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4
Ecosystems, their properties, goods and services
Coordinating Lead Authors:
Andreas Fischlin (Switzerland), Guy F. Midgley (South Africa)
LeadAuthors:
Jeff Price (USA), Rik Leemans (The Netherlands), Brij Gopal (India), Carol Turley (UK), Mark Rounsevell (Belgium),
Pauline Dube (Botswana), Juan Tarazona (Peru), Andrei Velichko (Russia)
Contributing Authors:
Julius Atlhopheng (Botswana), Martin Beniston (Switzerland), William J. Bond (South Africa), Keith Brander (ICES/Denmark/UK),
Harald Bugmann (Switzerland), Terry V. Callaghan (UK), Jacqueline de Chazal (Belgium), Oagile Dikinya (Australia),
Antoine Guisan (Switzerland), Dimitrios Gyalistras (Switzerland), Lesley Hughes (Australia), Barney S. Kgope (South Africa),
Christian Körner (Switzerland), Wolfgang Lucht (Germany), Nick J. Lunn (Canada), Ronald P. Neilson (USA), Martin Pêcheux (France),
Wilfried Thuiller (France), Rachel Warren (UK)
ReviewEditors:
Wolfgang Cramer (Germany), Sandra Myrna Diaz (Argentina)
This chapter should be cited as:
Fischlin, A., G.F. Midgley, J.T. Price, R. Leemans, B. Gopal, C. Turley, M.D.A. Rounsevell, O.P. Dube, J. Tarazona, A.A. Velichko, 2007:
Ecosystems, their properties, goods, and services. Climate Change 2007: Impacts, Adaptation and Vulnerability. Contribution of Working
GroupII to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, M.L. Parry, O.F. Canziani, J.P. Palutikof,
P.J. van der Linden and C.E. Hanson, Eds., Cambridge University Press, Cambridge, 211-272.
Ecosystems,their properties, goods and services Chapter 4
Table of Contents
Executive summary.....................................................213 Box4.4Coralreefs: endangered by climate change?......235
4.1 Introduction........................................................214 4.4.10 Cross-biome impacts.............................................237
Box4.5Crossing biomes: impacts of climate change
4.1.1 Ecosystem goods and services.............................215 onmigratory birds..................................................
239
4.1.2 Key issues..............................................................215 4.4.11 Global synthesis including impacts on
4.2 Current sensitivities..........................................215 biodiversity.............................................................239
4.2.1 Climatic variability and extremes ...........................215 4.5 Costs and valuation of ecosystem goods
andservices.........................................................245
4.2.2 Other ecosystem change drivers...........................216
Box4.1Ecological impacts of the European heatwave 4.6 Acclimation and adaptation: practices,
2003....................................................................... options and constraints....................................246
217
4.3 Assumptions about future trends..................218 4.6.1 Adaptation options................................................246
4.6.2 Assessing the effectiveness and costs of
4.4 Keyfutureimpactsandvulnerabilities.......219 adaptation options................................................247
4.4.1 Biogeochemical cycles and biotic feedback .........219 4.6.3 Implications for biodiversity ..................................247
4.4.2 Deserts...................................................................222 4.6.4 Interactions with other policies and policy
implications...........................................................248
Box4.2Vegetation response to rainfall variability in
the Sahel ................................................................
224 4.7 Implications for sustainable development...248
4.4.3 Grasslands and savannas......................................224 4.7.1 Ecosystems services and sustainable
4.4.4 Mediterranean ecosystems....................................226 development..........................................................248
4.4.5 Forests and woodlands..........................................227 4.7.2 Subsistence livelihoods and indigenous peoples...248
4.4.6 Tundra and Arctic/Antarctic ecosystems...............230 4.8 Keyuncertainties and research priorities...249
Box4.3Polar bears - a species in peril? ..........................231 Appendix4.1.................................................................250
4.4.7 Mountains...............................................................232
4.4.8 Freshwater wetlands, lakes and rivers...................233 References......................................................................252
4.4.9 Oceans and shallow seas ......................................234
212
Chapter 4 Ecosystems,their properties, goods and services
Executive summary increasingly high risk of extinction as global mean
temperatures exceed a warming of 2 to 3°C above pre-
industrial levels (medium confidence) [4.4.10, 4.4.11, Figure
During the course of this century the resilience of many 4.4, Table 4.1].
ecosystems (their ability to adapt naturally) is likely to be Projected impacts on biodiversity are significant and of key
exceeded by an unprecedented combination of change in relevance, since global losses in biodiversity are irreversible
climate, associated disturbances (e.g., flooding, drought, (very high confidence) [4.4.10, 4.4.11, Figure 4.4, Table 4.1].
wildfire, insects, ocean acidification) and in other global Endemic species richness is highest where regional
change drivers (especially land-use change, pollution and palaeoclimatic changes have been muted, providing
over-exploitationofresources),ifgreenhousegasemissions circumstantial evidence of their vulnerability to projected
andotherchangescontinueatorabovecurrentrates(high climate change (medium confidence) [4.2.1]. With global
confidence). averagetemperaturechangesof2°Cabovepre-industriallevels,
By2100,ecosystemswillbeexposedtoatmosphericCO2levels many terrestrial, freshwater and marine species (particularly
substantially higher than in the past 650,000 years, and global endemicsacross the globe) are at a far greater risk of extinction
temperatures at least among the highest of those experienced in than in the recent geological past (medium confidence) [4.4.5,
the past 740,000 years (very high confidence) [4.2, 4.4.10, 4.4.11, Figure 4.4, Table 4.1]. Globally about 20% to 30% of
4.4.11; Jansen et al., 2007]. This will alter the structure, reduce species (global uncertainty range from 10% to 40%, but varying
biodiversity and perturb functioning of most ecosystems, and amongregionalbiotafromaslowas1%toashighas80%)will
compromise the services they currently provide (high be at increasingly high risk of extinction, possibly by 2100, as
confidence) [4.2, 4.4.1, 4.4.2-4.4.9, 4.4.10, 4.4.11, Figure 4.4, global mean temperatures exceed 2 to 3°C above pre-industrial
Table 4.1]. Present and future land-use change and associated levels [4.2, 4.4.10, 4.4.11, Figure 4.4, Table 4.1]. Current
landscape fragmentation are very likely to impede species’ conservation practices are generally poorly prepared to adapt to
migration and thus impair natural adaptation via geographical this level of change, and effective adaptation responses are likely
range shifts (very high confidence) [4.1.2, 4.2.2, 4.4.5, 4.4.10]. to be costly to implement (high confidence) [4.4.11, Table 4.1,
4.6.1].
Several major carbon stocks in terrestrial ecosystems are
vulnerable to current climate change and/or land-use Substantial changes in structure and functioning of
impacts and are at a high degree of risk from projected terrestrial ecosystems are very likely to occur with a global
unmitigated climate and land-use changes (high warming of more than 2 to 3°C above pre-industrial levels
confidence). (high confidence).
Several terrestrial ecosystems individually sequester as much Betweenabout25%(IPCCSRESB1emissionsscenario;3.2°C
carbon as is currently in the atmosphere (very high confidence) warming) and about 40% (SRESA2 scenario; 4.4°C warming)
[4.4.1, 4.4.6, 4.4.8, 4.4.10, 4.4.11]. The terrestrial biosphere is of extant ecosystems will reveal appreciable changes by 2100,
likely to become a net source of carbon during the course of this withsomepositiveimpactsespeciallyinAfricaandtheSouthern
century(mediumconfidence),possiblyearlierthanprojectedby Hemisphere arid regions, but extensive forest and woodland
the IPCCThirdAssessmentReport(TAR)(lowconfidence)[4.1, decline in mid- to high latitudes and in the tropics, associated
Figure 4.2]. Methane emissions from tundra frozen loess particularly with changing disturbance regimes (especially
(‘yedoma’, comprising about 500 Pg C) and permafrost through wildfire and insects) [4.4.2, 4.4.3, 4.4.5, 4.4.10, 4.4.11,
(comprising about 400 Pg C) have accelerated in the past two Figure 4.3].
decades, and are likely to accelerate further (high confidence)
[4.4.6]. At current anthropogenic emission rates, the ongoing Substantial changes in structure and functioning of marine
positive trends in the terrestrial carbon sink will peak before and other aquatic ecosystems are very likely to occur with
mid-century, then begin diminishing, even without accounting a mean global warming of more than 2 to 3°C above pre-
for tropical deforestation trends and biosphere feedback, tending industrial levels and the associated increased atmospheric
strongly towards a net carbon source before 2100, assuming CO levels (high confidence).
2
continuedgreenhousegasemissionsandland-usechangetrends Climate change (very high confidence) and ocean acidification
at or above current rates (high confidence) [Figure 4.2, 4.4.1, (mediumconfidence)willimpairawiderangeofplanktonicand
4.4.10, Figure 4.3, 4.4.11], while the buffering capacity of the shallow benthic marine organisms that use aragonite to make
oceanswillbegintosaturate[Denmanetal.,2007,e.g.,Section their shells or skeletons, such as corals and marine snails
7.3.5.4]. While some impacts may include primary productivity (pteropods), with significant impacts particularly in the Southern
gains with low levels of climate change (less than around 2°C Ocean, where cold-water corals are likely to show large
mean global change above pre-industrial levels), synergistic reductions in geographical range this century [4.4.9, Box 4.4].
interactions are likely to be detrimental, e.g., increased risk of Substantial loss of sea ice will reduce habitat for dependant
irreversible extinctions (very high confidence) [4.4.1, Figure 4.2, species (e.g., polar bears) (very high confidence) [4.4.9, 4.4.6,
4.4.10, Figure 4.3, 4.4.11]. Box4.3,4.4.10,Figure4.4,Table4.1,15.4.3,15.4.5].Terrestrial
tropical and sub-tropical aquatic systems are at significant risk
Approximately 20 to 30% of plant and animal species underatleastSRESA2scenarios;negativeimpactsacrossabout
assessed so far (in an unbiased sample) are likely to be at 25%ofAfricaby2100(especiallysouthernandwesternAfrica)
213
Ecosystems,their properties, goods and services Chapter 4
will cause a decline in both water quality and ecosystem goods responsesinthepalaeorecord(Jansenetal.,2007)andtocurrent
and services (high confidence) [4.4.8]. climate anomalies such as El Niño events may emerge at much
shorter time-scales (Holmgren et al., 2001; Sarmiento and
Ecosystems and species are very likely to show a wide Gruber, 2002; Stenseth et al., 2002; van der Werf et al., 2004).
range of vulnerabilities to climate change, depending on Atcontinental scales, biomes (see Glossary) respond at decadal
imminence of exposure to ecosystem-specific, critical to millennial time-scales (e.g., Davis, 1989; Prentice et al., 1991;
thresholds (very high confidence). Lischke et al., 2002; Neilson et al., 2005), and groups of
Most vulnerable ecosystems include coral reefs, the sea-ice organismsformingecologicalcommunitiesattheregionalscale
biome and other high-latitude ecosystems (e.g., boreal forests), have shorter response times of years to centuries. Responses of
mountain ecosystems and mediterranean-climate ecosystems populations (i.e., interbreeding individuals of the same species)
(high confidence) [Figure 4.4, Table 4.1, 4.4.9, Box 4.4, 4.4.5, occuratintermediatetemporalscalesofmonthstocenturies,and
4.4.6, Box 4.3, 4.4.7, 4.4.4, 4.4.10, 4.4.11]. Least vulnerable underpin changes in biodiversity. These include changes at the
ecosystems include savannas and species-poor deserts, but this genetic level that may be adaptive, as demonstrated for example
assessment is especially subject to uncertainty relating to the for trees (Jump et al., 2006) and corals (Coles and Brown, 2003).
CO-fertilisationeffectanddisturbanceregimessuchasfire(low Fast physiological response times (i.e., seconds, hours, days,
2
confidence) [Box 4.1, 4.4.1, 4.4.2, Box 4.2, 4.4.3, 4.4.10, months)ofmicro-organisms,plantsandanimalsoperateatsmall
4.4.11]. scales from a leaf or organ to the cellular level; they underlie
organism responses to environmental conditions, and are
assessed here if they scale up to have a significant impact at
4.1 Introduction broader spatial scales, or where the mechanistic understanding
assists in assessing key thresholds in higher level responses.
The spatial distribution of ecosystems at biome scale has
An ecosystem can be practically defined as a dynamic traditionally been explained only in terms of climate control
complexofplant,animalandmicro-organismcommunities,and (Schimper,1903),butitisincreasinglyapparentthatdisturbance
the non-living environment, interacting as a functional unit regimessuchasfireorinsectsmaystronglyinfluencevegetation
(Millennium Ecosystem Assessment, Reid et al., 2005). structure somewhat independently of climate (e.g.,Andrew and
Ecosystems may be usefully identified through having strong
interactions between components within their boundaries and
weak interactions across boundaries (Reid et al., 2005, part 2). Atmosphere ~2000 )
800 C
Ecosystemsarewellrecognisedascritical in supporting human g
Atmosphere P-IND P
well-being (Reid et al., 2005), and the importance of their 600 (
s
Atmosphere LGM k
preservation under anthropogenic climate change is explicitly 400 c
o
t
highlighted in Article 2 (The Objective) of the United Nations s
200 n
) o
FrameworkConventiononClimateChange(UNFCCC). 2 b
30 0 r
In this chapter the focus is on the properties, goods and m a
k C
M
services of non-intensively managed and unmanaged (20
a
e
ecosystems and their components (as grouped by widely r 3
a .
accepted functional and structural classifications, Figure 4.1), e10 9
c 4
a 3
f
and their potential vulnerability to climate change as based on r
u 0
scenarios mainly from IPCC (see Chapter 2 and IPCC, 2007). S ) ) ) ) ) T
D r e E r e b C O
(t (t M (t (t ( W
S G F F F F
Certain ecosystem goods and services are treated in detail in G&
other sectoral chapters (this volume): chapters 3 (water), 5 (food, Figure 4.1. Major ecosystems addressed in this report, with their
2
fibre, fisheries), 6 (coasts) and 8 (health). Key findings from this global areal extent (lower panel, Mkm ), transformed by land use in
chapter are further developed in the synthesis chapters 17 to 20 yellow, untransformed in purple, from Hassan et al. (2005), except for
(this volume). Region-specific aspects of ecosystems are mediterranean-climate ecosystems, where transformation impact is
discussedinchapters9to16(thisvolume).Thischapterisbased from Myers et al. (2000), and total carbon stores (upper panel, PgC) in
plant biomass (green), soil (brown), yedoma/permafrost (light blue). D =
on work published since the Third Assessment Report of the deserts, G&S(tr) = tropical grasslands and savannas, G(te) = temperate
IPCC (TAR) (Gitay et al., 2001). We do not summarise TAR grasslands, ME = mediterranean ecosystems, F(tr) = tropical forests,
findings here, but refer back to relevant TAR results, where F(te) = temperate forests, F(b) = boreal forests, T = tundra, FW =
appropriate, to indicate confirmation or revision of major freshwater lakes and wetlands, C = croplands, O = oceans. Data are
from Sabine et al. (2004, Table 2.2, p. 23), except for carbon content of
findings. yedomapermafrost and permafrost (light blue columns, left and right,
Projecting the impacts of climate change on ecosystems is respectively, Zimov et al., 2006), ocean organic carbon content
complicated by an uneven understanding of the interlinked (dissolved plus particulate organic; Denman et al., 2007, Section
temporal and spatial scales of ecosystem responses. Processes 7.3.4.1), and ocean surface area from Hassan et al. (2005, Summary,
Table C2, p. 15, inserted as a number). Figures here update the TAR
at large spatial scales, i.e., the biosphere at the global scale, are (Prentice et al., 2001), especially through considering soil C to 3 m
generally characterised by slow response times on the order of depth (Jobbagy and Jackson, 2000), as opposed to 1 m. Approximate
centuries, and even up to millennia (Jansen et al., 2007). carbon content of the atmosphere (PgC) is indicated by the dotted
However, it is also important to note that some large-scale lines for last glacial maximum (LGM), pre-industrial (P-IND) and current
(about 2000).
214
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