Letter

Nature 443, 71-75 (7 September 2006) | doi:10.1038/nature05040; Received 5 December 2005; Accepted 3 July 2006

Methane bubbling from Siberian thaw lakes as a positive feedback to climate warming

K. M. Walter1, S. A. Zimov2, J. P. Chanton3, D. Verbyla4 and F. S. Chapin, III1

Large uncertainties in the budget of atmospheric methane, an important greenhouse gas, limit the accuracy of climate change projections1, 2. Thaw lakes in North Siberia are known to emit methane3, but the magnitude of these emissions remains uncertain because most methane is released through ebullition (bubbling), which is spatially and temporally variable. Here we report a new method of measuring ebullition and use it to quantify methane emissions from two thaw lakes in North Siberia. We show that ebullition accounts for 95 per cent of methane emissions from these lakes, and that methane flux from thaw lakes in our study region may be five times higher than previously estimated3. Extrapolation of these fluxes indicates that thaw lakes in North Siberia emit 3.8 teragrams of methane per year, which increases present estimates of methane emissions from northern wetlands (< 6–40 teragrams per year; refs 1, 2, 4–6) by between 10 and 63 per cent. We find that thawing permafrost along lake margins accounts for most of the methane released from the lakes, and estimate that an expansion of thaw lakes between 1974 and 2000, which was concurrent with regional warming, increased methane emissions in our study region by 58 per cent. Furthermore, the Pleistocene age (35,260–42,900 years) of methane emitted from hotspots along thawing lake margins indicates that this positive feedback to climate warming has led to the release of old carbon stocks previously stored in permafrost.

  1. Institute of Arctic Biology, University of Alaska Fairbanks, Alaska 99775, USA
  2. Northeast Science Station, Cherskii 678830, Russia
  3. Department of Oceanography, Florida State University, Florida 32306, USA
  4. Forest Science Department, University of Alaska Fairbanks, Alaska 99775, USA

Correspondence to: K. M. Walter1 Correspondence and requests for materials should be addressed to K.M.W. (Email: ftkmw1@uaf.edu).

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