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Science 10 February 2006:
Vol. 311. no. 5762, pp. 838 - 840
DOI: 10.1126/science.1121235
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Reports

Late Quaternary Atmospheric CH4 Isotope Record Suggests Marine Clathrates Are Stable

Todd Sowers

One explanation for the abrupt increases in atmospheric CH4, that occurred repeatedly during the last glacial cycle involves clathrate destabalization events. Because marine clathrates have a distinct deuterium/hydrogen (D/H) isotope ratio, any such destabilization event should cause the D/H ratio of atmospheric CH4 ({delta}DCH4) to increase. Analyses of air trapped in the ice from the second Greenland ice sheet project show stable and/or decreasing {delta}DCH4 values during the end of the Younger and Older Dryas periods and one stadial period, suggesting that marine clathrates were stable during these abrupt warming episodes. Elevated glacial {delta}DCH4 values may be the result of a lower ratio of net to gross wetland CH4 emissions and an increase in petroleum-based emissions.

Department of Geosciences and the Earth and Environmental Systems Institute, Pennsylvania State University, University Park, PA 16802, USA.

E-mail: sowers{at}geosc.psu.edu

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