Geology

Rapid Decompression

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Science  23 Jan 2004:
Vol. 303, Issue 5657, pp. 435
DOI: 10.1126/science.303.5657.435b

Abrupt changes in Earth's past climate are often associated with evidence for an increase in methane, a major greenhouse gas, in the atmosphere. One hypothesis is that these changes reflect sudden destabilization and release of large amounts of methane that are stored as clathrates on the continental shelves. Furthermore, extreme cases of destabilization have been proposed as a possible cause of some mass extinctions.

One way in which the methane in clathrates could be released abruptly would be as a consequence of large or numerous submarine landslides. Maslin et al. tested this relation by compiling dates of known submarine landslides during the past 45,000 years. Although the number of well-studied submarine slides is limited, 11 out of 27 slides occurred during two time intervals associated with known increases of atmospheric methane: about 15,000 to 13,000 and 11,000 to 8000 years ago. These relations broadly support the methane release hypothesis. Some of the slides also seem to be clustered around areas undergoing rapid postglacial rebound, suggesting that further extensive melting of ice sheets could lead to additional submarine slides. — BH

Geology 32, 53 (2004)

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