Preprints
https://doi.org/10.5194/cp-2022-80
https://doi.org/10.5194/cp-2022-80
 
17 Oct 2022
17 Oct 2022
Status: this preprint is currently under review for the journal CP.

Atmospheric methane since the LGM was driven by wetland sources

Thomas Kleinen1, Sergey Gromov2, Benedikt Steil2, and Victor Brovkin1 Thomas Kleinen et al.
  • 1Max Planck Institute for Meteorology, Bundesstr. 53, 20146 Hamburg, Germany
  • 2Max Planck Institute for Chemistry, Hahn-Meitner-Weg 1, 55128 Mainz, Germany

Abstract. Atmospheric methane (CH4) has changed considerably in the time between the last glacial maximum (LGM) and the preindustrial period (PI). We investigate these changes in transient experiments with an Earth System Model, focusing on the rapid changes during the deglaciation, especially pronounced in the Bølling Allerød (BA) and Younger Dryas (YD) periods. We consider all relevant natural sources and sinks of methane and examine the drivers of changes in methane emissions as well as in the atmospheric lifetime of methane. We find that the evolution of atmospheric methane is largely driven by emissions from tropical wetlands, while variations in atmospheric lifetime are not negligible but small. Our model reproduces most changes in atmospheric methane very well, with the exception of the mid-Holocene decrease in methane, though the timing of ice sheet meltwater fluxes needs to be adjusted slightly in order to exactly reproduce the variations of the BA and YD.

Thomas Kleinen et al.

Status: open (until 12 Dec 2022)

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Thomas Kleinen et al.

Thomas Kleinen et al.

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Short summary
We have modelled atmospheric methane continuously from the last glacial maximum to the present, using a state-of-the-art Earth System Model. Our model results compare well with reconstructions from ice cores and improve our understanding of a very intriguing period of Earth System history, the deglaciation, when atmospheric methane changed quickly and strongly.