K. M. Walter et al., Thermokarst Lakes as a Source of Atmospheric CH4 (methane) During the Last Deglaciation

Science, 26 October 2007, Vol. 318, No. 5850, pp. 633–636; DOI: 10.1126/science.1142924

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 and F. S. Chapin, III⁷

Abstract

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 33–87% 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.

^*Corresponding author; e-mail: ftkmw1@uaf.edu

Link to abstract: http://www.sciencemag.org/cgi/content/abstract/sci;318/5850/633