CHAPTER 1
2 Regulating services are provided
when ecosystems provide an
indirect service of human benefit,
such as carbon sequestration or
flood control.
3 Cultural services are provided by
the beauty and cultural, or even
religious, value of landscapes
and their flora and fauna.
Figure 1.7 assesses the Arctic’s
value in relation to these three types
of ecosystem services.
References
ACIA (2005) Arctic Climate Impact
Assessment. Scientific Report.
Cambridge: Cambridge
University Press.
CIA (2010) The World Factbook. Available
online at www.cia.gov/library/
publications/the-world-factbook/index.
html (last accessed 14 May 2010).
Duhaime, G. (2004) ‘Economic systems’
in Arctic Human Development Report.
Akureyri: Stefansson Arctic Institute.
Also available online at http://hdr.
undp.org/en/reports/regionalreports/
other/arctic_2004_en.pdf (last
accessed 14 May 2010).
GRID-Arendal (2004) Vital Arctic Graphics.
Available online at http://maps.grida.
no/go/collection/vital-arctic-graphics2004-edition (last accessed 14
May 2010).
Millennium Ecosystem Assessment
website: www.millenniumassessment.
org/en/index.aspx (last accessed 14
May 2010).
THE RAPIDLY CHANGING ARCTIC
2. Arctic climate and physical systems
ACTIVITY BOX 1
1 Understanding ACIA
a) Visit the Arctic Monitoring
and Assessment
Programme website (http://
amap.no/acia) and download
‘Impacts of a Warming
Arctic – Highlights’. This
is a 20-page summary of
the 1000-page ACIA
main report.
b) Use the images in the
document to write a brief
description of the physical
geography of the Arctic.
c) Using one side of A4
paper, make a list of
the key impacts of a
warming Arctic.
WWF International Arctic Programme
(2004) Cruise Tourism on Svalbard:
A risky business? Oslo: WWF
International Arctic Programme.
Also available online at http://
assets.panda.org/downloads/
wwfcruisetourismonsvalbard2004_
v5p3.pdf (last accessed 14 May 2010).
2Produce a factfile on the Inuit
people, which outlines the
nature of the lifestyle, culture
and beliefs. Use the internet
as a starting point for your
research.
3Download the 2004 Arctic
Human Development Report
from http://hdr.undp.org/en/
reports/regionalreports/other/
arctic_2004_en.pdf. Read the
introduction section to gain
a greater understanding of
Arctic geography.
4 Visit the NASA website (http://
earthobservatory.nasa.gov/
Features/Milankovitch) and
investigate the work of Milutin
Milankovitch in more detail.
Extra resources to accompany
this chapter are available on
the Top Spec web pages.
See page 4 for further information.
The climate of the Arctic is
characterised by long, dark winters
with little radiation receipt and
short, light summers. Above
66° 33'N (i.e. the Arctic Circle),
the sun is below the horizon at
midday in midwinter, whereas it is
above the horizon at midnight on
midsummer’s day.
These long, dark winters and
short, light summers are caused
by the nature of the Earth's orbit
around the Sun and its own axial
rotation tilted at 23° (see Figure 1.4)
to this orbital plane. The conditions
in December and June vary both in
the maximum daily solar altitude of
the Sun and in the intensity of the
solar radiation.
The reduced receipt of solar
energy in the Arctic compared
to temperate and tropical latitudes
because of low solar angles
results in low temperatures and
the formation of snow, ice and
permafrost (the cryosphere). Large
areas of the Arctic are covered by
snow and ice over a long period of
the year (see below), resulting in
high albedo, i.e. a large portion of
the sun’s energy is reflected back to
the atmosphere instead of heating
the surface.
Climate and
atmospheric circulation
The Arctic is the northernmost
component of the Earth’s climate
system. In contrast to the tropical
regions of the Earth that receive
an excess of heat, the Arctic and
Antarctic have a deficit (Figure 2.2).
The 18th-century English
meteorologist George Hadley
proposed an idea that the
Earth could be subdivided into
atmospheric circulation ‘cells’.
Three of these cells redistribute
the energy from the equator
towards the poles via atmospheric
circulation. From the equator to
approximately 30°N there is a cell
12
INFORMATION BOX 2.1 Night all day in winter and day all night in summer
One of the most northerly
settlements is situated on
Svalbard, Norway. The city of
Longyearbyen is located at
78°N and the little more than
2000 inhabitants have to adjust
to extreme light conditions.
Longyearbyen experiences
midnight sun from the end of
April to the end of August, and in
contrast the daylight disappears
completely and polar night
appears from the end of October
to mid-February (Figure 2.1).
a
b
Figure 2.1 Annual contrast with a) polar night at 11.30am; and b) midnight
sun. Both taken at Longyearbyen, Svalbard (78°N). Photos: Marta D. and
Pennina Neumann.
13
CHAPTER 2
THE RAPIDLY CHANGING ARCTIC
Percentage of hemisphere surface
0
25
50
75
INFORMATION BOX 2.2 ATMOSPHERIC CIRCULATION AND WEATHER
100%
2.5
Incoming
1.5
Deficit
1.0
an
Tr
sfe
10
r
0.5
Some aspects of atmospheric circulation in the Arctic
are cyclical and are associated with particular weather
patterns. These circulation patterns can be represented
as indices that compare air pressures at a location
within the Arctic and one outside. Two important
circulation patterns are the North Atlantic Oscillation
2.0
5
0
90º 80º 70º
0
60º
50º
40º
30º
20º
10º
(NAO) and the Arctic Oscillation (AO). The NAO
compares the air pressures in the Azores region with
those in the Icelandic area (Figure 2.4). Positive phases
are associated with warm, wet winters in Central
Europe whereas negative phases are associated with
dry, cold winters.
3.0
NAO Index
Radiation (105 cal/cm2/year)
oing
Outg
Northward energy transfer (1014 cal/sec)
Surplus
2.0
1.0
0.0
-1.0
EQ
-2.0
Latitude (ºN)
Figure 2.2 Excess of heat in the tropical regions and a deficit in the Arctic. Source: Weller, 2000.
-3.0
1900
1920
1940
1960
1980
2000
Year
Polar
Vortex
Polar
Jet Stream
Polar
Cell
H
Polar Easterlies
L
L
L
L
Ferrel
Cell
Westerlies
H
H
H
H
H
Hadley
Cell
Northeast Trades
L
L
L
L
Subtropical
Jet Stream
L
L
H
H
L
Southeast Trades
H
H
H
Westerlies
L
L
L
L
Polar Easterlies
H
Figure 2.3 A simplified schematic of the three cell global surface and upper air
circulation patterns. H denotes areas with constant high pressure (anticyclones)
and L areas where low pressure is frequent (cyclones). Blue arrows denote
downward flow developing an anticyclonic outspiral at low levels due to the high
pressures, whereas red arrows denote upward flow from low pressure areas.
Source: www.physicalgeography.net
14
called the Hadley Cell (named after
the originator of the idea). From 30°
to approximately 60° the Ferrel Cell
transports the air and in the Arctic
it is the Polar Cell that transports
the air and results in constant high
pressures over the North Pole
(see Figure 2.3).
Ocean currents and
sea ice dynamics
Ocean currents play a major role
in Arctic climate as well as in the
global energy balance. The currents
can be thought of as a giant pump
that reduces the large variation in
temperatures that occurs between
the equator and the poles. There are
two main sources of heat brought to
the Arctic Ocean:
• from the North Pacific Ocean
through the Bering Strait
• from the Atlantic, by the current
called the Gulf Stream.
The current that brings heat from
the Bering Strait to the Arctic
Ocean spreads in the upper ocean
of the western Arctic and influences
the thickness of the sea ice in the
Canada Basin. The Norwegian
Figure 2.4 The North Atlantic Oscillation, 1899–2008. The time series expressed as anomalies is shown in colour,
and the station based index is given by the thick blue line. The correlation between the two is 0.90 over 1899–2002.
Source: www.cgd.ucar.edu/cas/jhurrell/indices.info.html#naopcann
Atlantic Current branches into the
West Spitzbergen Current and the
Barents Sea through-flow (Figure
2.5). This inflow is more saline
and circulates deeper in the Arctic
Ocean in a counter-clockwise
direction. It takes decades for the
Atlantic water to reach the interior
of the Arctic Basin. The Arctic
outflow of water through deep
convection is of great importance
to more southerly regions where
cold waters from the Arctic are
discharged (see Information
Box 2.3).
In contrast to the Arctic’s
albedo, which affects the global
energy balance, the thermohaline
circulation simply redistributes the
Earth’s heat, making the Arctic
warmer and the tropics cooler.
The greatest warming is along the
European and Scandinavian coasts
which in Arctic latitudes can have
a mean annual temperature about
Figure 2.5 Currents in the Arctic Region. Red arrows denote warm surface currents
and blue arrows deep, cold currents. Source: National Snow and Ice Data Center.
15