Ice-core record of atmospheric methane changes: relevance to climatic changes and possible gas hydrate sources

• Published in: Geological Society, London, Special Publications
• Main Authors: Raynaud, D., Chappellaz, J., Blünier, T.
• Format: Text
• Language: unknown
• Published: Geological Society of London 2022
• Subjects: Antarctic; Greenland; The Antarctic; Antarc*; ice core
• Online Access: https://doi.org/10.1144/GSL.SP.1998.137.01.26; http://infoscience.epfl.ch/record/298336

This paper is part of the special publication Gas hydrates: relevance to world margin stability and climatic change (eds J.P. Henriet and J. Mienert). The Antarctic and Greenland ice contains an almost direct record of past atmospheric CH 4. The record over the last 200 years reveals a spectacular 150% increase of the CH 4 atmospheric mixing ratio since pre-industrial times. At the scale of a glacial-interglacial cycle the record shows a remarkable correlation with climatic changes, with high (low) CH 4 levels during warm (cold) periods. A striking feature of the glacial-interglacial CH 4 record is the presence of large and abrupt (at the scale of a century or less) changes during the last glaciation and glacial-interglacial transition. The classical interpretation for the origin of CH 4 changes prior to the industrial era involves mainly the wetland source. In the context of gas hydrates the question is to know whether the past ice-core record contains fingerprints of catastrophic hydrate release (CHR). We currently conclude that the available record shows no evidence for CHR but additional ice-core analyses are necessary to reach a more definitive conclusion.