Glacial/interglacial wetland, biomass burning, and geologic methane emissions constrained by dual stable isotopic CH4ice core records

• DOI: 10.1073/pnas.1613883114
• Publication Date: 2017-07-04T00:50:19Z
• Authors: Michael Bock; Jochen Schmitt; Jonas Beck; Barbara Seth; Jérôme Chappellaz; Hubertus Fischer
• Keywords: floodplain; 550; stable isotopes; precipitation; sea level; 01 natural sciences; Article; [SDU] Sciences of the Universe [physics]; glacial period; megafauna; stable isotope; 0105 earth and related environmental sciences; biomass; methane; temperature; interglacial; Upper Pleistocene; 15. Life on land; wetland; 6. Clean water; climate change; biome; priority journal; [SDU]Sciences of the Universe [physics]; 13. Climate action; ice core record; atmosphere; sunlight; ice core; fire; water table

SignificancePolar ice is a unique archive of past atmosphere. Here, we present methane stable isotope records (used as source fingerprint) for the current and two past interglacials and their preceding glacial maxima. Our data are used to constrain global emissions of methane. Tropical wetlands and floodplains seem to be the dominant sources of atmospheric methane changes, steered by past variations in sea level, monsoon intensity, temperature, and the water table. In contrast, geologic emissions of methane are stable over a wide range of climatic conditions. The long-term shift seen in both isotopes for the last 25,000 y compared with older intervals is likely connected to changes in the terrestrial biosphere and fire regimes as a consequence of megafauna extinction.