Reconciling the changes in atmospheric-methane sources and sinks between the Last Glacial Maximum and the pre-industrial era

We know from the ice record that the concentration of atmospheric methane, [CH4], at the Last Glacial Maximum (LGM) was roughly half that in the pre-industrial era (PI), buthow much of the difference was source-driven, and how much was sink-driven, remains uncertain. Recent developments include: a higher estimate of the LGM-PI change in methane emissions from wetlands―the dominant, natural methane source; and the possible recycling of OH consumed in isoprene oxidation―the principal methane sink. Here, in view of these developments, we use an atmospheric chemistry-transport model to re-examine the main factors affecting OH during this period: changes in air temperature and emissions of non-methane volatile organic compounds from vegetation. We find that their net effect was negligible(with and without an OH recycling mechanism), implyingthe change in [CH4] was almost entirely source driven―a conclusion that, though subject to significant uncertainties,can be reconciled with recent methane source estimates.


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Authors: Levine, J.G., Wolff, E.W., Jones, A.E. ORCIDORCID record for A.E. Jones, Sime, L.C. ORCIDORCID record for L.C. Sime, Valdes, P.J., Archibald, A.T., Carver, G.D., Warwick, N.J., Pyle, J.A.

On this site: Anna Jones, Eric Wolff, Louise Sime
1 January, 2011
Geophysical Research Letters / 38
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