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Carbon isotope ratios suggest no additional methane from boreal wetlands during the rapid Greenland Interstadial 21.2
Author(s) -
Sperlich Peter,
Schaefer Hinrich,
Mikaloff Fletcher Sara E.,
Guillevic Myriam,
Lassey Keith,
Sapart Célia J.,
Röckmann Thomas,
Blunier Thomas
Publication year - 2015
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1002/2014gb005007
Subject(s) - stadial , boreal , wetland , permafrost , peat , ice core , anomaly (physics) , northern hemisphere , atmospheric methane , environmental science , isotopes of carbon , climatology , atmospheric sciences , geology , oceanography , holocene , environmental chemistry , ecology , chemistry , greenhouse gas , total organic carbon , paleontology , physics , biology , condensed matter physics
Samples from two Greenland ice cores (NEEM and NGRIP) have been measured for methane carbon isotope ratios ( δ 13 C‐CH 4 ) to investigate the CH 4 mixing ratio anomaly during Greenland Interstadial (GI) 21.2 (85,000 years before present). This extraordinarily rapid event occurred within 150 years, comprising a CH 4 mixing ratio pulse of 150 ppb (∼25%). Our new measurements disclose a concomitant shift in δ 13 C‐CH 4 of 1‰. Keeling plot analyses reveal the δ 13 C of the additional CH 4 source constituting the CH 4 anomaly as −56.8 ± 2.8‰, which we confirm by means of a previously published box model. We propose tropical wetlands as the most probable additional CH 4 source during GI‐21.2 and present independent evidence that suggests that tropical wetlands in South America and Asia have played a key role. We find no evidence that boreal CH 4 sources, such as permafrost degradation, contributed significantly to the atmospheric CH 4 increase, despite the pronounced warming in the Northern Hemisphere during GI‐21.2.