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New Evidence Supports Global Methane Release 600 mya



http://www.nsf.gov/od/lpa/news/03/pr03140.htm

Arlington, Va.The Earth's most severe ice coverings are thought to have
occurred about 600 million years ago, with frozen ice sheets covering much
of the globe. Some scientists have suggested the oceans froze over during
that time, resulting in a white planet or "snowball Earth" that would have
reflected much of the Sun's heat and resulted in a condition of persistent
extreme cold.

Now, in a study published in the December 18 issue of the journal Nature,
scientists describe new evidence from south China that explains how the
planet might have thawed from its icy past. According to geologist Ganqing
Jiang of the University of California at Riverside and lead author of the
paper, the results point to the release of the powerful "greenhouse gas"
methane, than to the release of carbon dioxide, which has been believed to
be the mechanism by which the Earth re-warmed.

Where did the methane come from? "It probably arose from deposits known as
methane hydrates," said Jiang. "Methane hydrates likely were widespread in
sediments deposited under very cold conditions and would have been
released as a gas at the end of this ice age, rapidly warming Earths
climate."
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