Methane Release from Arctic Clathrates Could Threaten Global Climate
04.06.2008 - Other
A new study lead by the University of California at Riverside has shed light on the sudden climate warming which occurred about 635 million years ago. This study pinpoints methane release, a greenhouse gas about 30 times more potent than carbon dioxide.
According to the snowball hypothesis, millions of years ago the Earth was covered by a thick ice sheet which extended from pole to pole. Based on the isotope analysis of marine sediment samples retrieved in South Australia, this current study suggests that the destabilization of methane clathrates caused the last "snowball Earth" to come to an end. "The geologic deposits of this period are quite different from what we find in subsequent deglaciation. Moreover, they immediately precede the first appearance of animals on Earth," said Martin Kennedy, a professor of geology in the Department of Earth Sciences, who lead the research team.
The researchers behind this study posit that methane was first released in small doses, and then later on, in abundance from clathrates. A clathrate is methane ice which has formed beneath the ice sheet surface and which is kept stable under specific temperatures and pressures. As ice sheets become less stable, pressure is exerted against the clathrates and causes them to degas.
After methane was released in the lower latitudes, warming then caused more clathrates to destabilize. However, not all of the clathrates have released their methane. "The same methane clathrates are present today in the Arctic permafrost as well as below sea level at the continental margins of the ocean, and remain dormant until triggered by warming".
This raises concern as to the future climate system on Earth. It is estimated that, if the remaining clathrates of the Arctic region were to release the methane they hold, Earth could potentially warm some ten degrees.
