Universität zu Köln

Knoblauch, Christian ORCID: 0000-0002-7147-1008, Beer, Christian ORCID: 0000-0002-5377-3344, Schuett, Alexander, Sauerland, Lewis, Liebner, Susanne ORCID: 0000-0002-9389-7093, Steinhof, Axel, Rethemeyer, Janet, Grigoriev, Mikhail N., Faguet, Alexey and Pfeiffer, Eva-Maria (2021). Carbon Dioxide and Methane Release Following Abrupt Thaw of Pleistocene Permafrost Deposits in Arctic Siberia. J. Geophys. Res.-Biogeosci., 126 (11). WASHINGTON: AMER GEOPHYSICAL UNION. ISSN 2169-8961

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Abstract

The decomposition of thawing permafrost organic matter (OM) to the greenhouse gases (GHG) carbon dioxide (CO2) and methane forms a positive feedback to global climate change. Data on in situ GHG fluxes from thawing permafrost OM are scarce and OM degradability is largely unknown, causing high uncertainties in the permafrost-carbon climate feedback. We combined in situ CO2 and methane flux measurements at an abrupt permafrost thaw feature with laboratory incubations and dynamic modeling to quantify annual CO2 release from thawing permafrost OM, estimate its in situ degradability and evaluate the explanatory power of incubation experiments. In July 2016 and 2019, CO2 fluxes ranged between 0.24 and 2.6 g CO2-C m(-2) d(-1). Methane fluxes were low, which coincided with the absence of active methanogens in the Pleistocene permafrost. CO2 fluxes were lower three years after initial thaw after normalizing these fluxes to thawed carbon, indicating the depletion of labile carbon. Higher CO2 fluxes from thawing Pleistocene permafrost than from Holocene permafrost indicate OM preservation for millennia and give evidence that microbial activity in the permafrost was not substantial. Short-term incubations overestimated in situ CO2 fluxes but underestimated methane fluxes. Two independent models simulated median annual CO2 fluxes of 160 and 184 g CO2-C m(-2) from the thaw slump, which include 25%-31% CO2 emissions during winter. Annual CO2 fluxes represent 0.8% of the carbon pool thawed in the surface soil. Our results demonstrate the potential of abrupt thaw processes to transform the tundra from carbon neutral into a substantial GHG source.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Knoblauch, Christian UNSPECIFIED orcid.org/0000-0002-7147-1008 UNSPECIFIED Beer, Christian UNSPECIFIED orcid.org/0000-0002-5377-3344 UNSPECIFIED Schuett, Alexander UNSPECIFIED UNSPECIFIED UNSPECIFIED Sauerland, Lewis UNSPECIFIED UNSPECIFIED UNSPECIFIED Liebner, Susanne UNSPECIFIED orcid.org/0000-0002-9389-7093 UNSPECIFIED Steinhof, Axel UNSPECIFIED UNSPECIFIED UNSPECIFIED Rethemeyer, Janet UNSPECIFIED UNSPECIFIED UNSPECIFIED Grigoriev, Mikhail N. UNSPECIFIED UNSPECIFIED UNSPECIFIED Faguet, Alexey UNSPECIFIED UNSPECIFIED UNSPECIFIED Pfeiffer, Eva-Maria UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-599216
DOI:	10.1029/2021JG006543
Journal or Publication Title:	J. Geophys. Res.-Biogeosci.
Volume:	126
Number:	11
Date:	2021
Publisher:	AMER GEOPHYSICAL UNION
Place of Publication:	WASHINGTON
ISSN:	2169-8961
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language SOIL ORGANIC-MATTER; NET ECOSYSTEM EXCHANGE; LENA RIVER DELTA; ACTIVE-LAYER; TEMPERATURE SENSITIVITY; POLYGONAL TUNDRA; UNFROZEN WATER; CO2 PRODUCTION; GAS-PRODUCTION; HIGH-LATITUDE Multiple languages Environmental Sciences; Geosciences, Multidisciplinary Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/59921