Download Executive Summary As the protection of tropical forests, through

THE CARBON VALUE OF NATURAL GLOBAL CARBON SINKS
Executive Summary
As the protection of tropical forests, through avoided deforestation, is being
discussed in UNFCCC meetings as a means of off-setting and reducing global
carbon emissions, an assimilation of recent research is pointing to the value of other
landscapes as natural carbon sinks and sources. Discussions in this forum on
reducing emissions from environmental disturbance must therefore consider the role
that protection of additional landscapes can have in global initiatives to curb
greenhouse gas emissions.
Of the estimated 181 to 252 percent of global carbon emissions attributable to
deforestation, a growing proportion of those emissions are due to the degradation
and loss of additional carbon sinks that play a vital role in sequestration. Most
notable are the emissions from degraded, drained, and decomposing peatlands
which amount to the emission of approximately 632 Megatonnes of carbon every
year3. This is further exacerbated by the fires associated with peatland degradation
that contribute a further 1400 Megatonnes of carbon annually4.
Peatlands, along with tropical forests and tropical grasslands and savannas, are
widely distributed in developing countries worldwide, and these habitats are
reservoirs for a large proportion of terrestrial carbon. As progress moves towards
advancing global negotiations on reducing emissions from deforestation in
developing countries, it is essential that these negotiations incorporate the latest
scientific research in deciding how best this might best be achieved, and consider the
wider issue of degradation, not just of forests, but of other carbon-dense natural
habitats.
1
Stern (2006). The Stern Review: The economics of climate change.
Conservation International
3
Hooijer A, Silvius M, Wösten H & Page S. 2006. PEAT-CO2, Assessment of CO2
emissions from drained peatlands in SE Asia. Delft Hydraulics report.
4
Hooijer A, Silvius M, Wösten H & Page S. 2006.
2
Carbon storage in natural habitats
In an analysis of ecosystems and their properties provided by the Intergovernmental
Panel on Climate Change5, the amount of carbon stored in the plant biomass and
soils of other habitats, such as tropical forests, tropical grasslands and savannas,
tundra, freshwater wetlands, and temperate and boreal forests, was described,
revealing the pivotal role that protection of these habitats could also play in
ameliorating global climate change. This is illustrated in Figure 1 below.
Figure 1: The global areal extent (lower panel, Mkm2) of the major ecosystems, transformed
by land use in yellow, untransformed in purple, and total carbon stores (upper panel, PgC) in
plant biomass (green), soil (brown), yedoma/permafrost (light blue).
D = deserts, G&S(tr) = tropical grasslands and savannas, G(te) = temperate grasslands, ME
= mediterranean ecosystems, F(tr) = tropical forests, F(te) = temperate forests, F(b) = boreal
forests, T = tundra, FW = freshwater lakes and wetlands, C = croplands, O = oceans.
Approximate carbon content of the atmosphere (PgC) is indicated by the dotted lines for last
glacial maximum (LGM), pre-industrial (P-IND) and current (about 2000).
Source: Fischlin A., GF Midgley, JT Price, R Leemans, B Gopal, C Turley, MDA Rounsevell,
6
OP Dube, J Tarazona, AA Velichko (2007) .
5
Ecosystems, their properties, goods, and services. Climate Change 2007: Impacts, Adaptation and
Vulnerability. Contribution of Working Group II 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., (2007) Cambridge University Press, Cambridge, UK, 211-272.
6
Ecosystems, their properties, goods, and services. Climate Change 2007: Impacts, Adaptation and
Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the
Intergovernmental Panel on Climate Change.
In order to quantify the relative amount of carbon stored in each habitat, the amount
of carbon per million square kilometres was calculated (Table 1).
From these calculations, it can be seen that tropical forests are a large reservoir of
carbon; however, the importance of other habitats is also highlighted. Most strikingly,
tundra is revealed as one of the earth’s major carbon sinks, holding 206 billion
tonnes of carbon for every million square kilometres. This is more than three times
the carbon storage in tropical forests. Tundra accumulates carbon dioxide when plant
remains are frozen into the permafrost by freezing winters, thereby stopping the
decomposition of plant remains and trapping the carbon dioxide that would normally
be given off during this process.
The soil in freshwater wetlands and lakes is also a large storage depot of the world’s
carbon, storing 53.4 billion tonnes per million square kilometres. The IPCC analysis
included tropical, sub-tropical and boreal peatlands in this category. However,
estimates of peatlands themselves, covering a global area of approximately 4 million
square kilometres7, suggest that peatlands store an enormous amount of the world’s
terrestrial carbon: up to 528 billion tonnes8,9, equating to 132 billion tonnes for every
million square kilometres, and the equivalent of one-third of the world’s soil carbon10.
Current emissions from the decomposition of drained peatlands, coupled with
emissions from peatland fires resulting from drainage and degradation, are estimated
at 2 billion tonnes every year, representing almost 8% of global emissions from the
burning of fossil fuels.
Table 1 also demonstrates that the carbon content of temperate forests is only
slightly lower than tropical forests at 42.1 billion tonnes per million square kilometres,
as is the content of carbon stored in the shrub-dominated Mediterranean ecosystems
at 42.1 billion tonnes per million square kilometres.
Table 2 shows the distribution of the major categories of natural carbon sinks in
developing (non-Annex 1) countries, and illustrates the widespread distribution of
carbon-rich tropical forests and peatlands, as well as tropical grasslands and
savannas in these countries.
Conclusion
While the current focus of international discussions to alleviate climate change is on
the protection of tropical forests, this analysis of the carbon storage in a range of
ecosystems demonstrates the reservoir value of habitats that have so far received
very little consideration for protection under future carbon trading or emission
reduction schemes, and highlights a range of natural carbon sinks, in addition to
tropical forests, that could be quantified and included in future negotiations, either
bilaterally, or in international fora.
7
Global Peatland Initiative. 2002. World Peatland Map.
Gorham E. 1991. Northern peatlands: role in the carbon cycle and probable responses to climatic
warming. Ecological Applications 1: 182–195.
9
Immirzi CP, Maltby E. 1992. The Global Status of Peatlands and their Role in Carbon Cycling. A
report for Friends of the Earth by the Wetland Ecosystems Research Group. Report 11, Department
of Geography, University of Exeter, Exeter, UK. Friends of the Earth: London.
10
Hooijer A, Silvius M, Wösten H & Page S. 2006. PEAT-CO2, Assessment of CO2
emissions from drained peatlands in SE Asia. Delft Hydraulics report.
8
Table 1: The global extent of the major ecosystems, total carbon stores in plant biomass, soil and permafrost, percentage of total non-atmospheric CO2, and
the relative amount of carbon stored in each habitat (Mkm2 – million square kilometres; PgC – petagrams of carbon. 1 PgC = 1.1 billion tonnes).
Habitat
Global
Surface
Area (Mkm2)
Carbon stocks (PgC)
Total carbon
(billion
tonnes)
% of total nonatmospheric
CO2
Amount of
carbon (billion
tonnes) per Mkm2
Plant
Soil
Permafrost
Total
Deserts
27.7
5
200
205
225.5
3.6
8.1
Tropical grasslands and savannas
28
100
400
500
550
8.7
19.6
Temperate grasslands
15
190
190
209
3.3
13.9
Tropical forests
17
350
700
1050
1155
18.2
66.1
Temperate forests
10
150
300
450
495
7.8
47.6
Mediterranean Ecosystems*
3
10
120
130
143
2.3
42.1
Boreal forests
14
50
150
200
220
3.5
16.0
Tundra
5.6
150
900
1050
1155
18.2
206.3
Freshwater lakes and wetlands**
10.3
500
500
550
8.7
53.4
Peatlandsa ***
4
528
8.3
132.0
Croplands
14
300
300
330
5.7
23.6
Oceans****
349.3
700
700
770
12.2
2.2
Adapted from: Fischlin A., GF Midgley, JT Price, R Leemans, B Gopal, C Turley, MDA Rounsevell, OP Dube, J Tarazona, AA Velichko (2007), and aGlobal
Peatland Initiative (2002); Gorham E (1991); Immirzi CP & Maltby E (1992).
* Mediterranean ecosystems are located in mid-latitudes on all continents. Vegetation structure is mainly shrub-dominated, with limited woodlands, forests
and grasslands. Heavily utilised landscapes are dominated grasses, herbs and annual plants.
** Freshwater lakes and wetlands includes tropical, sub-tropical and boreal peatlands, in addition to lakes and rivers
*** Peatland data is based on global estimates of peatland alone
**** Ocean carbon content includes dissolved and particulate organic carbon
Table 2: The distribution of natural carbon sinks in developing (non-Annex 1) countries.
Tropical
grasslands &
savannas
Angola
Argentina
Bhutan
Bolivia
Botswana
Brazil
Burundi
Cameroon
Central African
Republic
Chad
Colombia
Côte d'Ivoire
Congo, DR
Eritrea
Ethiopia
Gambia
Ghana
Guinea
Guyana
India
Indonesia
Kenya
Malawi
Mali
Mauritania
Mexico
Mozambique
Namibia
Nepal
Temperate
grasslands
Argentina
Mongolia
South Africa
Uruguay
Tropical Forests
Bangladesh
Benin
Bolivia
Brazil
Cameroon
Central African
Republic
China
Colombia
Congo
Congo, DR
Costa Rica
Cote d’Ivoire
Ecuador
Equatorial Guinea
Gabon
Ghana
Guyana
Honduras
India
Indonesia
Liberia
Madagascar
Malaysia
Mexico
Nicaragua
Nigeria
Panama
Papua New Guinea
Peru
Temperate forests
Algeria
Argentina
Chile
China
Georgia
India
Iran
Lebanon
Mexico
Morocco
South Africa
Boreal forests
Kazakhstan
Tundra
None
Peatlands
Angola
Argentina
Bangladesh
Brazil
Burkina Faso
Cambodia
Cameroon
Central African
Republic
Chad
Chile
China
Congo
Congo, DR
El Salvador
Guatemala
Guinea
Guyana
Honduras
India
Indonesia
Kenya
Korea, DR
Korea, Republic
Lao
Madagascar
Malaysia
Mali
Mexico
Mozambique
Tropical
grasslands &
savannas
Niger
Nigeria
Papua New Guinea
Paraguay
Rwanda
Senegal
South Africa
Sudan
Swaziland
Togo
Uganda
Uruguay
Venezuela
Zambia
Zimbabwe
Temperate
grasslands
Tropical Forests
Philippines
Sierra Leone
Suriname
Thailand
Venezuela
Vietnam
Temperate forests
Boreal forests
Tundra
Peatlands
Myanmar
Nicaragua
Nigeria
Pakistan
Papua New Guinea
Peru
Philippines
Senegal
Sudan
Suriname
Tanzania
Thailand
Uganda
Venezuela
Vietnam
Zambia