The majority of the carbon stored in peatlands is in the saturated peat soil that has been sequestered over millennia. In the sub (polar) zone, peatlands contain on average 3.5 times more carbon per hectare than the above-ground ecosystems on mineral soil; in the boreal zone they contain 7 times more and in the humid tropics over 10 times more carbon.
Growing source of greenhouse gas (GHG) emissions
Large areas of organic wetland (peat) soils are drained for agriculture, forestry and peat extraction all over the world. As a result, the organic carbon that is normally underwater is suddenly exposed to the air, where it decomposes and emits carbon dioxide (CO2). Peat fires, such as those take place in Southeast Asia every year and also in Russia, release huge amounts of CO2 as well. Altogether global CO2 emissions amount to at least 2,000 million tonnes annually, equivalent to 6% of the global fossil-fuel emissions.
Another growing source of GHG emissions from peatlands is methane. The scientific database for methane effluxes from peatlands is much larger than that for CO2 or N2O. The following report on Methane emission from peat soils and article on Towards developing IPCC methane 'emission factor' for peatlands (organic soils) give more insights on this matter.
While Indonesia currently has the highest CO2 emissions from peatlands due to logging and drainage (~900Mtons per year), the peatlands degradation is a global problem. Download The Global Peatland CO2 Picture for CO2 emissions worldwide inventory.
Impact of climate change on peatlands
Another cause for concern is that climate change poses an enormous challenge to peatlands and CO2 emissions. For instance, warmer summer weather threatens to thaw the large peatland (permafrost) areas of Canada and Russia, causing them to decompose. There is also a risk that fossilised methane, stored under the permafrost areas, could be released.