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Limited contribution of permafrost carbon. Accepted version.pdf (893.78 kB)

Limited contribution of permafrost carbon to methane release from thawing peatlands

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journal contribution
posted on 2023-06-09, 06:58 authored by Mark D A Cooper, Cristian Estop-Aragonés, James P Fisher, Aaron Thierry, Mark H Garnett, Dan J Charman, Julian MurtonJulian Murton, Gareth Phoenix, Rachael Treharne, Steve V Kokelj, Stephen A Wolfe, Antoni G Lewkowicz, Mathew Williams, Iain P Hartley
Models predict that thaw of permafrost soils at northern high-latitudes will release tens of billions of tonnes of carbon (C) to the atmosphere by 21001-3. The effect on the Earth's climate depends strongly on the proportion of this C which is released as the more powerful greenhouse gas methane (CH4), rather than carbon dioxide (CO2)1,4; even if CH4 emissions represent just 2% of the C release, they would contribute approximately one quarter of the climate forcing5. In northern peatlands, thaw of ice-rich permafrost causes surface subsidence (thermokarst) and water-logging6, exposing substantial stores (10s of kg C m-2, ref. 7) of previously-frozen organic matter to anaerobic conditions, and generating ideal conditions for permafrost-derived CH4 release. Here we show that, contrary to expectations, although substantial CH4 fluxes (>20 g CH4 m 2 yr-1) were recorded from thawing peatlands in northern Canada, only a small amount was derived from previously-frozen C (<2 g CH4 m-2 yr-1). Instead, fluxes were driven by anaerobic decomposition of recent C inputs. We conclude that thaw-induced changes in surface wetness and wetland area, rather than the anaerobic decomposition of previously-frozen C, may determine the effect of permafrost thaw on CH4 emissions from northern peatlands.


Carbon Cycling Linkages of Permafrost Systems (CYCLOPS); G0937; NERC-NATURAL ENVIRONMENT RESEARCH COUNCIL; NE/K000241/1


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Nature Climate Change




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