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Science 26 October 2007:
Vol. 318. no. 5850, pp. 633 - 636
DOI: 10.1126/science.1142924
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Reports

Thermokarst Lakes as a Source of Atmospheric CH4 During the Last Deglaciation

K. M. Walter,1,2* M. E. Edwards,3,4 G. Grosse,5 S. A. Zimov,6 F. S. Chapin, III7

Polar ice-core records suggest that an arctic or boreal source was responsible for more than 30% of the large increase in global atmospheric methane (CH4) concentration during deglacial climate warming; however, specific sources of that CH4 are still debated. Here we present an estimate of past CH4 flux during deglaciation from bubbling from thermokarst (thaw) lakes. Based on high rates of CH4 bubbling from contemporary arctic thermokarst lakes, high CH4 production potentials of organic matter from Pleistocene-aged frozen sediments, and estimates of the changing extent of these deposits as thermokarst lakes developed during deglaciation, we find that CH4 bubbling from newly forming thermokarst lakes comprised 33 to 87% of the high-latitude increase in atmospheric methane concentration and, in turn, contributed to the climate warming at the Pleistocene-Holocene transition.

1 Water and Environmental Research Center, University of Alaska, Fairbanks, AK 99775, USA.
2 International Arctic Research Center, University of Alaska, Fairbanks, AK 99775, USA.
3 School of Geography, University of Southampton, UK.
4 College of Natural Sciences, University of Alaska, Fairbanks, AK 99775, USA.
5 Geophysical Institute, University of Alaska, Fairbanks, AK 99775, USA.
6 Northeast Science Station, Pacific Institute for Geography, Russian Academy of Sciences, Russia.
7 Institute of Arctic Biology, University of Alaska, Fairbanks, AK 99775, USA.

* To whom correspondence should be addressed. E-mail: ftkmw1{at}uaf.edu

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