Limited contribution of permafrost carbon to methane release from thawing peatlands

Cooper, Mark D A, Estop-Aragonés, Cristian, Fisher, James P, Thierry, Aaron, Garnett, Mark H, Charman, Dan J, Murton, Julian B, Phoenix, Gareth, Treharne, Rachael, Kokelj, Steve V, Wolfe, Stephen A, Lewkowicz, Antoni G, Williams, Mathew and Hartley, Iain P (2017) Limited contribution of permafrost carbon to methane release from thawing peatlands. Nature Climate Change, 7. pp. 501-511. ISSN 1758-678X

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Abstract

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.

Item Type: Article
Schools and Departments: School of Global Studies > Geography
Depositing User: Sharon Krummel
Date Deposited: 03 Jul 2017 14:01
Last Modified: 03 Jul 2017 14:03
URI: http://sro.sussex.ac.uk/id/eprint/68930

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Project NameSussex Project NumberFunderFunder Ref
Carbon Cycling Linkages of Permafrost Systems (CYCLOPS)G0937NERC-NATURAL ENVIRONMENT RESEARCH COUNCILNE/K000241/1