Land Use, Freshwater Flows and Ecosystem Services
in an Era of Global Change
Line Gordon
Doctoral Thesis in Natural Resources Management
Department of Systems Ecology
Stockholm University
SE-106 91 Stockholm, SWEDEN
Stockholm 2003
Doctoral dissertation 2003
Line Gordon
Department of Systems Ecology
Stockholm University
SE-106 91 Stockholm
Sweden
© 2003 Line Gordon
ISBN 91-7265-755-3 pp. 1-34
Printed in Sweden by
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Abstract
The purpose of this thesis is to analyse interactions between freshwater flows, terrestrial
ecosystems and human well-being. Freshwater management and policy has, in the
past, mainly focused on the liquid water part (surface and ground water run off) of
the hydrological cycle and on aquatic ecosystems. Although of great significance, this
thesis shows that such a focus will not be sufficient for coping with freshwater related
social-ecological vulnerability. The thesis illustrates that the terrestrial component of
the hydrological cycle, reflected in vapour flows (or evapotranspiration), serves multiple
functions in the human life-support system. A deeper understanding of the interactions
between terrestrial systems and freshwater flows is particularly important in light of
present widespread land cover change in terrestrial ecosystems.
The water vapour flows from continental ecosystems were quantified at a global scale
in Paper I of the thesis. It was estimated that in order to sustain the majority of global
terrestrial ecosystem services on which humanity depends, an annual water vapour flow
of 63 000 km3/yr is needed, including 6800 km3/yr for crop production. In comparison,
the annual human withdrawal of liquid water amounts to roughly 4000 km3/yr. A
potential conflict between freshwater for future food production and for terrestrial
ecosystem services was identified.
Human redistribution of water vapour flows as a consequence of long-term land cover
change was addressed at both continental (Australia) (Paper II) and global scales (Paper
III). It was estimated that the annual vapour flow had decreased by 10% in Australia
during the last 200 years. This is due to a decrease in woody vegetation for agricultural
production. The reduction in vapour flows has caused severe problems with saline soils.
The human-induced alteration of vapour flows was estimated at more than 15 times the
volume of human-induced change in liquid water (Paper II).
At a global level, it was found that deforestation from pre-agricultural times to the
present has caused a 4% decrease of vapour flows (Paper III). The increased vapour
flows from irrigated agriculture are of the same magnitude the decreased vapour flows
from deforestation. The results are geographically explicit and illustrate that a largescale human-driven global redistribution of vapour flows has occurred. Some regions
are experiencing a substantial decrease in vapour flows while others are experiencing
considerable increases.
The current redistributions of freshwater flows are substantial and have led to
unintentional side-effects on regional climates, water availability for societal production,
loss of productive capacity of the land and ultimately on social and economic
performance (Paper IV and V). An overarching question that has emerged during the
work with this thesis is whether the attempts by human society to fulfil the needs and
wants of its population, with regard to extraction of freshwater and ecosystem services
in the short term, are increasing societal vulnerability at a different temporal and spatial
scales (Paper V).
The complexity of the interactions between ecosystems and water flows and the
difficulty of monitoring their change clearly illustrates the need for an adaptive,
learning-based approach to management of the ecohydrological resource base that goes
beyond the scale of the drainage basin. There are several lessons to be learned from new
initiatives in adaptive management and management of common pool resources. With
the present high level international attention on freshwater issues right now there is a
window of opportunity for tackling these issues.
5
Table of contents
Abstract
5
List of Papers
8
Introduction
9
A time of global change – setting the scene
10
This is an interesting time to live, it is a time of rapid environmental change
10
Unfortunately, this is also a time of freshwater and environmental crises
10
Environmental change is inevitable
11
Change can give opportunity for human rethinking and reorganisation
Scope of the thesis
11
13
Human dependence on freshwater – broadening the perspectives
Freshwater for ecosystem services 15
Quantifying human dependence on freshwater for terrestrial ecosystem services
Quantifying freshwater needs for food production
16
17
Alterations of vapour flows through land cover change and tion 17
Quantifying vapour flow alterations at a continental and global scale
18
Cross-scale effects of changes in water vapour flows 19
Vegetation – river interactions
20
Vegetation – atmosphere interactions
Vegetation – soil interactions
21
Moving closer to thresholds
22
Concluding remarks
23
20
References 25
Acknowledgements
32
7
13
List of Papers
This thesis is based on the following papers, which are referred to in the text by their
Roman numeral:
I
Rockström, J., Gordon, L., Folke, C., Falkenmark, M., Engwall, M. 1999.
Linkages among water vapour flows, food production and terrestrial ecosystem
services. Conservation Ecology 3: 5. [online] http://www.consecol.org/vol3/iss2/
art5
II
Gordon, L., Dunlop, M., Foran, B. 2003a. Land cover change and water vapour
flows: Learning from Australia. Philosophical Transactions of the Royal Society
B
III
Gordon, L. Jönsson, B.F., Johannesen, Å., Steffen, W., Falkenmark, M.
and Folke, C. Large scale redistribution of global water vapour flows by
deforestation and irrigation. Manuscript prepared for Global Environmental
Change
IV
Gordon, L., Folke, C. 2000. Ecohydrological landscape management for human
well-being. Water International 25(2): 178-184
V
Gordon, L. 2003. Communication: Moving closer to social-ecological
thresholds? Freshwater and the resilience of terrestrial ecosystems. Ecological
Applications, submitted
The published and accepted papers are reprinted with the kind permission of the
publishers.
8
Introduction
Natural resources management is often characterised by partial views of the life-support
system that sustains society and there has been a general lack of integrative theories that
span over disciplines and deal with social-ecological sustainability (Holling and Meffe
1996, Gunderson and Holling 2002). This is the case for freshwater issues where our
understanding of human dependence on the hydrological cycle has been fragmented and
sectorial (Falkenmark 1997a). The purpose of this thesis is to broaden our understanding
of human dependence on the interactions of terrestrial ecosystems and freshwater flows,
in a time of rapid global social-ecological change. The thesis emphasises the need for a
more integrated, less sectorial view of the ecohydrological landscape in which human
activities take place and it mainly focuses on a global and continental scale.
This thesis illustrates that freshwater has multiple functions in the human life-support
system. It broadens the view of freshwater from seeing it merely as an economic good and
input for societal production, to an understanding of freshwater as the bloodstream of
the biosphere on which all human activities ultimately depend. An overarching question
that has emerged during this work is whether the attempts by human society to fulfil
the needs and wants of its population, with regards to extraction of ecosystem services
and freshwater, are increasing societal vulnerability at a different temporal and spatial
scale. The complexity of the interactions between ecosystems and water flows, and the
difficulty in monitoring their change clearly illustrates the need for an adaptive, learningbased, approach to management of the ecohydrological resource base, an approach that
goes beyond the drainage basin.
In this summary of the thesis it is emphasised that we live in a time of rapid
environmental change, which is a time of crises, but also provides an opportunity for
addressing new emerging questions in a less sectoral fashion. The main results of the
thesis are presented in three sections. First it is illustrated that humanity depends on
much more freshwater than what has previously been recognised, especially taking into
account the freshwater needs of terrestrial ecosystems, which generates life-supporting
services for humanity. The human transformation and redistribution of freshwater flows
as a consequence of land cover change is addressed in the next section, with specific
focus on change of water vapour flows. These kinds of changes can cause side-effects on
different temporal and spatial scales. This is illustrated in the third section of the results
and it is hypothesised that the large-scale human redistribution of freshwater flows has
moved systems closer to thresholds, making them more vulnerable to change. Finally, the
9
implications of these findings are viewed in the light of recent emerging initiatives that
concern management of complex dynamic systems.
A time of global change – setting the scene
This is an interesting time to live, it is a time of rapid environmental change
We are currently experiencing an unprecedented alteration of human – nature
interactions even at a global scale. Humanity has transformed two thirds of the Earth’s
surface, increased the carbon dioxide in the air by 30% and more than doubled the
amount of nitrogen sequestered every year at a global scale (Vitousek et al. 1997).
Human freshwater use has increased rapidly (Shiklomanov 2000, L’vovich and White
1990, Gleick 1993) and we now appropriate 54% of globally accessible runoff for use
in households, industry and irrigated agriculture (Postel et al. 1996). At the same time,
we are growing more food than ever before and there has been a rapid increase in global
food production and yields since industrialisation of agriculture (Faostat 2003). The
need for human labour in cultivating food has decreased rapidly (Redman 1999). The
present level of global communication has made even local information and knowledge
about resource extraction and ecosystem conditions increasingly available at a global
scale.
These changes are for better and for worse, but they illustrate the ubiquitous influence
of human activities on the biosphere (Vitousek et al. 1997, Turner et al. 1990). Humanity
is now a major force in the functioning of the Earth’s system (Turner et al. 1990, Tyson
et al. 2001, Steffen et al. 2003). This era has even by some scholars should be termed
Anthropocene in order to illustrate the ubiquitous human influence on the planet
(Crutzen and Stoermer 2000). At the same time we are, and always will be, dependent
on nature for the generation of ecosystem goods like food, fibre and timber, and for
services like carbon sequestration, pollination and photosynthesis (Daily 1997, Jansson
2002, Limburg and Folke 1999).
Unfortunately, this is also a time of freshwater and environmental crises
During the last decade, the global freshwater crisis (Gleick 1993) has been the focus
of substantial research efforts. There have been several reviews of human alterations
of rivers and runoff focusing on human water use, withdrawal and appropriation of
freshwater (Gleick 1993, Shiklomanov 2000, Postel et al. 1996). It has been estimated
that a large part of the global population already experiences water stress and that this
will increase by 2025, primarily as a result of population growth (Vörösmarty et al.
2000). Water will become a major constraint on global food production (Falkenmark
1986, Postel 1998) and it has been estimated that by 2025, 55% of the world population
will live in countries that can not be self-sufficient in food production due to difficulties
to mobilise water needed for irrigation (Falkenmark 1997b).
Humans have also transformed considerable parts of global freshwater systems often
with unanticipated side-effects (c.f. Jackson et al. 2001a, special issue in BioScience
(Rosenberg et al. 2000), special issue in Aquatic Sciences (Pahl-Wostel et al. 2002),
10
L’vovich and White 1990). Riverine systems have been altered substantially at a global
scale through e.g. habitat fragmentation in dammed rivers (Dynesius and Nilsson 1994),
consumptive use of freshwater leading to river depletion (L’vovich and White 1990), and
ageing of runoff due to storage in reservoirs (Vörösmarty 1997). Pollution loads in rivers
have increased (Meybeck 2003), in some regions even to a level where pesticides can be
found in bottled water (Pangare 2003).
We are also facing immense ecological problems like overexploitation of world fisheries
(Jackson et al. 2001b), rapid decline of biodiversity (Barbier et al. 1994), and climatic
change (Watson et al. 2001), just to mention a few. Humanity has modified disturbance
regimes and added new ones through e.g. climatic change and invasive species, while
the resilience of ecosystems, i.e. their capacity to absorb changes and disturbances, has
decreased in various regions and biomes (Gunderson and Holling 2002, Nyström et
al. 2000). These are things that decrease the natural capital and its capacity to sustain
human wellbeing (Daly and Cobb 1989, Folke 1991, Jansson et al. 1994) and may lead
to societal vulnerability (Kasperson et al. 1995).
Environmental change is inevitable
Although the scale of the human enterprise has rapidly increased during the last century,
this transformation of the Earth’s System does not occur in a vacuum. Since the beginning
of human society, nature has set preconditions for its development and human ingenuity
has shown a great ability in shaping and altering these preconditions (Redman 1999,
McIntosh et al. 2000, Grimm et al. 2000, Berkes et al. 2003, Berkes and Folke 1998).
Manipulation of the landscape for production of resources is unavoidable (Falkenmark
1997a, 1999) and environmental change is an inherent part of social-ecological system
development.
One of the greatest challenges facing humanity today is how to maintain the
generation of ecosystem goods and services while absorbing and shaping change to stay
on sustainable pathways of societal development (Gunderson and Holling 2002, Folke et
al. 2002). This challenge is enormous, especially considering the need for increased food
production for a growing world population (Rockström 2003), since this will require
further human appropriation of resources. This sets the scene for the start of this thesis.
Change can give opportunity for human rethinking and reorganisation
The large-scale social-ecological crises, now also experienced at a global scale,
highlight the need for better knowledge and understanding as well as new approaches
to management of social-ecological systems. The anthropocene is an era where most
aspects of the structure and functioning of Earth’s ecosystems cannot be understood
without accounting for the strong influence of humanity (Folke et al. 2002). This in turn
also requires a historical understanding of social-ecological relations as well as of the
perceptions that shape our relationship with nature (Reuss 2000, van der Leeuw 2000).
One way of addressing these relations is through the “pre-analytic visions” (Daly and
Cobb 1989), or mental conceptual worldview, that frame and shape the way in which
we relate to the environment. In this thesis our “pre-analytic visions” are addressed by
efforts in illuminating the ubiquitous influence of humanity on the hydrological cycle.
11
Figure 1. The partitioning of precipitation between the liquid water flows (ground water and surface
run off, or “blue water flow”) and the water vpour flow (evapotranspiration or “green water flow”).
The global environmental and freshwater crises have opened windows of opportunity
for reorganisation and there are several initiatives taking place today at a global scale.
The Millennium goals set up by the United Nations is one example, and the large
programmes The International Panel of Climatic Change (IPCC) and The Millennium
Ecosystem Assessments (MA) are others. United Nations has called this year (2003) the
”International year of freshwater” and freshwater resources management was one of five
prioritised areas at the Johannesburg Summit 2002.
This reorganisation also requires rethinking, and one question to ask is whether
we are discussing the right issues, or at least if there are other issues that need more
attention. One issue that only recently has been included in international freshwater
discussions is land use in relation to freshwater use and availability. Calder (1999) calls
this inclusion of land use a “blue revolution”. Even though land use has not received
proper attention until recently the need for this approach has been emphasised earlier
(e.g. L´vovich 1973).
During the period that the papers of this thesis has been written, the importance of
land use for freshwater and ecosystem management has become even more appreciated
and several new attempts have been made to increase understanding of these relations
(c.f. Falkenmark et al.1999, Falkenmark and Rockström 2003, special issue in Ecological
Applications (Baron et al. 2002), special issue in Transactions of the Royal Society of
London B (Falkenmark and Folke 2003)). Right now there is a window of opportunity
to make real progress in this area of research.
12
Scope of the thesis
A major challenge presently facing humanity, as described above, is to maintain the
capacity of ecosystems to generate goods and services (including food production) in a
time of rapid change. This thesis addresses this challenge by increasing the understanding
of human dependence on freshwater for ecosystem services with a focus on terrestrial
ecosystems, including croplands. Both quantitative and qualitative aspects are addressed,
primarily in Papers I and IV.
The thesis also quantifies the extent to which freshwater that flows from the ground
to the atmosphere has been altered by human activities at a continental (focusing on
Australia) and global scale. Today, humanity redirects water flows in several other ways
than just withdrawal of water from rivers and aquifers as land cover change, land use
and irrigation are such pervasive activities. The question is if these changes of freshwater
flows are large enough to become an important issue for management. To what extent do
humans influence water flows through land cover changes? Is it at a comparative scale
relative to liquid water usage or is it more or less negligible? This is mainly addressed in
Papers II and III.
The thesis also outlines a general understanding of potential side-effects of these
alterations and the consequences of human redistribution of water flows in the
landscape. This is primarily addressed in Papers IV and V. Paper V can almost be seen
as the conclusions of this thesis. It is hypothesised in Paper V that several regions might
be moving closer to undesirable social-ecological thresholds as a result of the widespread
redistribution of freshwater flows. A framework is suggested that addresses the inherent
cross-scale issues in freshwater management. Hopefully, this thesis can contribute to an
emerging understanding of the interactions of humans, land use and freshwater, and by
doing so help shape the way the ecohydrological landscape is managed to strengthening
rather than reducing social-ecological resilience.
Human dependence on freshwater –
broadening the perspectives
In the mid-1990’s Professor Malin Falkenmark coined the concepts “green water” (water
vapour flow) and ”blue water” (liquid water flow) ( Figure 1, from Paper I) (FAO 1996).
Green water is the flow of water from the ground to the atmosphere and blue water is
the regional groundwater and surface run off. In this thesis they are referred to as vapour
and liquid water flows. Falkenmark and colleagues have illustrated that one of the
problems with most water assessments and estimates of human water use is that they are
limited to liquid water, which only constitutes a small part of the annual renewable water
cycle (Figure 2, in Paper II). Falkenmark and Rockström (1993) showed, for example,
that there are four different types of water scarcity: A) short growing seasons, B) strong
risk or recurrent droughts, C) desiccation of the landscape due to soil mismanagement,
and D) limited water surplus feeding rivers and aquifers. Only one of these types (D)
relates to available liquid water and this is the one most often addressed (Falkenmark
and Rockström 1993).
It has been suggested that the annual global renewable liquid freshwater that is
accessible for human withdrawal amounts to 12 500 km3/yr (Postel et al. 1996). The
13
Table 1. Examples of interactions of freshwater and ecosystems that support the generation of
ecosystem services (modified and expanded from Gordon and Folke 2000).
Water movement
in the landscape
Elementary ecosystem
services
Seed dispersal
Colonisation of new
areas/ recolonisation after
disturbance
Water availability CO2-uptake
in the soil
Seed germination
Dynamics of
water
Facilitation of
water availability
for plant
production
Example of biomes where
the service is generated
Terrestrial
Terrestrial
Forest, lakes
Photosynthesis
Natural habitats –
croplands
All
Fish and meat production
Lakes, oceans, rangelands
Denitrification
Wetlands
Pest insect control
Natural habitats –
croplands
Nutrient release through
biodegradation
All
Facilitation of infiltration and Forests, grasslands
soil protection
Examples of freshwater
involvement
Transportation by surface
runoff
Transportation by surface
runoff
Freshwater is needed in
the soil for utilization in
transpiration, photosynthesis
etc.
Provides moist environments
Transpiration, split of H2Omolecule
Habitat, soil moisture in
rangelands can affect ratio
of palatable grass to shrubs,
watering points
Provides the interface of oxic
and anoxic environments
needed for denitrification to
occur
Interactions between dry/wet
periods can control pest
outbreaks
Important for ability of crops
to utilise water in the soil
Plants and microorganisms
increase soil permeability and
interception
amount of water withdrawal at a global level has increased from 104 km3/yr in the
year 1680, to 654 km3/yr at the turn of the 20th century and has since then risen rapidly
(L´vovich and White 1990). Some estimates indicate that humans now appropriate 3600
- 6780 km3/yr, the largest number includes instream dilution of pollution (L´vovich and
White 1990, Shiklomanov 1993, Postel et al. 1996).
Some of the water withdrawn can be recycled within society or returned to rivers
and aquifers (i.e. form return flow). This is however not the case for most of the
water withdrawn for use in agriculture, the sector that has the highest demand on
water withdrawal (e.g. Postel 1992, Pimentel et al. 1997). Agriculture is based on the
unavoidable transformation of water from liquid flows to vapour flows. This has been
termed consumptive water use as the transformation implies an ”irretrievable use of
14
water” (seen from the perspective of the water user) where liquid water is transformed
into vapour (L´vovich 1979). This is a very important distinction between different water
uses as it relates to what happens with water after use – is it returned to the rivers or does
it leave the area as vapour? It has been estimated that consumptive use in irrigation is
roughly 2600 km3/yr (see Paper II), and this is likely to increase with a growing world
population. Considerable changes in liquid water use thus seem unavoidable especially
in several regions facing serious water scarcity problems, with major implications
for their food security (Falkenmark 1997b, Falkenmark and Rockström 1993). Such
estimates of human freshwater use are limited to human water use as an input to societal
production. The essential role of freshwater in the processes of the biosphere serving
multiple functions that support human welfare is taken for granted.
Freshwater for ecosystem services
When this thesis was started, in 1998, the role of freshwater for ecosystem services
had recently been highlighted in international water forum (e.g. Stockholm Water
Symposium) and in scientific papers (Postel and Carpenter 1997, Gleick 1993, Folke
and Falkenmark 1998). This was in line with a current general trend of emphasising the
previously unperceived societal support capacity of ecosystems (e.g. Daily 1997, Baskin
1997, Limburg and Folke 1999). Ecosystems were, however, merely seen as another
sector (in addition to the traditional sectors of households, industry and irrigated
agriculture) that also needed to have access, and in some discussions even the “right”
to water. Although this was an important step forward in linking water and ecosystem
management, the discussions did, and still do mainly refer to aquatic ecosystems (c.f.
Postel and Carpenter 1997, Strange et al. 1999, Naiman and Turner 2000, Wallace et al.
2003, Baron et al. 2002).
This was the starting point for the papers of this thesis. Papers I, IV and V discuss the
role of freshwater for terrestrial ecosystem services. These papers illustrate that water
can be involved in the generation of services in several ways. Freshwater is needed in the
soil as it provides the production medium for vegetation just like it is needed as a habitat
for aquatic organisms. Several species take advantage of the movement of water in the
landscape e.g. for seed dispersal and transportation of organic matter. The dynamics of
freshwater in the landscape is also important. The denitrification process in wetlands is
an ecosystem service that reduces the risk for eutrophication of rivers and coastal areas
and which needs anoxic as well as oxic circumstances. Water can provide this dynamic
environment. The interactions of dry and wet periods in croplands can also help regulate
pests. For other examples, see table 1, based on Paper IV.
A growing understanding of the value of ecosystem services and their link to
freshwater resources has in some cases led to actual changes in the way that natural
resources and the landscape in which they are situated are managed. Paper IV illustrates
the case of the ”Working for Water” program in South Africa, a program with the aim
of reducing invading alien tree species in order to secure downstream water availability
(van Wilgen et al. 1998, Paper IV). In this case ecosystem management rather than
technological measures was initiated in order to secure water resources to downstream
cities. The long-term costs were estimated to be lower when management was based on
ecological knowledge and understanding rather than only engineering science (Cowling
et al. 1997).
15
Quantifying human dependence on freshwater for
terrestrial ecosystem services
Freshwater needs of terrestrial ecosystems do not refer to water withdrawals from rivers
and aquifers, but to the transformation of precipitation to vapour. One of the most well
known quantitative estimates of human dependence on ecosystems is the estimate by
Vitousek and colleagues who found that humans appropriated 40% of the global net
primary production (NPP) (Vitousek et al. 1986). To my knowledge, the only quantitative
estimate of human appropriation of vapour flows for societal support from terrestrial
ecosystems (prior to Paper I of this thesis) is based on this estimate. Postel and colleagues
(1996) estimated that humans appropriate 26% (or 18 200 km3/yr) of the water vapour
flow from terrestrial ecosystems for their use of NPP. The quantitative role of freshwater
flows in terrestrial systems focused only on water used to produce the actual biomass
appropriated by humans from these systems (Postel et al. 1996).
In Paper I, we address water dependence, in terms of the water vapour flow, of the
major terrestrial biomes that support society with the majority of terrestrial ecosystem
services. This is the first quantification of the amount of water needed in order to sustain
the large terrestrial biomes that generate ecosystem services (Paper I). We estimated the
amount of water vapour from these biomes at 63 200 km3/yr (for individual biomes, see
figure 3). In the paper, we also perform the first ”bottom-up” estimation of total water
vapour flows from the continents arriving at 70 000 km3/yr, which is in line with previous
estimates of global water budgets. Our estimation illustrates that human dependence on
freshwater is much larger than previously acknowledged, and that much of the water
perceived as non-used is actually already in use for the human life-support system.
Another focus for quantitative estimates of human dependence on its life-support
system has been the concept of carrying capacity or how large population a certain area
can sustain (Daily and Ehrlich 1992). The concept of carrying capacity has been turned
”upside down” in order to answer the question of how large an area of ecosystem support
is used to sustain a certain population at a fixed level of technology and consumption.
A similar idea was called ”ghost acreage” by Borgström (1967) and indicated the
agricultural area required for human food consumption. Odum (1989) further developed
this approach and used energy requirement for cities (the amount of energy consumed
per unit of area per year) and called this ”shadow area”. The most recent approach to
this concept is the ecological footprint method (Rees and Wackernagel 1994).
The ecological footprint is probably best known for its use in several aspects to reflect
the ecosystem area necessary to sustain current levels of resource consumption and
waste discharge by a given human population (Rees and Wackernagel 1994). In another
collaborative paper (not included in this thesis), we linked the ecological footprint of the
whole population in the Baltic Sea Drainage Basin to the need for freshwater to sustain
the productive capacity of the footprints (Jansson et al. 1999). It was found that the
footprint areas depended on a volume of vapour that is more than 50 times larger than
the amount of liquid water used directly in society (this study is further referred to in
Paper IV). By linking freshwater needs to the ecological footprint we could analyse the
water vapour dependence of the people in the region.
These kinds of quantitative analyses illuminate the ”hidden” ecosystem requirements
(just like the concept of ecosystem services), demonstrating that human activities can
not function without ecosystem support and can provide important information about
16
ecological constraints that may otherwise be overlooked in ecosystem management
(Deutsch et al. 2000). They are also important tools in shaping the “pre-analytic
vision”, or conceptual mindset, in policy making and can hopefully help reduce the
ecohydrological illiteracy that exists in many parts of society.
Quantifying freshwater needs for food production
Food production is generally recognised as the largest liquid water user (Postel 1992,
Gleick 1993) and water use for food production will increase due the growth of the
world population (Postel 1998, Falkenmark 1997b). However, more than 80% of the
global food production area occurs in rainfed agriculture (Gleick 1993). At the start of
this thesis, freshwater needs for food production in rainfed areas, at a global level, had
not yet been quantified, nor did scenarios for increased water needs in order to feed a
growing world population include food production from rainfed agriculture.
In 1998, Postel quantified the total amount of water used in both rainfed and irrigated
croplands at 7500 km3/yr (Postel 1998). In Paper I, we refine this estimate substantially
arriving at 6800 km3/yr. When, as in Paper I, water needs for future food production
to a growing world population are estimated, it is clear that there will continue to be
future trade-offs between ecosystem services and food production in terrestrial areas.
We hypothesise that land conversions will be driven by future water scarcity for food
production in tropical and sub-tropical regions that are experiencing rapid population
growth. It becomes apparent that water for rainfed agriculture can not be neglected in
water assessment and management. Several interesting solutions for overcoming yield
gaps exist today in many rainfed agricultural areas (Rockström and Falkenmark 2000)
that ought to be explicitly included in the discussions of water for food production.
The results in this thesis that relate to the role of freshwater in the generation of
terrestrial ecosystem services, including food production (primarily Papers I, IV and
V), illustrate that a partial view of freshwater as merely an input to societal production
is insufficient. Freshwater provides a basis for the capacity of ecosystems to sustain the
production of ecosystem goods and services. Freshwater is part of a web of multiple
functions on which human welfare depends, but which is seldom recognised and
managed intentionally in society. It is further emphasised that food production requires
much more freshwater than previously recognised. Rainfed, as well as irrigated, food
production needs to be managed from a freshwater perspective since water scarcity is a
major threat to future ability to feed a growing world population.
Alterations of vapour flows through land cover change
and irrigation
One ecosystem service that is often referred to is the generation of freshwater from
terrestrial ecosystems, especially from forests. That terrestrial ecosystems in general
“create” water is, however, a myth and the reality is much more complex (Calder 1999).
Many organisms are involved in the modification of the quantity, quality, pathway and
timing of freshwater flows (Papers II, III and IV). Two major partitioning points has
been distinguished in a terrestrial system, at the surface and in the soil (figure 1, from
Paper I) where precipitation is partitioned into evaporation, transpiration, runoff,
infiltration and ground water recharge.
17
The effects of vegetation alterations (especially from forests) on liquid and vapour
flows are well studied at a local and regional scale. General work on the influence
of vegetation, climate and land cover has illustrated that there are vegetation specific
behaviour influencing the water balance of a system (L´vovich 1973, Falkenmark et
al. 1999, Calder 1999). Catchment scale experiments have illustrated that forested
catchments in general have a higher vapour flow and lower liquid flow than grassdominated catchments in the same hydroclimate. The effects of deforestation depend on
the intensity and manner in which the clearance is carried out and on the character of the
old and new land cover and its management (Vertessy 1999, McCulloch and Robinson
1993, Bosch and Hewlett 1982, Zang et al. 1999, Bruijnzeel 1990).
The impacts of land cover change on vapour flows are also one aspect of biosphereatmosphere interactions that has been modelled in order to increase understanding of
the role of land cover change on climate (e.g. Eagleson 1986, Hutjes et al. 1998, Pielke
1998), and it has been suggested that large scale deforestation can reduce moisture
recycling and affect precipitation (Savenije 1995, 1996, Trenberth 1999).
The definition of human water use and availability has traditionally not included
human induced changes in freshwater flows due to land use and land cover change.
At present, 35% Earth’s surface has been converted to human land use in terms of
croplands and grazing (Goldewijk 2001). That the hydrological cycle has been altered as
a consequence of land cover change is, nevertheless, often mentioned in reviews of human
impact on the terrestrial water cycle (Naiman and Turner 2000, Vörösmarty 2002). To
my knowledge, one paper by L’vovich and White (1990) is the only quantitative estimate
at the scale of continents or the whole globe of the impact of land cover change on
freshwater flows. In 1990, L´vovich and White estimated the changes in runoff during
the past 300 years (1680-1980) caused by redirections of liquid water to water vapour
through irrigation. Their results suggest that the water vapour flows have increased from
86 km3/yr to 2,570 km3/yr during this period. They also made a rough estimate of global
alterations of water flows due to land cover change arriving at a decrease with 6540
km3/yr (9% of total vapour flows).
Quantifying vapour flow alterations at a continental and global scale
In Papers II and III, we quantify the human induced alterations of vapour flows as a
consequence of land cover change and irrigation (only in Paper III). We chose not to deal
with impacts of climatic change on freshwater flows, even though this is a growing area
of research and policy discussion (c.f. Vörösmarty et al. 2000, Schultze et al. 2001, The
Dialogue on Water and Climate (http://www.waterandclimate.org)).
In Paper II, we estimate the alterations of vapour flows in Australia, a continent that
has experienced rapid land cover change since Europeans arrived in the late 18th century.
During the last 200 years there has been a substantial decrease in woody vegetation
and a corresponding increase in croplands and grasslands. The shift in land use has
caused roughly a 10% decrease in water vapour flows from the whole continent. This
reduction corresponds to an annual freshwater flow of almost 340 km3 as compared
to the precipitation of 3390 km3/yr (L’vovich 1979) and the annual withdrawal of
liquid water of 20 km3 (AATSE 1999). We estimated the human-driven alteration of
freshwater flows at more than 15 times the volume of runoff freshwater that is diverted
18
and actively managed in society. The decreased vapour flows have caused water tables
to rise resulting in a widespread dryland salinisation of the soils. This is a perplexing and
costly challenge for the Australian society. The world’s driest country is at the moment
experiencing a large-scale environmental crisis due to too much water in the soil. An
integrated approach to terrestrial ecosystem and freshwater management is now being
generated, but it is a complex and difficult task for managers and policy makers and it
is difficult to get social acceptance for the vast changes that will have to take place (c.f.
Australia’s National Dryland Salinity Program http://www.ndsp.gov.au/).
In Paper III we do a geographically explicit estimate of the human induced alteration
of water vapour flows due to deforestation and irrigation at a global level (see figure 1-4
in Paper III). It was estimated that the decrease in vapour flows due to deforestation was
roughly 3000 km3/yr, or 4% of the annual vapour flows. This decrease was compensated
for by an increase of vapour flows from irrigated land, which was almost as large (2600
km3/yr). Although the net change of global vapour flow is quite small, the pattern of
vapour flows was found to have changed substantially. Some regions are experiencing
a large drop in vapour flows while others are experiencing large increases. It was
discussed in the paper that the extraction of local ecosystem goods and services, like
food, fibre and fuel, has through alterations of vapour flows led to unintentional effects
on regional climates and water availability for societal production. The paper illustrates
that optimising production of ecosystem services locally can compromise larger-scale
sustainability. From Papers II and III it is evident that human alteration of freshwater
flows from land cover change can have at least as large an impact on vapour flows as
irrigation.
Cross-scale effects of changes in water vapour flows
Annual freshwater availability is generally defined in terms of a flow of annually
renewable water (c.f. L’vovich 1979, Gleick 1993, Shiklomanov 2000). This illustrates
the important aspect that freshwater resources are always “on the move” from one place
to another. Freshwater provides essential links within and between different ecosystems.
In all of the papers in this thesis, the consequences of redistribution of water flows in
the landscape due to human activities like deforestation, introduction of new species,
grazing, crop production and irrigation are discussed. Human-induced changes of water
flows can cascade throughout the landscape and cause unintentional consequences at
other scales. These kinds of commutative hydrological alterations can affect downstream
ecosystems. It has been illustrated that erecting boundaries around nature reserves is not
enough to secure the functioning of those systems since they depend on processes outside
the borders (Pringle et al. 2000, Bengtsson et al. 2003). In the papers in this thesis, I have
focused on the role of changes in terrestrial systems and the cascading effects that these
have, primarily on the ability of terrestrial systems to generate ecosystem services.
These kind of cross-scale cascading effects was pointed out in Paper IV and further
elaborated on in Paper V. In Paper V, a framework for analysing these cross-scale
relations in freshwater management is proposed. The hydrological cycle is simplified into
three different pools of freshwater (rivers, atmosphere and soil) and fluxes of freshwater
between these pools. In the Anthropocene, humanity has altered the quantity and quality
of freshwater in the pools of the hydrological cycle (Vörösmarty and Sahaigan 2000).
Humanity has also changed the fluxes of freshwater between these pools (Papers II, III,
L’vovich and White 1990). Altering the fluxes through water withdrawals and/or land
19
cover change can affect the social-ecological systems that are dependent both on the
quantity and quality of freshwater within the pools, as well as the timing and variability
of freshwater between these. Paper V also illustrates that the different pools respond to
change at different temporal and spatial scales.
Throughout the work with this thesis, I have come across examples of regions and
biomes where alterations of water vapour flows due to historical land cover change have
caused severe side-effects. The regions referred to in this thesis are primarily Australia,
South Africa, the Sahel and the Amazon. These, and similar cases, are briefly summarised
below, synthesised as interactions between vegetation-river, vegetation-atmosphere and
vegetation-soil.
Vegetation – river interactions
The influence by humans on the abundance, distribution and quality of freshwater in
riverine systems are well studied primarily by hydrologists and aquatic ecologists (c.f.
Dysenius and Nilsson 1994, Naiman and Turner 2000, Meybeck 2003). One of the most
straightforward examples of cascading cross-scale effects of changes in land use is river
depletion caused by withdrawal of water for irrigation. In the Murray-Darling Basin, the
largest river system in Australia, the mean annual flow has dropped by 79% as compared
to the “natural” flow (MDBC 1999). Another well-known example is the decrease of
the Amu Darya’s and Syr Darya’s inflow into the Aral Sea, which today is only 10%
of the natural flow (Postel 1995). Other often cited examples of river depletion due to
upstream withdrawal of water include the Yellow River in China, the Nile, the Ganges,
the Indus and the Colorado River (Postel 1999). Unless compensated for, river depletion
decreases the options for downstream societies and ecosystems.
Vegetation alterations that redirect liquid water to vapour can reduce the amount
of water to downstream systems. Forest plantations can, for example, decrease run off
(Jewitt 2002) and the new South African Water Act classifies forest plantations as a
“stream flow reduction activity”. Forest companies have to pay for their water use, since
less of the precipitation reaches the river when forests are planted. As described in Paper
IV, invasive species from forest plantations are threatening water supply for downstream
users in South Africa (Le Maitre et al. 1996). Cities like Cape Town and Port Elisabeth
depend on runoff from the natural low biomass vegetation in the catchment. The region
is developing quickly with an expanding urban population that will further increase the
demand for freshwater to households and industries (van Wilgen et al. 1996). It was in
this context that the program “Working for Water”, which was mentioned earlier, was
developed. Today this programme works to clear catchments from alien species while
at the same time securing jobs and livelihoods for local communities (van Wilgen et
al. 1998, Binns et al. 2001). Invasive species in riparian areas are a problem in several
other parts of the world. It has, for example, been estimated that the annual costs of
the invasive woody species Tamarisk in the semi-arid western United States total USD
280-450/ha, with restoration costs of approximately USD 7400/ha. These costs relate
primarily to stream flow reduction (Zavaleta 2000).
Vegetation – atmosphere interactions
Cross-scale linkages in the landscape through water vapour flows, often called “moisture
20
recycling”, are receiving an increasing amount of attention (Trenberth 1999). The
“Global Change Community” has been particularly active in recognising the ability
of land cover change to influence climate through, among other things, vapour flow
alterations (Eagleson 1986, Hutjes et al. 1998, Pielke et al. 1998, Kabat et al. 2003).
Pielke et al. (1998) offer an extensive review of modeling and observational studies on
land – atmosphere linkages, and conclude that the evidence is convincing that land cover
change can significantly influence weather and climate and are as important as other
human-induced changes for the Earth’s climate. However, these models do not deal with
vapour flows explicitly, but model the compounded effects of changes in, e.g., albedo,
surface wind, and leaf area index.
Nevertheless, regional studies in West Africa (Savenije 1996, Xue and Shukla 1993,
Zheng and Eltathir 1998), USA (Baron et al. 1998, Pielke et al. 1999) and East Asia
(Fu and Yuan 2001, Fu 1994) have illustrated that changes in land cover affect vapour
flows, with impacts on local and regional climates. Likewise, biome specific models of
land cover conversions from rainforest (Salati and Nobre 1990, Shukla et al. 1990)
and savannah (Hoffman and Jackson 2000) to grassland have shown a decrease in
vapour flows and precipitation as well as effects on circulation patterns. There are also
indications that increased vapour flows through irrigation can alter local and regional
climates (Pielke et al. 1997, Chase et al. 1999).
In Papers III and V, we discuss these kinds of linkages with particular focus on the
Amazon and Sahel. It is concluded in these studies that changes in moisture recycling in
these regions might significantly affect ecosystem processes at a different scale. Since so
many regional studies have shown an alteration of climate from land cover change, it
is hypothesised and discussed in Paper III that the pervasive local alterations of vapour
flows from land cover changes that were found in Paper III, can also have implications
on the global climate.
Vegetation – soil interactions
Water can build up in the soil profile if the rate of water input to the system exceeds
the rate of water throughput. This can cause water logging and salinisation, which are
wellknown undesirable phenomena and extensively described for irrigated agriculture
(Postel 1999). The same phenomenon is described for Australia in Paper II, but as a
result of alterations in vegetation. The costs of salinisation in Australia have manifested
itself as production losses in rivers and in agricultural lands, as health hazards, and
as destruction of infrastructure in rural and urban areas. It is interesting to note that
the first signs of these salinisation problems appeared already in the early-20th century
(Wood 1924) but deforestation has increased rapidly since then.
Decreased infiltration into soil is often a result of poor management of crop- and
grazing land (Falkenmark and Rockström 1993, L’vovich 1979) and can reduce the
capacity of the system to produce biomass and thus increase vulnerability for farmers
who rely on this production. This is discussed in Paper V, as a well-known problem in
the Sahel region in Western Africa where many rainfed farming systems are experiencing
an agrarian crisis with notoriously low food crop yields (Falkenmark and Rockström
1993). The desiccation of the soil is one of the factors behind what is often blamed as
“desertification” or land degradation in the tropics. The precipitation in the region is
21
extremely variable and vulnerability of farming to droughts and dryspells becomes even
higher (Rockström 1997).
Changes in infiltration in rangelands can also be critical. On various scales within the
rangeland ecosystems, the partitioning of precipitation into infiltration and runoff is one
of the major structuring agents along with soil type, herbivory and fire (Walker 1993).
When rangelands experience low intensity but constant stress, the interactions between
water and soil can be changed, which ultimately can change the system to another stable
state dominated by unpalatable shrubs rather than grass. Obviously this altered ecology
will generate different ecosystem services. It has been emphasised that grazing by cattle
should mimic the temporal and spatial variability evident in wildlife grazing in order
to promote resilience of the desired grass-dominated ecosystem state (Walker 1993,
Niamir-Fuller 1998).
Moving closer to thresholds
It was hypothesised in Paper V that these changes across spatial and temporal scales
have pushed some systems closer to social-ecological thresholds. One of the suggested
reasons is the time- and space-lags often inherent in freshwater management. These
allow changes in land use and land cover initiated at a local scale to accumulate into
freshwater-driven surprises at a different scale. Time-lags and space-lags make it more
difficult for managers to respond to environmental feedback. The examples given of
cross-scale interactions in the hydrological cycle illustrate that some of these changes
might be irreversible, at least within a limited time frame of one to two generations.
These are not new insights in themselves. It has been emphasised during the last
decades that ecosystems are complex adaptive systems with inherent dynamics, nonlinearity, thresholds and limited predictability (Levin 1999). Jackson et al. (2001b) has
for example illustrated that there can be time-lags of decades to centuries between onset
of resource extraction (fisheries) and the consequent changes in ecological communities
and decreased resilience of these systems.
Some ecosystems have multiple stability domains and state shifts can occur when
resilience of these systems are lost through internally changing conditions, or through
externally altered parameters like disturbance regimes (Scheffer et al. 2001). These
state shifts, or passing of thresholds, can cause sudden loss of the system’s capacity to
generate ecosystem services (Folke et al. 2002). The transformation of the Earth System
described in the introduction includes alteration of disturbance regimes through, e.g.,
climatic change, fire suppression and introduction of new pesticides at the same time
as ecosystems seem to be losing their capacity to cope with such changes (Scheffer et al.
2001).
The interplay between the dynamics of the hydrological cycle, alterations of
disturbance regimes and resilience is still largely an open issue (Folke 2003). In Paper
V, the role of freshwater both as a variable that may be changed within a system (e.g.
soil moisture) and as an external variable (e.g. precipitation) was discussed. It has often
been emphasised in management of freshwater and ecosystems that it is not the average
amount of water flow that is of interest for ecosystem functioning, but alterations in
disturbances and extreme events like droughts or flooding. It is proposed in Paper V
that the change in fluxes between the different pools of freshwater should be discussed
22
in terms of change in quantity, quality, timing and variability (adapted from Baron et al.
2002). The role of freshwater in structuring and influencing ecosystem processes and
desirable states will most likely become a central issue in future research.
As is illustrated from several of the cases in Papers I-V of this thesis social and
economic vulnerability can increase when the system gets closer to thresholds. In the
Sahel and in Australia, farmers might pass a threshold where farming no longer will
sustain livelihoods and they become more and more dependent on subsidies, labour
migration, or aid (Paper V). However, in these cases as well as in the case described from
South Africa new management regimes have progressively evolved.
Two characteristics of such systems seem to be of importance in this context i)
emphasise the combination of different kinds of knowledge systems for management
of complex systems (different scientific knowledge, as well as local or traditional
knowledge), and ii) highlight the positive effects of diversification of production systems
(c.f. Mortimore and Adams 2001 (Sahel), Binns et al. 2001 (South Africa), Curtis and
Lockwood (2000) (Australia)). These examples illustrate the ability of the combined
social-ecological systems to reorganise and renew itself through learning and adaptation.
This ability has been described earlier for several societies (c.f. Berkes and Folke 1998,
Berkes et al. 2003, Olsson et al. 2004).
However, the challenge is indeed complex and although encouraging initiatives are
taken, there are diverging views of the ability of these systems to adapt and develop (c.f.
Battery and Warren 2001). The papers in this thesis illustrate the vast difficulties involved,
including cross-scale issues, time- and space-lags and inherent uncertainty concerning
responses to change. Freshwater management has throughout history provided several
interesting examples of successful management regimes that deal with the difficulties of
sharing a common property between different uses and stakeholders at different scales
(c.f. Ostrom 1990, Lansing 1991). As pointed out in Paper V a new challenge is how
to learn from these examples, as well as from other cases of management of complex
systems (Olson et al. 2004) in order to deal with changes also regarding invisible water
vapour that goes beyond the drainage basin.
Concluding remarks
During the last decades the world community has gone from ignorance of environmental
problems to perception of crises and major initiatives are taken today to reorganise
society into a more sustainable pathway of development. This thesis has address a small
part of the challenges involved by expanding on, and adding information to the issues
presently discussed in the area of freshwater and ecosystem management.
Vörösmarty (2002) argued that “there is a critical and growing need to articulate
the global scale nature of water vulnerability, in all its forms, while at the same time
taking advantage of knowledge drawn from the local scale and through case studies”.
This thesis has presented cases, primarily from Australia, South Africa and the Sahel
(Papers II, IV and V) which seems to have been pushed closer to thresholds which can
lead to social and economic crises. Further, the thesis has included global and continental
quantification of changes in hydrological fluxes (Papers II and III). The results from
these indicate that the cases from Australia, Sahel and South Africa do not occur in a
vacuum, but that similar changes most probably occurs in various parts of the world.
23
One aim of this thesis was to target the pre-analytic visions, or mental conceptual
framework, that frame and shape the way in which we relate to the environment. The
results in the thesis emphasise the need of a broadened perception of freshwater, from
seeing it only as an economic good, or input to society, to an appreciation of all the
different functions of freshwater in the human life-support system. Freshwater cycling
is the “bloodstream of the biosphere”. The work presented in this thesis has expanded
the discussions on freshwater for food and ecosystem services from mainly dealing with
the distribution of freshwater between its liquid water uses to addressing different parts
of the hydrological cycle, with specific focus on the terrestrial component. It has been
illustrated that this is particularly important in the light of the pervasive transformation
of terrestrial ecosystems from local to global scales. It has been stressed that the dynamic
role of freshwater in constantly changing complex adaptive ecosystems, and the way in
which it enhances or erodes resilience of desired states, are issues that require urgent
attention in order to avoid large scale social and economic crises. Redirections of
freshwater based on too limited perceptions will likely create increased vulnerability
(Paper V).
There are several signs of a brighter future. There is right now a window of
opportunity to address these issues. A broadened understanding of the invisible parts of
the hydrological cycle (the water vapour flows and soil moisture) is becoming increasingly
included in decisions of land and water. Several new initiatives on research of the
whole hydrological cycle exist, e.g. the Global Water System Project (www.gwsp.org).
There is strengthened international support of initiatives in freshwater and ecosystem
management, and the understanding is growing of its importance to human welfare.
Several innovative water initiatives are taken at different levels and in different parts of
the world to meet these new and enormous challenges. At a global level these includes
examples like the 1st to 3rd World Water Forum, the annual Stockholm Symposium, and
the Dialogues (e.g. on Water for Food and the Environment, on Water and Climate, and
on Water and Governance). Examples at a regional level are the European Union Water
Directive and the South African Water Law. There is also an emerging understanding
of the role of local scale initiatives since history has shown the success of several selforganised local initiatives to manage complex, adaptive systems. Learning from these
bottom-up examples of management can be crucial in the future management of
increasingly complex human dominated systems.
These signs give hope for the future. This is an interesting time to live.
24
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31
Till Min Morfar
Jag tillägnar denna avhandling till Dig, Morfar. När jag var liten lyckades Du omvandla en
märklig verklighet till fantasifulla sagor. Det är rätt svårt att förklara Svea Rikes Lag för en liten
5-årig tjej, men i din fantasi blev den till Morfars Sanna Vänners Förbund (hemligt) (MSVF(h)), där
bara Du och jag var medlemmar. Geografi blev till jakten på den försvunna Lakritsgruvan och
i alfabetet fanns det plats för både verkliga och overkliga djur. Ormor, fick börja på O istället
för M, till exempel. Du lät mig busa och bygga kojjor och försökte locka mig att följa med till
Stadshuskällaren för att äta blåbärsgröt. Du tyckte att jag stavade som en kratta innan jag ens
hade börjat skolan och Du tog med mig filmer förbjudna för barn under femton när jag bara var
tio. Jag tror att Din enorma tilltro till mig och min förmåga har underlättat mitt lärande, lekfullt lockat
fram min nyfikenhet och fått mig att i alla fall delvis ta hjälp av fantasin även i mina vetenskapliga
eskapader. Du ryckets bort från livet aldeles för tidigt, för ganska exakt 20 år sedan. Jag var
bara elva. Jag vill ge dig den här boken som tack för din inspiration, din livsglädje och din tilltro
till mig. Min Morfar, väldens bästa Sagomorfar!
Acknowledgements
The work with this thesis did certainly not occur in a vacuum, and none of this could
have been done without the fantastic support from several individuals and groups with
whom I have had stimulating discussions and fruitful collaboration. John Donne once
said:
“No man is an island, entire of itself;
every man is a piece of the continent, a part of the main...”
I would like to express my sincere gratitude towards the people who have in one way or
another contributed to my thesis. I will not be able to thank all of you by name, but you
are in my thoughts!
Two of the most inspiring people during my work with the thesis have been my
supervisors Carl Folke and Malin Falkenmark. Thanks for letting me be part of your
exciting bridge-building research on the frontier of science. And thanks for all the fried
sparrows (stekta sparvar) you have put into my mouth! Calle, you have a brilliant mind!
Your exceptional ability to synthesise and analyse the complexity of social-ecological
change is impressive and inspirational. It has been exciting working with you and I hope
our collaborations will continue! Malin, it has been wonderful to work with you and
share your never-ending energy, support and enthusiasm. Your holistic thinking and
truly integrative intellect has been a great inspiration throughout my research. Thanks
for helping me when time was tough, and for pushing and challenging me that little extra
at the end of this thesis. I hope you will continue doing this.
Johan Rockström, although not an official supervisor, your support has been
fantastic. You helped me out when I continued to run into the wall, head first, as I was
32
trying to understand the hydrology of croplands. Your help certainly was invaluable.
I admire your enormous work capacity, your research and your leadership, and I am
stimulated by your ambition to improve this world. I really look forward to our future
collaborations!
Thanks also to my two co-authors in Australia, Michael Dunlop and Barney Foran,
for your great support of my research as well as of the water vapour thinking. I am also
indebted to the rest of the people at the Resources Future Program at CSIRO Sustainable
Ecosystems, especially Brian Walker for inviting me and to Ray Bemelman for all
administrative support.
Will Steffen, you have been another extremely inspiring co-author! Thanks for
sharing your broad knowledge of the Earth System and help in lifting my perspectives
and refining research ideas.
Bror Fredrik Jönsson, thanks for all the time you have spent on the estimations in
paper III, and for finally solving the equations in the last minute. Åse Johannessen,
thanks for your efforts on paper III, for the friendship, and for good discussions!
Maria Tengö, I don’t know how I would have survived without our intellectually
stimulating discussions in various summer and winter cottages in Sweden. Thanks for
your smiles, enthusiasm and support.
Lisa Deutsch saved the quality of my papers and made them readable to an English
speaking audience. You put the language check of my papers high on your agenda,
although you were yourself drowning in work and family issues. And Miriam Huitric,
thanks for all the Cafe Lattes!
Patrick Fox and Jenny Barron, just like Johan, helped out at tough times, especially
with croplands and vapour flows. Sorry for bothering you with impossible questions…
I have also shared many stimulating discussions with you, Per Olsson. Both while
sharing room and at different meetings with our research school.
I have had the enormous fortune of participating in two wonderful groups of
interdisciplinary doctoral students, at Center for Research on Natural Resources and the
Environment (CNM) and the Research School of Ecological Land Use (ResELU). These
groups have inspired me to tackle more trans-disiplinary questions. At CNM I have also
had the opportunity of working more with popular science issues.
The whole Natural Resources Group at the Department of Systems Ecology has been
fantastic! It is a great atmosphere within the group and I have got many new friends
throught these years. I would like to thank everyone of you by name, but I think I´ll do
that in the corridor instead! I have also received superb support from the administration
at the department.
Jan Bengtsson, thanks for feedback on papers and stimulating discussions. Gunnel
Hedman, you have been a great mentor, outside of university and I have truly enjoyed
every minute of our meetings. Thanks for your generosity and discussions. I hope to have
more lunches with you from now on!
I would also like to mention some of my teachers throughout my life. I have had the
fortune to learn from many wise persons! A special thanks goes to Eva Berntzon, Jack
Lidström, and AnnMari and Lars-Erik Bergfeldt for triggering my academic interest.
33
If I had to pick just one learning experience that has helped me with this thesis it would
be my participation in the youth exchange program Young Partners in Development, coordinated by Centrum för Internationellt Ungdomsutbyte, in the year 1995. This was
before the start of this thesis, before I even knew about the research at the Department
of Systems Ecology. The six month in Burkina Faso and Östersund that I spent together
with my counterpart Minata Ouedragou from Burkina, has taught me more about the
way the world works than any of the academic papers I have read during my five years
of PhD-studies. Thank you Jonas Nyström and Johannes Wijkman for giving me the
opportunity of participating in YPD. By the way, if any of you believe in synchronicity,
the first time I met Johan Rockström was in the aeroplane to Ouagadougou.
Jenny Stormbom, you have taught me about love-to-life during our coffee-mornings at
Non Solo Bar. How would this thesis have survived without those mornings? Or rather,
how would I have survived? And a big enormous thank you to all my friends within and
outside the Academic life, who enrich my life and give me a context to my research. I
have missed you these last couple of months!
Dear parents, you have provided such a harmonious surrounding to grow up in, and
you have given me a curiosity of life and an interest of the complex interactions between
people and their surrounding, that is invaluable. The gratefulness I feel about your love
and support is not possible to express in words. My sister Tove, you have shown such
an uninterest, yet support, of my work! Thanks for that, as well as for the cover and
illustrations of this thesis.
Daniel, you fill my life with smiles, surf and sunshine! I enjoy our time together so
much, and I look forward to more adventures of life, together with you.
34