Permafrost thaw driven changes in hydrology and vegetation cover increase trace gas emissions and climate forcing in Stordalen Mire from 1970 to 2014

Permafrost thaw increases active layer thickness, changes landscape hydrology and influences vegetation species composition. These changes alter belowground microbial and geochemical processes, affecting production, consumption and net emission rates of climate forcing trace gases. Net carbon dioxid...

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Bibliographic Details
Published in:Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences
Main Authors: Varner, Ruth K., Crill, Patrick M., Frolking, Steve, McCalley, Carmody K., Burke, Sophia A., Chanton, Jeffrey P., Holmes, M. Elizabeth, Saleska, Scott, Palace, Michael W.
Language:unknown
Published: 2022
Subjects:
54 ENVIRONMENTAL SCIENCES
Stordalen
Active layer thickness
Northern Sweden
permafrost
Online Access:http://www.osti.gov/servlets/purl/1856519
https://www.osti.gov/biblio/1856519
https://doi.org/10.1098/rsta.2021.0022
Description
Summary:Permafrost thaw increases active layer thickness, changes landscape hydrology and influences vegetation species composition. These changes alter belowground microbial and geochemical processes, affecting production, consumption and net emission rates of climate forcing trace gases. Net carbon dioxide (CO 2 ) and methane (CH 4 ) fluxes determine the radiative forcing contribution from these climate-sensitive ecosystems. Permafrost peatlands may be a mosaic of dry frozen hummocks, semi-thawed or perched sphagnum dominated areas, wet permafrost-free sedge dominated sites and open water ponds. We revisited estimates of climate forcing made for 1970 and 2000 for Stordalen Mire in northern Sweden and found the trend of increasing forcing continued into 2014. The Mire continued to transition from dry permafrost to sedge and open water areas, increasing by 100% and 35%, respectively, over the 45-year period, causing the net radiative forcing of Stordalen Mire to shift from negative to positive. This trend is driven by transitioning vegetation community composition, improved estimates of annual CO 2 and CH 4 exchange and a 22% increase in the IPCC's 100-year global warming potential (GWP_100) value for CH 4 . These results indicate that discontinuous permafrost ecosystems, while still remaining a net overall sink of C, can become a positive feedback to climate change on decadal timescales.

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