REDD-plus and Biodiversity - Convention on Biological Diversity

<strong>REDD</strong>-<strong>plus</strong> <strong>and</strong> <strong>Biodiversity</strong>
one biological <strong>and</strong> the other physical, that transport carbon into the ocean depths. Physical processes
control the rate at which CO 2
dissolves in the oceans, <strong>and</strong> both physical <strong>and</strong> biological processes then
determine how the dissolved inorganic carbon is transported within the oceans. These processes are also
being affected by climate change.
Table 3.1. One estimate of global carbon stocks in terrestrial ecosystems (There remains uncertainty
around estimates of carbon stocks due to differences in field data used to calculate carbon densities <strong>and</strong>
methods for up-scaling these values. There is also great variation within any biome, e.g., wet temperate
forests can be 2-3 more carbon dense than the biome average.)
Biome Global Carbon Stocks (Gt C)
Vegetation Soil Total
Tropical forests 212 216 428
Temperate forests 59 100 159
Boreal forests 88 471 559
Tropical savannas 66 264 330
Temperate grassl<strong>and</strong>s 9 295 304
Deserts <strong>and</strong> semi deserts 8 191 199
Tundra 6 121 127
Wetl<strong>and</strong>s 15 225 240
Cropl<strong>and</strong>s 3 128 131
Total 466 2 011 2 477
133. The widespread <strong>and</strong> accelerating degradation of ecosystems has been <strong>and</strong> remains a significant
source of greenhouse gas emissions, <strong>and</strong> is reducing the potential of ecosystems to sequester carbon.
Although the largest share of CO 2
emissions are as the result of the combustion of fossil fuels, in 2005
about 18% of annual global greenhouse gas emissions were attributable to deforestation <strong>and</strong> other l<strong>and</strong> use
change <strong>and</strong> an additional 5.1-6.1 Gt CO 2
eq., or 10-12% of global emissions, stemmed from agricultural
l<strong>and</strong> management practices (mostly through release of nitrous oxide (N 2
O) <strong>and</strong> methane (CH 4
)), although
there is still uncertainty around the range of estimates. Degradation of natural grassl<strong>and</strong>s, for example,
can be a large source of carbon loss since cultivated soils generally contain 50-70 per cent less carbon
than those in natural ecosystems. The continuing rapid loss <strong>and</strong> degradation of northern, temperate <strong>and</strong>
tropical peatl<strong>and</strong>s is also a major source of greenhouse gas emissions, with an estimated 3 Gt CO 2
eq. (or
10% of global emissions) released each year by the drainage <strong>and</strong> conversion of peatl<strong>and</strong>s to agriculture or
forestry, <strong>and</strong> peat fires.
134. Given that forests contain almost half of all terrestrial carbon, continued deforestation <strong>and</strong> degradation
at current rates would significantly hamper mitigation efforts. An estimated 7 to 13 million
ha of forests are cleared each year, 3 releasing about 1.5 Gt C (5.5 GtCO 2
) into the atmosphere. In addition,
2 to 3 million hectares of tropical forests are degraded each year by unsustainable management. Reducing
these emissions would make a key contribution to climate mitigation <strong>and</strong> is critical for avoiding dangerous
climate change.
135. There is a wide range of different forest contexts: from primary forests to monoculture plantations
<strong>and</strong> these differ in their carbon stock, carbon sequestration potential, biodiversity value <strong>and</strong>
their resilience to climate change. Primary forests are generally more carbon dense <strong>and</strong> biologically
3
Estimates of the area of deforestation vary according to methodology, definitions of what constitutes a forest <strong>and</strong> due to natural
variation from year to year.
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