Nature 366, 443 - 445 (02 December 1993); doi:10.1038/366443a0

Synchronous changes in atmospheric CH4 and Greenland climate between 40 and 8 kyr BP

J. Chappellaz^*, T. Bluniert^†, D. Raynaud^*, J. M. Barnola^*, J. Schwander^† & B. Stauffert^†

^*Laboratoire de Glaciologie et Géophysique de TEnvironnement, BP 96, 38402 St Martin d'Heres Cedex, France
^†Physikalisches Institut, Sidlerstrasse 5, CH-3012 Bern, Switzerland

ICE-CORE reconstructions of atmospheric methane concentrations for the past 220 kyr have revealed large variations associated with different climatic periods^1–4. But the phase relationship between climate and methane has been uncertain because of dating uncertainties and the coarse sampling interval of available methane records. Here we present a high-resolution record of atmospheric methane from 40 to 8 kyr ago from the GRIP ice core in Green-land. Our improved resolution and dating allow us to conclude that the large changes in atmospheric methane concentration during the last deglaciation were in phase (200 years) with the variations in Greenland climate. Our results confirm the previous observation³ that methane increased to Holocene levels when much of the Northern wetlands was still ice-covered, lending support to the suggestion³ that low-latitude wetlands were responsible for the observed changes. We observe oscillations in methane concentration associated with the warm periods (interstadials) that occurred throughout the glacial period⁵, suggesting that the interstadials were at least hemispheric in their extent. We propose that variations in the hydrological cycle at low latitudes may be responsible for the variations in both methane and Greenland temperature during the interstadials.

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