associated with mires and small areas of open water
north of Inari, Finland (69º 12' N). (Photo: M.B. Usher, July 1999).
10.2.4. Boreal forest environments
When two or more distinct ecological communities or
habitats are adjacent, there is a unique opportunity for
organisms to live and reproduce in a diverse landscape.
Landscape diversity is controlled by the physical
arrangement of ecological communities. Climate
change, by influencing the distribution of forest species,
communities, and conditions, is a major factor controlling landscape diversity.
The Arctic encompasses the northern edge of the boreal
forest and the woody communities, often containing
shrubby trees, that are associated with the northern
treeline.These northern forests are often dominated by
four coniferous genera: the pines (Pinus spp.), spruces
(Picea spp.), larches (Larix spp.), and firs (Abies spp.), as
well as by two broadleaved genera, the birches (Betula
spp.) and the aspens (Populus spp.), most of which have
transcontinental distributions across Eurasia or North
America (Nikolov and Helmisaari, 1992). An example
of a pine-dominated forest near Inari, Finland (about
69º N) is shown in Fig. 10.2.This is typical of the nearnatural forest, with slow-growing trees, dead wood, and
natural regeneration in gaps where the dead and moribund trees allow sufficient light to penetrate to the forest floor.The forests frequently give way to mires and
small lakes leading to a mosaic structure of forest and
wetland. Figure 10.3, also near Inari in Finland, shows
this transition, with both pine trees and birch woodland
in the distance.The boreal forest region has a distinctive
set of biodiversity characteristics at each of the three
levels of biodiversity – genetic diversity, species diversity, and ecological communities.These are the key to
assessing vulnerability of the boreal forest biodiversity
to climate change.
The extensive ecotone between boreal forest and tundra (a treeline 13 500 km long) is a prominent feature
of the northern boreal region (some of the major
climate-related fluctuations of the treeline are discussed in Chapter 14). The juxtaposition of trees and
tundra increases the diversity of species that can
exploit or inhabit the tundra. For example, insectivorous ground-dwelling birds that feed in the tundra but
nest in trees are able to survive because of the mixture
of habitats. Local human inhabitants can obtain shelter
and make useful items for outdoor activities at this
interface. The probability of climate warming causing
the development of new treeline communities is
described in Chapter 14. During recent decades of
warming, the white spruce (Picea glauca) limit in Alaska
(and almost certainly in western Canada) has developed two populations with opposite growth responses
to the warming. Under extreme levels of projected
warming, white spruce with negative growth responses
would be likely to disappear from the dry central part
of the northern boreal forest. In moister habitats,
white spruce with positive growth responses to warming would expand in distribution. It is possible that
part of the southern tundra boundary in North
America would no longer border spruce forest but
all determine the future dynamics of glaciers.These in
turn influence the nunataks, the extent of areas of new
ground available for primary ecological succession after
glacial retreat, and the loss of ecosystems covered by
advancing glaciers.
552
would border aspen (Populus tremuloides) parkland
instead (Hogg and Hurdle, 1995).
The changes in boreal forests caused by fire and insect
disturbance produce higher order effects due to the patterns and timing of the habitat conditions that they create
at larger scales. Microtine rodents, birds, and hares
(Lepus timidus) in the Fennoscandian boreal region undergo cyclic population fluctuations, generally on a three- to
four-year cycle (Angelstam et al., 1985). Many factors
contribute to these population cycles, including predator
numbers, food plant quantity and/or quality, pathogens,
parasites, and habitat heterogeneity. Some weather and
climatic factors, such as snow depth, also directly influence animal numbers. In the future, population cycles of
boreal animals are likely to remain primarily under the
control of predators, although overall numbers of animals
will respond to the overall amount of suitable habitat
produced by events, such as forest fires, that are in turn
related to climate warming. A ten-year study of trophic
structure in the boreal forest in the Kluane area of southwest Yukon Territory, Canada, examined the ten-year
animal population cycle. In this region the boreal community is a top-down system driven by the predators,
and snowshoe hare (Lepus americanus) is a keystone species
without which much of the community would collapse
(Krebs et al., 2001). Hares influence all other cycles, and
hare cycles are themselves controlled by the interaction
of predator effect and food supply with little or no climate or fire effect detected. However, by the end of the
study, 30% of the white spruce forest in the study area
had been killed by spruce bark beetle (Dendroctonus
rufipennis), which was probably related to climate warming (see Chapter 14).The change in habitat condition in
the Kluane study area is one of the largest disturbances
resulting from climate warming in the region over the
last few centuries.
Specific areas of the boreal region are more species-rich
than others (Komonen, 2003). Areas that have not been
glaciated or which were deglaciated earliest are generally
more species rich than more recently deglaciated areas
(Komonen et al., 2003), suggesting that risks of major
migrations of the boreal forest increase the probability
of species loss. Boreal regions with a diversity of geological and soil substrates, such as Far East Russia, the
Scandes Mountains, and the northern Rocky Mountains
of North America, are relatively species-rich compared
to more uniform areas such as the Canadian Shield or
the Ob Basin. Boreal areas that have experienced interchange between the ecosystems (Asian Steppes, North
American Plains) or continents (Beringia) are relatively
species-rich.
Total species richness in the boreal region is greater than
in the tundra to the north and less than in the temperate
deciduous forest to the south, in line with levels of total
ecosystem productivity (Waide et al., 1999).The southern boreal region contains more species than the northern boreal region, and one effect of climate warming
is likely to be the addition of species to what is now the
Arctic Climate Impact Assessment
northern boreal region. A global summary of changes in
phenology (the distribution and timing of events) across
a number of organism groups already indicates the existence of a coherent signal of warming (i.e., poleward
and upward migration, earlier activity in spring) (Root
et al., 2003). However, the processes that eliminate
boreal species (fire, insects, and drought) operate quickly, while those that add species (migration) operate more
slowly.This raises the possibility that climate warming,
in certain areas, could result in reduced species richness
in the short term followed later by species gains as long
as migratory barriers were not limiting. However, intensive forest management in Fennoscandia is one of the
main causes of decline in the most rare or endangered
boreal forest species there (Nilsson and Ericson, 1992)
and managed forest landscapes do pose movement and
connection barriers to the species in them (Hanski and
Ovaskainen, 2000).
The conservation of certain boreal forest habitats is
particularly important for maintaining species diversity,
and climate change can bring serious challenges in this
respect. Of the major ecological regions of the earth,
boreal forest is distinctive for being conifer dominated
(Juday, 1997). Older conifer forests on productive sites
are the focal habitats of biodiversity conservation across
the boreal region for several reasons.They are particularly rich in canopy lichens, mosses, and bryophytes;
in the fungi responsible for decomposing wood; and in
specialized insects, for woodpeckers and other cavitynesting animals, and for insectivorous songbirds (Berg
et al., 1994; Essen et al., 1992).
The reason that old-growth (or natural) forests are so
important for the conservation of biodiversity lies in
the holistic approach to nature conservation. Natural
forests, with their J-shaped stem-number curve (a few
old, large trees and many small, young trees) provide a
range of habitats that support a range of different
species of plants and animals. Old trees provide nesting
holes for some bird species, diseased and moribund
trees provide a substrate for many species of fungi, dead
wood provides a resource for saproxylic (wood-feeding)
insects, and some moth species will only lay their eggs
on the foliage of young trees, etc.Wood-feeding arthropods form a diverse taxonomic group that is under
pressure throughout Europe (Pavan, 1986; Speight,
1986) and elsewhere. In contrast, managed forests of
younger trees tend to have little dead wood, few nesting holes for birds, and less light reaching the forest
floor and thus a less well developed dwarf shrub, herbaceous, moss, and lichen flora, which in turn supports
fewer invertebrates. A focus on the beetles of the northern forests (Martikainen and Kouki, 2003) has demonstrated both that these semi-natural forests contain a
relatively large number of rare species and that there
are difficulties in making accurate inventories.
Owing to the natural rate of stand-replacing disturbances (fire and insects) in the boreal forest, old-growth
conifer stands are not necessarily abundant even in
Chapter 10 • Principles of Conserving the Arctic’s Biodiversity
landscapes with little direct human impact. Human
modification of the boreal forest landscape typically
makes these old forests rarer because management for
wood products is usually based on the good returns
from cutting large conifers. In parts of the boreal
region, where commercial forest management is established or expanding, productive stands of mature and
old conifers are already rare (eastern Canada, northern
Fennoscandia; Linder and Ostlund, 1992) or the target
for early harvest (Siberia; Rosencranz and Scott, 1992).
One of the major effects of climate warming on boreal
forests is to increase tree death from fire and insects,
and conifer stands are more flammable and often more
susceptible to insect-caused tree death than broadleaved
forests.Thus the ecosystem of greatest conservation
interest, old conifer forest, is the one at most risk of
decline due to climate warming.
Fire is a natural and recurrent feature of boreal forests,
aiding the maintenance of biodiversity in these northern
forests. Fire is expected to pass through a forest every
100 to 200 years (Korhonen et al., 1998). Some species
are adapted to using the resources of burnt forests –
charred trees which are still standing, trees which have
started to decay, and the early stages of ecological succession following fire. Because fires in managed forests
are usually extinguished quickly, burnt forest habitats
have become rare and the species that depend on them
are increasingly threatened and even locally extinct. In
Finland, 14 species, mostly beetles (Coleoptera) and
bugs (Hemiptera), associated with burnt areas in forests
are threatened with extinction (Korhonen et al., 1998).
However, can extensive fires be tolerated in managed
forests when the trees are required for extraction and as
the raw material for the timber industry? Growth rates
of trees near the transition from forest to tundra are
extremely slow, which makes management of these far
northern forests uneconomic (except for the initial
exploitation of the few trees large enough to be used in
timber mills, etc.). However, with climate change (and
eutrophication by nitrogen deposition) productivity is
likely to increase, and so the management of these northern forests becomes a potentially more viable economic
activity, with consequent effects on forest biodiversity.
Fire itself is not the risk factor for the maintenance of
boreal forest species diversity, but rather the altered characteristics of fire that can result from climate warming,
especially amount, frequency, and severity. Conifer dominance itself promotes the occurrence of large, landscapescale fires through characteristics such as flammable
foliage and ladder fuels (defined by Helms (1998) as
“combustible material that provides vertical continuity
between vegetation strata and allows fire to climb into
the crowns of trees or shrubs with relative ease”).
Many boreal trees and other plants show adaptations to
fire such as seed dormancy until fire, serotinous cones,
fire-resistant bark, and sprouting habit. Many understory
plant species of the boreal forest have means of persistence from underground structures following fire or are
553
effective re-colonizers (Gorshkov and Bakkal, 1996;
Grime, 1979; Grubb, 1977; Rees and Juday, 2002).
Fire in the boreal forest sustains a set of species in early
post-fire communities that are distinct from later successional species.These include species from a range of
groups, including birds, beetles, spiders, and vascular and
non-vascular plants (Essen et al., 1992; Haeussler and
Kneeshaw, 2003; Rees and Juday, 2002). Changes in natural fire regimes by human management interacting with
climate warming can disrupt the specific fire regimes that
sustain these species. For example, in some circumstances
climate warming combined with human fire suppression
results in less frequent but more intense fire.This change
can kill species adapted to periodic light ground fires.
The boreal landscape also includes areas that never burn.
These fire-free areas are important for the persistence of
fire-sensitive species. Fire-free refuges occur across most
of Fennoscandia (Essen et al., 1992); in the southeast
Yukon Territory such an area contains an exceptionally
rich flora (Haeussler and Kneeshaw, 2003).With the more
frequent, more extensive, and more intense fires projected to result from climate warming, current fire refuges
are likely to burn for the first time in recent history, thus
reducing or locally eliminating fire-sensitive species.
After a sustained period of enhanced burning caused by
climate warming, some boreal forests are likely to undergo type conversion from conifer to broadleaf tree dominance as a result of the depletion of fuels (see Chapter
14). An abrupt shift in forest composition of that type
would significantly decrease the amount of old conifer
habitat present at a given time from the large landscape
perspective, possibly decreasing populations of some
dependent organisms to critically low levels.
The boreal forest is characterized by large numbers of
individuals of the few tree species with wide ecological
amplitude, in contrast to tropical forests that sustain a
small number of individuals of many species. Genetic
diversity in any species is in part the result of opportunity for gene recombinations and so follows the laws of
probability. In the boreal forest, probability favors the
survival of large numbers of different gene combinations
because of the characteristically large populations of each
species (Widen and Svensson, 1992).To the degree that
these genotypes reflect specific adaptations to local environments, they promote the survival and success of the
species (Li et al., 1997). For example, foresters have
developed seed transfer guidelines in order to define
areas in which it is safe to collect seed for planting in a
given site, based on their practical experience of failures
in tree plantations from seed collected outside the local
environment; boreal Alaska includes several hundred seed
transfer zones (Alden, 1991), suggesting that a high
degree of local adaptation may be typical.
The optimum growth and survival of the major boreal
tree species across their large and varied natural distributions requires the survival of a large proportion of
current genes, including genes that are rare today but
554
would help survival of the species under future environmental conditions. One of the main risks for boreal
forest from climate change is that major areas of the
current distribution of boreal tree species might become
climatically unsuitable for their survival faster than populations of the species could migrate, resulting in the
loss of many adaptive genes. Fire and insect outbreaks
are known to be triggered by warm weather (see
Chapter 14), and gene loss would be likely to result
from larger areas of more complete tree death. Gene
survival in a changing climate becomes even more difficult if the native gene diversity is already diminished, as
is usually the case in a managed forest and where human
activities have reduced forests to remnants (Lieffers et
al., 2003). In human-dominated landscapes the appropriate genes for an adaptive response of boreal forest
plants to some aspects of climate change may already be
rare if the trait was not associated with traits selected for
in the forest management program. In addition, when
the landscape is fragmented by human activities (for
example by roads, pipelines, power lines, industrial and
agricultural development, and excessive grazing), even
the plant species with adaptive genes are very unlikely to
migrate effectively under future climate change.
Nearly all the boreal forest tree species are open wind
pollinated, which facilitates a wide distribution of genes
(Widen and Svensson, 1992).The present boreal forest
is the product of major periods of global warming and
cooling that forced the boreal organisms to migrate far
to the south of current limits and back several times.
These climatic displacements imply that today’s plants
have considerable adaptive abilities as they have survived
past climate changes. Even so, some loss of genes is
almost inevitable in populations of trees and other plants
coping with the major and rapid environmental changes
that have been projected (see Chapter 4).
From the geological record, Spicer and Chapman
(1990) considered that climate change is most strongly
expressed at the poles.There is a dynamic equilibrium
between the climate, the soils, and the vegetation.
Arctic soils are crucial to the functioning of the terrestrial ecosystems (Fitzpatrick, 1997). Heal (1999) considered that “soil biology has changed dramatically
since…the 1970s” and “the emphasis and approach has
changed from descriptive to predictive, structure to
function, organism to process, local to global”. Much of
the descriptive data collected in the 1970s were summarized by Swift et al. (1979), where the soils of the
tundra and taiga were compared with those of temperate and tropical areas. However, these shifts in emphasis
highlight that scientific knowledge of arctic soils is out
of date, and is particularly weak because the information gained during the International Biological Programme (the first international collaborative research
program of the International Council of Scientific
Unions, running from 1964 to 1974, with a focus on
“the biological basis of productivity and human welfare”
– see Clapham, 1980 and Bliss et al., 1981) in the
1970s lacks experimental evidence relevant to the cur-
Arctic Climate Impact Assessment
rent issues of climate change. Evidence for the change
in ecological thinking is evident in the studies by
Robinson and Wookey (1997) on Svalbard, in which the
emphasis was on decomposition and nutrient cycling.
Soils have frequently been neglected when biodiversity
and its conservation are considered (Usher, in press).
However, soils often contain the most species-rich
communities in the Arctic, and so need to be considered in any planning or action for conserving biodiversity. However, many fundamental questions remain
(Heal, 1999).What are the physical drivers of change?
How will the ecological processes that occur within soil
respond to climate change? How will the populations
and communities of soil organisms adapt to climate
change? It is known that environmental perturbations
can change the dominance and trophic structure of the
nematode community (Ruess et al., 1999a) in the subarctic soils of northern Sweden, and that such changes
can have a large impact on microbial biomass and
microbial turnover rates (Ruess et al., 1999b). In the
boreal forest, there appears to be little correlation
between taxonomic diversity and the process rates
within the soils (Huhta et al., 1998), but it is not
known whether this is typical of other arctic soils
It is widely held that diversity promotes ecosystem
function, and so that biodiversity loss threatens to disrupt the functioning of ecosystems (Luck et al., 2003).
More research is needed on arctic soils to determine
whether the many species in these soils are all required,
or whether there is some “redundancy” whereby the
ecosystem could function efficiently with far fewer
species. Also, with climate change, it becomes increasingly important to understand the carbon fluxes
through arctic and subarctic soils – will there be net
accumulations of soil carbon or net losses of carbon in
the form of CO2 or CH4 to the atmosphere? Such
knowledge is critical for the development of conservation policies and for the management of arctic ecosystems and their biodiversity.
10.2.5. Human-modified habitats
The concept of the Arctic as a pristine environment is a
widespread fallacy. Humans have long been involved in
the Arctic, both directly and indirectly, with little effect
on its biodiversity, although hunting and gathering activities, and grazing of domesticated stock, must have had
some effect. Damming of rivers to create fish traps is one
of the few examples of early intensive environmental
modification by people, as is the effects of over-grazing in
Iceland. It is only since about 1800 that people have had
significant impacts on arctic biodiversity through intensive intentional, or unintentional, modification of terrestrial, freshwater, or marine environments.The main environmental modifications have been through:
• expansion of land management for agriculture
(including herding) and forestry, both of which
have been very limited;
Chapter 10 • Principles of Conserving the Arctic’s Biodiversity
555
• expansion of marine and, to a lesser extent, freshwater commercial fisheries, especially with the
advent of recent technologies;
• aquaculture as an emerging marine industry; and
• industrial, urban, and recreational developments,
which have expanded considerably in recent
decades, resulting in modifications to most types
of habitat, regional production and dispersal of
contaminants, and associated expansion of communication networks.
expected to compete successfully with the native
species. This is analogous to the experience of
species introductions on isolated islands.
4. Some species that breed in the Arctic migrate to
lower latitudes to avoid the extreme winter conditions. Migration places significant energetic stress
on the animals; this means that the animals have
evolved specific routes which provide access to
transit feeding areas.The modification of habitats
by people, both within and outside the Arctic, can
have significant impacts on particular migratory
species or populations.
The actual proportions of terrestrial, freshwater, and
marine habitats that are directly managed for human use
in the Arctic are still very small, in contrast with the situation in other areas of the world (except the Antarctic), where agricultural habitats growing crop plants
abound, and where derelict land, left over from activities such as mining, quarrying, or municipal development, is not uncommon. Agriculture within the Arctic
is very limited; forestry is slightly more frequent.
Around settlements and industrial developments there
have been substantial changes to the natural environment, and non-native (weed) species have been able to
establish in these disturbed habitats. However, the projected changes in climate are very likely to result in
significant expansion and intensification of these human
activities across the region, particularly where climate
warming is most marked.The greatest potential impacts
on biodiversity are likely to be through fragmentation
of terrestrial ecosystems and the expansion of marine
traffic as sea-ice conditions become less severe in the
Northeast and Northwest Passages.There are at least
four fundamental characteristics of arctic biodiversity
that make it sensitive to these developments.
1. Many arctic plants and animals have slow growth
rates and are long-lived as adaptations to the
short summer season. These characteristics limit
their capacity to respond to relatively rapid
changes in their environment, especially when
these recur over relatively short time periods.
Recurrent disturbance tends to select for species
with ruderal characteristics, some of which are
found in species living in sites where freeze–thaw
cycles predominate.
2.The low productivity of most habitats forces fauna
to forage or hunt over large areas. Finding suitable
habitats for breeding and shelter further extends
the range requirements.Thus fragmentation of
habitats and limitations to movement could potentially affect many species.
3. The flora and fauna have been selected to survive
under extreme climatic conditions. This has given
them a competitive advantage in the Arctic over
species from warmer climates. Climate warming
is very likely to result in a gradual northward
shift in arctic species as a result of a natural
northward shift in the ranges of more southerly
species. However, the projected increase in
human activities will also result in the introduction of non-native species, some of which are
These four characteristics of the flora and fauna of the
Arctic make them particularly sensitive to the expansion of human activities in the region. For example, the
effects of over-grazing by domestic livestock are clearly
evident in Iceland where the vegetation cover has been
lost and soil erosion is severe (Arnalds et al., 2001).
This has led to desertification, with more than 50% of
Iceland’s land area (excluding that under permanent
ice) being classified as either in “poor condition” or “bad
condition”.The history of desertification in Iceland was
outlined by Arnalds (2000), and stands as a reminder of
what can happen when the land’s vegetative cover is
damaged.The vegetation in other areas of the Arctic has
evolved in the presence of large herbivorous mammals,
unlike Iceland’s vegetation, a factor which was thought
by Arnalds (2000) to be significant.
Climate change is likely to cause gradual expansion at
the northern boundary and contraction at the southern
boundary of the range of arctic species. In contrast, the
expansion of human activities in response to climate
change is very likely to cause more rapid northward
movement and the introduction of non-native species.
The latter will occur mainly through accidental transport and release of individual organisms and propagules
beyond their current, natural distribution limits.
Such introductions, although having a very low probability of survival (the 10%:10% rule, resulting in only
1% becoming problematic (Williamson, 1996)), will
occasionally result in the establishment of populations
that expand rapidly, causing invasions which are highly
predictable in general but highly unpredictable in detail.
Thus, a key lesson is “to expect the unexpected”.
Conservation action needs to both prevent serious loss
of biodiversity and hence ecosystem function, and to
restore past damage. The work of the Soil Conservation Service in Iceland demonstrates the difficulty of
restoring grossly damaged ecosystems, how long the
process is likely to take, and the potential problems
that can be caused by non-native, invasive species.
In a changing environment it is also necessary to recognize that a few of the wild relatives of cultivated
plants occur in the Arctic (Heywood and Zohary,
1995). Being on the northern edge of their ranges,
these might have particular genetic traits that prove
valuable in breeding new varieties of crop plants for
use under different climatic conditions.
556
10.2.6. Conservation of arctic species
The Arctic is generally species-poor compared with
other large geographical areas of the world.There are,
however, a number of charismatic species that capture
people’s imagination; including the polar bear, the reindeer or caribou (Rangifer tarandus), the gyrfalcon (Falco
rusticolus), and the apparently frail Arctic poppy (Papaver
polare).Terrestrial mammals number only 48 species,
although some might be more properly considered as
subarctic species, straying into the Arctic by a short distance only. Of these 48 species, 9 occur in Greenland,
29 in Alaska, 31 in the Canadian Arctic, and 33 in the
Russian Arctic. Sage (1986) lists these species, but noted
some taxonomic uncertainties which could result in
these numbers changing slightly following further taxonomic research. Corresponding figures for breeding
birds, noting the caveat that some species breed only
very occasionally in the Arctic, are 183 for the Arctic as
a whole, and 61, 113, 105, and 136 for Greenland,
Alaska, Canada, and Russia respectively.
Arctic species, especially mammals and birds, feature
strongly in books on wildlife (e.g., CAFF, 2001; Sage,
1986) and ecology (e.g., Chernov, 1985; Stonehouse,
1989).The purpose of this section is not to list the
species of the Arctic, but to reinforce the ecological characteristics of the species that live in the Arctic. An understanding of these characteristics is essential for the conservation management of the Arctic’s biodiversity.
The main characteristic essential for a species to survive in
the Arctic is the ability to cope with cold temperatures.
Most species have evolved strategies for surviving the arctic winter, i.e., cold tolerance, with the remainder developing strategies for cold avoidance.There are many ways
of developing cold tolerance. For mammals that spend the
whole year in the Arctic, this often involves depositing a
Arctic Climate Impact Assessment
layer of fatty tissue under the skin, as occurs in species of
whales and seals.These species provide a valuable resource
for the local human populations that harvest them for
meat and for the oil that can be extracted from the blubber. A similar physiological system is used in some
seabirds, such as the Atlantic puffin (Fratercula arctica), a
vital oily food in the diet of the former inhabitants of the
North Atlantic island of St. Kilda (Quine, 1989).
Invertebrate animals have a different system of cold
tolerance.They accumulate glycerol in their tissues and,
although they are usually susceptible to freezing, are able
to “supercool” whereby the body fluids remain liquid at
temperatures well below the freezing point (Sømme and
Conradi-Larsen, 1977a).The majority of the alpine, arctic, and antarctic insects and mites are able to supercool,
developing glycerol concentrations of up to 42 µg/mg of
fresh weight and being able to survive temperatures below
-15 ºC (Sømme, 1981).This has an effect on the life
cycles of these invertebrates in that they cannot reach the
reproductive state until they are two to three years old,
largely because they have to empty their guts before they
supercool and have relatively limited opportunities for
growth during the short arctic summer (Birkemoe and
Sømme, 1998; Sømme and Birkemoe, 1999). However, it
is known that some species enter a reproductive diapause
when reared at constant temperature in the laboratory
(e.g., the collembolan Hypogastrura tullbergi), and that this
diapause can only be terminated by exposure to cold
(Birkemoe and Leinaas, 1999).This poses the question as
to whether, with the warming of the terrestrial environment, some invertebrate species may be unable to breed.
Hodkinson et al. (1998) have reviewed the whole subject
in relation to invertebrates that live in arctic soils.
Cold avoidance is a strategy adopted by a number of
species of vertebrate animals. Arctic rodents, such as the
insular vole (Microtus abbreviatus) of the Alaskan and
Fig. 10.4. The eight main international flyways used by shorebirds (waders) on migration.Within each flyway reasonably constant
routes are used between the breeding grounds and the wintering grounds, although the southbound and northbound routes might
differ. Each flyway comprises many different individual routes used by the different species and by different populations within a
species.All arctic areas used by breeding shorebirds are included in these eight flyways. (Based on Thompson D. and Byrkjedal, 2001).
Chapter 10 • Principles of Conserving the Arctic’s Biodiversity
557
Canadian Arctic, avoid the coldest conditions by living
within or under the snow (Stonehouse, 1989). Reindeer
and caribou migrate to the forest on the southern edge of
the Arctic, to over-winter in the more sheltered conditions of the boreal forest, before migrating north in the
spring to the arctic tundra grazing grounds. Many of the
fish species of the Arctic Ocean follow the edge of the sea
ice in its seasonal movements southward during the
autumn/winter and northward in the spring/summer.
tive state until climatic conditions in a particular year
favor reproduction. Perennial plants have overwintering
organs, such as roots and buds, which are protected by
snow or soil from the coldest temperatures. One of the
very few annual species is the snow gentian (Gentiana
nivalis), which occurs in the north American Arctic and
Greenland; in Europe it is predominantly a mountain
species (Fig. 10.5).The snow gentian flowers and sets
seed rapidly in the summer, and is said to have a seed
bank so that it can survive climatically adverse years
without flowering or with very restricted flowering,
and hence demonstrates extreme year-to-year variability in population size (Raven and Walters, 1956).
Some species of bird have perfected the cold avoidance
strategy by undergoing long-distance migrations.
BirdLife (2002) featured the movement of the buffbreasted sandpiper (Tryngites subruficollis) which nests
predominantly in the Canadian Arctic (with a small population in the Alaskan Arctic), but over-winters in South
America in an area stretching from southern Brazil,
through the northeast corner of Argentina, and into
Paraguay.This is an example of one of the eight recognized flyways, known as the Mississippi Flyway, for
shorebirds that breed in the Arctic (Thompson D. and
Byrkjedal, 2001). Figure 10.4 shows the routes between
the arctic breeding grounds, the staging areas which
allow the birds to feed while they are en route, and the
wintering grounds (which are often in the Southern
Hemisphere). Conservation efforts for these migratory
species must be international so that the species gain
protection along the whole of flyway as well as in the
arctic breeding grounds.
It is more difficult to characterize the strategies of
plants in terms of cold tolerance or cold avoidance.
Virtually all arctic plants are perennial, and so are able
to reproduce over several years or remain in a vegeta-
Anoxia is a potential problem for species that overwinter in the Arctic. Marine mammals surface in order
to obtain fresh air, and use a number of ways to maintain
breathing holes in sea ice.The migration of fish in relation to the extent of the sea ice may also be related to
the oxygen content of the seawater as well as to temperature.Terrestrial invertebrates have also developed
mechanisms to cope with anoxia: for example, the two
mite species studied by Sømme and Conradi-Larsen
(1977b) survived for at least three months at 0 ºC under
anoxic conditions, whereas a species from further south
in Norway died within six to eight days under similar
conditions. Arthropods form lactate under anoxic conditions, with concentrations rising to nearly 2 µg/mg fresh
weight, indicating this as a possible mechanism for coping with the anaerobic conditions that might prevail in
arctic soils during winter.
As well as developing strategies for cold tolerance and
cold avoidance, arctic species need to cope with freeze–
thaw cycles in spring and autumn, and warm conditions
in summer when there might be excess water due to
the ice melt or desiccation due to low precipitation
(Hodkinson et al., 1998). Over the year, each species
has to be able to survive many ecological conditions.
This is particularly evident in two features of arctic
populations: extended life cycles and extreme year-toyear variability in population size.
It has already been mentioned that very few arctic plant
species are annuals, and that the soil arthropods are generally not reproductive until two or three years old (whereas in temperate Europe and North America such species
would have at least one generation per year). An example
of the extended life cycle was given by CAFF (2001)
where the life cycle of “woolly bear” larva of the moth
Gynaephora groenlandica can vary from 7 to 14 years. In
much of northern Europe and America such “woolly
bears” (of other moth species) have an annual life cycle.
Fig. 10.5. The snow gentian is one of the very few species of
vascular plants in the Arctic that have an annual life history;
germinating, flowering, and setting seed within the short growing
season of the arctic summer. (Photo: M.B. Usher, July 1997).
There is often extreme year-to-year variability in the
sizes of arctic populations.This is particularly evident in
relation to the occasional outbreaks of the autumnal
moth, Epirrita autumnata.The larvae of this moth can
cause widespread defoliation of downy birch (Betula
pubescens) trees, for example in Arctic Finland, and in the
most severe cases the trees subsequently die.These two
558
features of arctic populations – the extended life cycles
and the extreme fluctuations in size – both make conservation management, and particularly the monitoring of
species, more difficult.
Although the Arctic might be species-poor compared to
other regions of the world, there are very few arctic
species that are currently threatened with extinction.
BirdLife (2002) produced a world map, shaded from
white (no species of bird known to be threatened with
extinction), through shades of yellow and orange, to red
(where at least 25 species are threatened).The majority
of the Arctic is white, although there are some areas of
pale yellow in the Russian Arctic. How this map might
change with climatic warming is not known, but the situation in the Arctic at the start of the 21st century is
healthier than in virtually any other major geographical
region. If the arctic environment is conserved, with particular attention given to arctic ecosystems (Muir et al.,
2003), it is possible that a smaller proportion of the
Arctic’s species will be threatened with extinction than
in other geographical areas.
This ecosystem approach to conservation has been
defined as “the comprehensive integrated management of
human activities based on best available scientific knowledge about the ecosystem and its dynamics, in order to
identify and take action on influences which are critical to
the health of the ecosystems, thereby achieving sustainable use of ecosystem goods and services and maintenance of ecosystem integrity” (as quoted by Muir et al.,
2003).The ecosystem approach can thus be applied either
to the marine environment or to the terrestrial and freshwater environments of the Arctic, and is discussed further
in section 10.5. It is fundamental to the conservation of
any species that its ecosystem is conserved, with its variety of species and the genetic variability of those species.
As relatively few arctic species are currently threatened
with extinction, the Arctic must be one of the places
where an ecosystem approach can most readily be adopted, bringing together the human, plant, animal, microbial, marine, freshwater, and terrestrial perspectives.
10.2.7. Incorporating traditional
knowledge
Other chapters within this assessment address the
impacts of climate change on indigenous peoples and
local communities, as well as on their traditional
lifestyles, cultures, and economies. Other chapters also
report on the value of traditional knowledge, and the
observations of indigenous peoples and local communities in understanding past and future impacts of climate
change.This section focuses on the relationship between
biodiversity and climate change, impacts on indigenous
peoples, and the incorporation of traditional knowledge.
There has been increasing interest in recent years in
understanding traditional knowledge. Analyses often link
traditional knowledge with what is held sacred by local
peoples. Ramakrishnan et al. (1998) explored these links
Arctic Climate Impact Assessment
with a large number of case studies, largely drawn from
areas of India, but also including studies based in other
parts of Asia, Africa, the Middle East, and southern
Europe. A focus on northern America, again with a
number of case studies, was reported by Maynard
(2002).The many case studies demonstrate that traditional knowledge is held by peoples worldwide, except
perhaps in the most developed societies where the link
between people and nature has largely been broken.
A recognition of this breakdown is the first step toward
restoring biodiversity and its conservation in a changing
world using knowledge that has been built up over centuries or millennia. As Ramakrishnan et al. (2000)
reported “although the links between traditional ecological knowledge on the one hand, and biodiversity conservation and sustainable development on the other, are
globally recognized, there is a paucity of models which
demonstrate the specificity of such links within a given
ecological, economic, socio-cultural and institutional
context”.They state that “we need to understand how
traditional societies…have been able to cope up with
uncertainties in the environment and the relevance of
this about their future responses to global change”.
These concepts point the way to a greater integration of
the knowledge of indigenous peoples into the present
and future management of the Arctic’s biodiversity.
A recent report by the Secretariat for the Convention on
Biodiversity on interlinkages between biological diversity and climate change (SCBD, 2003) specifically addresses projected impacts on indigenous and traditional peoples.The term “traditional peoples” is used by the
Intergovernmental Panel on Climate Change in its
report on climate change and biodiversity (IPCC, 2002)
to refer to local populations who practice traditional
lifestyles that are often rural, and which may, or may
not, be indigenous to the location.This definition thus
includes indigenous peoples, as used in the present
assessment.The SCBD report began by noting that
indigenous and traditional peoples depend directly on
diverse resources from ecosystems for many goods and
services.These ecosystems are already stressed by current human activities and are projected to be adversely
affected by climate change (SCBD, 2003). In addition to
incorporating the main findings of the IPCC report
(IPCC, 2002), the SCBD report concluded as follows:
1.The effects of climate change on indigenous and
local peoples are likely to be felt earlier than the
general impacts.The livelihood of indigenous peoples will be adversely affected if climate and landuse change lead to losses in biodiversity, especially
mammals, birds, medicinal plants, and plants or animals with restricted distribution (but have importance in terms of food, fiber, or other uses for these
peoples) and losses of terrestrial, coastal, and
marine ecosystems that these peoples depend on.
2. Climate change will affect traditional practices of
indigenous peoples in the Arctic, particularly fisheries, hunting, and reindeer husbandry.The ongoing interest among indigenous groups relating
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Chapter 10 • Principles of Conserving the Arctic’s Biodiversity
to the collection of traditional knowledge and
their observations of climate change and its
impact on their communities could provide future
adaptation options.
3. Cultural and spiritual sites and practices could be
affected by sea-level rise and climate change.
Shifts in the timing and range of wildlife species
due to climate change could impact the cultural
and religious lives of some indigenous peoples.
Sea-level rise and climate change, coupled with
other environmental changes, will affect some, but
not all, unique cultural and spiritual sites in coastal
areas and thus the people that reside there.
4.The projected climate change impacts on biodiversity, including disease vectors, at the ecosystem
and species level could impact human health. Many
indigenous and local peoples live in isolated rural
living conditions and are more likely to be exposed
to vector- and water-borne diseases and climatic
extremes and would therefore be adversely affected by climate change.The loss of staple food and
medicinal species could have an indirect impact
and can also mean potential loss of future discoveries of pharmaceutical products and sources of
food, fiber, and medicinal plants for these peoples.
The SCBD report commented directly on the incorporation of traditional knowledge and biodiversity by noting
that the collection of traditional knowledge, and the
peoples’ observations of climate change and its impact
on their communities, could provide future adaptation
options.Traditional knowledge can thus be of help in
understanding the effects of climate change on biodiversity and in managing biodiversity conservation in a
changing environment, including (but not limited to)
genetic diversity, migratory species, and protected areas.
The report also noted the links between biodiversity
conservation, climate change, and cultural and spiritual
sites and practices of indigenous people, emphasizing
that shifts in the timing and range of wildlife species
could impact on the cultural and religious lives of some
indigenous peoples. A detailed consideration of the links
between cultural and spiritual sites and practices on the
one hand and indigenous peoples on the other has been
published recently (CAFF, 2002b). Although this report
focused on sacred sites of indigenous peoples in the
Yamal-Nenets Autonomous Okrug and the Koryak
Autonomous Okrug in northern Russia, it also examined
wider arctic and international aspects with some consideration given to the conservation value of sacred sites for
indigenous peoples in Alaska and northern Canada.
Local people have knowledge about biodiversity,
although it might neither be recognized as such nor formulated using the terminology of scientific biodiversity,
that can be of great assistance in the management of arctic biodiversity. Muir (2002b) discussed the models and
decision frameworks for indigenous participation in
coastal zone management using Canadian experience,
and pointed out that commercial harvesting of fish and
marine mammals, as well as the effects of tourism, can
conflict with local peoples’ subsistence harvesting rights
for fish and marine mammals.Traditional knowledge is
multi-faceted (Burgess, 1999) and very often traditional
methods of harvesting and managing wildlife have been
sustainable (Jonsson et al., 1993). It is these models of
sustainability that need to be explored more fully as the
biodiversity resource changes, and the potential for its
sustainable harvesting changes with a changing climate.
10.2.8. Implications for biodiversity
conservation
In terms of conserving arctic ecosystems and habitats,
CAFF (2002a) stated that “the overall goal is to maintain and enhance ecosystem integrity in the Arctic and
to avoid habitat fragmentation and degradation”.
This goal is elaborated by recognizing the holistic nature
of biodiversity conservation, including not just the flora
and fauna, but also the physical environment and the
socio-economic environment of people living within the
area. It is the socio-economic factors that particularly
affect arctic ecosystems, exerting pressures that have
the potential to degrade habitats, to force declines in
population sizes and numbers of species, and to reduce
the functioning of ecosystems. Habitat fragmentation is
probably the greatest threat to arctic ecosystems, which
seem particularly ill-equipped to deal with it.
Although an important means of conserving the natural
and cultural heritage is through protected areas, it is not
a panacea.The arctic countries, through CAFF, have promoted the establishment of the Circumpolar Protected
Area Network (CPAN), which aims to link protected
areas throughout the Arctic; to ensure adequate representation of the various biomes; and to increase the public’s understanding of the benefits and values of protected areas throughout the Arctic.
This is a useful start to the conservation of the arctic biodiversity, but many productive areas, such as coastal
zones and marine ecosystems, are currently very underrepresented in the CPAN (CAFF, 2002a). At best, protected areas will only cover a relatively small proportion
of the total land and sea area of the Arctic, and so conservation thinking is required beyond the established protected areas.This means that conservation of biodiversity
must be integral to all aspects of social policy, including
health and education of local people, planning for visitors
and the associated developments, control and regulation
of developments, and all aspects of the use of land, water,
and air. Biodiversity conservation must be an important
aspect of thinking, or as CAFF (2002a) stated, there
needs to be a principle of “conservation first”.
CAFF recommended that “the Arctic States in collaboration with indigenous people and communities, other
Arctic residents, and stakeholders (1) identify important
freshwater, marine and terrestrial habitats in the Arctic
and ensure their protection through the establishment of
protected areas and other appropriate conservation
measures, and (2) promote an ecosystems approach to
560
resource use and management in the circumpolar Arctic,
through, inter alia, the development of common guidelines and best practices”.This provides a way forward,
but the generalities need to be expanded into the detail
needed for the practical application of biodiversity conservation alongside the sustainable development of the
Arctic, and the sustainable use of its resources, for the
benefit of local people and visitors alike. A consensus
approach, as fostered at an Arctic Council meeting on
freshwater, coastal, and marine environments (Muir et
al., 2003), needs to be promoted and developed on a
circumpolar basis.
10.3. Human impacts on the
biodiversity of the Arctic
The projected climatic changes in the Arctic, particularly
the projected decrease in sea-ice extent and thickness,
will result in increased accessibility to the open ocean
and surrounding coastal areas.This is very likely to make
it easier to exploit marine and coastal species, over a
larger area and for a greater proportion of the year.
Decreased extent and thickness of sea ice and increased
seawater temperatures will, however, also result in
changes in the distribution, diversity, and productivity of
marine species in the Arctic and so will change the environment for hunters and indigenous peoples. However,
increased traffic and physical disturbance caused by
increased access to the marine areas is likely to pose a
more significant threat to biodiversity than increased
hunting pressure. On land, snow and ice cover in winter
enable access into remote areas by snowmobile and the
establishment of ice roads; however, in summer, transportation and movement become more difficult. A shorter winter season and increased thawing of permafrost in
summer, potentially resulting from a warming climate,
could reduce hunting pressure in remote areas.
There are at least four types of pressure acting on
marine, coastal, freshwater, and terrestrial habitats that
affect both their conservation and biodiversity: (1) issues
relating to the exploitation of species, especially stocks
of fish, birds, and mammals, and to forests; (2) the
means by which land and water are managed, including
the use of terrestrial ecosystems for grazing domesticated stock and aquatic ecosystems for aquaculture; (3)
issues relating to pollutants and their long-range transport to the Arctic; and (4) development issues relating
to industrial development and to the opening up of the
Arctic for recreational purposes.These factors were discussed by Hallanaro and Pylvänäinen (2002) and Bernes
(1993), who included hydroelectricity generation as a
major impact on freshwater systems.
10.3.1. Exploitation of populations
Exploitation and harvest of living resources have been
shown to pose a threat to arctic biodiversity. Species like
the Steller sea cow (Hydrodamalis gigas), in the Bering
Sea, and the great auk (Pinguinus impennis), in the North
Atlantic, were hunted for food by early western explor-
Arctic Climate Impact Assessment
ers and whalers, and became extinct in the 18th and
19th centuries, respectively. Increasing demands
for whale products in Europe, and improvements to
the ships and harvesting methods intensified the
exploitation of several arctic baleen whale species from
the 17th century onward. Over-exploitation resulted in
severely depleted populations of almost all the northern
baleen whale species, and few have recovered their pre17th century population sizes. For example, even though
a few individuals have been observed in recent years, the
bowhead whale (Balaena mysticetus) is still considered
extinct in the North Atlantic.The Pacific population is
bigger, but still considered endangered. Both subpopulations used to number in the tens of thousands. Many
baleen whales, feeding on zooplankton, were a natural
part of the arctic ecosystems 400 years ago.Their large
biomass implies that they may have been a “keystone”
species in shaping the biodiversity of the Arctic Ocean.
Many populations of charismatic arctic species have been
over-exploited over the last few hundred years.The history of the slaughter of walruses (Odobenus rosmarus) in
the North Atlantic and Pacific is well documented
(Gjertz and Wiig, 1994, 1995).The walrus survived
because its range of distribution included inaccessible
areas, and the species is now expanding back into its
previous distributional range due to its protection and to
a ban on harvesting the animals in many areas.The International Polar Bear Treaty (1973) protected the polar
bear (Ursus maritimus) after several sub-populations
became severely depleted due to hunting (Prestrud and
Stirling, 1994). Some subspecies of reindeer/caribou
have also been close to extinction due to hunting pressure both in the European and North American Arctic
(Kelsall, 1968). Similarly, several goose populations have
approached extinction due to hunting on the breeding
and wintering grounds (Madsen et al., 1999).
There have also been effects on a number of tree
species.Wood has always been a valued commodity and
since the first human populations were able to fell trees
and process the felled trunks, forests have been cut for
their timber. During the last few centuries, systems of
forest management have developed to enable the forest
to be regenerated more rapidly, either naturally or artificially by planting young trees.The need to exploit these
Table 10.4. Percentage distribution of age classes of coniferous
forests in countries with arctic territory (Hallanaro and
Pylvänäinen, 2002).The index, I, is the ratio of the percentage of
trees over 80 years old to the percentage less than 40 years
old, and so indicates the naturalness of the forests.
0–40 yr 41–80 yr 81–100 yr >100 yr Index (I)
Murmansk
(Russia)
31
19
5
45
1.61
Norway
33
21
13
33
1.39
Finland
32
33
13
22
1.09
Karelia
(Russia)
40
19
7
34
1.02
Sweden
52
22
10
16
0.50
Chapter 10 • Principles of Conserving the Arctic’s Biodiversity
Fig. 10.6. The reef forming deep-sea coral, Lophelia pertusa
(white coral, upper left hand corner), occurs on the continental
shelf and shelf break off the northwest European coast.The red
gorgonian, Paragorgia arborea, occurs on these reefs.The brittle
star, Gorgonocephalus caputmedusae (yellow, center), frequently
occurs on top of the gorgonians to take advantage of stronger
currents. (Photo: CAFF, 2001; reproduced with permission from
CAFF, Iceland).
forests for wood is demonstrated by the age structure of
the trees in national forest estates (Table 10.4). Natural
(unmanaged) forests have a large proportion of old trees
compared to young trees, whereas managed forests have
a large proportion of younger trees (often managed on
rotations of 40 to 80 years).Table 10.4 appears to indicate a positive correlation between northerliness and
naturalness (indicated by the index, I).
Since around the 1970s, modern management systems,
improved control, and changed attitudes have largely
diminished threats from sports hunting and harvesting
for subsistence purposes. Most of the previously overexploited populations are recovering or showing signs of
recovery. However, there are still examples where hunting is a problem. In accordance with the International
Polar Bear Treaty, local and indigenous peoples are
allowed to hunt polar bears. In Canada, populations in
some of the 14 management areas were over-exploited
in the 1990s, and hunting was stopped periodically in
some of these areas (Lunn et al., 2002). Similarly, in
Greenland, uncertainties about the number of polar
bears taken, and about their sex and age composition,
have created concerns about the sustainability of the
current harvest (Lunn et al., 2002). In southwestern
Greenland, seabird populations have been over-exploited
for a number of years by local peoples and the populations of guillemots (Uria spp.) have decreased by more
than 90% in this area (CAFF, 2001).
Arctic and subarctic oceans, like the Barents, Bering, and
Labrador Seas, are among the most productive in the
world, and so have been, and are being, heavily exploited.
For example, (1) commercial fish landings in Canada
decreased from 1.61 million tonnes in 1989 to 1.00 million tonnes in 1998 (Anon, 2001a); (2) the five-fold
decline in the cod (Gadus morhua) stock in the Arctic
Ocean between about 1945 and the early 1990s; and (3)
the huge decline (more than 20-fold) in the herring
561
Fig. 10.7. Fragments and larger pieces of dead coral, Lophelia
pertusa, from a trawling ground on the Norwegian continental
shelf at a depth of about 190 m.The benthic communities have
been severely disturbed and are virtually devoid of larger animals. (Photo: CAFF, 2001; reproduced with permission from
CAFF, Iceland).
(Clupea harengus) stock in the Norwegian Sea (Bernes,
1993). A report on the status of wildlife habitats in Canada
stated that “Canadian fisheries are the most dramatic
example of an industry that has had significant effects on
the ocean’s habitats and ecosystems” (Anon, 2001a).
Considerable natural annual variability in productivity,
mainly due to variations in the influx of cold and warm
waters to the Arctic, is a considerable challenge for
fisheries management in the Arctic. Collapses in fish
populations caused by over-exploitation in years of low
productivity have occurred frequently and have resulted
in negative impacts on other marine species.The stocks
of almost all the commercially exploitable species in the
Arctic have declined, and Bernes (1993) went as far as to
state that several fish stocks are just about eliminated.
Hamre (1994) suggested that the relative occurrence of
species at some trophic levels has been displaced. Such
changes in the few commercially-valuable fish species
can have tremendous impacts on the coastal communities which are dependent upon the fishing industry for
their livelihoods (CAFF, 2001). Even though supporting
information is scarce, it is likely that the disappearance
of the big baleen whales and the heavy exploitation
(or over-exploitation) of fish stocks over many years
have changed the original biodiversity and ecosystem
processes of the subarctic oceans.
Heavy exploitation of benthic species, such as shrimps and
scallops, also affects other species in the benthic communities. Bottom trawls damage species composition and so
affect the food web. An example is the damage that can be
caused to the cold water coral community.This coral reef
habitat, often in deep water near the edge of the continental shelf, supports many other species such as gorgonians
and brittle stars (Fig. 10.6). Passes over this community
with a trawl leave only fragments of dead coral that can
support no other species (Fig. 10.7). It has been estimated
that, within commercial fishing grounds, all points on the
sea floor are trawled at least twice per year.
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Arctic Climate Impact Assessment
10.3.2. Management of land and water
Changes in both land and water use influence biodiversity in the Arctic.This is different to the situation in
most of the more southern biomes where changes in
land use predominate (Sala and Chapin, 2000). In the
Arctic, the limited expansion of forestry and agriculture
is likely to be restricted to particularly productive environments, although there is greater potential for aquaculture in the Arctic.
In the Arctic, the original change in land use might not be
obvious and impacts may be progressive and long-lasting.
Thus the gradual increase in grazing pressure, particularly
by sheep, has resulted in the loss of sward diversity and
eventual soil erosion.This was probably a contributory
factor in the extinction of agricultural colonies in
Greenland between AD 1350 and 1450. In Iceland,
“desert” with unstable and eroding soils resulted from a
combination of removal of the 25% forest cover and the
introduction of sheep since settlement in the 9th century.
Soil rehabilitation is now a priority, but is a long, slow
process. Establishment of long-term grass swards has had
some success, and planting birch (Betula pubescens) and
native willows (Salix lanata and S. phylicifolia) is proving a
successful conservation measure, using mycorrhizal inocula, for re-establishing species and habitat diversity of grasslands, shrublands, and woodlands that were lost through
overgrazing (A. Aradottir, Icelandic Soil Conservation
Service, pers. comm., 2004; Enkhtuya et al., 2003)
although non-native species can cause problems.
Draining of peatlands, and other wetlands including
marshes and salt marshes, has been widely undertaken
to bring the land into productive use, mainly for
forestry but to a limited extent also for agriculture.
In general there is an inverse correlation between the
extent of drainage and northerliness. Data for relatively
small areas are not available, but national data are presented in Table 10.5.The index, P, gives an indication of
how much of the national peatland has been drained,
which in the most northerly areas is relatively small.
Drainage has a major impact on biodiversity. Invariably
Table 10.5. Extent of peatland (Data: Hallanaro and Pylvänäinen,
2002).The index, P, is the proportion of the total peatland not
drained (the figure in the second column minus the sum of the
figures in the third and fourth columns) to the total peatland
area. Because different countries use different definitions for
peatland, the data are not comparable between countries,
although the values of P are comparable between countries.
Country
Total area of
Area
peatland (mil- drained for
lion hectares)
forestry
Area
drained for
agriculture
Fig. 10.8. In Norwegian Finnmark the number of reindeer trebled between 1950 and 1989 resulting in extensive overgrazing
of the vegetation.The ground to the left and above the fence
had been overgrazed, while that to the right and in the foreground had been protected from grazing. Note the presence of
shrubs and the green nature of the herbaceous ground cover.
(Source: Hallanaro and Pylvänäinen, 2002; reproduced with permission from Georg Bangjord, Statens Naturoppsyn, Norway).
most of the species characteristic of the wetland are
lost, except where small populations survive in drainage
ditches.The newly created habitats are more prone to
invasion by non-native species, and soil erosion may
become more problematic. Migratory bird species may
lose nesting places, and the land cannot retain as much
water as before and so runoff increases during and
immediately after storms. Drainage therefore has a
major effect on the functioning of ecosystems, as well as
encouraging biodiversity loss, usually for very limited
economic gains at a time when climate change is likely
to increase both the risk and rate of desertification in
the Arctic. Biodiversity conservation in the Arctic should
recognize the importance of wetlands as functional
ecosystems with their full biodiversity complement.
Overgrazing on the tundra can be severe; the subject has
been reviewed by Hallanaro and Usher (in press). In
Finland, there were around 120000 reindeer at the start
of the 20th century.This increased to around 420000
animals by 1990, but subsequently declined to around
290000 animals by 2000.The effects of overgrazing are
clearly shown wherever areas of countryside are fenced
off. Figure 10.8 shows an area of Norwegian Finnmark
where the density of reindeer trebled between 1950 and
1989. Overgrazing eliminates ground cover by shrubs
and dwarf shrubs, as well as reducing the cover of herbs,
P
Iceland
1.00
Small
0.13
0.86
Karelia
(Russia)
5.40
0.64
0.09
0.86
Norway
3.00
0.41
0.19
0.80
Sweden
10.70
1.50
0.60
0.80
Finland
10.40
5.70
0.60
0.39
Fig. 10.9. Changes in grazing pressure in Finnmarksvidda, northern Norway, between 1973 and 1996.The increase in areas of
lichen communities assessed as being overgrazed rises from
none in 1973 to approximately two-thirds of the area in 1996.
(Source: Hallanaro and Pylvänäinen, 2002; reproduced with permission from The Nordic Council of Ministers, Denmark).
Chapter 10 • Principles of Conserving the Arctic’s Biodiversity
563
grasses, and lichens. A more detailed analysis of the area
where this photograph was taken is shown in Fig. 10.9.
Over the 23 years from 1973 to 1996, the area changed
from one having around a sixth of the land being moderately to heavily grazed (with the remainder being slightly
grazed), to one having around two-thirds being overgrazed, a little under a third being moderately to heavily
grazed, and only a small proportion (probably less than
5%) being slightly grazed.
areas the lichens have been almost completely grazed
out of the plant communities, or have been trampled,
exposing bare ground which is then subject to erosion.
Lichens, which are capable of surviving the harshest of
environmental conditions, are frequently the most
important photosynthetically active organisms in tundra
ecosystems. Albeit slow-growing, many lichen species
only thrive at low temperatures, and there is concern
that if climate change results in a reduction in the number of lichen species or individuals, there could be a massive release of CO2 to the atmosphere (Dobson, 2003).
The combination of very low growth rates, overgrazing
by domesticated or wild mammals and birds, and climate
change indicates that large areas of the Arctic are susceptible to huge habitat changes in the future. Potentially,
the lichen cover could be replaced by bare ground, with
the risk of erosion by wind and running water, or by
species that are currently not native to the Arctic.
The long-term effects of overgrazing are unknown, but
if it results in the elimination of key species, such as
shrubs, the recovery of the overgrazed ecosystems will
be very slow. If all the key plant species remain in the
community, even at very low densities, and are able to
re-grow and set seed after the grazing pressure is lifted,
then recovery could be faster.Two factors are important
– the intensity of the grazing pressure and the period of
time over which it occurs. Experimental exclosures have
shown that, once grazing pressure by large herbivores is
lifted, the regrowth of shrubs and tree species can be
remarkable. Outside the fence, willows are reduced to
small plants, of no more than a couple of centimeters
high and with a few horizontal branches of up to 20 cm.
These plants have few leaves and generally do not
flower. Inside the fence the willows grow to at least
40 cm high, and are full of flowers with abundant seed
set (Fig. 10.10). It is unknown how long these dwarf,
overgrazed plants can both survive and retain the ability
to re-grow after the grazing pressure is reduced.There
have been no studies on the associated invertebrate fauna
of these willows. So, it also unknown whether the phytophagous insects and mites are able to survive such a
“bottleneck” in the willow population, or for how long
they can survive these restricted conditions.
Although the vascular plants are the most obvious, it is
the lichen component of arctic habitats that can be most
affected by overgrazing. In areas with reindeer husbandry, the lichen cover has generally thinned on the
winter grazing grounds. In the most severely impacted
Fig. 10.10. Whortle-leaved willow (Salix myrsinites) fruiting and
growing in a grazing exclosure on limestone grassland that had
been heavily overgrazed. After about 20 years without grazing
by sheep or deer, this willow forms an understorey with other
shrubs to a sparse woodland of birch (Betula pubescens) and
rowan (Sorbus aucuparia) trees. (Photo: M.B. Usher, June 1998).
Forests provide shelter during the coldest months of the
year, and some of the mammals that feed on the tundra
in summer migrate to the forests in winter. Pressure on
herbaceous ground vegetation, especially on the lichens,
can be severe.This is likely to be more of a problem in
managed forests where the trees are grown closer
together, less light reaches the forest floor, and the
herbaceous and lichen layer is thus sparser. Overgrazing
of the forest floor vegetation, including the young regeneration of tree species, is a problem in some areas and a
potential problem in all other areas. Overgrazing, however, may not just result from agricultural and forestry
land use; it may also result from successful conservation
practices. For example, the population of the lesser snow
goose (Chen caerulescens) in northern Canada rose from
2.6 million in 1990 to 6 million in 2000 as a result of
protection. In summer, the geese feed intensively on the
extensive coastal salt marshes (of western Hudson Bay),
but large areas are now overgrazed, the salinity of the
marshes is increasing, and vegetation has deteriorated.
These examples demonstrate the potential fragility of
ecosystems in which the food web is dominated by a few
key species – a situation not uncommon in the Arctic.
The introduction of species into species-poor northern
ecosystems is a disturbance which can have major
impacts on the existing flora and fauna.The impact of
introduced foxes and rats on seabird populations on arctic islands is particularly strong. A similar situation also
occurs when new species are introduced into isolated
freshwater ecosystems or when conditions change within
a lake. For example, opossum shrimps (Mysis relicta)
were introduced into dammed lakes in the mountains of
Sweden and Norway by electric companies to enhance
prey for burbot (Lota lota) and brown trout (Salmo trutta). Unexpectedly, the shrimps ate the zooplankton that
was a food source for Arctic char (Salvelinus alpinus) and
whitefish (Coregonus lavaretus), leading to an overall
decline in fish production. Arctic char provide many
interesting insights into arctic species.The resident population in Thingvallavatn, Iceland, was isolated from the
sea 9600 years ago by a volcanic eruption, and became
564
trapped within the lake.There are now four distinct
forms that, although closely related genetically, are very
different with respect to morphology, habitat, and diet.
The Arctic has been described as a “theatre of evolution”
as the few resident species capitalize on those resources
that are not contested by other species.This encourages
genetic diversification, a feature that is strongly shown
by the Arctic char, a genetically diverse species and the
only freshwater fish inhabiting high-arctic waters
(Hammer, 1989, 1998).
The subtle and sensitive interactions within food webs
are illustrated by an experiment at Toolik Lake LTER
(Long Term Ecological Research) site in Alaska. Lake
trout (Salvelinus namaycush) play a key role controlling
populations of zooplankton (Daphnia spp.), snails
(Lymnaea elodes), and slimy sculpin (Cottus cognatus).
To test the hypothesis that predation by lake trout controls populations of slimy sculpin, all large trout were
removed from the lake. Instead of freeing slimy sculpin
from predation, the population of burbot rapidly
expanded and burbot became an effective predator,
restricting slimy sculpin to rocky littoral habitats, and
allowing the density of its prey, chironomid larvae, to
remain high.This is an example of changes in “topdown” control of populations by predators, contrasting
with “bottom-up” control in which lower trophic levels
are affected by changes in nutrient or contaminant loading (Vincent and Hobbie, 2000; see also Chapter 8).
Disturbance resulting from management in marine
ecosystems has not been widely studied, other than by
observing the impacts of trawling on seabed fauna and
habitats (Figs. 10.6 and 10.7) and preliminary consideration of the potential impacts of invasive species through
aquaculture, ballast water, and warming (Muir et al.,
2003). Impacts of trawling are not particularly apparent in
shallow waters where sediments are soft and organisms
are adapted to living in habitats that are repeatedly disturbed by wave action. In deeper waters, undisturbed by
storms and tides, large structural biota have developed,
such as corals and sponges, and which provide habitats for
other organisms.These relatively long-lived, physically
fragile communities are particularly vulnerable to disturbance and are not adapted to cope with mechanical damage or the deposition of sediment disturbed by trawls.
Fish farming also affects marine ecosystems.This can be
local due to the deposition of unused food and fish feces
on the seabed or lake floor near the cages in which the
fish are farmed. Such deposits are poor substrates for
many marine organisms, and bacterial mats frequently
develop.There can also be polluting effects over wider
areas due to the use of veterinary products. Over a wider
area still, escaped fish can interbreed with native fish
stocks, thereby having a genetic effect.Thus, commercial
fishing and fish farming can have adverse effects on arctic
biodiversity. Sustainable management practices may be
difficult to develop, but their introduction and implementation are essential if the fishery industries are to
persist into the future.
Arctic Climate Impact Assessment
There is a particular need to assess the potential problems faced by migratory fauna.The challenges met by
migratory species are illustrated by the incredible dispersion of shorebirds to wintering grounds in all continents (Fig. 10.4). Recent evidence on waders from the
East Atlantic flyway compares the population trends in
seven long-distance migrant species that breed in the
high Arctic with 14 species that have relatively short
migrations from their breeding grounds in the subarctic.The long-distance migrants all show recent population declines and are very dependent on the Wadden
Sea on the Netherlands coast as a stopover feeding
ground.The waders with shorter migrations are much
less dependent on the Wadden Sea and show stable or
increasing populations.The emerging hypothesis is that
waders with long migrations are critically dependent on
key stopover sites for rapid refueling. For the Wadden
Sea, although the extent available has not changed, the
quality of resources available has declined through
expansion of shellfish fisheries (Davidson, 2003).
There is evidence of a similar impact on migratory
waders at two other sites. In Delaware Bay, a critical
spring staging area in eastern North America, the impact
is again due to over-exploitation of food resources by
people. Similarly, the requirements of people and waders
are in conflict in South Korea where a 33 km seawall at
Saemangeum has resulted in the loss of 40000 hectares of
estuarine tidal flats and shallows.This site is the most
important staging area on the East Asian Australasian
Flyway, hosting at least 2 million waders of 36 species
during their northward migration. At least 25000 people
are also dependent on this wetland system.
Thus, there are many forms of physical and biological
disturbance in the Arctic (as well as in southern regions
used by arctic species during migration). Such disturbances arise directly or indirectly from human intervention and the management of land and water. Although
deliberate intervention can generate unexpected consequences, there is no doubt that conservation management is essential if the biodiversity of the Arctic is to be
protected. In particular, implementation of international
agreements, such as the Convention on the Conservation
of Migratory Species of Wild Animals (also known as the
Bonn Convention) and the Ramsar Convention on
Wetlands, is increasingly urgent as a means to protect
wetland and coastal areas.
10.3.3. Pollution
Pollution levels in the Arctic are generally lower than
in temperate regions (AMAP, 1998, 2002). Locally,
however, pollution from mining, industrial smelters,
military activities, and oil and gas development has
caused serious harm or posed potential threats to plant
and animal life. Long-range transport of pollutants from
sources outside the Arctic, in the atmosphere, rivers,
or ocean currents, is also of concern (Anon, 2001a;
Bernes, 1993). Particular problems include nitrogen
and phosphorus causing eutrophication (especially in the
Chapter 10 • Principles of Conserving the Arctic’s Biodiversity
565
Baltic Sea), organic wastes from pulp mills creating an
oxygen demand in the benthos, the effects of toxic metals (especially mercury), and bioaccumulation of organic
compounds such as polychlorinated biphenyls (PCBs).
sources. Long-range transport of sulfur and acid rain to
the Arctic has reduced in recent years. The problems of
acidification due to sulfur deposition are well known
and ameliorative procedures have been established
(Bernes, 1991). Acidification results in lakes becoming
clear and devoid of much of their characteristic
wildlife, so causing considerable local loss of biodiversity. Data from well water in Sweden (Bernes, 1991)
showed a north–south gradient in acidification, with
fewest effects in the north. Liming the inflow waters of
some lakes has seen a recovery or partial recovery in
pH, the aquatic plant and animal communities, and
recolonization and recovery of the fish populations.
An analysis of Scandinavian rivers (Bernes, 1993) also
showed a north–south gradient, with relatively few
acidified rivers in the arctic areas.
A recent report on the status of wildlife habitats in the
Canadian Arctic (Anon, 2001a) listed four major classes
of pollutant in the Arctic: mercury, PCBs, toxaphene, and
chlorinated dioxins and furans (Table 10.6).Two main
points are evident from Table 10.6: that pollutants are
carried over long distances in the atmosphere and that
pollutants accumulate in arctic food chains. Pollution is
an international issue that needs to be resolved in a
multi-national manner. However, wildlife is possibly
more tolerant than might first appear because no arctic
species are known to have become globally extinct due
to pollution. However, the trends in pollutant uptake
(see Table 10.6) are of concern.
Emissions of sulfur from industrial smelters and mining
in the Russian Arctic have caused environmental disasters, killing vegetation and damaging freshwater ecosystems (AMAP, 1998). These impacts have, however,
been restricted to relatively small areas surrounding the
Table 10.6. Major groups of pollutants in freshwater ecosystems and species in the Canadian Arctic (Anon, 2001a).
Mercury
• mercury is the most important metal in arctic lakes from a
toxicological viewpoint
• observations show, and models confirm, that about a third
of the total mercury that enters a high-arctic lake is
retained in the sediments, around half is exported downstream, and the rest is lost to the atmosphere
• mercury concentrations consistently exceed guideline limits
in fish for subsistence consumption or commercial sale
• mercury concentrations in fish tend to increase with
increasing fish size
PCBs
• subarctic lakes first show PCB concentrations in the 1940s
(±10 years)
• high-arctic lakes show no significant PCB concentrations
until the 1960s (±10 years)
• PCB concentrations in fish tend to increase with increasing
fish size
Toxaphene
• toxaphene is the major organochlorine contaminant in all
fish analyzed
• highest toxaphene levels are generally seen in fish that are
strictly piscivorous
• toxaphene concentrations in fish tend to increase with
increasing fish size
Chlorinated dioxins and furans
• chlorinated dioxins and furans are found in fishes from
some Yukon lakes
• levels of chlorinated dioxins and furans in fish throughout
the Canadian Arctic are low compared to levels in fish
obtained either near bleached Kraft mills or in the lower
Great Lakes
Pollution is also a threat to the boreal forests.The problems of increased aerial deposition of nitrogen have
been well documented (e.g., Bell, 1994), and result in
both eutrophication and acidification.The acidifying
effects of sulfur deposition tend to be least severe in the
Arctic, owing to its distance from areas where sulfur
oxide (SOx) gases are emitted. However, there are areas
of the Arctic where the degree of acid deposition
exceeds the soil’s capacity to deal with it, i.e., the critical load (Bernes, 1993).
Levels of anthropogenic radionuclides in the Arctic are
declining (AMAP, 2002). Radionuclides in arctic food
chains are derived from fallout from atmospheric nuclear
tests, the Chernobyl accident in 1986, and from European reprocessing plants. Radiocesium is easily taken up
by many plants, and in short food chains is transferred
quickly to the top consumers and people, where it is concentrated. Radiocesium has been a problem in arctic food
chains, but after atmospheric nuclear tests were stopped
40 years ago, and the effects of the Chernobyl accident
have declined, the problem is diminishing. Hallanaro and
Pylvänäinen (2002) discussed the effects of the nuclear
tests in Novaya Zemla, Russia and the Chernobyl accident, and concluded that neither had “resulted in any evident changes in biodiversity”.
Oil pollution in the Arctic has locally caused acute
mortality of wildlife and loss of biodiversity. Longterm ecological effects are also substantial: even 15
years after the Exxon Valdez accident in Alaska, toxic
effects are still evident in the wildlife (Peterson et al.,
2003). A more acute form of pollution is due to major
oil spills, although minor discharges are relatively common. Devastation of wildlife following an oil spill is
obvious, with dead and dying oiled birds and the
smothering of intertidal algae and invertebrate animals.
The type of oil spilled, whether heavy or light fuel oil,
determines the effects on the fish. Light oils that are
partially miscible with seawater can kill many fish, even
those that generally occur only at depth (Ritchie and
O’Sullivan, 1994). Less sea ice resulting from a warming climate is likely to increase accessibility to oil, gas,
and mineral resources, and to open the Arctic Ocean
566
to transport between the Pacific and Atlantic Oceans.
Such activities will increase the likelihood of accidental
oil spills in the Arctic, increasing the risk of harm to
biodiversity. A warmer climate may, however, make
combating oil spills easier and increase the speed at
which spilled oil decomposes.
With the possible exception of mercury, heavy metals
are not considered a major contamination problem in
the Arctic or to threaten biodiversity (AMAP, 2002).
The Arctic may, however, be an important sink in the
global mercury cycle (AMAP, 2002). Mercury is mainly
transported into the Arctic by air and deposited on
snow during spring; the recently discovered process
involves ozone and is initiated by the returning sunlight
(AMAP, 2002). Mercury deposited on snow may
become bioavailable and enter food chains, and in some
areas of the Arctic levels of mercury in seabirds and
marine mammals are increasing.
Persistent organic pollutants (POPs) are mainly transported to the Arctic by winds. Even though levels in
the Arctic are generally lower than in temperate
regions, several biological and physical processes,
such as short food chains and rapid transfer and storage
of lipids along the food chain, concentrate POPs in
some species at some locations. AMAP (2002) concluded that “adverse effects have been observed in some of
the most highly exposed or sensitive species in some
areas of the Arctic”. Persistent organic pollutants have
negative effects on the immune system of polar bears,
glaucous gulls (Larus hyperboreus), and northern fur
seals (Callorhinus ursinus), and peregrine falcons (Falco
peregrinus) have suffered eggshell thinning. The ecological effects of POPs are unknown.
The direct effects of pollutants on trees are compounded by the effects of diseases and defoliating arthropods,
and by interactions between all three. Across Europe,
these have been codified into the assessment of crown
defoliation and hence crown density (e.g., Innes, 1990).
Each country prepares an annual report to allow the
international situation to be assessed and trends determined.These assessments provide a measure of forest
condition and changes in condition.These assessments
are currently made in the main timber producing areas
of Europe, but it would be of benefit to establish an
international forest condition monitoring network
across the boreal forests of the subarctic.
A warmer Arctic will probably increase the long-range
transport of contaminants to the Arctic. Flow rates in
the big Siberian rivers have increased by 15 to 20%
since the mid-1980s (see Chapter 6) due to increased
precipitation. Northerly winds are likely to increase in
intensity with climatic warming, bringing more volatile
compounds such as some POPs and mercury into the
Arctic. Conservation action must aim to reduce the
amounts of the pollutants resulting in chronic effects
from entering arctic ecosystems, and to reduce the risk
of accidents for pollutants resulting in acute effects.
Arctic Climate Impact Assessment
10.3.4. Development pressures
Biodiversity in the Arctic is affected by pervasive,
small-scale, and long-lasting physical disturbance and
habitat fragmentation as a side-effect of industrial and
urban developments and recreation. Such disturbances,
often caused by buildings, vehicles, or pedestrians, can
alter vegetation, fauna, and soil conditions in localized
areas. A combination of these “patches” can result in a
landscape-level mosaic, in effect a series of “new”
ecosystems with distinctive, long-term, biodiversity
characteristics. These are becoming more widespread
in the Arctic and in some cases can, through enhanced
productivity and vegetation quality, act as “polar oases”
having a wide influence on local food webs.
Forbes et al. (2000) reviewed patch dynamics generated
by anthropogenic disturbance, based on re-examination
of more than 3000 plots at 19 sites in the high and low
arctic regions of Alaska, Canada, Greenland, and Russia.
These plots were established from 1928 onward and
resurveyed at varying intervals, often with detailed soil
as well as vegetation observations. Although these
patches have mostly experienced low-intensity and
small-scale disturbances, “none but the smallest and
wettest patches on level ground recovered unassisted to
something approaching their original state in the medium term (20–75 years)”. Forbes et al. (2000) concluded that “in terms of conservation, anthropogenic patch
dynamics appear as a force to be reckoned with when
plans are made for even highly circumscribed and
ostensibly mitigative land use in the more productive
landscapes of the increasingly accessible Arctic”.
Development in the marine environment of the Arctic
is currently very limited. However, a recent report on
the status of wildlife habitats in the Canadian Arctic
(Anon, 2001a) stated that “the Arctic landscapes and
seascapes are subject to…oil and gas and mining developments [which] continue to expand”. Muir’s (2002a)
analysis of coastal and offshore development concluded
that pressures on the marine environment are bound to
increase.There will be further exploration for oil and
gas. If substantial finds are made under the arctic seas
then development is likely to take place.While most
known oil reserves are currently on land, offshore
exploration, such as that west of the Fylla Banks 150
km northwest of Nuuk in Greenland (Anon, 2001b),
will continue to have local impacts on the seabed. Muir
(2002a) also predicted that marine navigation and transport are likely to increase in response to both economic
development and as the ice-free season extends as a
result of climate change, with the consequent infrastructure developments.
Recreational use of arctic land by people, largely from
outside the Arctic, is increasing. Although hikers and
their associated trails potentially present few problems,
this is not the case for the infrastructure associated with
development and for off-road vehicles. Potential problems with trails are associated with vegetation loss along
Chapter 10 • Principles of Conserving the Arctic’s Biodiversity
and beside the trail.This leads to erosion of the skeletal
soils by wind, frost, or water.There is current discussion
about the use of trekking poles (Marion and Reid, 2001)
and whether, by making small holes in the ground that
can fill with water, followed by freeze–thaw cycles, they
increase the potential for erosion.
Use of off-road vehicles has increased with their greater
accessibility.They can also exert greater environmental
pressures than trampling by people. As a result various
laws and regulations have been introduced to reduce or
eliminate the damage that they cause. In Russia, offroad vehicles are frequently heavy, such as caterpillar
tractors. Although it is forbidden to use these in treeless
areas in summer, violations are thought to be common.
Norway has prohibited off-road driving throughout the
year, although different rules apply to snowmobiles.
Use of the latter is becoming more frequent, with
10–11 per thousand of the population owning them in
Iceland and Norway by the late 1990s; this increases to
17 in Finland, 22 in Sweden, and 366 in Svalbard.
The Fennoscandian countries have established special
snowmobile routes to concentrate this traffic and so
prevent more widespread damage and disturbance to
snow-covered habitats.
Implications of infrastructure development and habitat
fragmentation, especially the construction of linear features such as roads and pipelines, are less clearly understood. However, Nellemann et al.’s (2003) research gave
some indications about effects on reindeer. Reindeer generally retreat to more than 4 km from new roads, power
lines, dams, and cabins.The population density dropped
to 36% of its pre-development density in summer and
8% in winter. In areas further than 4 km from developments, population density increased by more than 200%,
which could result in overgrazing of these increasingly
small “isolated” areas. If reindeer, easily able to walk
across a road, behaviorally prefer to avoid roads, what are
the effects of such developments on smaller animals, vertebrates and invertebrates, that are less capable of crossing such obstacles? This indicates that arctic habitats must
be of large extent if they are to preserve the range of
species associated with such habitats. How large should
habitats be? Two developments 8 km apart, on the basis
of Nellemann et al.’s (2003) research, can only accommodate 8% of the wild reindeer density (using winter
data), and so developments will have to be more distant
from each other if there is not to be undue pressure on
the reindeer population and the habitats into which they
move. Nellemann et al.’s (2001) conclusion was that the
impacts of development in the Arctic extend for 4 to
10 km from the infrastructure. So, two developments
separated by 20 km may leave no land unimpacted.
Developments must therefore be carefully planned, widely separated, and without the fragmentation of habitats by
roads, trails, power lines, or holiday cabins.
As well as potential impacts from development, habitats
will change with a changing climate. An example of
where this is important for tourism is in the Denali
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National Park, the most visited national park in Alaska.
Bus tours provide the main visitor experience by providing viewing of wildlife and scenery along the park road.
The Denali park road begins in boreal forest at the park
headquarters and extends through treeline into broad
expanses of tundra offering long vistas. Climate-driven
changes in the position of forest versus tundra would
have significant effects on the park by changing the suitability of certain areas for these experiences. A treegrowth model for the park has been developed based on
landscape characteristics most likely to support trees
with positive growth responses to warming versus landscapes most likely to support trees with negative responses (M.W.Wilmking, Columbia University, pers. comm.,
2004).The results were projected into the 21st century
using data from the five general circulation models climate scenarios used in the ACIA analysis.The scenarios
project climates that will cause dieback of white spruce
at low elevations and treeline advance and infilling at high
elevations.The net effect of tree changes is projected to
be a forest increase of about 50% along the road corridor, thus decreasing the possibility for viewing scenery
and wildlife at one of the most important tourist sites in
Alaska.The maps of potential forest dieback and expansion should be useful for future planning.
Developments have two important implications for
conservation, and both can potentially be implemented
a priori. First, what regulations are needed to reduce
environmental risks? A study for the Hudson Bay area of
Canada (Muir, 2000) provided possible mechanisms for
safeguarding local communities, biodiversity, and the
environment, while not totally restricting development.
Second, how can competing interests be reconciled?
Muir (2002a) advocated forms of integrated management, although stating that such “approaches to integrated management which reconcile economic and
conservation values will be complex and consultative”.
There is a need for biodiversity conservation interests
to form an integral part of any consultations over the
use of the marine, coastal, freshwater, and terrestrial
resources of the Arctic.
10.4. Effects of climate change on the
biodiversity of the Arctic
This section examines how climate change might affect
the biodiversity of the Arctic.The effects are grouped
into six categories: potential changes in the ranges of
species and habitats (section 10.4.1); changes in their
amounts, i.e., the extent of habitats and population sizes
(sections 10.4.2 and 10.4.3); possible genetic effects
(section 10.4.4); changes in migratory habits (section
10.4.5); likely problems from non-native species (section 10.4.6); and implications for the designation and
management of protected areas (section 10.4.7).
The discussions should be read alongside the appropriate sections of Chapters 7 (tundra and polar desert
ecosystems), 8 (freshwater ecosystems), and 9 (marine
systems), which also include analyses of the effects of
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climate change.This section should also be read alongside the appropriate sections of Chapters 11 (wildlife
conservation and management) and 14 (forests and
agriculture). In this chapter analyses are oriented
toward the conservation of arctic genes, arctic species,
and arctic ecosystems.
10.4.1. Changes in distribution ranges
In a warming environment it is generally assumed that the
distribution range of a species or habitat will move northward, and that locally it will move uphill. Although such
generalizations may be true, they hide large differences
between species and habitats, in terms of how far they will
move and whether they are actually able to move.
Some of the earlier studies were undertaken in Norway
and investigated the “climate-space” then occupied by a
few communities and plant species.The “climate-space”
comprised two factors – altitude and distance inland
(Holten and Carey, 1992). Figure 10.11 shows the effect
of a probable climate change scenario on the distribution
of blueberry (Vaccinium myrtillus) heaths.The heath is predicted to move uphill, with its mean altitude changing
from about 760 m to about 1160 m.The questions for
the conservation of this type of heathland are whether all
heaths below 700 m will cease to exist (and how quickly
this will happen) and whether the heaths can actually
establish at altitudes of between about 1300 and 1600 m.
Similar studies for other plant species generally predict
that they will move to occupy a climate-space that is at a
higher altitude and further inland (Holten, 1990).
Norway spruce (Picea abies) presently occurs throughout
Fennoscandia and Russia, more or less as far north as the
shore of the Arctic Ocean. If winter temperatures rise by
4 ºC, the distribution range projected for Norway
Arctic Climate Impact Assessment
spruce virtually halves, with the majority of the southern and southwestern populations disappearing (Holten
and Carey, 1992). Owing to the barrier caused by the
Arctic Ocean, Norway spruce cannot expand its distribution northward, and so is squeezed into a smaller
area. Holten and Carey (1992) also projected the distribution of beech (Fagus sylvatica), a tree whose present
distribution is more southern.They forecast that this
species will spread northward into the Arctic, and may
potentially replace the spruce in some of the more
coastal areas.The distribution range of the beech thus
expands as it shifts north and moves into the Arctic,
there being apparently no barriers to its expansion
(except perhaps for the size of its seed which makes dispersal more difficult).
In modeling changes in distribution ranges, attempts are
made to identify the “climate-space” which a species or
habitat currently occupies, and then to identify where
that climate-space will occur under scenarios of climate
change, for example in 2050 or 2100. Such models
assume that the species or habitat currently occupies its
optimal climate-space, and that the species or habitat will
be able to move as the climate changes.This brings up a
range of questions about the suitability of areas for moving through and of barriers, such as mountains for terrestrial species and habitats, or the difficulty of moving from
lake to lake, or river to river, for freshwater species. Such
models have been used to project what might happen to
species on nature reserves (Dockerty and Lovett, 2003),
in mountain environments (Beniston, 2003), and to the
species of the major biomes isolated on nature reserves
(Dockerty et al., 2003). Dockerty et al. (2003) predicted
that the relict arctic and boreo-arctic montane species in
temperate regions are all likely to have a decreased probability of occurrence in the future.
Arctic species and habitats are thus likely to be squeezed
into smaller areas as a result of climate change.
However, there are some caveats. Cannell et al. (1997),
exploring interactions with pollutant impacts (the CO2
fertilization effect and nitrogen deposition), concluded
that the movement of plant species may be less than
expected, but that the stress-tolerant species, including
those characteristic of the Arctic, are likely to be lost.
Oswald et al. (2003) also explored possible changes in
Fig. 10.11. A correlative model showing the current (black
squares) and predicted (shaded purple) range of Vaccinium
heaths in Norway.The grid cells represent steps of 100 m in altitude on the vertical axis and 5 km distance from the sea on the
horizontal axis.The model is derived from the then most probable scenario of climate change in Norway, i.e., a 2 ºC increase in
July temperatures and a 4 ºC increase in January temperatures
(Holten and Carey, 1992).
Fig. 10.12. A representation of extent of understanding and the
quality or quantity of data when applied to modeling problems.
For the majority of potential applications in conservation the
level of understanding of the system is low and the quantity of
data small, and so the modeling would fall in the lower left corner of Zone 4 (Usher, 2002a).
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Chapter 10 • Principles of Conserving the Arctic’s Biodiversity
plant species in northern Alaska, and concluded that the
responses of species and habitats are likely to be heterogeneous.The continued northward push of the more
southern species and habitats has been outlined by
Pellerin and Lavoie (2003) in relation to changes in
ombrotrophic bogs due to forest expansion. It is these
individualistic responses to climate change (Graham and
Grimm, 1990), by species and habitats, which make prediction difficult. Individualistic responses appear to be
the norm rather than the exception for plants and invertebrate animals (Niemelä et al., 1990).
The individualistic responses of species may produce
novel effects.This is illustrated using the example of a
simple and hypothetical community with a broadly similar abundance of three species: A, B, and C (community
A+ B+ C). Under a climate change scenario with species
moving northward, if species A moved rapidly, species B
moved more slowly, and species C hardly moved at all,
this could result in a community dominated by species
A with species B as a sub-dominant (community A+ b) in
the north and a community dominated by species C with
species B as a sub-dominant (community C+ b) more or
less where A+ B+ C used to occur. It is possible that neither A+ b nor C+ b would be recognized as communities,
and so, in the geographical contraction of A+ B+ C, two
new communities – A+ b and C+ b – had arisen, both of
which were novel. Climate change could thus give rise
to some new habitat types, and although this might not
change the overall biodiversity of the Arctic at the
species level, there could be changes to biodiversity at
the habitat level.
Current distribution ranges of plants and animals in the
marine environment depend upon the ocean currents as
well as on the extent of the sea-ice cover at different
times of the year.With the projected decrease in sea-ice
cover and the more northerly position of the ice edge,
the distribution of the algae, phytoplankton, invertebrates, and fish will also change. An analysis of the
effects of climate change on marine resources in the
Arctic (Criddle et al., 1998) left much in doubt, stating
that “the effects of climate variation on some Bering Sea
fish populations are fairly well known in terms of empirical relationships but generally poorly known in terms of
mechanisms”.The authors proposed a program of
research to help predict the effects of climate change on
the commercially-exploited fish stocks and more widely
on marine biodiversity as a whole.
The lack of knowledge on this topic was addressed by
Starfield and Bleloch (1986).They presented a simple
model of the context within which most conservation
work could be undertaken (Fig. 10.12). Conservation
generally has little understanding of the system to be
conserved, and managers have poor data upon which to
build models.The conservation of biodiversity falls in
zone 4.This is the zone where statistical models are
most helpful, indicating expectations with some probability attached and often very wide confidence limits.
What are the implications for conservation? The most
detailed assessment of changes in distribution ranges of
species and ecosystems in relation to conservation are
probably the studies on national parks and other conser-
Tundra
Taiga/Tundra
Boreal conifer forest
Temperate evergreen forest
Temperate mixed forest
Savanna/Woodland
Shrub/Woodland
Grassland
Arid lands
Fig. 10.13. The present MAPSS vegetation distribution in Canada’s national parks. Nine vegetation zones are shown, excluding the
permanent ice in the north (reproduced with permission from Daniel Scott, University of Waterloo, Canada).
Fig. 10.14. The projected MAPSS vegetation distribution in Canada’s national parks using two scenarios of climate change.
Although the details of these two projections differ, they both demonstrate the northward movement of vegetation zones relative
to current conditions (reproduced with permission from Daniel Scott, University of Waterloo, Canada).
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Arctic Climate Impact Assessment
vation areas in Canada (Scott and Lemieux, 2003; Scott
and Suffling, 2000; Scott et al., 2002).The large scale of
biomes and environmental conditions in Canada facilitate
the definition of spatial patterns by models with a grid
resolution of 0.5º latitude by 0.5º longitude.The studies
of 36 national parks and other designated conservation
areas involved the application of two global vegetation
models (BIOME3 and MAPSS) which represent the
effects of enhanced CO2 on nine or ten biome types consistent with IPCC analysis.The different number of biomes is because BIOME3 combined boreal and taiga/
tundra biomes which were separated in MAPSS. Five general circulation models (three equilibrium models:
UKMO, GFDL-R30, and GISS; two transient models:
HadCM2 and MPI-T106) were applied, providing some
direct cross-reference to the present assessment.
A northward movement of the major biomes was projected in all five scenarios, changes in the dominant
biomes of tundra, taiga/tundra, and boreal conifer forest were particularly clear (compare Fig. 10.13, which
shows present conditions, with Fig. 10.14, which shows
two projections for the northerly movement of the
Canadian vegetation zones). As is the case for the ACIAdesignated climate models (see Chapter 4), although the
trends were similar between models, the actual values
and local spatial patterns showed considerable variation.
Regardless of the vegetation and climate change scenarios used, the potential for substantial changes in biome
representation within the national parks was shown
repeatedly. At least one non pre-existing biome type
appeared in 55 to 61% of parks in the MAPSS-based
scenarios and 39 to 50% in the BIOME3-based scenarTable 10.7. Potential impacts of climate change on the arctic
national parks and other protected areas (H.G. Gilchrist,
Canadian Wildlife Service, pers. comm., 2004).
Impact
Effects of impact
Northward treeline
extension
Up to 200–300 km movement in the
next 100 years (where movement is
not impeded by soil condition)
Increased active layer
May extend northward by 500 km,
and permafrost thawing causing altered drainage patterns
Sea-level rise
Variable, either moderated by isostatic
rebound or exacerbated by subsidence
Reduced sea- and lake- Altered sea mammal distributions
ice seasons
(especially for polar bears and ringed
seals), as well as more northerly
distribution of ice-edge phytoplankton
blooms, zooplankton, and fish
Increased snow pack
and ice layers
Reduced access to browse for
ungulates
Greater severity and
length of insect
seasons
Increased harassment of ungulates
and potential for pest outbreaks in
boreal forests
Altered migration
patterns
Diminished genetic exchange among
arctic islands
Altered predator–prey Changes in species abundance, and
and host–parasite
potentially the establishment of novel
relationships
interactions between pairs of species
ios. Representation of northern biomes (tundra, taiga/
tundra, and boreal conifer forest) in protected areas was
projected to decrease due to the overall contraction of
these biomes in Canada. Projections for the southern
biomes were more variable but their representation in
protected areas generally increased.
The seven arctic national parks range in size from Vuntut
in Yukon Territory at 4345 km2 to Quttinipaaq (formerly
Ellesmere Island) at 37775 km2 in Nunavut.The parks
cover a range of conditions from high arctic polar desert
and glaciers to taiga, extensive wetlands, coastal areas,
lakes, and rivers.They also contain, and were often designated to conserve, a variety of species and populations; for
example, they contain one of the greatest known musk
oxen (Ovibos moschatus) concentrations, calving grounds
for Peary caribou (Rangifer tarandus pearyi), migration corridors and staging areas, one of the largest polar bear denning areas, spawning and over-wintering sites for Arctic
char, considerable species richness with over 300 plant
species in one area, plus important historical, cultural, and
archaeological sites and unique fossils from Beringia.
Some of the significant impacts of climate change within
the arctic national parks are outlined in Table 10.7.
10.4.2. Changes in the extent of arctic
habitats
The previous section showed that distribution ranges of
many arctic habitats are likely to decrease with climate
change and that this generally implies a reduction in the
overall extent of the habitat.The response of each habitat is likely to be individualistic (Oswald et al., 2003),
and to depend upon the dynamics of the populations and
communities, as well as on a range of species interactions such as competition, predation, parasitism, hyperparasitism, and mutualism. Habitat extent will depend
upon the individualistic responses of the component
species, and these in turn will depend upon the physiological responses of the individuals that form those
species populations (see section 10.4.3).
In the marine environment far less is known about the
potential effects of warmer temperatures, increased
atmospheric CO2 concentrations, and increased irradiance by ultraviolet-B (UV-B) on the species populations
and habitats. A review of marine nature reserves by
Halpern and Warner (2002) showed that changes in population sizes and characteristics can be fast. Compared
with undesignated areas, their study indicated that the
average values of density, biomass, organism size, and
diversity all increased within one to three years of designation.These rapid responses, the result of protection
through conservation designation, indicate that marine
organisms and marine habitats have the potential to
respond quickly to changed environmental conditions.
Change will occur, and in general it appears that arctic
habitats are likely to have smaller population sizes within
smaller distribution ranges.What will replace them?
Habitats that currently occur in the sub-Arctic or in the
Chapter 10 • Principles of Conserving the Arctic’s Biodiversity
northern boreal zone are likely to move northward, and
their responses to climate change are likely to be individualistic. So it is possible that habitats currently south
of the Arctic might migrate northward and occur “naturally” within the Arctic, as for example with the northward movement of beech forest (section 10.4.1).
This will make it difficult to establish, if indeed there is a
distinction, whether species and habitats of the Arctic in
the future are native or non-native (see section 10.4.6).
Owing to the different responses of habitats and species,
it is likely that novel species assemblages will occur in
the future, being habitat types that are currently
unknown or not envisaged.Thus, the current habitat
classifications are likely to have to change as novel habitat types evolve in response to rapid climate change.This
has considerable implications for species and habitat conservation and for management today, and may lead to
alterations in the priorities for biodiversity conservation
in the future.While the name of a species is more or less
stable, and so easily incorporated into legislative frameworks (i.e., appended lists of protected species), a habitat’s name and description is less stable, implying a need
for periodic reviews of legislative frameworks.
10.4.3. Changes in the abundance of arctic
species
As sections 10.4.1 and 10.4.2 imply, it is the species
composition of an area that will change, forcing changes
to the communities in which they occur.The individualistic responses of the species (Oswald et al., 2003) will
depend upon the dynamics of the species populations,
the competitive or mutualistic interactions between
species, and the biochemical and physiological responses
of the individuals.
Biochemistry and physiology are fundamental to how an
individual responds to its environment and to changes in
that environment. Rey and Jarvis (1997) showed that
young birch (Betula pendula) trees grown in an atmosphere with elevated CO2 levels had 58% more biomass
than trees grown in ambient CO2 concentrations.
They also found that the mycorrhizal fungi associated
with the roots of the experimental trees differed; those
grown in elevated CO2 levels were late successional
species, while those grown in ambient CO2 levels were
the early successional species.This showed the complexity of understanding the effects of climate change on the
conservation of biodiversity. Normally, with regenerating birch trees, the whole successional suite of fungi
would be expected to occur on the young trees’ roots as
they emerge from the seed, establish themselves, grow,
and then mature. Does the work of Rey and Jarvis’
(1997) imply that more attention needs to be given to
protecting the early successional mycorrhizal species?
They will clearly be needed in the ecosystem if climate
cools or CO2 levels fall in the future.
Other physiological studies have detected a 4 to 9%
thickening of the leaves of lingonberry (Vaccinium
571
vitis-idaea) under enhanced UV-B radiation, whereas the
deciduous blueberry and bog blueberry (V. uliginosum)
both had 4 to 10% thinner leaves under similar conditions (Björn et al., 1997). Growth of the moss
Hylocomium splendens was strongly stimulated by enhanced UV-B radiation, as long as there was additional
water, whereas the longitudinal growth of the moss
Sphagnum fuscum was reduced by about 20%. Björn et
al.’s (1997) results for lichen growth under enhanced
UV-B radiation were variable, leading them to conclude
that “it is currently impossible to generalize from these
data”.They also investigated the decomposition of litter
from Vaccinium plants grown under normal conditions
and under conditions of enhanced UV-B radiation. Litter
from the V. uliginosum plants treated with UV-B radiation
had a decreased α-cellulose content, a reduced cellulose/lignin ratio, and increased tannins compared to the
control litter, and so was more resistant to decomposition. Slower decomposition was also observed for V. myrtillus litter. Björn et al. (1997) did not investigate the
palatability of the leaves to invertebrate animals. Moth
larvae, particularly those in the family Geometridae (the
“loopers” or “spanworms”), are a large component of the
diet of many passerine birds in the boreal forest and near
the forest/tundra margin. If the larval population densities are reduced due to a lack of palatability of the leaves
on which they feed, the effects of UV-B radiation could
be far-reaching on the below- and above-ground food
webs of the terrestrial Arctic.
Changes in phenology, the time of year when events happen, will also affect the size of populations. A number of
studies have already shown that vascular plants are flowering earlier, insects (especially butterflies) are appearing
earlier in the year, some birds are starting to nest earlier
in spring, amphibians are spawning earlier, and migratory
birds are arriving earlier (see a review by Usher, 2002b).
Some of these phenological observations are beginning to
be used as indicators of the effects of climate change on
biodiversity, although most studies are just recording data
on the changes in species populations in the earlier part
of the year (usually spring) and do not record data for the
end-of-summer changes that could be affecting plant
growth rates in the autumn or autumnal flight periods for
species of insect.The important ecological impact of
phenology concerns how changes will affect interactions
between pairs of species. If one species changes its phenology more than another, will this then increase or
decrease the effects of competition, herbivory, predation,
parasitism, etc.? If synchrony occurs, and the organisms
become less synchronous, this could have considerable
effects on population sizes and biodiversity.
In the marine environment, seabirds show strong preferences for regions of particular sea surface temperatures
(SSTs) (Schreiber, 2002). Some seabird populations have
been found to respond to long-term climatic changes in
the North Atlantic Ocean (Aebischer et al., 1990;
Thompson P. and Ollason 2001), the North Pacific
Ocean (Anderson and Piatt, 1999; Bertram et al., 2001;
Jones I. et al., 2002; Sydeman et al., 2001;Veit et al.,
572
1997), and Antarctica. Although global SSTs are generally increasing, this long-term trend is superimposed on
cyclical patterns created by climatic oscillations, such as
the North Pacific, North Atlantic, and Arctic Oscillations
(Francis et al., 1998; Hare and Mantua, 2000; Hurrell et
al., 2003;Wilby et al., 1997).These oscillations cause
periodic reversals in SST trends, two of which have
occurred since 1970 in the Northern Hemisphere; from
1970 much information has been accumulated on
seabird population trends in the circumpolar Arctic
(Dragoo et al., 2001; Gaston and Hipfner, 2000).
To examine the effect of SST changes on seabird populations at a global scale, data on population changes
throughout the distribution ranges of the common
guillemot or murre (Uria aalge) and Brünnich’s guillemot or thick-billed murre (U. lomvia) were examined to
document how they changed in response to climate
shifts, and potential relationships with SSTs (D.B. Irons,
U.S. Fish and Wildlife Service, pers. comm., 2003).
Both species breed throughout the circumpolar north
from the high Arctic to temperate regions, although
Brünnich’s guillemots tend to be associated with colder
water than common guillemots and are the dominant
species in the Arctic (Gaston and Jones, 1998).
The analysis showed that positive population trends
occurred at guillemot colonies where SST changes were
small, while negative trends occurred where large increases or large decreases in SST occurred. Highest rates of
increase for the southerly species, the common guillemot,
occurred where SST changes were slightly negative, while
increases for the arctic-adapted Brünnich’s guillemot were
most rapid where SST changes were slightly positive.
These results demonstrate that most guillemot colonies
perform best when temperatures are approximately stable, suggesting that each colony is adapted to local conditions (D.B. Irons, U.S. Fish and Wildlife Service, pers.
comm., 2003).This study also demonstrates how seabirds
respond to changes in climatic conditions in the Arctic
over large temporal and spatial scales.
A study on the Atlantic puffin in the Lofoten Islands,
northern Norway, has shown that sea temperatures from
March through July (which is the first growth period for
newly hatched Atlantic herring) and the size of herring in
the food intake of adult puffin together explain about 84%
of the annual variation in fledging success of puffin chicks
(T. Anker-Nilssen, Norwegian Institute for Nature
Research, pers. comm., 2003). Although there are relatively few data for the marine environment, what there
are (especially for seabirds) indicate reduced population
sizes for many of the marine wildlife species of the Arctic,
and so conservation activity must aim to ameliorate such
declines. Protected areas are an important aspect of such
activity and are discussed further in section 10.4.7.
Arctic Climate Impact Assessment
Biological Diversity. For example, Groombridge’s (1992)
book on biological diversity had 241 pages on species
diversity, 80 pages on the diversity of habitats, but only
6 pages on genetic diversity. Similarly, Heywood’s (1995)
Global Biodiversity Assessment had only 32 pages on the
subject of “genetic diversity as a component of biodiversity” of its total of 1140 pages.
The reason for this discrepancy is because species tend
to be tangible entities and many are easily recognizable.
The species concept does not work well, however, for
the single-celled forms of life, which often live in soils
or sediments under freshwater or the sea, where the
genetic variability is often more important than the
species itself. Habitats are also recognizable, often on the
basis of their species, but present complications because
they tend to merge into one another. Compared with
these tangible entities, genetic variability is often not
recognizable and can only be detected by sophisticated
methods of analysis using molecular techniques. Of the
millions of species that exist, very little is known about
their genetic diversity except for a few species of economic importance, a few species that are parasites of
people or their domestic stock, and a few other species
that geneticists have favored for research (e.g., the
Drosophila flies). As in all other parts of the world, relatively little is known about the genetic variability of
species that occur in the Arctic.
What then can be done to conserve the Arctic’s genetic
diversity? On the basis that natural selection requires a
genetic diversity to operate, conservation practice should
aim to find a surrogate for the unknown, or almost
unknown, genetic diversity.This is best done by conserving each species over as wide a distribution range as possible and in as many habitats as possible.This ensures
maximum geographical and ecological variability, assuming that local adaptation of species represents different
genotypes. Attempting to map population genetics to
landscape processes is relatively new (Manel et al., 2003)
and has been termed “landscape genetics”. Manel et al.
(2003) stated that it “promises to facilitate our understanding of how geographical and environmental features
structure genetic variation at both the population and
individual levels, and has implications for…conservation
biology”. At the moment it must be assumed that the
geographical and environmental features have structured
the genetic variation, and this assumption must be made
before the links can be proved. How this variability has
actually arisen is unclear.
10.4.4. Changes in genetic diversity
Throughout continental Europe, a continuous postglacial
range expansion is assumed for many terrestrial plant and
animal species.This has often led to a population structure in which genetic diversity decreases with distance
from the ancestral refugium population (Hewitt, 2000),
and so northern populations are often genetically less
diverse than their southern counterparts (Hewitt, 1999).
Little attention had been paid to genetic diversity, despite
it being one of the major themes in the Convention on
Among discontinuously distributed species, such as those
living on remote islands, this pattern can be obscured by
Chapter 10 • Principles of Conserving the Arctic’s Biodiversity
differences in local effective population sizes. For example, considerable genetic diversity exists among populations of common eider ducks (Somateria mollissima) nesting throughout the circumpolar Arctic. Historical and
current processes determining phylogeographic structure
of common eiders have recently been reconstructed,
based on maximum parsimony and nested clade analysis
(A. Grapputo, Royal Ontario Museum, pers. comm.,
2004;Tiedemann et al., 2004). Five major groups (or
“clades”) have been identified; the three most different
include common eiders from Alaska, Svalbard, and
Iceland.The remaining two include eider populations
from the eastern Canadian Arctic and West Greenland,
and from northwest Europe.
Nested clade analysis also suggests that the phylogeographic patterns observed have a strong historical pattern
indicating past fragmentation of eider populations due to
glacial events. Following the retreat of the glaciers, eiders
surviving in refugia expanded to re-colonize their range,
and populations apparently remixed.These refugial populations occurred across Arctic Canada and Greenland
(A. Grapputo, Royal Ontario Museum, pers. comm.,
2004), and apparently in a single refugium in northwest
Europe (Tiedemann et al., 2004).The oldest population
split was estimated between Pacific eiders and birds that
colonized the western Canadian Arctic islands about
120000 years ago after the retreat of ice sheets in the
previous glacial maximum. In North America, this was
likely to have been followed by a second expansion that
began in warmer periods about 80000 years ago from
Alaska eastward across the Palearctic to establish populations in the eastern Canadian Arctic and West Greenland.
In Europe, genetic analyses suggest that common eiders
underwent a postglacial range expansion from a refugium
in Finland, north and west to the Faroe Islands and subsequently to Iceland. Despite this relatively recent mixing
of haplotypes, extant populations of common eider ducks
are strongly structured matrilineally in the circumpolar
Arctic.These results reflect the fact that current longdistance dispersal is limited and that there is considerable
philopatry of female eiders to nesting and wintering areas
(Tiedemann et al., 2004).
In contrast to common eider ducks, king eider ducks
(Somateria spectabilis) show a distinct lack of spatial
genetic structure across arctic North America (Pearce et
al., 2004). In the western Palearctic, the king eider has
been delineated into two broadly distributed breeding
populations in North America, in the western and eastern Arctic, on the basis of banding (ringing) data (Lyngs,
2003) and of isotopic signatures of their diet while on
wintering grounds (Mehl et al., 2004, in press).These
studies indicated the use of widely separated Pacific and
Atlantic wintering areas. Despite this, recent studies of
microsatellite DNA loci and cytochrome b mitochondrial DNA show small and non-significant genetic differences based on samples from three wintering and four
nesting areas in arctic North America, Russia, and
Greenland (Pearce et al., 2004). Results from nested
clade analysis and coalescent-based analyses suggest his-
573
torical population growth and gene flow that collectively
may have homogenized gene frequencies. However, the
presence of several unique mtDNA haplotypes among
birds wintering in West Greenland suggested that gene
flow may now be more limited between the western and
eastern arctic populations than in the past (Pearce et al.,
2004); this would be consistent with recent banding data
from eastern Canada and West Greenland (Lyngs, 2003).
Collectively, these two examples of closely related duck
species illustrate how climatic events can influence the
genetic structure of arctic species over time.They also
show how historical periods of isolation, combined with
little gene flow currently (matrilineally, at least), have
contributed to maintain genetic diversity. However, the
fact that the common and king eider differ so markedly
in their degree of genetic diversity throughout the
circumpolar Arctic, despite sharing many ecological
traits, suggests that the effects of more rapid climate
change on genetic diversity may be difficult to predict.
There are at least three features of this genetic variability that need to be considered in the conservation of
the Arctic’s biodiversity. First, the genetic structure of
a species at the edge of its range, where it is often fragmented into a number of small and relatively isolated
populations, is often different from that at the center
of the range, where populations can be more contiguous and gene flow is likely to be greater. It is these
isolated, edge-of-range populations that are possibly
undergoing speciation, and which might form the basis
of an evolution toward different species with different
ecologies in the future.
Second, hybridization can be both a threat and an opportunity. Although arctic examples are rare, it can be a
threat where two species lose their distinctive identities,
as is happening with the introduction of Sika deer (Cervus
nippon) into areas where red deer (C. elaphus) naturally
occur.This is one of the potential problems with the
introduction into the Arctic of non-native species (section 10.4.6). Hybridization can also be an opportunity.
The hybrid between the European and American
Spartina grasses doubled its number of chromosomes and
acts as a newly evolved species in its own right.
Third, there are suggestions (Luck et al., 2003) that the
genetic variability of populations is important in maintaining the full range of ecosystem services. Although
this concept is little understood, it is intuitively plausible
because, as factors in the environment change, individuals of differing genetic structure may be more or less
able to fulfill the functional role of that species in the
ecosystem.Thus, with a variable environment, the
ecosystem needs species whose individuals have a variable genetic makeup.
Although little is known about genetic variability, a geographically spread suite of protected areas, encompassing
the full range of habitat types, is probably the best conservation prescription for the Arctic’s biodiversity that can
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Arctic Climate Impact Assessment
currently be made. It should be appropriate for conserving the biodiversity of habitats and species, and is probably
also appropriate for conserving genetic biodiversity.
10.4.5. Effects on migratory species and
their management
Migration was briefly addressed in sections 10.2.6 and
10.3.2, and the eight major international flyways for
shorebirds breeding in the Arctic are shown in Figure
10.4. Migration is a cold and ice avoidance strategy
used by birds, marine mammals, and fish. Although
some species of insect also migrate, it is uncommon for
the milkweed butterfly (Danaus plexippus), well known
for its migrations through North America, to migrate in
the spring and early summer as far north as the
Canadian Arctic.
The goose species of the western Palearctic region provide
good examples of migratory species that have been the
subject of considerable research and conservation action
(Madsen et al., 1999). Of the 23 populations, five populations of greylag goose (Anser anser anser and A. a. rubirostris)
do not nest in the Arctic; neither do the two populations
of Canada goose (Branta canadensis) which are not native to
the region.The remaining 16 populations of seven species
(11 subspecies) are listed in Table 10.8.There are a variety
of flyways, some moving southeast from the breeding
grounds in northeast Canada, Greenland, and Iceland, and
others moving southwest from the breeding grounds in
the Russian Arctic, both into Western Europe.The three
populations of barnacle goose (Branta leucopsis) can be used
as an example (see Box 10.1).
The examples demonstrate a number of features of
migratory populations and their conservation.The geese
require sufficient food resources to make two long jour-
neys each year.The summer feeding grounds in the
Arctic and the winter feeding grounds in temperate
Europe provide the majority of the food requirements.
However, while on migration, the geese need to stage
and replenish their energy reserves. In years when winter comes early and Bjørnøya is iced over before the
geese arrive, it is known that many are unable to gain
sufficient energy to fly on to Scotland and there can be
very heavy mortality, especially of that year’s young.
Although the three populations appear from the brief
descriptions in Box 10.1 to be geographically isolated
from each other, there is a very small amount of mixing
between these populations, and so gene flow is probably
sufficient for this one species not to have sub-speciated.
The examples also demonstrate that conservation efforts
need to be international. For each of the three populations, protection is required for parts of the year in the
breeding grounds, in the wintering grounds, and in the
staging areas. Conservation action needs to be taken
wherever the geese land.The fact that there is some
straying from the main flight paths implies that conservation is required all along these migration routes. In
Europe, the Bonn Convention aims to provide such an
instrument for the conservation of migratory species; this
could form a model for all migratory species, including
those that use the Arctic for part of their life cycle.
Climate change could affect these species through
changes in their habitats. For the Greenland nesting population it would be possible for their breeding grounds
to move northward because there is land north of the
current breeding range.This could hardly happen for the
populations breeding on Svalbard and in Russia because
there is very little ground north of the current breeding
areas (just the north coast of Svalbard and the north of
Novaya Zemlya). Because many of the wintering
Table 10.8. The sixteen goose populations that nest in the Arctic and overwinter in the western Palearctic.The data were extracted
from Madsen et al. (1999).
Breeding area
Wintering area
Taiga bean goose
Anser fabalis fabalis
Scandinavia and Russia
Baltic
Tundra bean goose
Anser fabalis rossicus
Russia
Central and Western Europe
Pink-footed goose
Anser brachyrhynchus
Iceland and Greenland
Great Britain
Pink-footed goose
Anser brachyrhynchus
Svalbard
Northwest Europe
White-fronted goose
Anser albifrons albifrons
Russia
Western Europe
Greenland white-fronted goose
Anser albifrons flavirostris
West Greenland
British Isles
Lesser white-fronted goose
Anser erythropus
Scandinavia and Russia
Central and southeast Europe
Greylag goose
Anser anser anser
Iceland
Scotland
Greylag goose
Anser anser anser
Northwest Europe
Northwest and southwest Europe
Barnacle goose
Branta leucopsis
East Greenland
British Isles
Barnacle goose
Branta leucopsis
Svalbard
Scotland and northern England
Barnacle goose
Branta leucopsis
Russia and the Baltic
Northwest Europe
Dark-bellied brent goose
Branta bernicla bernicla
Russia
Western Europe
Light-bellied brent goose
Branta bernicla hrota
Northeast Canada
Ireland
Light-bellied brent goose
Branta bernicla hrota
Svalbard
Northwest Europe
Red-breasted goose
Branta ruficollis
Russia
Black Sea
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Chapter 10 • Principles of Conserving the Arctic’s Biodiversity
Box 10.1.The three populations of barnacle goose in the western Palearctic
The western population of barnacle goose (Branta leucopsis) in the western Palearctic breeds near the coast
along northeast Greenland from about 70º to 78º N. On the autumn migration the geese stage in Iceland, near
the south coast, where they spend about a month feeding before they fly on to the wintering grounds along the
west coast of Ireland and the west and north coasts of Scotland. In the spring the geese leave the British Isles in
April and stage on the northwest coast of Iceland for three or four weeks before flying back to Greenland to
recommence the annual cycle.These geese are legally protected in Greenland from 1 June to 31 August, although
a few are legally hunted by local people. In Iceland the geese are protected in the spring, although it is considered
that some are illegally killed, but few are thought to be killed in autumn. In the United Kingdom the geese are fully
protected as a result of domestic legislation and of being listed in Annex I to Council Directive 79/409/EEC on
the conservation of wild birds (also known as the Birds Directive).
A second (or central) population of about 25000 birds breeds in Svalbard between about 77º and 80º N. After
breeding, the geese leave Svalbard in August, and many arrive on Bjørnøya at the end of August staying until late
September or early October when they fly on to the Solway Firth in southwest Scotland.They return north in the
spring, staging in the Helgeland Archipelago off the coast of Norway (between 65º and 66º N) for two to three
weeks before flying on to Svalbard.The geese are legally
protected in Svalbard, Norway, and the United Kingdom,
and it is thought that very few are illegally shot.
The eastern population breeds in northern Russia, from
the Kola Peninsula in the west to Novaya Zemlya and
the Yugor Peninsula in the east. In the autumn the birds
fly southwest, along the Gulf of Bothnia and the southern part of the Baltic Sea, staging on the Estonian and
Swedish Baltic islands.The majority of the birds winter
on the North Sea coast of Denmark, Germany, and the
Netherlands.The species is legally protected in Russia,
although Madsen et al. (1999) reported that it appears
that many are shot and that both the adults and the
eggs are used as an important part of the diet of local
people. Within the countries of the European Union,
the geese are fully protected by the Birds Directive.
grounds are managed as grasslands for cattle and sheep
grazing, it is possible that these may change less than the
breeding grounds.The staging areas are also likely to
change, and it is possible that the distance between
breeding and wintering grounds might become longer,
requiring more energy expenditure by the migrating
birds.This leaves a series of unknowns, but at present
these goose populations are increasing in size, are having
an economic impact on the wintering grounds, and have
raised what Usher (1998) has termed “the dilemma of
conservation success”.This is the problem of reconciling
the interests of the local people with the need to conserve species that the people either depend upon harvesting or that damage their livelihoods.
10.4.6. Effects caused by non-native species
and their management
Biological invasions have fascinated ecologists for well
over 50 years (Elton, 1958).The many problems caused
by non-native species are becoming more apparent, and
the World Conservation Union (IUCN) identifies them
as the second most important cause of loss in global
biodiversity (the primary reason being loss and fragmen-
Barnacle geese from the Greenland population overwintering on
the island of Islay, western Scotland
tation of habitats). A word of caution is, however, needed with language.Why a species is geographically where
it is currently found cannot always be determined; if it is
known to be there naturally, it is generally referred to as
“native”. If it has been brought in from another geographical area by human agency, either intentionally or
unintentionally, it is referred to as “non-native” (Usher,
2000, discussed these distinctions and the gradations
between them).The term “non-native” is essentially
synonymous with “alien”, “exotic”, and “introduced”,
all of which occur in the literature.Williamson (1996)
described the “10:10 rule”, suggesting that 10% of
species introduced to an area would establish themselves
(i.e. they do not die out within a few years of introduction, and start to reproduce) and that 10% of these
established species would become “pests”.While this
rule seems reasonably true for plants, it seems to underestimate the numbers of vertebrate animals that become
problematic (Usher, 2002b). It is this 1% (10% of 10%)
of species that are introduced, or rather more for vertebrate animal species, which can be termed “invasive”.
To date, the Arctic has escaped the major problems that
invasive species have caused in many other parts of the
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Arctic Climate Impact Assessment
world. During the 1980s there was a major international
program on the ecology of biological invasions.The synthesis volume (Drake et al., 1989) does not mention the
Arctic (or the Antarctic), although global patterns of
invasion into protected areas indicated that the problems
diminished with latitude north or south of the regions
with a Mediterranean climate (Macdonald I. et al., 1989).
as arctic rivers and lakes become warmer.There are also
potential problems with fish that escape from fish farms
and enter the natural environment and breed with native
fish stock.The genetic effects of this interbreeding can
be profound, altering the behavior of the resulting fish
stock, as has been found with Atlantic salmon (Salmo
salar) in Norway.
In terrestrial ecosystems, climate change is very likely to
mean that more species will be able to survive in the
Arctic. It is arguable whether new species arriving in the
Arctic can be classified as “native” or “non-native” when
the rapidly changing climate is anthropogenically driven.
However, with a changing climate new species will very
probably arrive in the Arctic, some of which will establish
and form reproducing populations. Although there is no
obvious candidate for a non-native species to be invasive
in the Arctic, it needs to be remembered that at least 1%
of species introduced into the Arctic are likely to become
invasive. At present there are no means of determining
the major risks, but the introduction of disease organisms, for wildlife and people, is a distinct possibility.
In the marine environment one of the major potential
problems is the discharge of ballast water.With thinning
of the sea ice and the opening up of the Arctic Ocean to
more shipping for more of the year, the possibility of the
introduction of non-native species is greater and the
environmental risks are increased. Analyses of ballast
water have shown that it can contain a large number of
different species of marine organisms, including marine
algae and mollusks that are potentially invasive. Also,
ballast water has occasionally been found to contain
organisms that could be pathogenic to people. Regulating discharges of ballast water in not easy, nor is its
enforcement always possible, but to prevent the threat of
invasive marine organisms it is essential that international agreements regulate such discharges in coastal waters
and on the high seas of the Arctic.
In the boreal forests, the insects, as a group, pose the
most serious challenge because of their ability to increase
rapidly in numbers and because of the scarcity of effective
management tools. From past experience, it is probable
that many forest-damaging insects have the potential to
appear at outbreak levels under a warmer climate and
increased tree stress levels, but this has not been observed
to date.Two examples demonstrate the risks. First, the
bronze birch borer (Agrilus anxius) has been identified as a
species that can cause severe damage to paper birch
(Betula papyrifera), and may be effective in limiting the
birch along the southern margin of its distribution (Haak,
1996). It is currently present at relatively low levels in the
middle and northern boreal region of North America.
Second, an outbreak of the Siberian silkworm (Dendrolimus sibiricus) in west Siberia from 1954 to 1957 caused
extensive tree death on three million hectares of forest.
Movement of outbreak levels northward would considerably alter the dynamics of Siberian forests.
There are similar concerns in the freshwater environment. In much of northern Europe and northern
America, it is the introduction of fish species that cause
most problems. For example, in Loch Lomond in
Scotland the invasive ruffe (Gymnocephalus cernuus) eats
the eggs of an arctic relict species, the powan (Coregonus
lavaretus), thereby threatening this species in one of its
only British habitats (Doughty et al., 2002). Similarly, in
North America the invasion of the Great Lakes by the
lamprey (Petromyzon marinus), first seen in Lake Erie in
1921, led to the collapse of a number of fisheries following its establishment and first known breeding in the
1930s. For example, the trout fishery in Lake Michigan
was landing about 2600 tonnes of fish each year between
1935 and 1945, but this dropped to 155 tonnes by 1949
when the fishery essentially ended (Watt, 1968).
Although these examples are outside the Arctic, they
highlight potential problems with non-native fish species
The effects of introduced Arctic foxes on seabird populations is an example that links the marine and terrestrial
environments. Seabirds commonly nest on offshore
islands, in part to avoid terrestrial predators to which
they are vulnerable, both to the loss of eggs and chicks
and to direct predation on adults. Several seabird populations have declined when mammalian predators were
accidentally or intentionally introduced to nesting
islands (Burger and Gochfeld, 1994). Arctic foxes were
intentionally introduced for fur farming in the late 1800s
and early 1900s on several of the Aleutian Islands of
Alaska. Before these introductions, the islands supported
large populations of breeding seabirds and had no terrestrial predators. Although most fox farming ended prior
to the Second World War, the introduced animals persisted on many islands, preying on breeding seabirds at rates
affecting their population sizes (Bailey, 1993). Evidence
from southwestern Alaska (Jones R. and Byrd, 1979),
and comparisons of islands with and without foxes in the
Shumagin Islands (Bailey, 1993), suggest it is likely that
foxes are responsible for the reduced seabird population
sizes on islands supporting foxes.Those species nesting
underground, in burrows or in rock crevices, were less
affected (Byrd et al., 1997).
Foxes have recently been eradicated from several islands
(Bailey, 1993) and the responses of seabird populations
have been dramatic. Pigeon guillemot (Cepphus columba)
populations began to increase within three to four years
following fox removal at Kiska Island and 20-fold increases occurred in guillemot numbers at Niski-Alaid Island
within 15 years of fox removal (Byrd et al., 1994).The
introduction of Arctic foxes to the Aleutian Islands, and
their influence on native seabird species, provides a dramatic example of how the intentional introduction or
movement of species can influence arctic biodiversity.
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Chapter 10 • Principles of Conserving the Arctic’s Biodiversity
The report by Rosentrater and Ogden (2003) contained
the cautionary note “presently, the magnitude of the
threat of invasive species on Arctic environments is
unclear: however, the potential impacts of this threat
warrant further investigation and precautionary action
on species introductions, especially since climate change
is expected to result in the migration of new species into
the region”.The risk to the environment and to biodiversity of intentionally introducing any non-native
species into the Arctic must be established before the
species is introduced. Experience worldwide indicates
that it is often too late if the risk is assessed after the
introduction; it might then also be too late to control
the spread and effects of the invasive species.The precautionary action is to stop the arrival of the invasive
species in the first place because its later eradication may
be impossible, and even if possible worldwide experience shows that it is likely to be extremely expensive.
10.4.7. Effects on the management of
protected areas
Establishment of protected areas has been a core activity of conservation legislation throughout the world.
The concept is implemented in different ways by different national governments, with differing degrees of success, as is clear from reviews of international activities
(e.g., IUCN, 1991).This section reviews the underlying
ecological concepts related to the conservation of biodiversity and the potential effects of climate change.
Reviews by CAFF (2001, 2002a) showed that much
progress has been made in designating protected areas
in the Arctic, but that further progress is needed, especially in the marine environment. Halpern and Warner
(2002) indicated that marine reserves are very effective
at conserving biodiversity, and Halpern (2003) considered that marine protected areas need to be large in
extent. In the terrestrial and freshwater environments,
some of the largest protected areas worldwide occur in
the Arctic. Few studies explore whether such protection
is achieving its stated aims.
In general the establishment of protected areas has a
scientific foundation. As Kingsland (2002) stated “its
goal is to apply scientific ideas and methods to the
selection and design of nature reserves and to related
problems, such as deciding what kinds of buffer zones
should surround reserves or how to establish corridors
to link reserves and allow organisms to move from one
area to another. As in other areas of conservation biology, designing nature reserves is a ‘crisis’ science, whose
practitioners are driven by an acute sense of urgency
over the need to stem the loss of species caused by
human population growth”. This to some extent misses
a vital point: the social sciences are also involved with
conservation. Why is it important to conserve biodiversity, why are particular species favored over
others, or how do people fit into the conservation
framework? Such questions are not addressed here,
despite their importance to the local communities of
the Arctic (section 10.2.7); this section focuses on the
scientific bases of conservation.
Three main facets of ecological thinking have affected
the design of potential protected areas.The concepts of
island biogeography, of habitat fragmentation, and the
establishment of metapopulations (and of corridors) are
not unrelated and can all impact upon protected areas in
a changing climate.
The concept of island biogeography (MacArthur and
Wilson, 1967) includes the idea that the number of
species on an island is dynamic, representing the equilibrium between the arrival of new species and the
extinction of existing species. Larger islands would have
greater immigration rates, and possibly smaller stochastic extinction rates, than small islands, and hence the
equilibrium number of species would be greater.
Similarly, distant islands would have smaller immigration rates than similarly sized islands nearer the source
of immigrants, but would probably have similar extinction rates, and so would have fewer species. Using many
sets of data for island biota, these concepts are formulated into the empirical relationship:
S = CAz
where S is the number of species on the island, A is the
area of the island, and C and z are constants (C represents
the number of species per unit area, and z generally takes
a value of about 0.3.This relationship implies that if the
island area is increased ten-fold, the number of species
will about double). Although there have been few island
biogeographical studies in the Arctic, Deshaye and
Morisset (1988, 1989) confirmed that larger islands in
the subarctic (in the Richmond Gulf, northern Québec,
Canada) contain more species than smaller islands.
Island biogeography has thus been used to justify larger
rather than smaller protected areas.With climate
change, and with arctic wildlife populations and their
distribution ranges likely to diminish (sections 10.4.1 to
10.4.3), use of the precautionary principle would also
suggest that larger rather than smaller protected areas
should be established.
Fragmentation of ecosystems has been viewed as the
“islandization” of habitats. Although fragments cannot be
thought of as real islands, the use of island biogeographical concepts tends to apply relatively well (Harris,
1984).This has led to the formulation of “rules” for the
design of protected areas, starting with Diamond
(1975), but leading to more sophisticated designs as in
Fig. 10.15. Size and shape are the key factors in the
design of protected areas, but the inclusion of fragments
of natural ecosystems is helpful for biodiversity conservation. Under a changing climate, fragmentation of arctic ecosystems should be avoided. Fragmentation always
causes problems (Saunders et al., 1987), even if at some
scales it might appear to increase biodiversity (Olff and
Ritchie, 2002).
578
Arctic Climate Impact Assessment
of protected areas (see the example of the Canadian
national parks in section 10.4.1).This means that designation should reflect both the present value of the areas
for biodiversity as well as the projected future value
(the potential value).
Fig. 10.15. A representation of the biodiversity conservation
value of potential protected areas, based on a study of insects in
farm woodlands but also applicable to other habitats and other
taxonomic groups (Usher, 2002a).The scaling should change to
reflect the larger areas prescribed for the Arctic. Habitats are in
black and habitat fragments are small white circles. Linear features, such as small rivers, are represented by straight lines.
With fragmentation an integral part of modern development, corridors appear to be a useful concept. How
does the landscape fit together such that individuals can
move from habitat patch to habitat patch? As pointed out
by Weber et al. (2002), land managers and wildlife biologists must collaborate to determine the patterns of protected areas within the landscape that will be of most
benefit to wildlife. Some scientists advocate corridors:
Saunders and Hobbs (1991) gave a number of examples
where corridors appear to work. Others have argued
that corridors allow invasive species entry into protected
areas, while more recent research calls into question the
whole value of corridors. Albeit a beguilingly simple
concept, at present neither the value of corridors, nor
their lack of value, has been proven.With climate change
underway, it is thus best to avoid the necessity for corridors by focusing on larger protected areas and a reduction in the processes leading to habitat fragmentation.
This will promote real connectivity, rather than an
apparent connectivity, for species and habitats.
However, will the protected areas that exist today, even if
they have been located in the best possible place to conserve biodiversity, still be effective in the future with climate change? The answer is probably “no”. Designations
have been widely used, but are based on assumptions of
climatic and biogeographic stability and usually designated to ensure the maintenance of the status quo. Available
evidence indicates that these assumptions will not be sustainable during the 21st century. So what can be done to
make the network of protected areas more appropriate to
the needs of the Arctic and its people?
First, today’s protected areas should encompass land
or water that will potentially be useful for biodiversity
conservation in the future.This is where models of the
changing distribution of species and habitats are useful
and where their outputs should be included in the design
Second, boundaries may need to be more flexible. In general, boundaries are lines on maps, and enshrined in legislation, and so are difficult to change.The present practices
could be described as having “hard boundaries”. An alternative could be that the boundaries change with changes
in the distribution of the flora or fauna being protected.
That is, over time (probably decades rather than years) the
location of the protected areas would shift geographically
(this could be described as the protected areas having “soft
boundaries”). However, it is important that sociological
and developmental pressures do not destroy the value of
the protected areas in safeguarding the biodiversity that is
their raison d’etre – nothing would be worse than in 50
years time having a network of sites that were protecting
very little. More flexible systems of designation, adding
areas which are or will become important, and dropping
areas that are no longer important, would appear to be
one way forward to conserve biodiversity within the
Arctic. A system of designations with “soft boundaries” has
not yet been tried anywhere in the world, but could
become a policy option that is pioneered in the Arctic.
Protected area designations are a major policy and
management system for the conservation of biodiversity,
as well as for historical and cultural artifacts. Climate
change might result in designated communities and
species moving out of the designated area; communities
and species new to the area will tend to colonize or
visit, especially from the south; and assemblages of
species without current analogues will form as individual species respond to climate change at different rates
and in different ways. It will therefore be necessary to
adjust such concepts as “representative communities”
and “acceptable limits of change” that are part of the
mandate of many national and international designations.
The expected changes will include many surprises
resulting from the complex interactions that characterize
ecosystems and the non-linearity of many responses.
The scientific basis of biodiversity conservation planning
in the era of climate change argues against procedures
designed to maintain a steady state.There are four general policy options to respond to climate change that
have been used in the Canadian national parks (summarized by Scott and Lemieux, 2003).
1. Static management. Continuing to manage and
protect current ecological communities and
species within current protected area boundaries,
using current goals.
2. Passive management. Accepting the ecological
response to climate change and allowing evolutionary processes to take place unhindered.
3. Adaptive management. Maximizing the capacity of
species and ecological communities to adapt to cli-
Chapter 10 • Principles of Conserving the Arctic’s Biodiversity
579
mate change through active management (for
example, by fire suppression, species translocation,
or suppression of invasive species), either to slow
the pace of ecological change or to facilitate ecological change to a new climate adapted state.
4. Hybrid management. A combination of the three
previous policy options.
of management. From a scientific perspective, monitoring will allow more data to be collected and, if coupled
with research, will also allow a greater understanding of
the mechanisms involved with change. In time, therefore, with increasing data and increasing understanding,
the conservation of biodiversity would move in the plane
shown in Figure 10.12 from the bottom left hand corner
and, perhaps only slightly, toward the top right hand
corner.With data and understanding it should be possible in the future to build better models and hence make
better predictions.
It is likely that adaptive management will be the most
widely applied.This is likely to include actions to maintain, for as long as possible, the key features for which
the original designation was made, for example by
adjusting boundaries. Past experience indicates that
intervention strategies tend to be species-specific, and to
be strongly advocated, but this must not detract from
the more scientific goal of conserving the Arctic’s biodiversity in a holistic manner.
10.4.8. Conserving the Arctic’s changing
biodiversity
Preceding sections have addressed issues such as the
effects of climate change on the size and spatial extent of
species populations and the communities in which the
species occur, the need to conserve genetic diversity,
potential problems resulting from the arrival of nonnative species, and problems faced by migrant species.
This section addresses a few topics that cut across those
already discussed.The two main topics discussed here
are taxonomy and monitoring.
Biodiversity depends upon taxonomy. It is necessary to
be able to name species and habitats, or to understand
variation in DNA, to be able to start to think about
biodiversity and its conservation, and to communicate
thoughts.Taxonomy is therefore fundamental to the
work on biodiversity (Blackmore, 2002). It is necessary
to know the species being considered – knowledge of
birds, mammals, and fish is certainly satisfactory, but is
this true for all the insects in the Arctic and their roles in
the arctic freshwater and terrestrial ecosystems? Knowledge of vascular plants (flowering plants and ferns) is
probably satisfactory, but is this true for the mosses, liverworts, lichens, and algae that are responsible for much
of the photosynthesis, in the sea, freshwaters, and on
land? As in almost all parts of the world, is there knowledge about the species of protozoa or bacteria that are
associated with the processes of decomposition in arctic
soils and in the sediments under lakes or on the sea
floor? There are many areas of arctic taxonomy that
require exploration and research, and it is vital to the
conservation of the Arctic’s biodiversity that these taxonomic subjects are addressed.
Monitoring is important for understanding how the
Arctic’s biodiversity is changing and whether actions to
conserve this are being successful. As Cairns (2002)
pointed out, monitoring needs to occur at both the
system level and the species level. Monitoring will help
now, and in the future, to determine if current predictions are correct and to modify and improve the systems
Conservation of the Arctic’s biodiversity at present relies
upon two approaches. One is through the establishment
of protected areas, and this was discussed in section
10.4.7. Greater knowledge of taxonomy and monitoring
of what is happening within those protected areas are
both important for their future management.The other
approach is more educational, bringing biodiversity
thinking into all aspects of life in the Arctic. Considerations of biodiversity need to be explicit in planning for
developments at sea or on land. Biodiversity needs to be
considered explicitly in the management of land, freshwater, and the sea. Links between biodiversity and the
health of the local people need to be established.
Biodiversity forms the basis of most tourism into the
Arctic, but facilities for tourists need particular care so
as not to damage the very reason for their existence
(Rosentrater and Ogden, 2003). Biodiversity conservation as a concept therefore needs to permeate all aspects
of life in the Arctic.
If it is accepted that protected areas are only ever going
to cover a relatively small percentage of the land and sea
area of the Arctic (possibly between 10 and 20%), then it
is the land and sea outside the protected areas that will
hold the majority of the Arctic’s biodiversity. Just as within protected areas it is vital to have knowledge of taxonomy and programs of monitoring, there must also be taxonomic knowledge and monitoring throughout the Arctic.
The majority of the biodiversity resource in the nonprotected areas must not be sacrificed because a minority
of that resource is within protected areas. Apart from the
Antarctic, it is probably easier to achieve this balance
between protected areas and the rest of the land and sea
area in the Arctic than in other areas of the world, but it
will require international effort if the Arctic’s biodiversity
is to be conserved for future generations to use and
enjoy. All this, in the face of climate change, will need
“building resilience” (the expression used by Rosentrater
and Ogden, 2003) into all arctic ecosystems, whether or
not they lie within protected areas.
10.5. Managing biodiversity conservation
in a changing environment
To conclude this chapter on conserving the Arctic’s biodiversity, it is appropriate to explore a number of topics
that have been implicit in the various descriptions and
discussions of sections 10.1 to 10.4. Four topics are
addressed in this final section: documenting the current
580
biodiversity; predicting changes in that biodiversity
resource over the next 50 or 100 years; determining
how that biodiversity resource is actually changing; and
managing the Arctic’s biodiversity resource in a sustainable manner.
Each topic generates a number of questions, and their
answers involve many concepts, most of which have
already been introduced in this chapter. Sixteen recommendations are made in relation to the various discussions and conclusions in this section.
10.5.1. Documenting the current biodiversity
The Arctic nations have very good inventories of their
mammals and birds (listed by Sage, 1986). Although it is
possible that a few more species might have been recorded in the Arctic since the mid-1980s, it is unlikely that
the numbers of 183 species of bird and 48 species of terrestrial mammal will have changed significantly.
It is notable that Sage (1986) was unable to provide
similar lists for any other taxa of wildlife in the Arctic.
From the literature on the Arctic it would probably now
be possible to prepare reasonably good inventories of
the marine mammals, freshwater and marine fish, and
vascular plants. Although this is as much as most nations
in the world can compile for national inventories, such
lists omit the most species-rich taxa. Large numbers of
species of bryophyte (mosses and liverworts), lichen
(or lichenized fungi), fungi, and algae occur, as well as
many species of invertebrate animals.Terrestrially, it is
likely that the insects and arachnids (mites and spiders)
will be the most species-rich, whereas in the sea it is
likely to be the crustaceans and mollusks that are most
species-rich. However, there are many other taxonomic
groups, especially the nematodes and many marine taxa
of worms, sponges, and hydroids, as well as singlecelled organisms in which the “species” concept is more
difficult to apply.
Inventories are important.They form the building blocks
for biodiversity conservation because, unless the biodiversity is known, it is not possible to begin to conserve
it or to recognize when it is changing. Documentation of
the numbers and types of species living in the Arctic has
focused mainly on terrestrial systems and is detailed in
Chapter 7.The Arctic has around 1735 species of vascular plants, 600 bryophytes, 2000 lichens, 2500 fungi,
75 mammals, 240 birds, 3300 insects dominated by the
Diptera (two-winged flies), 300 spiders, 5 earthworms,
70 enchytraeid worms, and 500 nematodes.This species
diversity represents a small but variable percentage of
the world’s species, with some groups relatively strongly
represented.Thus, there are about 0.4% of the world’s
insects but 6.0% of the Collembola; as well as 0.6% of
the world’s ferns but 11.0% of the lichens.There is currently no comparable documentation of numbers of
species in the freshwater and marine environments of
the Arctic, although there is significant environmental
overlap for some taxa, for example, the birds.
Arctic Climate Impact Assessment
An excellent example of an arctic inventory is the work
done on Svalbard (Elvebakk and Prestrud, 1996;
Prestrud et al., 2004). An overview is given in Table
10.9, giving Svalbard a species richness of about 5700
(terrestrial, freshwater, and marine environments combined). However, this total does not include many of the
single-celled organisms, such as the protozoa, and so a
full inventory would be substantially longer.
Many species, particularly vascular plants, are endemic
to the Arctic. However, there are few endemic genera.
This has been attributed to the youthfulness of the arctic
flora and fauna, with insufficient time undisturbed to
allow the evolution of endemic genera.The proportions
in many taxa that are endemic to the Arctic, especially
for the lower plants and invertebrates, is unknown, a
feature that deserves more attention.The level of information varies widely between taxonomic groups, especially for the soil invertebrates and lower plants that have
been examined at few sites. In contrast, information on
vascular plants, birds, and mammals is detailed, both in
terms of species identification, and in terms of population size and distribution.
In documenting current arctic biodiversity as a basis for
conservation, a key feature is that many of the vertebrate
Table 10.9. Species richness in the terrestrial, freshwater, and
marine environments of Svalbard (summarized from Elvebakk
and Prestrud, 1996, and Prestrud et al., 2004). Detailed species
lists are contained in the references quoted.
Number
of species
Plants
Cyanobacteriaa
Algaea,b
1049
Fungi and lichenised fungic
Mosses and
73
liverwortsd
1217
373
Vascular plantse
173
Animals
Marine crustaceaf
467
Marine mollusksf
Other marine
invertebratesf
Marine vertebrates (fish)f
252
924
70
Terrestrial and freshwater arachnidsg
134
Terrestrial and freshwater insectsg
289
Other terrestrial and freshwater invertebratesg
617
Birdsh,i
Mammalsh,j
Total
aSkulberg
53
9
5700
(1996); Hansen J. and Jenneborg (1996); bHasle and Hellum von
Quillfeldt (1996) cAlstrup and Elvebakk (1996); Elvebakk and Hertel (1996);
Elvebakk et al. (1996); Gulden and Torkelsen (1996); dFrisvoll and Elvebakk (1996);
eElven and Elvebakk (1996); f Palerud et al. (2004); gCoulson and Refseth (2004);
hStrøm and Bangjord (2004); i202 species recorded, of which 53 are known to be
breeding, to have bred in the past, or are probably breeding; j23 species recorded
(plus another 8 species which are known to have been introduced), of which 9
are known to be breeding or to have bred in the past.
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Chapter 10 • Principles of Conserving the Arctic’s Biodiversity
species spend only a small proportion of their time in
the Arctic.This adaptive behavior is found in most birds,
some marine mammals, and some freshwater and
marine fish. As a result, documentation of their status
and conservation action for them is dependent on international cooperation. It is also probable that the main
threats to these migratory species occur during their
migrations or during their winter period outside the
Arctic. Current threats include changes in land- and
water-use, human exploitation of resources upon which
the animals depend, direct cropping of the animals for
food or sport, accidental killing (as in the by-catch
resulting from other fisheries), or pollution. A particular
benefit of detailed and long-term observations, particularly for migratory birds that cover all continents (Figure
10.4), is that they provide a highly sensitive indicator of
global environmental change.
nerable” respectively. Good data are necessary for such
changes in population size to be known or estimated.
After drawing up biodiversity inventories, individual
items (species or habitats) can be assessed for their ability to survive into the future. For example, the IUCN
has established criteria for assessing the degree of threat
to the continued existence of species (IUCN, 1994).
Many nations have used these IUCN criteria as the basis
for compiling their national “Red Lists”. Species are
allocated to the various threat groups on the basis of
criteria (Table 10.10).These criteria are grouped into
four sets, which are briefly outlined here (see IUCN,
1994 for the various nuances).
Third, the total population size can be used.The thresholds are less than 250 mature individuals and declining,
or less than 50 mature individuals, for the “critically
endangered” category.These thresholds are raised to 2500
and 250 for the “endangered” category and 10000 and
1000 for the “vulnerable” category. At these small total
population sizes it is feared that inbreeding could occur,
thus reducing the genetic variability within the species.
Consequently, conservation action is needed, encouraging
all of the mature individuals to contribute to future generations so that the present genetic diversity is not lost.
First, there is a criterion of the known or suspected
reduction in a species’ population size. If this is known
to have declined by at least 80% over the last ten years
or three generations, then the species might be categorized as “critically endangered”. Similarly, if the reduction in population size is more than 50% or more than
20% over the last ten years or three generations, then
the species could be categorized as “endangered” or “vul-
Finally, assessments can be on the basis of quantitative
analyses estimating the risk of extinction in the wild over
a period of either a number of years or over a number of
generations, whichever is the longer. For the “critically
endangered” category, the risk of extinction in the wild
would have to be greater than 50% over 10 years or
three generations. For the “endangered” category, the
risk would have to be at least 20% within 20 years or
Second, there is a criterion relating to the known or estimated decline in the range of the species. Again somewhat
arbitrary thresholds are set where the extent of occurrence is estimated to be less than 100 km2, 5000 km2, and
20000 km2, or the area of occupancy is estimated to be
less than 10 km2, 500 km2, and 2000 km2, for the “critically endangered”, “endangered”, and “vulnerable” categories respectively. For these, the populations must be
severely fragmented or located in a single place and either
declining or demonstrating extreme fluctuations, in order
to be categorized as “critically endangered”.There are
similar weaker criteria for the “endangered” and “vulnerable” categories (for example, populations must be at no
more than 5 or 10 places respectively).
Table 10.10. The categories proposed by the IUCN for assessing the vulnerability, and hence the conservation priority, of species
(abstracted from IUCN, 1994).
Species Data
IUCN category
evaluated adequate and code
Notes
Yes
Yes
Extinct (EX)
There is no reasonable doubt that the last individual of the species has died
Yes
Yes
Extinct in the wild
(EW)
As above, but the species survives in cultivation, in captivity, or in at least one naturalized
population outside its native distribution range
Yes
Yes
Critically endangered The species is facing an extremely large risk of extinction in the wild in the immediate
(CR)
future
Yes
Yes
Endangered (EN)
The species is facing a large risk of extinction (but not as large as the category above)
in the wild in the near future
Yes
Yes
Vulnerable (VU)
The species is facing a large risk of extinction in the wild in the medium-term future
Yes
Yes
Lower risk (LRcd,
LRnt, LRlc)
The species does not fit into the above categories, but this category can be divided into
three. Conservation dependent taxa are those that have a conservation program, cessation
of which is likely to result in the species being moved into one of the above categories
within five years. Near threatened taxa are those that are close to being vulnerable.
Least concern taxa are those that do not fit into either of the above categories
Yes
No
Data deficient (DD)
There are insufficient data for a decision to be made about allocating the species to any
of the above categories
No
No
Not evaluated (NE)
The species has not been assessed for sufficiency of data and hence does not fit into any
of the above categories
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Box 10.2. Five examples of the causes and possible consequences of genetic variability
1. Low levels of genetic variation in arctic plants, especially in the high Arctic, have been considered to result from
widespread vegetative propagation and low sexual recruitment.The Swedish-Russian Tundra Ecology Expedition
in 1994 provided the opportunity to sample 16 sites in a coastal transect from the Kola Peninsula to eastern
Russia and up to 77º N. Four sedge species, Carex bigelowii, C. ensifolia, C. lugens, and C. stans, all showed a relatively high degree of genetic variation within most populations.Those populations with the lowest variation
were associated with sites that were recently glaciated (10 000 years ago) rather than populations from refugia
which were already deglaciated 60000 to 70 000 years ago (Stenstrom et al., 2001).Thus, although individual
species may be geographically widespread, their genetic makeup and ecotypic variation, and hence their capacity
to react to change, can be variable.
2. In Sweden, the rare wood-inhabiting polyporous fungus, Fomitopsis rosea, illustrates the limitation of genetic variability resulting from isolation of populations. Populations in isolated forest stands in Sweden had much narrower
genetic structure than populations within the continuous taiga forests of Russia (Seppola, 2001).This suggests that
habitat fragmentation can restrict genetic differentiation and potentially limit responses to environmental change.
3. Survival of reciprocal transplants of Dryas octopetala between snowbed and fellfield sites was followed for
15 years. Non-native genotypes have shown variable mortality rates after experiencing the rapid environmental
change of transplanting. Some non-native transplants have survived, with variable rates between sources, but
were far fewer than native transplants within their own environment. McGraw (1995) concluded that the existence of ecotypes adapted to different environments improves the probability that the species as a whole will
survive rapid environmental change.
4. Musk oxen (Ovibos moschatus), despite a circumpolar distribution, have extremely low genetic variability and it is
uncertain how they will respond to environmental change or to new parasites and diseases. However, since 1930,
reintroduction following local extinction has proved successful from Greenland to Alaska, from Alaska to Wrangel
Island, and from Alaska to the Taymir Peninsula. Reintroductions in Norway have been less successful (Gunn, 2001).
5.The genetic composition of plant populations, for example the purple saxifrage (Saxifraga oppositifolia) and the moss
campion (Silene acaulis), determines their capacity to respond to short- or long-term environmental change. Species
and populations also respond to the contrasting wet and dry micro-environments within high-arctic habitats.
Evidence indicates that current populations in the high Arctic are derived from survivors in refugia during the last
glaciation and from migrants that colonized more recently. It is likely that heterogeneity of sites and populations,
combined with the history of climate variation, has provided the present flora with the resilience to accommodate
substantial and even rapid changes in climate without loss of species (Crawford 1995; Crawford and Abbott 1994).
five generations, whereas for the “vulnerable” category it
would have to be at least 10% within 100 years. Such an
assessment depends on good data as well as on a suitable
model that can be used to assess the risks.
The IUCN criteria are predicated upon species conservation. However, genetic diversity is also a part of the
Convention on Biological Diversity. Many species have
widespread distributions within the Arctic and occur in
different habitats, landforms, and communities.This is a
feature of the low species diversity, providing the opportunity for species to exploit resources and environments
with little or no competition. Under the conditions of
low species diversity, it is thought that the width of the
ecological niche of the remaining species is wide.
Measures of species richness underestimate the genetic
diversity and there is a need to increase documentation of
genetic variation within species, especially for those of
conservation concern. Ecotypic differentiation is likely to
be an important attribute in species response to climate
change and is recognized as a key characteristic of arctic
biodiversity. Five examples that illustrate genetic variabil-
ity, its causes, and possible consequences emphasize the
importance of both understanding and maintaining genetic variation within species by conserving diverse populations as a basis for conservation – an application of the
precautionary principle (see Box 10.2).
This poses a number of questions for nations with arctic
territory and for nations interested in the Arctic’s biodiversity. Can inventories be prepared for more taxa
than just the mammals and birds, which already exist?
Are there data of sufficient quality and quantity to allocate the species to the IUCN categories? Are the data
good enough and are there suitable models that can be
used to estimate the risks of extinction? Are there sufficient taxonomists to be able to recognize, identify, and
list the Arctic’s species? Although the work of the IUCN
is aimed at species, it is also important to have an inventory of habitats. Initially, however, on a circumpolar basis
there needs to be agreement on the classification of habitats in the marine environment, the freshwater environment, and the terrestrial environment.This will require
ecological expertise and international agreement, but is
Chapter 10 • Principles of Conserving the Arctic’s Biodiversity
a requisite first step in drawing up an inventory of the
Arctic’s habitats, and then assessing which habitats are
priorities for conservation action.
These considerations lead to the first four recommendations.These are made without attempting to allocate
responsibility for undertaking the work involved.
1.There needs to be a supply of trained ecologists
who can devise appropriate circumpolar classifications of habitats and then survey these so as to
measure their extent and quality and to establish
their dynamics.
2.There needs to be a supply of trained taxonomists
who can draw up inventories of the Arctic’s
species.There are already good data on which
species of vertebrate animals and vascular plants
are to be found in the Arctic, so particular attention needs to be given to the training of taxonomists who can work with non-vascular plants,
invertebrate animals, fungi, and microorganisms
(protozoa, bacteria, etc.).
3. Inventories need to be generated for the Arctic’s
biodiversity (both species and habitats), indicating
for each entry in the inventory where it occurs and
either the size of the overall species population or
the extent of the habitat. Such inventories need to
be on a circumpolar basis rather than on a national
basis as nations with arctic territory also have territory south of the Arctic.
4.The genetic diversity of many of the Arctic’s species
is presently poorly known or unknown. Much
research is needed to explore this aspect of the
Arctic’s biodiversity and conservation management
will need to ensure that genetic diversity is not lost.
10.5.2. Identifying changes in the Arctic’s
biodiversity
In section 10.4, seven series of changes were explored,
focusing on the distribution range of species and habitats,
on the total size of species populations and the extent of
habitats, and on genetic variability within populations.
Each of these interacts with the success and failure of
non-native species to establish themselves in the Arctic,
with the migration routes and timing of migration of
migratory species, and with the selection and management of protected areas. Change is expected, and each
species is likely to respond in an individualistic way so
that novel assemblages of species are very likely to occur
in the future. Sources of information on changes to biodiversity are many and varied and analyses of past
changes can provide insights into the future (Box 10.3).
Change in ecological communities is often referred to as
“ecological succession”. A distinction is drawn between
“primary succession”, which occurs on new substrates
such as when a glacier recedes (Miles and Walton,
1993), and “secondary succession”, which occurs following a disturbance or perturbation. A preservationist atti-
583
tude might be to maintain what occurs today and so
manage a habitat in such a way as to oppose ecological
succession. A conservationist attitude would be to work
with ecological succession.This dichotomy of thinking is
highlighted by Rhind (2003), who said “we have become
fixated with the idea of preventing natural succession
and, in most cases, would not dream of allowing a grassland or heathland to develop into woodland”. In the
Arctic, climate change will drive primary and secondary
successional changes and, in the interests of conserving
the Arctic’s biodiversity, management should work with
these changes rather than opposing them.
Species might adapt to new environmental conditions if
they have a sufficient genetic diversity and sufficient
time.This is outlined in Chapter 7 where it is stated
that a key role of biodiversity is to provide the adaptive
basis for accommodating the extreme levels of environmental variability that characterize much of the Arctic.
The genetic level of biodiversity allows populations to
meet the challenges of an extremely variable arctic
environment and this ensures persistence of the populations, at least in the short to medium term. Over the
longer term, such genetic diversity is the basis for evolutionary change leading to the emergence of new subspecies and species.With projections of a rapidly changing climate, genetic diversity is important as a kind of
insurance that the species will be able to successfully
meet the environmental challenges that they will face.
As stated by Walls and Vieno (1999) in their review of
Finnish biodiversity “…mere biological information is
not enough for successful biodiversity conservation.
Conservation decisions and the design of biodiversity
management are primarily questions of social and economic policy…Biodiversity conservation requires, in
fact, the whole spectrum of sociological, economic and
policy analyses to complement the basic biological information”.Traditional knowledge was addressed in section
10.2.7, but the implications of Walls and Vieno’s (1999)
comment are that the knowledge gained in the past is
insufficient since the aspirations of today’s people for the
future also need to be considered.This highlights one of
the central divisions of thought about biodiversity conservation. Is it “nature-centric”, because it is believed that
nature has an inherent right to exist? Or, is biodiversity
conservation “human-centric”, because it is believed that
the biological world must be molded to suit the needs of
people, now and in the future? The problem with the former approach is that it can neglect the fact that humans
(Homo sapiens) are an integral part of the ecosystem and
the food web.The problem with the latter is that it places
H. sapiens as the only species that really matters, and
hence it is of limited concern if other species become
extinct. A middle way needs to be found.
In the Arctic, people have been part of the food web
more or less since the end of the last ice age when ecological succession began with the northward movement
of plants and animals, in the sea and on land, as the ice
retreated. As well as the obvious changes in distribution,
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Arctic Climate Impact Assessment
Box 10.3. Some sources of information on changes in the Arctic’s biodiversity
Paleo-ecological evidence
Probably the most dramatic ecological event in arctic prehistory was the conversion of a vegetation mosaic dominated by semi-arid grass–steppe with dry soils and a well developed grazing megafauna to a mosaic dominated by
wet-moss tundra without a large grazing fauna.There are three main hypotheses to explain the changes.
• The “pleistocene overkill hypothesis”.This suggests that Beringia was colonized by people with hunting skills who
developed spears with stone micro-blades which enabled them to drive the megafauna to extinction and that it
was this loss of grazing that caused the vegetation change. Corroborative evidence for intensive killing comes
from paleolithic sites where large quantities of bones have been unearthed. At Mezhirich in the Ukraine, bones
of 95 individual mammoths (Mammuthis primigenius) were found.
• The “climate hypothesis”.This assumes that an arid, continental climate prevailed in Beringia during the Pleistocene
giving low summer precipitation and dry soils, promoting productive steppe vegetation which supported the
populations of large grazers (mammoths, bison, and horses). As the climate became wetter during the Holocene,
snow depth increased, the moss–lichen cover developed, and herbaceous vegetation reduced.This vegetation
change is shown in the Pleistocene pollen and plant macrofossil record and it is hypothesized that the vegetation
change resulted in the decline and eventual extinction of the megafauna.
• The “keystone-herbivore hypothesis”.This hypothesis combines the overkill and climate hypotheses with a more
detailed understanding of vegetation changes that results from current knowledge of changes in both grazing and
climate (Zimov et al., 1995).
Evidence from refugia such as Beringia, which remained without ice cover during past glaciations as a result of local
climate conditions, and changes in sea level have been important in documenting long-term development of species
and genetic diversity. Documentation of past ecological changes through analyses of plant and animal remains in
stratified terrestrial, freshwater, and marine sediments has contributed much to the analysis of climate change.
Historical documentation
Historical records show that Greenland was first colonized by Norsemen around AD 986.The population rose to
about 3000 based on up to 280 farms and enhanced by fishing and trading in walrus skins and ivory.The colony
became extinct in the 15th century, probably due to climatic deterioration and possibly disease. Analysis of the
vegetation in the vicinity of the farms and habitations indicates that about 50 vascular plants were probably introduced by the Norsemen and have survived to the present day – an ecological footprint detected and quantified
through historical documentation (Fogg, 1998). It is the historical records of fishing, whaling, and sealing in the arctic seas that provide some of the most detailed documentation of the distribution and population changes of
marine fauna.These are extensively detailed in Chapters 11 and 13.The data reflect the impacts of variation in climate and exploitation often over the past 50 to 100 years or more.
number, extent, etc., there are likely to be many more
subtle changes in the functions of ecosystems and in the
physiology of individuals, but prediction of what these
changes might be is largely elusive. Predictions are based
on models.The concept of modeling biodiversity conservation has already been addressed (see Fig. 10.12) and has
been shown to be within the domain of statistical models
rather than precise models that give a definitive result.
However, despite such limitations, models are useful in
attempting to explore the likely changes to the Arctic’s
biodiversity and their effects on the human population.
For example, in Finland models have been used to project the likely changes in the distribution of the major
forest trees – pine (Pinus sylvestris), spruce (Picea abies)
and birch (Betula spp.) – predicting the movement
north of the two coniferous species (Kuusisto et al.,
1996). At the same time, the models have projected that
whereas at present only the southern fifth of Finland is
thermally suitable for cultivating spring wheat, by 2050
it is likely that this crop could be grown throughout the
southern half of Finland. Herein lies the social problems. Finland currently is a country with an economy
largely based on forestry and it has a biodiversity rich in
forest species. If the economy were to change to one
more agriculturally based, how would this affect the
social structure of the human population? Would the
loss of the forest biodiversity and the loss of the social
aspects of its use (e.g., collecting berries and mushrooms, hiking, and other leisure activities in the forest)
be acceptable?
These considerations of change lead to two further
recommendations.
5. Management of the Arctic’s biodiversity must work
with ecological succession and not against it.This
thinking needs to be incorporated into all aspects
Chapter 10 • Principles of Conserving the Arctic’s Biodiversity
585
Indigenous knowledge
Insights into environmental and ecological change that are based on indigenous knowledge are now fully recognized
and increasingly documented (see Chapters 3 and 12).The documentation includes insights into changes in biodiversity over recent decades, particularly regarding species of importance to hunters.The knowledge is specific to
local areas but can be accumulated and compared across regions. For example, maps of migration routes indicate
species-specific changes around Hudson Bay (McDonald et al., 1997), whereas recent changes in fish and wildlife,
described by Inuvialuit hunters in Sachs Harbour, illustrate specific evidence of other responses to climate changes
(Krupnik and Jolly, 2002):
Two species of Pacific salmon caught near the community.
Increased numbers of Coregonus sardinella (least cisco).
Fewer polar bears in area because of less ice.
Increasing occurrence of “skinny” seal pups at spring break-up.
Observation of robins; previously unknown small birds.
Increased forage availability for caribou and muskox.
Changes to timing of intra-island caribou migration
Identification of current and future changes
Documentation of changes in many mammals, birds, and fish is already well developed in national programs of
individual arctic nations and internationally for migratory species. Monitoring is particularly strong where international agreements and commercial interests are involved and where individual species are classified as
“endangered” on the national or international “Red Lists” drawn up using IUCN criteria (see section 10.5.1).
There are, however, other aspects of biodiversity where documentation of change is seriously lacking.
Documentation of changes in various aspects of plant diversity is very weak. There are only two programs that
approximate to systematic, circumpolar observations of plants. (1) One is the International Tundra Experiment
(ITEX), which has routinely recorded changes in vegetation cover and plant performance at about 30 sites
(including some alpine and antarctic sites). Experimental passive warming of about 1 to 2 ºC is achieved by
installing replicated open-topped chambers, with adjacent plots without experimental warming as controls.
ITEX has been in operation for a decade, but initial data synthesis has already begun (Arft et al., 1999). The
serious limitation in ITEX as a monitoring program is that individual sites are largely dependent on short-term
research funding. (2) The other, on a totally different spatial scale and level of resolution, is the use of satellite
measurements to detect changes in vegetation greenness (Myneni et al., 1997). This assessment of change in
greenness between 1981 and 1991 cannot be validated owing to the total lack of systematic ground observations at a compatible spatial scale.
of the management of biodiversity in the sea, in
freshwater, and on the land.
6. Models need to be further developed to explore
changes in biodiversity under the various scenarios
of climate change. Again, these models will need
to explore biodiversity change in the sea, in freshwater, and on land.
10.5.3. Recording the Arctic’s changing
biodiversity
There are two aspects to recording the Arctic’s changing
biodiversity that need to be addressed: monitoring (or
surveillance) and indicators. Monitoring involves the
periodic recording of data so that trends can be detected. Usually, it also involves assessing progress toward
some target, but often it only involves determining if the
resource being monitored still exists and how the
amount of that resource is changing (and this is often
referred to as surveillance). Indicators are regularly
monitored measures of the current state of the environment, the pressures on the environment, and the human
responses to changes in that state.This three-point set of
indicators is often referred to as the “pressure-stateresponse model” (Wilson et al., 2003). It is often easier
to find indicators of state than indicators of either pressures or responses.
Monitoring of wildlife has a long history.There have
been attempts to coordinate monitoring, as outlined for
the Nordic Nations by From and Söderman (1997).
The aim in these nations was “to monitor the biodiversity and its change over time with appropriate and applicable mechanisms, and to monitor the cause-effect relationship between pressure and response on biodiversity
by using specific biological indicators”.There were five
implications of these objectives: (1) the program would
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Arctic Climate Impact Assessment
Box 10.4.The seven long-term objectives for CAFF’s biodiversity monitoring (CAFF, 2002c)
Overall objective
To provide an information basis for sound decision-making regarding conservation and sustainable use of arctic
flora and fauna.
Detailed objectives
1. To detect change and its causes amongst flora and fauna of the circumpolar Arctic.
2. To strengthen the infrastructure for and harmonization of long-term monitoring of arctic flora and fauna.
3.To provide an early warning system and strengthen the capacity of arctic countries to respond to environmental events.
4. To ensure the participation of arctic residents, including indigenous peoples, and to incorporate their knowledge
into monitoring.
5. To establish a circumpolar database of biodiversity monitoring information and contribute to existing European
and global database systems.
6. To contribute to national, circumpolar, European, and global policies concerned with conservation of biodiversity
and related environmental change.
7. To integrate circumpolar biodiversity monitoring information with physical and chemical monitoring information
of the Arctic Monitoring and Assessment Programme and others.
exclude chemical and physical aspects of environmental
monitoring; (2) the focus would be on ecosystems and
species and the data would be analyzed in the simplest
manner to provide appropriate, qualitative, and quantitative information; (3) another focus would be anthropogenic changes, although the analyses would need to
distinguish these from natural changes; (4) monitoring
would include, among others, threatened habitats and
species, and hence their disappearance or extinction
would become known; and (5) the monitoring would
not directly focus on administrative performance indicators, although it might provide important information
for understanding these.The main problem with this
Nordic monitoring program is that it relates only to the
terrestrial environment, although this does include wetland and coastal habitats. More attention needs to be
paid to the marine environment.
Progress is being made in relation to monitoring biodiversity in the Arctic (CAFF, 2002c) with the Circumpolar Biodiversity Monitoring Program. Its goal is “to
improve understanding of biodiversity through harmonization and/or expansion of existing programs and networks.The proposed approach focuses on three large
ecosystems (terrestrial, freshwater, marine) and selected
criteria include ecological importance, socio-economic
importance, and feasibility”. CAFF (2002c) then continued with accounts of a number of monitoring programs,
covering Arctic char, caribou and reindeer, polar bear,
ringed seal, shorebirds (also known as waders), seabirds,
geese, and work in relation to the International Tundra
Experiment.The strengths of this proposal are that the
connections between the marine, freshwater, and terrestrial environments are recognized and that the monitoring would be on a circumpolar basis; the weakness is
that so few actual species are being monitored, although
the aspirations are more ambitious. At present there is
no explicit botanical monitoring, and the invertebrate
animals have been overlooked. For example, a program
focused on the many species of fritillary butterfly of the
genus Clossiana (although taxonomically this has now
been divided into a number of genera), which occur in
northern Asia, northern Europe, and North America,
would indicate much about the effects of climate change
on insects and their food plants, and on the interrelationships between plants and specialized herbivores.
For the future, the Circumpolar Arctic Biodiversity
Monitoring Network project is challenging, having the
twin goals to “develop the infrastructure, strengthen
ecological representation, and create data management
systems for circumpolar Arctic species biodiversity
monitoring networks”, and to “establish functional links
between these arctic networks and European and global
biodiversity observation systems and programs”.The
long-term objectives of CAFF’s biodiversity monitoring
are listed in Box 10.4.
Monitoring is widely advocated. For example, BirdLife
(2000) indicated that it wished to “monitor and report
on progress in conserving the world’s birds, sites and
habitats”, but also that it wished to monitor the effectiveness of its work in achieving the objectives set out in
its strategy. Usher (1991) posed five questions about
monitoring.These related to the purpose (what are the
objectives?), the methods to be used (how can the objectives be achieved?), the form of analysis (how are the
data, which will be collected periodically, to be analyzed statistically and stored for future use?), the interpretation (what might the data mean and can they be
interpreted in an unbiased manner?), and fulfillment
(when will the objectives have been achieved?). It is
vital that all five questions are asked and answered
before a monitoring scheme begins. All too frequently
ad hoc monitoring programs provide data that cannot be
analyzed statistically and so the confidence that can be
placed in resulting trends is minimal.
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Chapter 10 • Principles of Conserving the Arctic’s Biodiversity
The basic need is for the establishment of a circumpolar
network of sites where large-scale (hectares or square
kilometers) replicated plots can be distributed where
vegetation cover and composition can be documented.
Following scientific principles, the network could be
spatially located to test the hypotheses of vegetation
change that have been generated during the ACIA
process. Establishment of some sites within the CPAN
could further test the performance of this approach to
conservation. Further, fine-scale observations, for example of species performance, could be nested within the
landscape-scale plots. Such a hierarchy of spatial scales
would be similar to that defined in the Global Terrestrial
Observing System (GTOS) led by the FAO. 171 arctic
sites and a number of arctic site networks are currently
registered on the Terrestrial Ecosystem Monitoring Sites
of the GTOS, and they could provide the basis for an
appropriate monitoring network.The GTOS has developed a Biodiversity Module with seven core variables to
guide development in the program (threatened species,
species richness, pollinator species, indicator species,
habitat fragmentation, habitat conversion, and colonization by invasive species).The relationship with the sister
programs, the Global Ocean Observing System (GOOS)
and the Global Climate Observing System (GCOS),
needs to be clarified.This would correspond with the
recommendations in Chapters 7, 8, and 9. Each chapter
identifies the need for improved systematic, long-term
observation and monitoring programs.
Based on the aspects of the conservation of biodiversity
identified in this chapter, further attention should be
given to the five subsidiary aspects of monitoring outlined in Box 10.5. It would be too resource intensive to
Box 10.5. Five other aspects of monitoring that relate to the principles of biodiversity
conservation outlined in this chapter
Phenology monitoring
This has a long tradition, especially in Russia, but has not been developed to meet future needs. Observation of
the timing of specific phenomena, for example leaf and flower emergence, arrival and departure of migratory
birds, and timing of emergence and feeding of specific insects, can be directly related to climatic conditions if
repeated annually. Such observations are particularly suited to remote rural communities where other monitoring
is not feasible. It also has a strong educational potential.
Genetic diversity
This is generally poorly and unsystematically documented.The establishment of a baseline for future detection of
change is a priority. Selection of a limited number of distinct taxonomic and functional groups, with particular conservation concern, should allow establishment of an initial circumpolar baseline, including storage of appropriate material.
Invertebrate fauna
Both the diversity and distribution of invertebrates, especially in soils and freshwater sediments, are poorly documented, despite their importance as a basis for food webs and in the decomposition of organic matter and nutrient cycling. Establishment of basic survey information is best developed through a short-term targeted program at
a limited number of existing research bases and field sites, supplemented where necessary so as to obtain a representative coverage of broad habitat types.
Integrated monitoring
Potential cause and effect variables would be recorded; this is seen to be increasingly important as the complexity
of the systems is recognized.The ACIA has provided the best available understanding of the complex system
responses to climate change.The next critical step is to express these as system models and test these through
existing and expanded data at a limited number of selected field sites, so as to test and refine the hypotheses and
to assess the potential establishment of long-term integrated monitoring.
A rapid response network
The ACIA has highlighted the probability of increased frequency and intensity of climatic events, increased outbreaks of pests and diseases, increased pollution, and other environmental accidents.The timing and location of such
events are currently unpredictable.Yet the need for rapid initial documentation of impacts on biodiversity as a basis
for longer-term observations is regularly required.The use of existing distributed field stations to provide an initial,
international rapid response network is a logical development that would benefit from a feasibility study.
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Arctic Climate Impact Assessment
(a) Global level
(a) Long-distance animal migration
routes are sensitive to climaterelated changes such as alterations
in habitat and food availability.
The amplification of warming in
the Arctic thus has global
implications for wildlife.
Terns
Waders
Whales
(b) Regional level
attempt to monitor all aspects of the
Arctic’s biodiversity. So in order to
reduce the amount of work required
indicators are often advocated. For indicators to be valuable they should ideally
fulfill the following four criteria (modified from Wilson et al., 2003). First, they
should reflect the state of the wider
ecosystems of which they are a part.
Second, indicators should have the
potential to be responsive to the implementation of biodiversity conservation
policies.Third, indicators should be capa-
(b) At the regional level, vegetation and the animals associated with it will shift
in response to warming, thawing permafrost, and changes in soil moisture
and land use. Range shifts will be limited by geographical barriers such as
mountains and bodies of water. Shifts in plankton, fish, and marine mammals
and seabirds, particularly those associated with the retreating ice edge, will
result from changes in air and ocean temperatures and winds.
ble of being measured reliably on a regular (not necessarily annual) basis, and
should be comparable with similar measures at greater spatial scales. Fourth, they
should have, or have the potential for,
strong public resonance. Such a set of
criteria for indicators fits well with the
set of seven long-term objectives of
CAFF’s Circumpolar Arctic Biodiversity
Monitoring Network proposal, outlined
in Box 10.4.
Polar bears
Trees and shrubs
Whales
Birds
Salmon
Caribou
(c) Landscape level
(c) At the landscape level, shifts in the mosaic of soils
and related plant and animal communities will be
associated with warming-driven drying of shallow
ponds, creation of new wet areas, land use change,
habitat fragmentation, and pests and diseases. These
changes will affect animals' success in reproduction,
dispersal, and survival, leading to losses of northern
species and range extensions of southern species.
Fig. 10.16. A representation of the effects of climate change on biodiversity at different spatial scales.The text focuses on species
diversity and to some extent on habitat diversity, but genetic diversity is not included.
Chapter 10 • Principles of Conserving the Arctic’s Biodiversity
These discussions lead to three further recommendations.
7. Circumpolar monitoring networks need to be fully
implemented throughout the Arctic.The proposals
are challenging, but data on the state of the Arctic’s
biodiversity, on the drivers of change in that biodiversity, and on the effectiveness of responses to
those changes, needs to be collected, analyzed, and
used in the development of future arctic biodiversity policy.
8. Attention needs to be given to establishing the
kinds of subsidiary aspects of monitoring, examples of which are outlined in Box 10.5.These are
vital if a holistic view is to be taken of the Arctic’s
biodiversity, its conservation in the face of a changing climate, and the management of the biodiversity resource for future generations of people to
use and enjoy.
9. A suite of indicators needs to be devised and
agreed, monitoring for them undertaken, and the
results made publicly available in a format (or formats) so as to inform public opinion, educators,
decision-makers, and policy-makers.
10.5.4. Managing the Arctic’s biodiversity
“The Arctic is a distinct and significant component of the
diversity of life on Earth” was a statement made at a
meeting in 2001 to celebrate ten years of arctic environmental cooperation (Vanamo, 2001).This probably
encapsulates why the conservation of the Arctic’s biodiversity is not only essential to the peoples of the Arctic
but also why the Arctic is important globally. It sets the
imperative to do something to conserve the biodiversity
of one of the more pristine geographical parts of the
(d) PLOT LEVEL
(d) Changes in snow conditions, ice layers,
the cavity beneath the snow, summer temperatures, and nutrient cycling act on individual plants, animals, and soil microorganisms
leading to changes in populations. It is at the
level of the individual animal and plant where
responses to the climate take place leading
to global-scale vegetation shifts.
589
world, but nevertheless a geographical area that is
threatened with a series of human-induced changes due
to developments and over-exploitation within the Arctic,
and to long-range pollution and climate change, which
are both global problems.
One of the first requirements is to collate information
about the best way to manage the Arctic’s biodiversity in
a changing climate.This will be based on knowledge
held by local people together with knowledge that has
been gained by scientists, either through observation or
experiment.There have been a number of attempts to
bring together guidelines for best practice, usually either
in a nation or for a particular area. An example would be
the proposals developed in Finland for practical forest
management (Korhonen et al., 1998).These guidelines
integrate concern for the environment with the needs of
production forestry, and the use of forests for recreation, protection of the quality of soil and water, and the
management of game species.They provide an example
of what can be done when all the interest groups work
together for a common goal. Such an approach would
also be useful on a circumpolar basis for the conservation and sustainable use of the Arctic’s biodiversity.
This leads to a further recommendation.
10. Best practice guidelines need to be prepared for
managing all aspects of the Arctic’s biodiversity.
These need to be prepared on a circumpolar basis
and with the involvement of all interested parties.
The value of protected areas has been discussed
(section 10.4.7), as well as the plans for developing a
comprehensive network of these areas throughout the
Arctic. Such a start is excellent, setting aside areas of
land, freshwater, and sea where nature has primacy
over any other forms of land- and water-use. The three
questions that need to be asked are how quickly can
this network of protected areas be completed, how will
they need to change as the climate is changing, and are
they doing what they were designed to do? First, the
reviews by CAFF (2001, 2002a) indicated that there
were some of the Arctic’s habitats, especially in the
marine environment, that were not adequately covered
by the CPAN. It is important that work on establishing
a comprehensive CPAN is undertaken so that protection can be afforded to the breadth of the Arctic’s biodiversity before any is lost. Second, work on understanding how climate change will affect each protected
area will allow management to have a greater chance of
protecting the biodiversity in that area, or of adopting
the “soft boundary” approach outlined in section
10.4.7. Work needs to be undertaken, and made widely available in management guidelines, on the management of these protected areas; an example for the protected areas in Finland is as in Anon (1999). Work also
needs to analyze how climate change is likely to affect
each of the protected areas. Such work has been carried out for the Canadian national parks (Scott and
Suffling, 2000), stressing the importance of sea-level
rise for the many national parks that are located on the
590
coast. These considerations give rise to two further
recommendations.
11.The CPAN needs to be completed and then
reviewed so as to ensure that it does actually cover
the full range of the Arctic’s present biodiversity.
12. An assessment needs to be made for each protected area of the likely effects of climate change, and
in the light of this assessment the management
methods and any revisions of the area’s boundary
need to be reviewed.
In undertaking these reviews, one of the important
questions is whether or not the protected area is conserving what it was designed to conserve.This is not
always a simple task, especially with year-to-year variation in population sizes and with longer term changes in
habitat quality, but such assessments are becoming more
commonplace (e.g., Parrish et al., 2003).
Protected areas are just one method for attempting to
conserve the Arctic’s biodiversity. Although biodiversity
conservation is the primary focus of management within
the protected areas, they will only ever cover a relatively
small proportion of the land and water area of the Arctic,
and thus will only contain a small proportion of the
Arctic’s biodiversity resource. Hence, it is imperative that
biodiversity is also considered in the land and water outside protected areas. Forms of integrated management
need to be adopted whereby biodiversity is not forgotten
among all the other competing claims for space on land
or at sea.The kind of approach proposed for the Canadian Arctic, with forms of integrated management of
coastal and marine areas (M.A.K. Muir, Arctic Institute
of North America and CAFF, pers. comm., 2003), is just
one example of practical applications of a biodiversity
approach to the wider environment.The need is to incorporate biodiversity thinking into all forms of policy
development, not just environmental policies, but also
policies on education, health, development, tourism, and
transport.This is clearly a part of this wider environmental approach for biodiversity conservation. In this way
more of the Arctic’s biodiversity is likely to be protected
in the face of a changing climate than by relying solely on
the protected areas.These considerations give rise to two
further recommendations.
13. Integrated forms of management, incorporating
the requirement for biodiversity conservation,
need to be explored for all uses of the land, freshwater, and sea in the Arctic.
14. Biodiversity conservation needs to be incorporated
into all policy development, whether regional,
national, or circumpolar.
In order to assist in these processes, the “ecosystem
approach”, sometimes also referred to as the “ecosystembased approach”, has been advocated (Hadley, 2000).
This sets out a series of 12 principles, some of which are
science-oriented, but all of which form an essentially
socio-economic context for conservation. In relation to
Arctic Climate Impact Assessment
climate change in the Arctic, two of the 12 principles
are particularly relevant. Principle 5 focuses on ecosystems services, and is that “conservation of ecosystem
structure and function, in order to maintain ecosystem
services, should be a priority target for the ecosystem
approach”. Principle 10 states that “the ecosystem
approach should seek the appropriate balance between,
and integration of, conservation and use of biological
diversity”. An example of the possible application of this
approach for the marine environment in the Arctic is as
reported by CAFF et al. (2000, the summary of the
presentation by K. Sherman) and Muir et al. (2003).
Since this approach is still comparatively new, its details
have as yet been worked out in very few situations.
Hence, a further recommendation.
15.The ecosystem approach (or ecosystem-based
approach) should be trialed for a number of
situations in the Arctic, so as to assess its ability to
harmonize the management of land and water both
for the benefit of the local people and for the benefit of wildlife.
In all this work, it should be remembered that the conservation of the Arctic’s biodiversity is necessary for
itself, for the peoples of the Arctic, and more generally
for this planet.These concepts were implicitly enshrined
in the Convention on Biological Diversity, the final text
of which was agreed at a conference in Nairobi, Kenya,
in May 1992.Within a year, the Convention had received
168 signatures. As a result, the Convention entered into
force on 29 December 1993, and there is now considerable international activity to implement the Convention
in the majority of nations globally.This gives rise to a
final recommendation.
16. All nations with arctic territory should be working toward full implementation of the Convention
on Biological Diversity, coordinating their work
on a circumpolar basis, and reporting both individually and jointly to the regular Conferences of
the Parties.
10.5.5. Concluding remarks
Biodiversity is not the easiest of concepts to grasp.
On the biological side, biodiversity needs to be considered at three scales – variation within species (genetic
diversity), variation between species (species diversity),
and variation among assemblages of species (habitat
diversity).Whereas habitat diversity in the Arctic’s land,
freshwater, and sea would probably be measured in hundreds of habitats, species diversity would be measured in
thousands or tens of thousands of species, and genetic
diversity in millions of genes.These are all influenced by
a changing climate. On the geographical side, biodiversity can be considered at many different scales, from the
individual plant or animal and its immediate surroundings, to the whole world. Again, a changing climate can
affect each of these scales, and indeed the effects at one
scale may be different to the effects at another.
Chapter 10 • Principles of Conserving the Arctic’s Biodiversity
This chapter has shown that the Arctic’s biodiversity is
important in relation to the biodiversity of the world at
the largest extreme and to local people at the smallest
extreme.The types of impacts that climate change might
have are illustrated in Fig. 10.16, which endeavors to
highlight the importance of four of the spatial scales.
Each of the ecological processes is affected by climate
change, whether the migrations at the global scale or
decomposition of dead plant and animal material at the
plot level. A small shift in a climatic variable can have
very different effects at these scales, and a small change
at one scale can cause other changes in scales both above
and below. Cause and effect are often difficult to determine, and so models to project changes as a result of climate change are still problematic.
Herein lies the difficulty in conserving the Arctic’s biodiversity. Among this multitude of scales, what are the
priorities? Should the primary focus be on habitats,
species, or genes? Which of the many spatial scales is
the most important? It is clear that not every aspect of
the Arctic’s biodiversity can be conserved, so priorities
have to be attached to actions that can conserve the
greatest amount of biodiversity or, in some situations,
the greatest amount of useful biodiversity. But to set
these priorities, information is required about the present state of biodiversity and about how it is changing.
With such information, models of a more or less
sophisticated type can be used to project what might
happen in the future. It is within this context that the
16 recommendations have been made, and their acceptance should assist the peoples of the Arctic in conserving their biodiversity into the future.
Acknowledgements
Michael Usher would like to thank the contributing authors for their
inputs to this chapter, but especially Magdalena Muir for the provision of
much literature and Pål Prestrud for arranging a meeting in Oslo in May
2004. Michael Usher's participation in the ACIA has been funded by the
Universities of Alaska, USA, and Oslo, Norway, and by the Joint Nature
Conservation Committee (UK) through CAFF, Iceland; for all of this
funding he is grateful.
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Chapter 11
Management and Conservation of Wildlife in a Changing
Arctic Environment
Lead Author
David R. Klein
Contributing Authors
Leonid M. Baskin, Lyudmila S. Bogoslovskaya, Kjell Danell, Anne Gunn, David B. Irons, Gary P. Kofinas, Kit M. Kovacs,
Margarita Magomedova, Rosa H. Meehan, Don E. Russell, Patrick Valkenburg
Contents
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .598
11.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .599
11.2. Management and conservation of wildlife in the Arctic . . .599
11.2.1. Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .599
11.2.2. Present practices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .600
11.2.3.The role of protected areas . . . . . . . . . . . . . . . . . . . . . . . . . .602
11.2.4. Change in human relationships with wildlife and managing
human uses of wildlife . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .605
11.3. Climate change and terrestrial wildlife management . . . . .606
11.3.1. Russian Arctic and sub-Arctic . . . . . . . . . . . . . . . . . . . . . . . . .606
11.3.2.The Canadian North . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .610
11.3.2.1. Historical conditions and present status . . . . . . . . .610
11.3.2.2. Present wildlife management arrangements and
co-management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .612
11.3.2.3. Hunting as a threat to wildlife conservation . . . . . .613
11.3.2.4. Additional threats to wildlife conservation . . . . . . . .615
11.3.3.The Fennoscandian North . . . . . . . . . . . . . . . . . . . . . . . . . . . .616
11.3.3.1. Management and conservation of wildlife under
change . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .616
11.3.3.2. Hunting systems . . . . . . . . . . . . . . . . . . . . . . . . . . . .616
11.3.3.3. Monitoring systems . . . . . . . . . . . . . . . . . . . . . . . . . .617
11.3.3.4. Flexibility of hunting systems under climate change 617
11.3.4.The Alaskan Arctic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .617
11.3.4.1. Minimizing impacts of industrial development on
wildlife and their habitats . . . . . . . . . . . . . . . . . . . . .620
11.4. Management and conservation of marine mammals and
seabirds in the Arctic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .622
11.4.1. Russian Arctic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .623
11.4.2. Canadian Arctic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .626
11.4.3. Fennoscandian North . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .628
11.4.4. Alaskan Arctic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .632
11.4.5. Future strategies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .634
11.4.5.1. North Pacific, Bering, Chukchi, and Beaufort Seas . .636
11.5. Critical elements of wildlife management in an Arctic
undergoing change . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .636
11.5.1. User participation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .636
11.5.1.1. Lateral collaboration and cooperation . . . . . . . . . . . .637
11.5.2. A regional land use perspective . . . . . . . . . . . . . . . . . . . . . . . .638
11.5.3. Concluding recommendations . . . . . . . . . . . . . . . . . . . . . . . . .639
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .641
Personal communications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .641
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .641
Appendix. Canadian co-management of the Porcupin Caribou
Herd, toward sustainability under conditions of climate
change . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .644
598
Summary
Climate changes in the Arctic in the past have had
major influences on the ebb and flow in availability of
wildlife to indigenous peoples and thus have influenced their distribution and the development of their
cultures. Trade in animal parts, especially skins and
ivory of marine mammals, and trapping and sale of
fur-bearing animals go far back in time. Responsibility
for management and conservation of wildlife in the
Arctic falls heavily on the residents of the Arctic, but
also on the global community that shares in the use of
arctic resources. A sense of global stewardship toward
the Arctic is critical for the future of arctic wildlife
and its peoples.
This chapter, drawing on Chapters 7 to 9, emphasizes
that throughout most of the Arctic, natural ecosystems
are still functionally intact and that threats to wildlife
typical for elsewhere in the world – extensive habitat
loss through agriculture, industry, and urbanization –
are absent or localized. There is increasing evidence
that contaminants from the industrialized world to the
south are entering arctic food chains, threatening the
health and reproduction of some marine mammals and
birds and the humans who include them in their diets.
Protection of critical wildlife habitats in the Arctic is
becoming recognized by those living inside as well as
outside the Arctic as essential for both the conservation of arctic wildlife and its sustainable harvest by
residents of the Arctic.
Management of wildlife and its conservation, as practiced in most of the Arctic, is conceptually different to
that at lower latitudes where management efforts often
focus on manipulation of habitats to benefit wildlife.
The history of over-exploitation of marine mammals
and birds for oil and skins to serve interests outside the
Arctic is now being balanced by international efforts
toward conservation of the flora and fauna of the
Arctic, focusing on maintaining the Arctic’s biodiversity and valuing its ecosystem components and relationships. Case studies from Russia and Canada focusing on
harvest strategies and management of caribou (wild
reindeer) highlight the complex nature of this species.
One reports the development of a co-management system, involving shared responsibility between users of
the wildlife and the government entities with legal
authority over wildlife, giving local residents a greater
role in wildlife management.
Throughout much of the Arctic, harvesting of wildlife
for food and furs through hunting and trapping has
been the most conspicuous influence that residents of
the Arctic have had on arctic wildlife in recent
decades. It was the overexploitation of wildlife during
the period of arctic exploration and whaling, largely in
the 18th and 19th centuries, that led to the extinction
of the Steller sea cow in the Bering Sea and the great
auk in the North Atlantic, and drastic stock reductions
and local extirpation of several other terrestrial and
Arctic Climate Impact Assessment
marine mammals and birds. In regions of the Eurasian
Arctic, the adoption of reindeer herding by indigenous
hunting cultures led to the extirpation or marked
reduction of wild reindeer (caribou) and drastic
reductions of wolves, lynx, wolverines, and other
potential predators of reindeer. Heavy grazing pressure by semi-domestic reindeer along with encroachment of timber harvest, agriculture, hydroelectric
development, and oil and gas exploration have altered
plant community structure in parts of the Fennoscandian and Russian Arctic. Large-scale extraction of
nonrenewable resources accelerated in the Arctic
during the latter half of the 20th century with impacts
on some wildlife species and their habitats, especially
in Alaska from oil production, in Canada from mining
for diamonds and other minerals, and in Russia primarily from extraction of nickel, apatite, phosphates, oil,
and natural gas. Among the factors that influence
arctic wildlife, harvest of wildlife through hunting and
trapping is potentially the most manageable, at least at
the local level. Indigenous peoples throughout much
of the North are asserting their views and rights in
management of wildlife, in part through gains in
political autonomy over their homelands. Arctic residents are now starting to influence when, where, and
how industrial activity may take place in the Arctic.
Part of this process has been the consolidation of the
efforts of indigenous peoples across national boundaries to achieve a greater voice in management of
wildlife and other resources through international
groups such as the Inuit Circumpolar Conference and
the Indigenous Peoples Secretariat of the Arctic
Council. The stage appears to be set for indigenous
peoples of the Arctic to become major participants in
the management and conservation of arctic wildlife.
The legal institutions, however, encompassing treaty
and land rights and other governmental agreements
vary regionally and nationally throughout the Arctic,
posing differing opportunities and constraints on how
structures for wildlife management and conservation
can be developed.
This chapter provides examples from throughout the
Arctic which show that conservation of wildlife
requires sound management and protection of wildlife
habitats at the local, regional, and national levels if the
productivity of those wildlife populations upon which
arctic peoples depend is to be sustained. Wildlife populations and their movements in both the marine and
terrestrial environments transcend local, regional, and
national boundaries, thus successful management and
conservation of arctic wildlife requires international
agreements and treaties. The chapter concludes that
responsibility for maintaining the biodiversity that
characterizes the Arctic, the quality of its natural environment, and the productivity of its wildlife populations must be exercised through global stewardship.
Guidelines are provided for effective management and
associated conservation of wildlife in a changing Arctic
with emphasis on the complexity and limitations of
managing wildlife in marine systems. The guidelines
Chapter 11 • Management and Conservation of Wildlife in a Changing Arctic Environment
599
also stress the need for development of regional land
and water use plans as a basis for protection of critical
wildlife habitats in relation to existing and proposed
human activities on the lands and waters of the Arctic.
11.2. Management and conservation of
wildlife in the Arctic
11.1. Introduction
The term “wildlife” is used in this chapter in the modern sense inclusive, relevant to the Arctic, of nondomesticated birds and mammals living primarily in
natural habitats in both terrestrial and marine environments.Wildlife management is an applied science that
had its main development in continental Europe and
North America. Aldo Leopold pioneered the development of modern, science-based wildlife management in
the United States early in the 20th century, publishing
in 1933 the first college-level text on wildlife management (Leopold, 1933).The initial focus of wildlife management was on species hunted or harvested by humans
and has been parallel to, but distinct from, fishery management.Where practiced in most countries of the
world today, however, it encompasses all aspects of conservation of wildlife species (including amphibians and
reptiles) whether hunted or not, and encompasses harvest regulation, habitat protection and enhancement,
wildlife population inventory and monitoring, and related ecosystem dynamics and research. Aldo Leopold’s
writings on environmental ethics and philosophy
(Leopold, 1938, 1949, 1953) have also played a major
role in the developing conservation and environmental
movements following the Second World War.
What can be learned from present wildlife management systems in the Arctic that can be drawn upon to
alter existing systems or to design new ones to more
effectively deal with climate-induced changes, and
other changes that may occur in the future? Climate is
the driver of change that has been the primary focus of
the Arctic Climate Impact Assessment, however, it is
important to remember that changes from other causes are also underway within the Arctic and that these
are also affecting arctic ecosystems, as well as the
economies, lifestyles, and dependency on wildlife of
people in the Arctic. Many of these changes will
continue along similar trajectories into the future,
influenced by changing climate. The effects of climate
change on wildlife populations, their productivity, and
their distributions, will increasingly threaten arctic
wildlife at the species, population, and ecosystem
levels. Systems for management and conservation of
wildlife in the Arctic will face new challenges and
must become adaptable to the changes taking place in
the natural environment accelerated by climate
change. However, management and conservation of
wildlife serve human interests, therefore in addition to
becoming adaptable to those changes taking place in
the natural environment, efforts toward management
and conservation of wildlife in the Arctic must also be
adaptable to those changes taking place among human
societies, both within the Arctic and within the global
community as a whole.
The objectives of this chapter are:
• To present an overview of structures for management and associated conservation of wildlife of
land and sea in the Arctic, emphasizing current
functioning structures.
• To assess the effectiveness of existing structures for
management and conservation of wildlife in the
Arctic in view of wide variation in regional social,
economic, and cultural conditions.
• To emphasize the role of indigenous people in
management of wildlife and its conservation in
the Arctic.
• To explain how the distinctive regional and cultural
perspectives of arctic residents affect management
and conservation of wildlife in the Arctic within
the context of the broader perspectives of the
Arctic by the global community.
• To assess the adaptability of existing structures for
management and conservation of wildlife in the
Arctic within the context of expected climate
change, and in association with resource extraction, other industrial development, the local economy, and community life.
11.2.1. Background
Wildlife provided the foundation for the establishment
of people and the development of their cultures in the
Arctic. Wildlife was the primary source of food for
humans living in the Arctic, and provided materials
for clothing, shelter, fuel, tools, and other cultural
items. Arctic-adapted cultures show similarity but also
diversity in their dependency on specific species of
wildlife. Caribou and reindeer, both the wild and semidomesticated forms (all are the same species, Rangifer
tarandus, reindeer being the term used for the Eurasian
forms, and caribou for those native to North America),
are of primary importance to most inland dwelling
peoples throughout the Arctic. Marine mammals support indigenous peoples in coastal areas of the Arctic.
Birds are also important in the annual cycle of subsistence harvest of wildlife in most arctic environments.
Many wildlife species of the Arctic that are migratory,
especially birds, but also marine mammals and some
caribou and wild reindeer herds, are dependent during
part of their annual life cycles on ecosystems outside
the Arctic. As a consequence, efforts to ensure the conservation and sustainable human harvests of migratory
species require management and conservation efforts
that extend beyond the Arctic. The indigenous peoples
of the Arctic include the marine mammal hunting
Iñupiaq and Inuit of Alaska, Canada, and Greenland;
the Dene who hunt the caribou herds of arctic Canada;
the hunting, fishing, and reindeer herding Saami of the
arctic regions of Fennoscandia and adjacent Russia; the
reindeer herding and woodland hunting Dolgans of the
central Siberian Arctic; and nearly twenty other cultur-
600
al groups present throughout the circumpolar region
(see Chapter 12).
Past climate changes have had major influences on the
ebb and flow in availability of wildlife to indigenous peoples and thus have influenced the distribution of indigenous peoples in the Arctic and the development of their
cultures.The accelerated climate warming observed in
recent decades (Chapters 2 and 4), however, is resulting
in major and more rapid changes in the ecology of arctic
wildlife (Chapters 7, 8, 9), necessitating reassessment of
structures for the management and conservation of arctic wildlife. As northern cultures developed, including
those of indigenous and non-indigenous arctic residents,
their relationships to wildlife were also influenced
beyond strictly subsistence dependency through trade or
other economic relationships, both internal to their own
cultures and with other cultures.Trade in animal parts,
especially skins and ivory of marine mammals; the semidomestication of reindeer; and trapping and sale of furbearing animals go far back in time. Over the last two to
three centuries cash income has become important for
indigenous and non-indigenous residents from selling
meat and hides and as well as through home industries
producing saleable craft items from animal parts (see
Chapters 3 and 12). Arctic wildlife is valued by many
living outside the Arctic for its attraction for viewing and
photographing, especially whales, seabirds, polar bears
(Ursus maritimus), and caribou; for incorporation in art
depicting the arctic environment; and for associated
tourism. Sport and trophy hunting of wildlife bring
many to the Arctic, with associated economic benefits to
local residents through services provided. Others value
the Arctic through virtual recognition of and fascination
for the role of wildlife species in the dynamics of arctic
ecosystems, many of whom may never visit the Arctic
but learn about arctic wildlife through the printed and
visual media. Responsibility for management and conservation of wildlife in the Arctic clearly falls heavily on the
residents of the Arctic, now especially through empowerment of indigenous people, but also on the global
community that benefits from the exploitation of arctic
resources and shares in the appreciation of the wildlife
and other values of the arctic environment. A consequence of conservation efforts affecting wildlife and
their habitats, generated largely outside the Arctic, has
been the many “protected areas” (UNESCO Biosphere
Reserves, national parks, wildlife refuges, nature preserves, and sanctuaries) established by arctic countries,
often with the encouragement and support of international conservation organizations such as the Conservation of Arctic Flora and Fauna (CAFF), the World
Conservation Union (IUCN), and the World Wide Fund
for Nature (WWF). A sense of global stewardship
toward the Arctic is critical for the future of arctic wildlife and its peoples.
11.2.2. Present practices
Throughout most of the Arctic, natural ecosystems are
still functionally intact (see Chapters 7, 8, 9). Most
Arctic Climate Impact Assessment
threats to wildlife typical for elsewhere in the world –
extensive habitat loss through agriculture, industry, and
urbanization – are absent in much of the Arctic or are
localized. Similarly, introduced and invading wildlife
species are few throughout most of the Arctic and tend
to be localized at the interface between forest and tundra. Changes, however, are accelerating. Contaminants
from the industrialized world to the south have reached
arctic food chains, threatening the health and reproduction of some wildlife, especially marine mammals and
birds, and the humans who include them in their diet
(AMAP, 1998a,b, 2002). Energy and mineral extraction
developments in the Arctic, although localized and widely scattered, tend to be of large scale, for example the
Prudhoe Bay oil field complex in Alaska, the mining and
associated metallurgical developments in the Taymir and
Kola regions of Russia, and the hydroelectric development in northern Quebec.These contribute to the pollution and contamination of the arctic waters, atmosphere, and lands and result in local loss of wildlife
through habitat destruction, excessive hunting, and other
cumulative impacts. Protection of critical wildlife habitats in the Arctic is becoming increasingly recognized as
essential for both the conservation of arctic wildlife and
management of its harvest by arctic residents as pressures from outside the Arctic for exploitation of its
resources increase (CAFF, 2001a; NRC, 2003).
Management of wildlife and its conservation, as practiced in most of the Arctic, is conceptually different in
the minds of arctic dwellers in contrast to most people
living at lower latitudes where management efforts often
focus on manipulation of habitats to benefit wildlife
(Fig. 11.1).Thus, “management of wildlife” in the Arctic
may seem to some inappropriate terminology that has
Fig. 11.1. Management and conservation of wildlife in the Arctic
is driven by internal and external forces that involve wide-ranging
interests and uses of wildlife.These include traditional harvest
and dependency by indigenous peoples, the effects of resource
extraction and associated industrial development, tourism, and
valuation of wildlife at national and international levels through
legal structures and conservation efforts.
Chapter 11 • Management and Conservation of Wildlife in a Changing Arctic Environment
developed through its application outside the Arctic.
Arctic residents have often seen little justification for
conventional wildlife management throughout much of
the Arctic in the past, and have questioned the need for
science-based wildlife management when harvest levels
have posed little threat to sustained viability of the
species harvested (e.g., Huntington, 1992).To the contrary, many arctic peoples see the current health of arctic
ecosystems as evidence of their effectiveness as conservationists over the centuries and their often aggressive
resistance in the past to commercial overexploitation of
marine mammals and birds for oil and skins (Burch,
1998). Prior to the presence of Europeans in the Arctic,
the archeological evidence indicates that communities
and entire cultures either moved or died out as a consequence of changing climate and associated unsustainable
levels of wildlife harvest (Knuth, 1967; Schledermann,
1996), as was also the case at lower latitudes (Grayson,
2001). As well, these perceptions grow from historical
conditions of “internal colonialism” in which southern
populations viewed the arctic resources as open to access
and available for exploitation, contrasting to indigenous
views of territoriality with soft borders and property
held in common by groups (Osherenko and Young,
1989). In recent years, many indigenous residents have
resisted systems for wildlife management and conservation imposed from outside the Arctic, particularly when
these rely heavily on new and strange technologies and
are based on tenets that are unfamiliar or inappropriate
to arctic cultures (Klein, 2002).
Increased emphasis by those living outside the Arctic on
conservation of the flora and fauna of the Arctic and
associated emphasis on maintaining its biodiversity, and
valuing all its ecosystem components and relationships,
has understandably appeared hypocritical to many arctic
indigenous peoples dependent on sustainable harvest of
arctic wildlife (e.g., Freeman and Kreuter, 1994).Thus,
some indigenous peoples have questioned the justification for wildlife management in the Arctic as a discrete
aspect of ecosystem or land use management, when in
much of the Arctic the need is for integrated land,
coastal, and oceanic plans for management.
The legacy of relations and emergent conditions require
the development of wildlife management approaches in
the Arctic that foster collective action among a highly
diverse set of stakeholders and also assume high ecological uncertainty (Jentoft, 1998;Young and Osherenko,
1993). Research on the sustainability of common property resources of the past two decades, which has questioned conventional approaches of “state control” as
reflected in Hardin’s (1968) Tragedy of the Commons,
points to social institutions as key determinants of
human behavior and ecological change (Berkes and
Folke, 1998; Hanna et al., 1996; Ostrom, 1990;
Ostrom et al., 2002;Young, 2001).The findings of
institutional analysis identify design principles that are
critical for effective institutional performance, and note
how effective institutions of wildlife management can
reduce transaction costs among actors and build trust
601
among players. In some regions of the Arctic, the settlement of indigenous land claims has provided opportunities to create new institutional arrangements with these
principles in mind, and thus giving local communities a
greater role in the practice of wildlife management if
not in determining the premises on which it is based
(e.g., Adams et al., 1993; Berkes, 1989; Caulfield,
1997; Freeman, 1989; Huntington, 1992; Osherenko,
1988; Usher, 1995).
Throughout much of the Arctic, harvesting of wildlife
for food and furs through hunting and trapping has, nevertheless, been the most conspicuous influence that residents of the Arctic have had on arctic wildlife in recent
decades. It was the overexploitation of wildlife during
the period of arctic exploration and whaling in the 18th
and 19th centuries that led to the extinction of the
Steller sea cow (Hydrodamalis gigas) in the Bering Sea and
the great auk (Pinguinus impennis) in the North Atlantic,
and drastic stock reductions and local extirpation of several other terrestrial and marine mammals and birds.
In many regions of the Eurasian Arctic, the adoption of
reindeer herding by indigenous hunting cultures led to
the extirpation or marked reduction of wild reindeer
and drastic reductions of wolves (Canis lupus), lynx (Lynx
lynx), wolverines (Gulo gulo), and other potential predators of reindeer (Chapter 12). In recent decades heavy
grazing pressure by semi-domestic reindeer has altered
plant communities in parts of the Fennoscandian and
Russian Arctic, that has in some areas been exacerbated
by encroachment into traditional grazing areas of timber
harvest, agriculture, hydroelectric development, and oil
and gas exploration (e.g., Forbes, 1999). Large-scale
extraction of nonrenewable resources accelerated in the
Arctic during the latter half of the 20th century with
consequences for some wildlife species and their habitats, especially in Alaska from oil production, in Canada
from mining for diamonds and other minerals, and in
Russia primarily from extraction of nickel, apatite, phosphates, oil, and natural gas (CAFF, 2001a).
Among the factors that influence arctic wildlife, harvest
of wildlife through hunting and trapping is potentially
the most manageable, at least at the local level. At a
more regional level, these influences come through decisions on wildlife habitat as a land use issue. Indigenous
peoples throughout much of the North are asserting
their views and rights in wildlife management, in part
through increased political autonomy over their homelands or involvement in cooperative management
regimes (Caulfield, 1997; Huntington, 1992; Klein,
2002; Nuttall, 1992, 2000). However, people still feel
largely limited in controlling the influences on wildlife
and wildlife habitats brought about through climate
change, or large-scale resource extraction in both the
marine and terrestrial environments, changes largely
resulting from the effects of, and pressures generated by,
people living outside the Arctic. Similarly, arctic residents are generally poorly informed about conditions
and management of migratory species in their wintering
environments far from the Arctic, especially waterfowl
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Arctic Climate Impact Assessment
Box 11.1.The Inuit Circumpolar Conference
The Inuit Circumpolar Conference (ICC) defends the rights and furthers the interests of Inuit in Greenland,
Canada, Alaska, and Chukotka – in the far east of the Federation of Russia. Established in 1977, the ICC maintains
national offices in each of the four countries and has official observer status in the United Nations Economic and
Social Council. Noted for its efforts to conserve and protect the environment and to promote sustainable development, the ICC also defends and promotes the human rights of Inuit, the Arctic’s original inhabitants.
and some whale species, and seek greater involvement in
management of migratory species governed by international treaties.The influence that Canadian arctic peoples
had, however, in the negotiations leading to the 2001
Stockholm Convention on Persistent Organic Pollutants
has shown the potential for concerted action by arctic
peoples at the global level (Downie and Fenge, 2003).
Throughout most of the Arctic where efforts have been
directed at conservation and management of wildlife, the
primary focus has been on regulation of the harvest of
wildlife to ensure the long-term sustainability of the
wildlife populations and the associated human harvest
from them. Secondly, protection of wildlife habitats
from loss or degradation has been acknowledged as
essential for the sustainability of wildlife populations,
however, where large-scale development activity has
occurred local interests in wildlife have often been poorly represented in land use decisions. Although there are
similarities throughout much of the Arctic in the distribution of wildlife species and their use by humans, there
are major local and regional differences in the importance of specific wildlife species in the local subsistence
and cash economies.These differences relate to past traditions of use of wildlife, relative availability of wildlife
for harvest, and the role that wildlife play in the local
economy. For example, in Eurasia, commercial harvest
of wildlife is generally supported by legal structures that
assign wildlife ownership to the land owner, in contrast
to North America where wildlife remains the property
of the state and commercial harvest of wildlife is prohibited or discouraged.
Along with the increasing political autonomy of indigenous peoples in recent decades, these arctic residents are
developing their capacity to influence when, where, and
how industrial activity may take place in the Arctic.
Part of this process has been the consolidation of the
efforts of indigenous peoples across national boundaries
to achieve a greater voice in management of wildlife and
other resources through international groups such as the
Inuit Circumpolar Conference (see Box 11.1) and the
Indigenous Peoples Secretariat of the Arctic Council.
In addition to the eight arctic countries that make up
membership of the Arctic Council, indigenous organizations have representation as Permanent Participants of
the Council and include the Russian Association of
Indigenous Peoples of the North, the Inuit Circumpolar
Conference, the Saami Council, the Aleutian International Association, the Arctic Athabaskan Council, and
the Gwich’in Council International.
Through the resulting increased political voice and sharing of interests, the stage appears set for indigenous peoples of the Arctic to become major participants in the
management and conservation of arctic wildlife.The legal
institutions, however, encompassing treaty and land rights
and other governmental agreements vary regionally and
nationally throughout the Arctic, posing differing opportunities and constraints on how structures for wildlife
management and conservation can be developed.
Conservation of wildlife in the Arctic requires sound
management and protection of habitats at the local,
regional, national, and international levels if the productivity of those wildlife populations that arctic peoples are dependent upon is to be sustained.Wildlife
populations and their movements in both the marine
and terrestrial environments often transcend local,
regional, and national boundaries, thus successful management and conservation of arctic wildlife, requiring
scientific investigation, monitoring, and management
action, must also transcend political boundaries through
international agreements and treaties (CAFF, 2001a).
Many of the pressures on arctic wildlife originate outside the Arctic, such as contaminants in marine wildlife,
habitat alteration through petroleum and mining developments, and climate changes exacerbated by increased
concentrations of greenhouse gases. It seems clear that
responsibility for maintaining the biodiversity that characterizes the Arctic, the quality of its natural environment, and the productivity of its wildlife populations
must be supported through a sense of stewardship at
both the local and global levels.
11.2.3.The role of protected areas
A goal of ecosystem conservation in the Arctic as elsewhere is maintenance of the health of the unique complex of ecosystems that characterize the Arctic, and in
doing so, to attempt to ensure the protection and sustainability of the unique biodiversity for which the Arctic
is valued both by arctic residents and the rest of the
world community. An important process in the efforts to
achieve this goal has been the identification of natural
habitats of critical importance in the life cycles of wildlife species, and their subsequent protection through
legal processes at local, regional, national, and international levels of government. Although “protected areas”
are often established with the well-being of a single
species or a group of related species being the primary
focus (e.g., Ramsar sites for waterfowl, Round Island in
Alaska for walrus (Odobenus rosmarus); see Fig. 11.2), all
Chapter 11 • Management and Conservation of Wildlife in a Changing Arctic Environment
603
I Strict Nature Reserve / Wilderness Area
II National Park
III Natural Monument
IV Habitat / Species Management Area
V Protected Landscape / Seascape
VI Managed Resource Protected Area
Fig. 11.2. Protected areas (>500 hectares) in the Arctic by IUCN Categories
I-VI (compiled by UNEP-WCMC as quoted in CAFF, 2001a).
forms of life that are encompassed within these units
generally benefit. Conversely, other areas may be protected primarily in recognition of the unique biodiversity that they encompass. In 1996, CAFF developed a
Strategy and Action Plan for a Circumpolar Protected
Area Network. Execution of the plan was designed to
perpetuate the dynamic biodiversity of the arctic region
through habitat conservation in the form of protected
areas to represent arctic ecosystems, and to improve
physical, informational, and managerial ties among
circumpolar protected areas. As a result of CAFF’s
efforts, jointly with other international governmental
and non-governmental organizations, and local, regional,
and national governments and interests, nearly 400 protected areas (greater than 10 km2) were established
throughout the Arctic in 2000, totaling over 2.5 million
km2 (CAFF, 2001a).
Selection of areas needed for protection in the interest of
wildlife conservation is not a task easily accomplished
even when there is broad public and governmental support for the process. Identifying those areas of critical
habitat needing protection for the effective conservation
of wildlife in the Arctic requires comprehensive habitat
inventories and assessment of all existing and proposed
land uses within areas under consideration. Part of these
assessments is the weighing up of consequences of the
present and proposed uses of the areas under consideration for protection (e.g., subsistence, commercial, and
sport hunting; reindeer grazing; transportation corridor
construction; and other resource extraction uses).
Establishment of protected areas critical to effective conservation of wildlife, and acceptance and respect for their
legal protection, generally requires advance involvement,
open discussion, and often compromise among all poten-
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Box 11.2. Balancing nature conservation and industrial development in Canada
There should be no new or expanded large-scale industrial development in Canada until a network of protected
areas is reserved which adequately represents the natural region(s) affected by that development.The Conservation First Principle (WWF Canada, 2001).
An essential element of conserving Canada’s natural heritage is to permanently protect an ecologically viable, representative sample of each of the country’s terrestrial and aquatic natural regions.These protected areas conserve a
basic level of natural habitat for Canadian wildlife and the ecological processes that provide freshwater, fertile soils,
clean air, and healthy animals and plants. In many places, these natural areas are crucial to the continued livelihoods
and cultural integrity of Canada’s indigenous peoples.
Protecting representative samples of every natural region in Canada should be accomplished in a way that fully
respects the constitutional rights of indigenous peoples, and provides genuine economic opportunities for local
residents.This goal can with careful planning be accomplished without sacrificing jobs or economic development.
Canada signed and ratified the international Convention on Biological Diversity in 1992.The same year, all Canadian
Ministers responsible for wildlife, parks, the environment, and forestry (federally, provincially, and territorially) agreed
in the Tri-Council Commitment to take a critical first step in conserving biodiversity by completing a network of
ecologically representative protected areas in land-based natural regions by 2000, and by accelerating the protection of representative protected areas in Canada’s marine natural regions.
The area of representative protected areas in Canada doubled in the 1990s, but the Tri-Council Commitment has
not yet been met. Not all natural terrestrial regions have been moderately or adequately represented in protected
areas, and marine regions remained largely unrepresented. Canadian government bodies have continued to approve
new oil and gas leases, forest allocations, mining projects, hydro dams, and other large-scale development projects in
Canada’s natural habitats. WWF Canada (November 2001) stated that: “Every time a development project is proposed in a natural region that is not yet adequately represented by protected areas, we erode the options to
establish these natural and cultural safeguards”.
tial users of the areas and representatives of the governments with legal responsibility for their establishment.
An example of the complex process for justification and
establishment of protected areas for wildlife conservation
was initiated in northern Yukon Territory of Canada and
adjacent Alaska through an agreement between Canada
and the United States establishing the International
Porcupine Caribou Board.Through these international
efforts a report on the sensitive habitats of the Porcupine
Caribou Herd was prepared (IPCB, 1993) and is being
used in an ongoing process of providing justification and
protection of critical habitats within existing protected
areas in Alaska and Yukon Territory, and in the regional
planning process and establishment of additional protected areas in northernYukon Territory. Non-governmental
organizations can and have played an important role in
the establishment of protected areas for wildlife conservation in the Arctic. Another example is the “Conservation First Principle” concept under development for
the Canadian North through shared governmental and
non-governmental efforts (see Box 11.2).
Protected areas set aside by governmental action, merely
through establishment of their boundaries, do help to
bring about public recognition of the importance of
their role in wildlife conservation. Unless their establishment is accompanied by enforceable laws that govern
their use, however, the areas remain protected in name
only and remain vulnerable to overexploitation of the
wildlife, and habitat alteration and destruction through
competing land uses. Political pressures generated by
large and often multinational industries interested in
protected areas as loci for energy or mineral extraction,
mass tourism, or other developments destructive to
wildlife and their habitats, may be successful in persuading governments to allow them into these areas. Examples of where the protection offered to arctic areas set
aside for wildlife conservation has been violated are
widespread throughout the Arctic (e.g., seismic exploration for oil in the Arctic National Wildlife Refuge and
atomic bomb testing in the Alaska Maritime National
Wildlife Refuge, both in Alaska; illegal harassment of
walrus in the Wrangel Island Reserve and uncontrolled
poaching of wildlife in Kola Peninsula reserves by military personnel, both in Russia).
Although the importance of existing protected areas and
the need for establishment of additional protected areas
for effective conservation of wildlife in the Arctic are
internationally recognized, climate change adds an additional layer of complexity in use of protected areas as a
tool in wildlife conservation. If plants and animals
change their distribution in response to a changing climate as is expected (Chapters 7, 8, 9), critical habitats of
wildlife (seabird nesting colony sites, reindeer/caribou
calving grounds, waterfowl and shore-bird nesting and
staging areas, marine mammal haul-out areas) will also
change in their distribution over time. Consequently,
Chapter 11 • Management and Conservation of Wildlife in a Changing Arctic Environment
anticipating the needs for new protected areas important
for conservation as wildlife and their habitats change in
their distributions on the landscape will be an extremely
difficult process.The process will necessarily need to be
dynamic, with ongoing assessment of wildlife habitat use
and dependency.This should enable recognition of the
continued importance of some existing protected areas,
and conversely, recognition that others that become
abandoned by wildlife may no longer be needed, though
they may retain value for protection of plant species or
other ecosystem components.Wildlife management and
conservation in an Arctic under the influence of climate
change must be adaptive to ecosystem level changes that
are not feasibly reversible within the human timescale,
such as the northward movement of boreal ecotones into
the Arctic along with the associated wildlife.Thus, protected areas will have value as areas where climateinduced or other externally influenced changes within
ecosystems can be observed and monitored, free of
major direct human impacts.
The establishment and use of protected areas is an essential component of conservation of wildlife and their
habitats in the Arctic and in the protection of the biodiversity that characterizes arctic ecosystems. However,
protected areas alone cannot ensure the sustained
integrity of arctic ecosystems under the influences of a
changing climate and accelerating pressures from
resource extraction, tourism, and associated construction of roads, pipelines, and other transportation corridors. Of major concern is the fracturing of habitats
through development activities, especially transportation
corridors that may restrict the free movement and
exchange of plants and animals between habitats even
though significant parts of these habitats may have protected status. Ecological requirements for subpopulations of both plants and animals may be encompassed
within protected areas, but the long-term integrity and
sustainability of arctic ecosystems and the wildlife and
other organisms within them requires opportunity for
genetic exchange between components. Although critical
habitat units may merit rigid protection, the intervening
natural environment must be managed so that movement
of species within entire ecosystems remains possible.
Establishment of protected areas should be consistent
with subsistence harvesting activities and not designed to
exclude them. Management of the harvest of wildlife
must be adaptable to changes that may take place in the
population status of wildlife species.
Transportation corridors, especially roads and their associated vehicle traffic, may fracture habitats and limit free
movement of species within ecosystems, however, they
also provide corridors for the movement of invasive
plant and animal species, with often detrimental consequences for native species with which they may compete, prey upon, parasitize, or infect. “Invasive species” is
an all-inclusive generic term. It includes plants and animal species truly exotic to most regions of the Arctic
and subarctic, such as the dandelion (Taraxacum officinale), house mouse (Mus musculus), and Norway rat
605
(Rattus norvegicus) that have inadvertently been introduced by humans.There are, however, invasive species
native to adjacent biomes, such as the moose (Alces alces)
and snowshoe hare (Lepus americanus), that have expanded into parts of the North American Arctic from the
boreal forest with consequences for arctic species and
ecosystems. Humans have also been responsible for the
deliberate introduction of plant and animal species into
the Arctic. Examples are the introduction of lupine
(Lupinus spp.) and coniferous trees to Iceland associated
with erosion control and forest reestablishment, which
through their subsequent dispersal have become nuisance
species in areas where they crowd out native or introduced forage species for domestic livestock, and threaten preservation of the natural biodiversity. Among animals, the deliberate introduction of Arctic foxes (Alopex
lagopus) to the Aleutian and Commander Islands in the
18th century for harvest of their pelts led to the marked
reduction or extirpation of populations of marine birds,
waterfowl, and other ground nesting birds.The intensive, decades-long efforts of the U.S. Fish and Wildlife
Service to eliminate the Arctic foxes on many of the
Aleutian Islands has resulted in rapid reestablishment of
successful bird nesting on islands from which the foxes
have been removed, but this has involved a great expenditure of effort and money. It can be expected that the
appearance of invasive species in the Arctic will increase
through deliberate and accidental human activities, as
well as by natural dispersal assisted by transportation
corridors and parameters of climate change that may
favor the new species over native plants and animals.
It is important to remember that the decrease in biodiversity with increasing latitude that is a characteristic of
arctic ecosystems is partly a consequence of the slow
rate of dispersal of species into the Arctic following
deglaciation. It is very likely that climate change, especially the climate warming projected to occur throughout much of the Arctic (see Chapter 4), and other forces
will accelerate the “natural” movement of plant and animal species into the Arctic. It remains for human judgment to determine whether invading plant and animal
species are to be considered part of the natural ongoing
process of ecosystem change in the Arctic, whether they
pose threats to the natural biodiversity of arctic ecosystems, or whether they are detrimental to human efforts
to manage arctic ecosystems for human exploitation.
Important tasks facing managers of wildlife in a changing
Arctic will be assessing consequences for native species
and ecosystems of the effects of invasive species within
the constraints of a changing climate. It may also be necessary, where regionally appropriate, to develop procedures that restrict invasion of species that may have
undesirable consequences for native species.
11.2.4. Change in human relationships with
wildlife and managing human uses of wildlife
On the basis of early archeological evidence, human
cultures with the technologies that allowed them to
live under the climatic extremes of the Arctic while
606
exploiting its marine resources did not appear until
the mid-Holocene Epoch ~7000 years ago (Giddings,
1967). The entrance of humans to the Americas from
Asia via Beringia 7000 to 8000 years earlier, however,
occurred near the end of the Pleistocene Epoch when
sea levels were lower, land areas greater, and the environment markedly different to how it later became in
the Holocene (Meltzer, 1997). During much of the
Holocene, following the first major wave of human
movement into North America, as the Pleistocene ice
retreated from the land, changes in human distribution, demography, culture, and movements were predominantly tied to changes in availability of wildlife.
Humans located where species that were essential
components of their diets, and provided materials
for their clothing, shelter, tools, and weapons, were
available. This pattern of human use of the land and
adjacent sea prevailed as the Arctic was settled and
cultures evolved in adaptation to the wildlife and other
resources available for their exploitation (Schledermann, 1996; Syroechkovskii, 1995).
Wildlife species in both marine and terrestrial systems
have undergone changes in their abundance and distribution in the past, and therefore in their availability for use
by people in the Arctic. Some of these changes have
resulted from heavy commercial exploitation of marine
wildlife for their skins and oil and of terrestrial mammals
largely for their pelts. Longer-term changes in distribution and abundance of wildlife in the Arctic are thought to
have been largely the result of changes in climate affecting
temperature, precipitation, snow characteristics, and seaice conditions and their influence on food chain relationships (see Chapters 7, 8, 9). All the peoples of the Arctic
and the animals they hunt and use are subject to the
vagaries of arctic climate.The global warming observed
in the latter half of the 20th century, consistent with projections by general circulation models, has advanced most
rapidly in certain parts of the Arctic, however, there have
been regional inconsistencies (see Chapters 2, 4, 6).The
western Canadian Arctic and the Alaskan Arctic have
shown decadal temperature increases of 1.5 ºC, whereas a
nearly opposite cooling trend has been recorded in
Labrador, northern Quebec, Baffin Island, and adjacent
southwest Greenland (Serreze et al., 2000). Nevertheless,
although some regions of the Arctic may not have experienced the pronounced warming in recent decades that has
characterized most of the Arctic, changes in other climate-related parameters such as precipitation, frequency
and severity of storm events, and thinning and reduced
seasonal extent of sea ice are being observed in all regions
of the Arctic (Chapter 2). Increases in ultraviolet-B (UVB) radiation levels in the Arctic associated with thinning of
the atmospheric ozone layer may have consequences for
life processes of both plants and animals, however little is
known of possible effects on wildlife (Chapter 7).
However, to the extent that increased UV-B radiation levels may result in differential changes in tissue structure
and survival of plant species, resulting in changes in their
quality and abundance as food for herbivores, wildlife and
their food chain relationships will be affected.
Arctic Climate Impact Assessment
As a general rule the numbers of plant and animal
species decline with increasing latitude from the equator
to the poles, as does the complexity of species interrelationships and associated ecosystem processes. Since
external influences tend to be buffered by the complexity of biological processes within ecosystems, the less
complex arctic ecosystems can be expected to respond
more dynamically to climate change than the more complex systems that exist at lower latitudes, and this seems
to have been the case during past periods of climate
change (Chapter 7). An additional compounding factor is
that rates of climate-related change in much of the
Arctic, reflected in climate warming and decrease in seaice thickness and extent, exceed those at lower latitudes.
11.3. Climate change and terrestrial
wildlife management
11.3.1. Russian Arctic and subarctic
Hunting is an important part of the Russian economy,
both through harvest of wildlife products and through
pursuit of traditional sport and subsistence hunting.
Fur production has been an essential part of the economy of the Russian North throughout history. Management of wildlife also has a long history in Russia, from
early commercial and sport hunting to the creation of a
complicated multifunctional state system under the
Soviet government. Early attempts at regulation of
hunting are known from the 11th century, and these
attempts at wildlife management were connected with
protection of species or groups of species.The first
national law regarding hunting was imposed in 1892 as
a reaction to widespread sport hunting, the establishment of hunter’s unions, and the efforts of naturalists
and others with interests in wildlife.These early efforts
toward managing wildlife were based on wildlife as a
component of private property.
Under the Soviet system, wildlife management developed on the basis of state ownership of all resources of
the land, including wildlife, and a state monopoly over
foreign trade and fur purchasing. Commercial hunting
was developed as an important branch of production
within the national economy.The state-controlled wildlife management system resulted in an elaborate complex of laws as the basis for governing commercial and
sport hunting, for investigation of resources and wildlife
habitats, for organization of hunting farms or collectives,
for establishment of special scientific institutes and laboratories, for incorporation of scientific findings in wildlife management, and for the development of a system of
protected natural areas. Justification for identifying natural areas deserving protection in the Russian Arctic
became apparent as major segments of the Russian economy increased their dependence on exploitation of arctic
resources during the Soviet period, stimulated by the
knowledge that 70 to 90% of the known mineral
resources of the country were concentrated in the
Russian North (Shapalin, 1990). More than 300 protected natural areas of varying status were established for
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Chapter 11 • Management and Conservation of Wildlife in a Changing Arctic Environment
restoration and conservation of wildlife resources in the
Russian Far North (Baskin, 1998).
(Zabrodin et al., 1989).Variation by region in characteristics of the harvest of wildlife in the Russian Arctic and
subarctic is compared in Table 11.1. Participation in commercial hunting by the able-bodied local population was
25 to 30%. Profit from hunting constituted 52 to 58%
of the income of the indigenous population. Of the meat
of wild ungulates harvested, the amount obtained per
hunter per year was 233 kg for professional hunters,
143 kg for semi-professional hunters, and 16 kg for
novice hunters.The proportion of total wild meat harvested that was purchased by the state was 60%. Of that
purchased by the state, 73% was for consumption by the
local population. Fish has also been an important food
resource for local populations, as well as for the professional hunters/ fishers. A professional hunter’s family
would use about 250 kg of fish per year, and 2000 kg of
fish were required per year to feed a single dog team
(eight dogs). By the end of the 1980s state purchase of
wildlife and fish was 34% of potential resources, and
local consumption was 27% (Zabrodin et al., 1989).
Wildlife management was concentrated in a special
Department of Commercial Hunting and Protected
Areas within the Ministry of Agriculture. Local departments were organized in all regions of the Russian
Federation for organization, regulation, and control of
hunting with the intent to make them appropriate for
actual conditions. Hunting seasons were established for
commercial and sport hunting by species, regulation of
numbers harvested, and designation of types of hunting
and trapping equipment to be used.The major hunting
activity was concentrated in specialized hunting farms.
Their organization was initially associated with designated areas.The main tasks of the state hunting farms were
planning, practical organization of hunting, and management for sustained production of the wildlife resources.
At the same time, the system of unions of sport hunters
and fishers was organized for regulation of sport hunting
and fishing under the control of the Department of
Commercial Hunting and Protected Areas (Ammosov et
al., 1973; Dezhkin, 1978).
Indigenous residents of the Russian Arctic and subarctic have not had limitations on hunting for their
subsistence use. However, all those engaged in professional, semi-professional, and sport hunting have been
required to purchase licenses. Indigenous people
involved in the state-organized hunting system were
also provided with tools and consumer goods. The
main problems that have confronted effective wildlife
management in the Russian Arctic are widespread
poaching, uneven harvest of wildlife, and loss of wildlife habitats and harvestable populations in connection
with industrial development.
Commercial hunting has been primarily concentrated in
the Russian Far North (tundra, forest–tundra, northern
taiga), which makes up 64% of the total hunting area of
the Russian Federation. During the latter decades of the
Soviet system the Russian Far North produced 52% of
the fur and 58% of the meat of ungulates and other wildlife harvested.The proportional economic value of the
three types of resident wildlife harvested was 41% for fur
(sable (Martes zibellina) – 50%, arctic fox – 9%, ermine
(Mustela erminea) – 18%), 40% for ungulates (moose –
41%, wild reindeer – 58%), and 19% for small game
(ptarmigan (Lagopus spp.) – 68%, hazel grouse (Tetrastes
bonasia) – 15%, wood grouse (Tetrao urogallus) – 11%)
The wildlife management system in the Russian Arctic
was not destroyed by the transformation of the political
and economic systems that took place at the end of the
Table 11.1. Regional variation in wildlife harvest in the Russian Arctic and subarctic under the Soviet system (Zabrodin et al., 1989).
European
Russia
Western
Siberia
Eastern
Siberia
Northern Far
East Russia
Share of area (%)
7
14
25
54
Ranking of relative biological productivity
4
2
1
3
Proportion of available resource harvested (%)
23
48
76
63
9
15
34
42
Sable (%)
–
14
24
23
Polar fox (%)
5
7
3
4
15
18
12
20
4
8
42
15
51
26
4
8
Purchased by the state (%)
33
37
61
58
Local consumption (%)
67
63
39
42
Expenditure (%)
Breakdown of value by species within region
Fur
Ungulate
Moose (%)
Wild reindeer (%)
Game
Partridge (%)
Distribution of the harvest
608
20th century, but it was weakened. Partly as a consequence of this weakening, but also due to expansion of
industrial development in the Russian Arctic and the
effects of climate change, there has been the development
of several major threats to effective wildlife conservation.
• Transformation of habitats in connection with industrial development. From an ecological standpoint the
consequences of industrial development affect biological diversity, productivity, and natural dynamics
of ecosystems. As far as environmental conditions are
concerned it is important to note that apart from air
and water pollution there is a possibility of food pollution. In terms of reindeer breeding, hunting, and
fishing, industrial development has resulted in loss of
habitats and resources, a decrease in their quality and
biodiversity, and destruction of grazing systems
(Dobrinsky, 1995, 1997;Yablokov, 1996;Yurpalov et
al., 2001). A considerable portion of the biological
resources presently exploited is from populations
outside regions under industrial development
(Yurpalov et al., 2001).
• Reduction in wildlife populations as a result of
unsystematic and uncontrolled exploitation
through commercial hunting.
• Curtailment of wildlife inventory and scientific
research, resulting in loss of information on population dynamics, health, and harvest of wildlife.
• Changes in habitat use by wildlife, in migration
routes, and in structure and composition of plant
and animal communities as a consequence of
climate change. Such changes include increased
frequency and extent of fires in the northern taiga,
displacement northward of active breeding dens of
the Arctic fox on the Yamal Peninsula (Dobrinsky,
1997), as well as in other areas (Yablokov, 1996),
and replacement of arctic species by boreal species
as has occurred in the northern part of the Ob
Basin (Yurpalov et al., 2001).
Arctic Climate Impact Assessment
also existed for velvet antlers. However, under existing
conditions in most of the Russian North where there are
no roads and settlements are few, hunting of wild reindeer at river crossings remains the most reliable and productive method of harvest (see the case study on river
crossings as focal points for wild reindeer management in
the Russian Arctic in Box 11.3). Additionally, concentration of hunting effort at specific river-crossing sites provides an opportunity to influence hunting methods and
for monitoring the number of animals killed. A proposal
has been made to protect the traditional rights of indigenous hunters by granting them community ownership of
some of the reindeer river crossings.This would presumably allow them to limit increasing competition from
urban hunters for the reindeer. At present, indigenous
people hunt reindeer only for their personal or community needs, but as owners of reindeer harvest sites at
river crossings they would have a basis for developing a
commercial harvest. Some large industrial companies
have indicated a readiness to support commercial harvest
of reindeer by indigenous people by assisting in the transportation of harvested reindeer to cities and mining settlements. Already, there are plans to open some of the
more accessible river crossings for hunting by people
from nearby towns and this will include personal use as
well as commercial sale of the harvested reindeer.
However, there is a need for development of regulations
to prevent excessive harvesting of the reindeer and associated alteration of their migration routes.The inability in
the past to predict the availability over extended periods
of time of wild reindeer for human harvest because of
their natural long-term population fluctuations led many
indigenous peoples in the Arctic to include more than
one ecologically distinct resource (e.g., reindeer and fish)
Both commercial and sport hunting are permitted
throughout the Russian North. Commercial hunting for
wild reindeer for harvest of velvet antlers is permitted
for 20 days in the latter part of June. Commercial hunting of reindeer for meat can take place from the beginning of August through February. Sport hunting is permitted from 1 September to 28 February. A license is
required to hunt reindeer (cost for sportsmen about
US$4, for commercial enterprise about US$3).There
are no restrictions on numbers of reindeer to be hunted.
Hunting is permitted everywhere, with the exception of
nature reserves. Regional wildlife harvest systems are
compared in Table 11.2, together with associated wildlife population trends, threats to wildlife and their habitats, and conservation efforts.
In recent years in the Russian North, marketing of venison experienced an economic revival. In mining settlements in 2001 the cost of venison commonly approached
US$2.5 per kilogram, making commercial hunting of
reindeer potentially profitable. A significant demand has
Fig. 11.3. Harvesting by indigenous people of wild reindeer in
the Russian North and caribou in North America was traditionally done at river crossings on migration routes.This continues
to be an efficient method of hunting reindeer and caribou in
some regions, a hunting system that lends itself to managed control of the harvest.
609
Chapter 11 • Management and Conservation of Wildlife in a Changing Arctic Environment
as their primary food base. Similarly, a balance between
harvest of reindeer for local consumption and commercial sale in communities in the Russian North would
appear to offer greater flexibility for management of the
reindeer and sustainability of local economies than largescale commercial harvesting of reindeer. Flexibility in
options for management of wild reindeer will be essential
in the Arctic of the future that is expected to experience
unpredictable and regionally variable ecological consequences of climate change. Increased adaptability of the
arctic residents to climate change will be best achieved
through dependence on a diverse resource base.This
applies to the monetary and subsistence economies of
arctic residents, as well as to the species of wildlife tar-
geted for management, if wildlife is to remain an essential base for community sustainability.
Changes have occurred over time in methods and patterns of harvesting wild reindeer in the Russian North
and these changes provide perspective on wildlife management in a changing climate. Since prehistoric times
indigenous peoples throughout Eurasia and North
America have hunted wild reindeer and caribou during
their autumn migration at traditional river crossings.
Boats were used to intercept the swimming animals
where they were killed with spears (Fig. 11.3).
This method of harvesting wild reindeer may offer
potential for management of wild reindeer under the
Table 11.2. Comparison of wildlife harvest systems in the Russian North.
Harvest system
Wildlife population trends Threats to wildlife and their habitats
Conservation efforts
Over-harvest of
ungulates, drastic
decline in wild
reindeer
Over-harvest of ungulates by military and
for subsistence, fracturing of habitats by
roads and railroads, habitat degradation
from industrial pollution
Laplandsky Reserve (1930)
2784 km2. Pasvik Reserve
(1992) 146 km2 (International, with Norway’s
Oevre Pasvik Park 66.6 km2)
Over-grazing by reindeer, habitat damage
by massive petroleum development with
roads and pipelines, hunting by workers,
control of predators
Nenetsky Reserve (1997)
3134 km2 (near Pechora
delta – waterfowl and
marine mammals)
Low hunting pressure,
populations stable
Industrial development, forest and
habitat destruction, fragmentation by
roads and pipelines, pollution from
pipeline leaks
Reserves: Malaya Sosva
2256 km2, Gydansky 8782
km2,Yugansky 6487 km2,
Verkhne-Tazovsky 6133 km2
Decline or extirpation
of wild reindeer
subpopulations near
Norilsk, inadequate
survey methods
Wild reindeer total counts are basis for
management; lack of knowledge of identity
and status of discrete herds; extensive habitat loss from industrial pollution; habitat
fracturing and obstructed movements by
roads, railroad, pipelines, and year-round ship
traffic in Yenisey River for metallurgical and
diamond mining, and oil and gas production
Reserves: Putoransky
18 873 km2,Taimyrsky
17 819 km2, Bolshoy
Arctichesky 41692 km2;
region-wide ecosystem/
community sustainability
plan being developed
Little information,
assumed stable
Low human (Evenki) density and poor
economy result in little threat at present
to wildlife and habitats
Need is low due to
remoteness and low
population density.
No nature reserves
Heavy harvest of reindeer and snow sheep
for market results in
population declines,
introduced muskox
increasing
Diamond mining provides markets for meat
leading to over-harvest and non-selective
culling, decrease in sea ice restricts seasonal
migrations of reindeer on Novosiberski
Islands to and from mainland
Ust Lensky Reserve
14 330 km2. Muskox
introduction adds new
species to regional
biodiversity and
ecosystem level
adjustments
Increases in wild reindeer, snow sheep, and
large predators with
decline in reindeer
herding, muskoxen on
Wrangel Island increasing
Major decline in reindeer herding, movement of Chukchi to the coasts, poor economy, and low extractive resource potential
results in greatly reduced threats to wildlife
inland from the coasts, increased pressure
on marine mammals for subsistence
Reserves:Wrangel Island
22256 km2, Magadansky
8838 km2, Beringia
International Park –
proposed but little political
support
Kola Peninsula
Hunting for subsistence and
for local market sales
Nenetsky Okrug,Yamal, Gydan
Intensive reindeer husbandry, Decline in wolves,
control of large predators,
wolverines, and foxes
incidental subsistence hunting, Arctic fox trapping
Khanty-Mansiysky Okrug
Hunting focus on wild
reindeer, moose, and furbearers; indigenous hunting
culture in decline
Taymir
Hunting focus on wild
reindeer and waterfowl,
mostly subsistence, commercial harvest of velvet antlers
at river crossings, restrictions
limiting commercial antler
harvest being enforced
Evenkiya
Hunting for subsistence and
local markets, primarily
moose, wild reindeer, and
bear, little trapping effort
Yakutia (Sakha)
Hunting primarily for wild
reindeer, moose, snow sheep,
and fur bearers, heavy commercial harvest as well as for
subsistence, decline of reindeer
herding increases dependency
on subsistence hunting
Chukotka
Wild reindeer, snow sheep,
and marine mammals hunted
for subsistence by Chukchi
and Yupik people
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Arctic Climate Impact Assessment
Box 11.3. River crossings as focal points for wild reindeer management in the Russian Arctic
Harvesting wild reindeer at river crossing sites (see Fig. 11.3) has played a significant role in regional economies
and the associated hunting cultures in the Russian North (Khlobystin, 1996). Many crossing sites were the private
possession of families (Popov, 1948). When reindeer changed crossing points it sometimes led to severe famine,
and entire settlements vanished (Argentov, 1857;Vdovin, 1965). Such changes in use of migration routes are
thought to result from fluctuations in herd size and interannual climate variability. Under the Soviet government,
large-scale commercial hunting at river crossings displaced indigenous hunters.
Importance of river crossings for wild reindeer harvest
On the Kola Peninsula and in western Siberia there are few known locations for hunting reindeer at river crossings. In Chukotka, a well-known place for hunting reindeer was located on the Anadyr River at the confluence
with Tahnarurer River. In autumn, reindeer migrated from the tundra to the mountain taiga and hunters waited
for them on the southern bank of the Anadyr River. Reindeer often select different routes when migrating from
the summering grounds. Indigenous communities traditionally arranged for reconnaissance to try to predict the
migration routes. In Chukotka, mass killing sites at river crossings were known only in the tundra and forest–
tundra, not in the taiga (Argentov, 1857). In Yakutia, reindeer spend summers on the Lena Delta where forage is
abundant and cool winds, and the associated absence of harassment by insects, provide favorable conditions for
reindeer. In August–September, as the reindeer migrate southwestward, hunters wait and watch for them on the
slightly elevated western bank of the Olenekskaya Protoka channel of the Lena Delta where the reindeer traditionally swim across the channel. In the Taymir, 24 sites for hunting reindeer by indigenous people were located
along the Pyasina River and its tributaries (Popov, 1948).The killing sites at river crossings occupy fairly long sections of the river. In more recent times when commercial slaughtering occurred, hunter teams occupied sections
10 to 20 kilometers long along the river and used observers to signal one another by radio about approaching
reindeer; motor boats carrying the hunters then moved to points on the river where hunting could take place
(Sarkin, 1977). In the more distant past, hunters used canoes and needed to be more precise in determining
sites and times of the reindeer crossing. Reindeer are very vulnerable in water, and although their speed in
water is about 5.5 km/hr (Michurin, 1965) humans in light boats could overtake the animals. In modern times,
using motorboats and rifles, hunters were able to kill up to 70% of the animals attempting to cross the rivers at
specific sites. A special effort was made to avoid killing the first reindeer entering the water among groups
approaching the river crossings. Experience showed that if the leading animals were shot or disturbed those following would be deflected from the crossing. Conversely, if the leading animals were allowed to cross, following
animals continued to cross despite disturbance by hunting activities (Savel’ev, 1977).
recent drastic changes that have taken place in social
and economic conditions among the indigenous peoples
of the Russian North resulting from the dissolution of
the Soviet Union. Can management of wild reindeer
through harvesting primarily at river crossings ensure
sustainable harvests from the large migratory herds
under conditions of human social and economic change
compounded by the effects of climate change on the
reindeer and their habitats? Addressing this question
may be possible by comparing the population dynamics
of reindeer and caribou herds in regions of the Arctic
with differing climate change trends (Post and Forchhammer, 2002; Human Role in Reindeer/Caribou
Systems project, see www.rangifer.net).
11.3.2.The Canadian North
11.3.2.1. Historical conditions and present status
In comparison to ecosystems at lower latitudes in Canada
most ecosystems in the Canadian Arctic are considered
functionally intact, although the consequences for marine
ecosystems of contaminants introduced from industrial
activity to the south and climate-induced thawing are not
known. Most threats typical for elsewhere in the world –
such as habitat loss through agriculture, industry, and
urbanization – are localized. Introduced species primarily
associated with agriculture at lower latitudes are scarce,
or largely confined to areas near communities. Invasive
wildlife species from the south, such as moose and snowshoe hares, are primarily restricted to the tundra–forest
interface.Within most arctic ecosystems, resource use
through hunting is the most conspicuous influence that
people have on wildlife with the exception of localized
resource extraction and expanding tourism. Among the
factors that can influence arctic wildlife, hunting is
potentially the most manageable and its quantitative
assessment needed for management is feasible. Although
hunting is not currently considered a threat to terrestrial
wildlife in the Canadian Arctic, it has recently interacted
with other factors such as weather to locally reduce caribou abundance on, for example, some arctic islands
(Gunn et al., 2000). Managed hunting is considered an
important part of wildlife conservation through its
emphasis on sustainability of harvest. Hunting, however,
poses a threat when it causes or contributes to undesired
declines or through interaction with other species with
detrimental consequences.The latter is especially rele-
Chapter 11 • Management and Conservation of Wildlife in a Changing Arctic Environment
611
Commercial harvest at river crossings
During the Soviet period, large-scale commercial harvest of reindeer at river crossings displaced indigenous
hunters from these traditional hunting sites (Sarkin, 1977; Zabrodin and Pavlov, 1983). In Yakutia, after commercial
hunting began in the 1970s, hunting techniques included the use of electric shocks to kill reindeer as they came
out of the water. In recent years these commercially harvested reindeer populations in Yakutia declined precipitously (Safronov et al., 1999). In the Taymir, indigenous people practiced subsistence hunting at river crossings until
the 1960s. However, by 1970, hunting regulations had banned hunting at river crossings by indigenous people and
other local residents because of concern that over-harvest of the reindeer would occur.The Taymir reindeer
increased greatly in the following years. Biologists working with the reindeer proposed reinstatement of the traditional method of killing animals at river crossings in order to establish a commercial harvest from the large Taymir
population and to stabilize the population in line with the carrying capacity of the available habitat.The Taymir
state game husbandry system was established by 1970. Up to 500 hunters participated in the annual harvests.
All appropriate river hunting locations on the Pyasina River and the Dudypta, Agapa, and Pura tributaries were
taken over for the commercial harvests. Large helicopters and in some cases refrigerated river barges were used
to transport reindeer carcasses to markets in communities associated with the Norilsk industrial complex. Over a
period of 25 years about 1.5 million reindeer were harvested by this system (Pavlov et al., 1993). After 1992,
there was a decrease in the number of reindeer arriving at most of these river crossings, resulting in an abrupt
decline in the harvest from about 90000 per year in peak years to about 15 000 per year in subsequent years.
This was associated with the disproportionate harvest of female reindeer (Klein and Kolpashchikov, 1991).
Consequences of climate change
Climate change may affect river crossings as sites for controlled harvest of reindeer in several ways. If patterns
of use of summering areas change in relation to climate-induced changes in plant community structure and plant
phenology then migratory routes between summer and winter ranges may also change.Thus, some traditional
crossings may be abandoned and new crossings established. Changes in the timing of freeze-up of the rivers in
autumn at crossing sites may interfere with successful crossings by the reindeer if the ice that is forming will not
support the reindeer attempting to cross.These conditions have occurred infrequently in the past in association
with aberrant weather patterns; however timing of migratory movements would also be expected to change
with a consistent directional trend mirroring seasonal events.
vant in marine systems where knowledge of ecosystem
relationships and processes are less well understood than
they are for terrestrial systems. Hunting remains inextricably part of the long relationship between indigenous
people of the Arctic and their environment, and they see
themselves as part of the arctic ecosystems within which
they dwell (Berkes and Folke, 1998).
Fluctuations in caribou numbers over decades in the
Canadian Arctic have been a frequently reiterated observation in indigenous knowledge (e.g., Ferguson and
Messier, 1997), and this parallels archaeological evidence from western Greenland (Meldgaard, 1986).The
increased hunting that followed European colonization,
with the introduction of firearms and commercial hunting, accentuated or over-rode natural fluctuations in
caribou numbers and contributed to the so-called caribou crisis of low numbers between 1949 and 1955
(Kelsall, 1968). Subsequently, the herds of barrenground caribou increased five-fold.The number of caribou on the mainland tundra in four of the largest herds
(Bathurst, Beverly, Qamanirjuaq, and Bluenose) was
estimated at 1.4 million in the mid-1990s and numbers
are believed to be remaining relatively stable.
Historically, muskoxen (Ovibos moschatus) were sufficiently
numerous to be an important part of the indigenous culture on the mid-arctic islands, but were less so on the
mainland until a brief pulse in commercial hunting for
hides in the late 1800s and early 1900s (Barr, 1991).
However, sharp declines in muskox numbers on the
Northwest Territories (NWT) mainland followed unregulated commercial trade in muskox hides. Muskox numbers quickly collapsed and within 30 years only a handful
of scattered herds remained on the mainland. Muskox
hunting was banned between 1917 and 1967, after which
populations had started to recover by the 1970s when
subsistence hunting was resumed under quotas. Numbers
of muskoxen in the NWT and Nunavut have been recently
estimated at about 100000 on the arctic islands and about
20000 on the mainland (Gunn and Fournier, 1998).
Hunting was not the cause of all known historic wildlife declines – muskoxen virtually disappeared from
Banks and western Victoria Islands in the late 1800s,
before European influences. Inuvialuit elders have
memory from their youth of an icing storm that
encased vegetation in ice and many muskoxen died on
Banks Island (Gunn et al., 1991). Muskox numbers
612
rebounded on Banks Island from a few hundred to
3000 by 1972 and to 64 000 by 2001 (Nagy et al.,
1996; J. Nagy pers. comm., 2001).
The number of polar bears killed by hunters increased
with European exploration and trading in the Canadian
Arctic. Hunting for hides was not significant until the
1950s when prices climbed in response to market
demands. Snow-machines were becoming available in the
1960s, leading to increased hunting and stimulating
international concern over sustainability of the polar
bear harvest. In 1968, regulations imposed quotas to
reduce hunting of polar bears. Canada has about 14800
polar bears of the entire arctic population of 25000 to
30 000 bears (IUCN Polar Bear Specialist Group, 1998).
11.3.2.2. Present wildlife management
arrangements and co-management
The federal and territorial governments responded to the
wildlife declines in the NWT during the first half of the
20th century with well-meaning but mostly poorly
explained regulations that restricted hunting.These regulations largely ignored local knowledge and emphasized
hunting as a threat, which alienated indigenous hunters
and left them feeling bitter.Those feelings still influence
discussions about hunting, although changes in management practices as a result of establishing new management
regimes in recent years may be reducing mistrust (Kruse
et al., 2004; Richard and Pyke, 1993; Usher, 1995).
Co-management is a type of regime that has emerged in
response to such conditions of conflict and mistrust to
shift power and responsibility to boards comprising wildlife users, as well as government representatives.
Co-management agreements establish boards of user
representatives and agency managers, and typically have
authority for wildlife management subject to conservation, public safety, and public health interests. Although
overall authority for management is vested in the appropriate government ministry and/or indigenous governing
organization, co-management boards make day-to-day
decisions on wildlife and are valuable in assessing problems, achieving regional consensus, and making recommendations to user communities, management agencies,
and government policy-makers. Co-management potentially helps to ensure that indigenous ecological knowledge is included in wildlife management, although there
is debate over its effectiveness in this regard (Usher,
1995). Under land claims legislation, the territorial
government determines a total allowable harvest using
species-specific methods and recommends to the boards
the allowable harvest for species that are regulated. If the
total allowable harvest exceeds the basic needs levels,
then the surplus can be allocated to non-beneficiaries or
for commercial wildlife harvest, including sale of meat
and guided hunts for non-resident sport/trophy hunters.
The NWT and Nunavut territorial governments use a
variety of methods for determining allowable harvest.
Differences in methodology are a complex of practicali-
Arctic Climate Impact Assessment
ty, species life history, and management history. For caribou and muskox harvest management, pragmatic flexibility often takes precedence over application of theory
(Caughley, 1977; Milner-Gulland and Mace, 1998).
Aerial surveys are used to track caribou and muskox
population trends. For barren-ground caribou, the survey findings have not been used to limit subsistence
hunting, although they have been used to set quotas for
commercial use. In a few instances, communities voluntarily took action to reduce hunting on some arctic
islands, based on hunter reports of decline in caribou
numbers. In contrast to caribou, muskoxen are hunted
under an annual quota based on a 3 to 5% harvest of the
total muskoxen estimated within the management unit.
The local community decides whether the quota is for
subsistence or commercial use.
Managing polar bears has taken a different direction
from managing caribou and muskoxen, at least partly
because tracking polar bear abundance is logistically
difficult and prohibitively expensive.The total allowable
harvest is based on modeling the maximum number of
female bears that can be taken without causing a population decline (Taylor et al., 1987).The flexible quota
system, allowing sex-selective hunting, assumes that the
sustainable annual harvest of adult females (greater than
two years of age) is 1.6% of the estimated population,
and that males can be harvested at twice that rate.
Within the total annual quota, each community is allocated a maximum number of males and females. If the
quota of females killed is exceeded, the total quota for
the subsequent year is reduced by the exceeded
amount. During the period 1995–1996 to 1999–2000
the average annual harvest of polar bears in Canadian
territories, combined with harvest statistics reported in
Alaska and Greenland, was 623 animals while the sustainable harvest estimate was 608 (Lunn et al., 2002).
Communities and territorial governments developed
and jointly signed Local Management Agreements in the
mid-1990s that provide background, provide for use of
both scientific and traditional knowledge, and provide
the procedure for estimating population size and establishing the annual harvest quota.
Progress has also been made in developing comanagement for other marine mammals, notably the
small whales in the eastern and western Canadian Arctic.
Conservation and management of the beluga whale
(Delphinapterus leucas) in Alaska and the NWT is through
the Alaskan and Inuvialuit Beluga Whale Committee,
which includes representatives from communities and
governments as well as technical advisors (Adams et al.,
1993). However, only representatives from beluga hunting
communities vote on hunting issues. In the eastern Arctic
less progress has been made toward co-management for
narwhal (Monodon monoceros) partly because of a failure to
involve fully the Inuit hunters (Richard and Pike, 1993).
Advisory and co-management boards and agreements are
not necessarily a guarantee of widespread hunter support
(Usher, 1995). Klein et al. (1999) compared caribou management under the Beverly–Qamanirjuaq Caribou
Chapter 11 • Management and Conservation of Wildlife in a Changing Arctic Environment
Management Board with management of the Western
Arctic Caribou Herd in Alaska through a statewide Board
of Game.They concluded that information was not flowing effectively from user representatives on the co-management board to the user communities, thus the users
did not feel as involved in management of the caribou as
in Alaska where regionally based biologists collecting data
for management had more interaction with the users.
How do co-management arrangements help to meet the
goals of sustainability in conditions of climate change?
Experience with Canadian co-management arrangements demonstrates that these systems can be critical
tools for tracking the trends in climate change, reducing
human vulnerabilities, and facilitating optimal human
adaptation to impacts in single-species management.
Trust relations growing from formal co-management
arrangements also provide conditions from which innovative ecological monitoring and research involving
local/traditional knowledge and science add to the system’s capacity to cope with change. In short, a focus on
biological aspects of wildlife management should be
complemented with institutional considerations to
understand their full effectiveness in addressing the
possible impacts of climate change.
Co-management is defined both with respect to institutional features of an arrangement (Osherenko, 1988)
as well as by outcome of sharing of decision-making
authority by local communities of resource users and
agencies in the management of common pool resources
(Pinkerton, 1989). Power-sharing arrangements can
emerge through informal relations between parties
(e.g., regional biologists and local hunters), as a result
of formal agreements, or, as is most common, from a
combination of de jure and de facto relations. Structures
for co-management of wildlife therefore differ from
conventional state resource management systems in
which decision-making is bureaucratically organized and
driven primarily by the principles of scientific management. As well, co-management differs from local control in which a resource user community pursues selfdetermination, largely independent of external parties.
In practice, these arrangements result in considerable
latitude in the range of authority and responsibility
exercised by resource users (Berkes, 1989).
In the Canadian Arctic, formal co-management has
become a common feature of the political landscape
either through constitutionally entrenched land-claims
agreements or as stand-alone arrangements. Implementation is typically directed through boards of users and
agency representatives that are advisory to government
ministers, agencies, local communities, and various
indigenous governance bodies. In most cases, comanagement agreements have been struck to specify
community rights to hunting and provide a meaningful
role for indigenous subsistence users in management
decision-making. In several cases they have proven critical in achieving compliance when facing scarcity of
resource stocks (e.g., Peary Caribou (Rangifer tarandus
613
pearyi) of Banks Island and co-management system of the
Inuvialuit Final Agreement).
What is the significance of co-management to sustainability? Meeting the goals of sustainability requires that
resource managers, local communities, and other parties
cooperate in resource management.These management
functions typically include ecological monitoring and
impact assessment, research, communication between
parties, policy-making, and enforcement. As a part of
this process, there is a need for adequate and integrated
knowledge at multiple scales of population regulators,
habitat relationships, and potential impacts of human
activity, including harvesting, on the population (Berkes,
2002; Berkes and Folke, 1998).
A case study of the Canadian co-management of the
Porcupine Caribou Herd, toward sustainability under
conditions of climate change, is given in the Appendix.
11.3.2.3. Hunting as a threat to wildlife
conservation
Hunting can become a threat to wildlife conservation if
population size changes unpredictably in response to
environmental perturbations or density dependent
changes (unless the population size is closely monitored
and hunting is adjusted quickly). Most large mammals in
the Arctic are relatively long-lived and thus somewhat
resilient to interannual environmental variability that
may result in loss of a single age class through breeding
failure or heavy mortality of young animals. However,
extreme conditions such as icing of vegetation or deep
snows restricting access to forage may result in near total
mortality across age classes (Miller, 1990) or rarely,
regional extirpation of populations or subspecies (Vibe,
1967). Muskoxen are large-bodied grazers capable of
using low quality forage during winter and with a predominantly conservative lifestyle.Thus, they are adapted
to buffering some of the consequences of variable weather and forage supplies (Adamczewski, 1995; Klein,
1992; Klein and Bay, 1994). Caribou, in their much
greater range of latitudinal distribution (muskoxen are
rarely found in the boreal forests) are less strongly
coupled as a species by feedback loops to their forage
(Jefferies et al., 1992). However, their more energetic
life style, associated with their morphology and behavior,
predisposes them to feeding selectively for high quality
forage, necessitating extensive movements and often long
seasonal migrations between the barren grounds and the
boreal forests (Klein, 1992). Long migrations may be an
evolutionary strategy that buffers localized variables in
forage quality and availability, which may be weatherrelated. Icing of vegetation in winter and fires on winter
ranges in summer are examples of these weather-related
influences on winter forage availability. Caribou are vulnerable to other aspects of weather that affect quality and
availability of forage on calving grounds, the level of
insect harassment and parasitism, and in the Canadian
Arctic Archipelago, freedom of inter-island movement.
In the northernmost arctic islands, environmental vari-
614
ability becomes more significant as many processes are
near their limits of variability, such as plant growth,
which plays a large role in determining herbivore reproduction and survival. Consequently, annual variation in
population attributes such as pregnancy rates and calf
survival is high. For example,Thomas (1982) documented annual pregnancy rates of between 0 and 80% for
Peary caribou and the range in calf production and survival between 1982 and 1998 was 23 to 76 calves per
100 cows for caribou on Banks Island (Larter and Nagy,
1999).The amount of environmental variability may
exceed the capability of large mammals to buffer changes
and lead to unexpected surges in recruitment or mortality. Rate of population change and size will be more
unpredictable and thus hunting will be at more risk of
being out of phase with the population trend. Changes in
caribou numbers on Banks Island is an example of hunting accelerating a decline likely to have already been
underway in response to an environmental change
(severe snow winters). Caribou declined from 11000 in
1972 to perhaps less than 1000 (Nagy et al., 1996; J.
Nagy pers. comm., 2001).
North of Banks Island is the range of the Peary caribou,
which are only found on Canada’s high-arctic islands.
Trends in Peary caribou numbers are only available from
(a)
(b)
Fig. 11.4. Throughout the Arctic, traditional modes of transport
(a) have been largely replaced by mechanized all-terrain vehicles
(b) that permit people in many regions of the Arctic to range
more widely for subsistence hunting.While this spreads wildlife
harvest over greater areas it also requires more extensive survey of the status of wildlife populations as a basis for wildlife
management (photo: D.R. Klein).
Arctic Climate Impact Assessment
the western high-arctic islands where numbers have fluctuated within a long-term decline from 26000 in 1961
to 1000 by 1997 (Gunn et al., 2000). In 1991,
the Committee on the Status of Endangered Wildlife in
Canada classified caribou on the high-arctic and Banks
islands as Endangered based on the steep population
declines during the 1970s and 1980s.This was believed
to have been caused by climatic extremes – warmer than
usual autumn storms causing dense snow and icing,
which limit access to forage (Miller, 1990).
Institutional circumstances that may lead to wildlife vulnerability to hunting start with limitations in the ability
to detect population declines. Detecting declines in caribou or muskox numbers partly depends on recognizing
trends in population size (Graf and Case, 1989; Heard,
1985).The aim is to conduct regular surveys, but high
costs and large survey areas have increased survey intervals to the extent that population changes have been
missed. For example, the inter-island caribou population
of Prince of Wales and Somerset Islands was considered
to be relatively stable between 1974 and 1980 (estimated at 5000 caribou in 1980). In the early 1990s, Inuit
hunters reported seeing fewer caribou on those two
islands, which triggered a survey, but not until 1995.
The survey revealed that caribou had declined to less
than 100 (Gunn et al., 2000).
Problems with detecting population declines are not just
technical. Hunters frequently distrust survey techniques
and disbelieve the results, especially when declines in
caribou are reported (Klein et al., 1999), but the same
may be true for muskoxen and hunted whales (Richard
and Pike, 1993). Disbelief stems from historical relationships that have involved poor communication, as
well as cultural differences in relying on abstract concepts and numbers as opposed to personal observation.
Further differences arise over interpretation of factors
causing declines – for example, whether caribou have
moved away from the survey area or whether numbers
declined because deaths exceeded births (Freeman,
1975; Miller and Gunn, 1978). However, merging
information derived from scientific investigation and
existing weather records with information gleaned from
indigenous hunters is increasingly employed as a tool in
monitoring wildlife population response to climate
change (Ferguson and Messier, 1997; Kofinas, 2002).
Socio-economic factors can affect the vulnerability of
wildlife to hunting.The two territories of NWT and
Nunavut have been described as having a “Fourth World”
economy (Weissling, 1989) with the indigenous population often forming enclaves within the larger communities that are economically dominated by the North
American society.The growing human population in the
north, nevertheless, remains heavily dependent on hunting and fishing (Bureau of Statistics, 1996). At present,
wage earning provides the cash needed for the purchase
and operation of equipment and supplies necessary for
hunting and fishing, which have become highly dependent
on mechanized transport (Wenzel, 1995) (Fig. 11.4),
Chapter 11 • Management and Conservation of Wildlife in a Changing Arctic Environment
which in turn creates the need for at least part-time
work. However, wage-earning opportunities are relatively
limited, shifting the emphasis to commercial use of wildlife and fisheries, but the distinction between subsistence
and commercial use is by no means simple. In West
Greenland, for example, small-scale sales of minke whales
(Balaenoptera acutorostrata) and fin whales (B. physalus)
were considered necessary to maintain cash flow to purchase supplies for subsistence hunting (Caulfield, 1993).
But managing for commercial use that is not focused on
maximizing profits is inconsistent with systems for management of commercial harvest. Clark (1976) explained
the economic rationale for the ease with which commercial harvesting can lead to over-harvesting, especially for
long-lived species with low rates of reproduction.
Finally, a mixture of concern and defensiveness exists in
response to “outside” (i.e., southern Canada and elsewhere) views or opinions about wildlife harvest and
management. In a workshop on future action over the
endangered Peary caribou, this was recognized as a serious issue (Gunn et al., 1998), especially in the context
of allowing caribou hunting while considering reduction
of wolf predation through translocations or other predator control methods. Response to “outside” opinions
stems partly from previous experience with some organized animal rights activists and some who see hunting as
a threat to animal welfare or conservation. Indigenous
hunters, who view their dependency on local resources
as sustainable in contrast to the heavy dependency by
southern urban dwellers on nonrenewable resources,
perceive such urban-based organizations as a threat to
their way of life.This view has proven to be the case, for
example in the movement against seal hunting that led
to the European Common Market’s ban on seal skins,
which resulted in a substantial loss of income from sealskins in some Inuit communities (Wenzel, 1995).
11.3.2.4. Additional threats to wildlife
conservation
The risk that hunting can become unsustainable and
cause or contribute to population declines may lie in the
unexpected (Holling, 1986).The unexpected ranges
from shortcomings in data collection or predictive models, to environmental changes accumulating in unanticipated ways not encompassed by traditional knowledge.
Within this context, this includes threats to wildlife
from outside the Arctic, such as atmospheric transfer of
contaminants and climate change, even if there is uncertainty as to how those threats may unfold in practice.
However, management of use of wildlife and associated
conservation of wildlife is most difficult in the absence
of available methods to monitor both the harvest levels
and the status of the populations that are harvested.
Global climate change and the atmospheric transport of
contaminants are factors that are already affecting some
arctic populations. Global warming in the near future is
projected to trigger a cascade of effects (Oechel et al.,
1997). Evidence consistent with projections of global
615
climate change in the western Arctic includes Inuvialuit
reports of ecological changes such as the appearance of
previously unknown birds and insects following trends of
warmer weather (IISD, 1999). Along the mainland central arctic coast, Inuit are expressing concerns for the
deaths of caribou crossing sea ice as freeze-up is later
and break-up earlier than before (Thorpe, 2000).
Sustainability of wildlife for hunting can be affected by
influences of climate change on the hunted populations.
For example, an increased difficulty in finding winter
forage is likely for caribou on the western arctic islands
if warmer temperatures bring a greater frequency of
freezing rain and deeper snow. Annual snowfall for the
western high Arctic increased during the 1990s and the
three heaviest snowfall winters coincided with Peary
caribou numbers on Bathurst Island dropping from
3000 to an estimated 75 caribou between 1994 and
1997. Muskoxen declined by 80% during the same three
winters (Gunn et al., 2000).
Atmospheric and aquatic transport of contaminants has
resulted in contaminants reaching detectable levels in
arctic wildlife (AMAP, 1997, 2002; Elkin and Bethke,
1995), although effects on population ecology are poorly
understood. Although many contaminants that may be
detrimental to living organisms are of anthropogenic
origin, many derive from natural sources. Persistent
organochlorine compounds are carried in the atmosphere, but cadmium is almost entirely from natural
sources and mercury is from ocean degassing, natural
breakdown, and atmospheric and anthropogenic sources
(AMAP, 1997). Bioaccumulation of contaminants can
reach levels in marine mammals that pose threats to
humans who consume them, especially pregnant and lactating women and their infants (see Chapter 15).
If global warming imposes increased environmental
stress on wildlife it is likely to interact with contaminants. For example polar bears, at the top of the marine
food chain, accumulate contaminants by eating ringed
seals (Phoca hispida) and other marine mammals. Relatively high levels of organochlorine compounds and metals are found in polar bears, with relatively strong
regional patterns (AMAP, 1997). In female polar bears,
although the existing body levels of organochlorine compounds may be sequestered effectively when fat reserves
are high, the sequestration away from physiological pathways may be inadequate during a poor feeding season
(AMAP, 1997; Polischuk et al., 1994). On western
Hudson Bay, there is a trend for female bears to have less
fat reserves as sea ice break-up occurs progressively earlier, forcing them ashore where they are required to fast
for increasingly longer periods (Stirling et al., 1999).
How contaminants in marine systems may change with a
changing climate, and what may be the consequences for
wildlife and the humans who consume wildlife is not
understood, yet an understanding of the nature of the
threats posed by contaminants in arctic systems and the
processes and pathways involved is critical for the management and conservation of arctic wildlife.
616
Arctic Climate Impact Assessment
11.3.3.The Fennoscandian North
kill individual large carnivores or groups of them regardless of the status of the species. No wolves have been
permitted to reestablish in the Saami reindeer herding
areas, which lie north of approximately 63º N.
11.3.3.1. Management and conservation of
wildlife under change
In the boreal forest and mountainous areas of northern
Fennoscandia the major hunted wildlife species are
moose, grouse, dabbling ducks and some diving ducks,
and bean geese (Anser fabalis).There is increased interest,
largely among urban dwellers, to conserve large carnivores.These predatory species are now recovering from
high hunting pressures during past decades by farmers
and reindeer herders in defense of their livestock.
Nevertheless, there have been centuries-long habitat
changes in the Fennoscandian Arctic brought about by
human activities, including community development and
expansion, road and other transportation corridor construction, hydropower development, mining, tourism
development, forest clearing, and establishment of military training or test sites (Fig. 11.5).This has resulted in
substantial reduction of available habitat for wildlife as
well as fragmentation of existing habitats.The consequences for wildlife have been limitations on the freedom of seasonal movements of wildlife, as well as
restricted dispersal, and associated genetic exchange,
fragmentation of wildlife populations, and lowered overall productivity of the land and waters of northern
Fennoscandia for wildlife.
In Norway and Sweden, wolves were completely exterminated during the mid-20th century. Animals from
Finland/Russia have recently recolonized the southern,
forested part of the peninsula. Bears (Ursus arctos) were
exterminated in Norway, except for a small population
on the border with Russia and Finland. Recovery of
bears by dispersing animals from Sweden has occurred
in some border areas farther to the south. Decisions
have been made that determine areas in which these
predators will be tolerated and areas where they will be
excluded, largely on the basis of the presence of freely
ranging domestic livestock and Saami reindeer. In the
exclusion zones in Norway, targeted hunts are held to
1900
1940
The climate record and outputs from climate models
(Chapter 2 and 4) indicate little change in temperature
patterns in northern Fennoscandia in recent decades, in
contrast to other parts of the Arctic. Similarly, models
projecting future climate trends in the Arctic suggest
slow rates of warming in Fennoscandia. An exception is
the north coastal region of Norway where models project substantial increases in winter temperature and precipitation.The effects of global warming in the region
include ablation of mountain glaciers, altitudinal
advances in the treeline, increases in magnitude of defoliating insect outbreaks, and, possibly, a decline in the
frequency and magnitude of small mammal population
cycles (see Chapter 7).Thus far, there has been little
serious research effort focused directly on how changing
temperature and precipitation will influence wildlife
populations in Fennoscandia.
11.3.3.2. Hunting systems
In general, the moose hunt is based on licenses issued by
the regional governments to hunting teams. Each license
allocates the number of moose to be harvested from the
specific land area for which the license is issued, whether
it is private or government owned land.The hunting quota
is based on population estimates derived from hunter
observations and aerial surveys, including assessment of
sex and age composition, but consideration is given to the
number of traffic accidents and damage done by moose to
forest stands.The timing and length of moose hunting seasons vary within and between countries.
Large carnivore populations are estimated through
observations incidental to surveys of other wildlife, local
or regional field studies of carnivore species and their
prey relationships, and other techniques. Hunting quotas
and conservation measures are based on population esti1990
1998
CAFF Boundary
Wilderness areas
Fig. 11.5. Natural habitat fragmentation in northern Norway is exemplified by the decrease in wilderness areas in Norway north of
the CAFF boundary since 1900.Wilderness is defined as an area lying more than five kilometers from roads, railways, and regulated
water-courses (Norwegian Mapping Authority as quoted in CAFF, 2001a).
Chapter 11 • Management and Conservation of Wildlife in a Changing Arctic Environment
mates, reproductive rates, and levels of predation on
reindeer, sheep, and other domestic animals.
The hunting system for ptarmigan and grouse rests
primarily on setting of the hunting season dates, which
traditionally fall between late August and mid-February.
In some areas there is a bag limit, often based on local
monitoring programs. Grouse hunting in mountain areas
is currently undergoing discussion and the different
hunting systems are under evaluation from both the biological and hunters’ perspectives.
Wildlife management for hunter harvest of ducks is
based primarily on setting the start and duration of the
hunting season within the period from late August
through late November. Some areas are closed to hunting, including areas around villages.
11.3.3.3. Monitoring systems
In the Fennoscandian countries there is a strong tradition
for hunters to report the number of animals killed, and
hunters voluntarily assist in wildlife surveys.This is a
valuable aid to wildlife management in Finland, Sweden,
and Norway and efforts continue to improve the hunter
reporting system to ensure greater reliability of the
information obtained. Systems for monitoring the
population status of moose and large carnivores are
among the most highly developed, whereas the least
developed system is for ducks, with systems for monitoring ptarmigan and grouse populations intermediate.
There is a concern in some areas of the Arctic that these
hunter-based systems will be less effective because many
young hunters who were born and raised in the rural
areas of the North, and having familiarity with the specific wildlife habitats and wildlife of their region, are
moving to urban areas to seek employment. Consequently, the number of hunters living close to the land in the
Fennoscandian Arctic is decreasing while those from
urban centers outside the region are increasing.
11.3.3.4. Flexibility of hunting systems under
climate change
With increasing temperatures, in concert with other
long-term changes, such as wetland eutrophication,
populations of some waterfowl species, for example
whistling swans (Cygnus columbianus), eider ducks
(Somateria spp.), and greylag geese (Anser anser), are
expected to increase in size and to expand their distribution. Consequently, there will be demand for hunting
opportunities on these species in areas where today there
is no hunting.The procedure for establishing hunting regulations under the present system should be adaptable to
allow changes in hunter harvest levels to ensure optimal
sustainable harvest through hunting of these waterfowl
species. Restrictions on hunting have also allowed
recovery of species such as common eider (Somateria
mollissima) and barnacle goose (Branta leucopsis) that nest
in the high Arctic, to the point where it may be justified
to reconsider opening hunting seasons on them.
617
Adjustments in moose hunting in response to moose
population changes can be achieved through flexibility in
establishment of hunting quotas. However, some difficulties can be foreseen. For example, if temperatures during the early part of the hunting season are high there
may be difficulties preserving the meat in the field without access to cold storage rooms.This may limit hunting
to periods of suitable weather before snow accumulation.This might make it difficult for small hunting teams
to fill their quotas. If snow arrives early in the autumn/
early winter, access to the hunting grounds may be limited due to difficulties for vehicle travel on logging roads.
For the large carnivores, there is similar flexibility in the
establishment of hunting quotas.
For grouse and ducks, discussions on hunting regulations
mainly concern timing of the hunting season. If the season
starts too early the birds are still unfledged and considered
too small to hunt. If the hunting season starts too late in
the North migratory birds may have already moved south.
Possibilities exist to adjust hunting and the associated
management systems in the Fennoscandian North to
changes in wildlife populations that may result from the
effects of climate change. However, social and economic
factors that relate to the various interests in wildlife by
local residents and those who come from outside the
region also need to be considered in developing wildlife
management plans. Management of wildlife in the
Fennoscandian Arctic under conditions of a changing climate must be “adaptive” and thus capable of responding
to changes in ecosystem dynamics that at times may be
unpredictable and therefore unanticipa