Glacial/interglacial wetland, biomass burning, and geologic methane emissions constrained by dual stable isotopic CH₄ ice core records ...

• Main Authors: Bock, Michael, Schmitt, Jochen, Beck, Jonas, Seth, Barbara, Chappellaz, Jérôme, Fischer, Hubertus
• Format: Text
• Language: English
• Published: National Academy of Sciences NAS 2017
• Subjects: 530 Physics; Antarctic; Antarc*; ice core
• Online Access: https://dx.doi.org/10.7892/boris.106529; https://boris.unibe.ch/106529/

Atmospheric methane (CH₄) records reconstructed from polar ice cores represent an integrated view on processes predominantly taking place in the terrestrial biogeosphere. Here, we present dual stable isotopic methane records [δ13CH₄ and δD(CH₄)] from four Antarctic ice cores, which provide improved constraints on past changes in natural methane sources. Our isotope data show that tropical wetlands and seasonally inundated floodplains are most likely the controlling sources of atmospheric methane variations for the current and two older interglacials and their preceding glacial maxima. The changes in these sources are steered by variations in temperature, precipitation, and the water table as modulated by insolation, (local) sea level, and monsoon intensity. Based on our δD(CH₄) constraint, it seems that geologic emissions of methane may play a steady but only minor role in atmospheric CH₄ changes and that the glacial budget is not dominated by these sources. Superimposed on the glacial/interglacial ...