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Global warming? Scientists find methane source in Arctic seas.

Researchers have located large emissions of the greenhouse gas methane from the East Siberian Arctic Shelf. They now want to determine if the emissions are tied to global warming.

By Peter N. SpottsStaff writer / March 4, 2010

Scientists have discovered large emissions of methane, a potent global warming gas, bubbling up from the East Siberian Arctic Sea.

Hinrich Baesemann/Newscom/File

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Scientists studying global warming in the Arctic have discovered a previously unknown source of methane working its way into the atmosphere, a source that is releasing large amounts of the gas each year.

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Methane is, molecule for molecule, a far more potent global-warming gas than carbon dioxide. The newly discovered emissions are welling up from the continental shelf off Siberia's northern coast

They are estimated at nearly 8 million metric tons a year, making them roughly equal to the amount that, until now, scientists had attributed to emissions from all the world's oceans combined, the researchers calculate. Still, the emissions represent no more than about 1 percent of total global emissions.

Their study is set for publication in tomorrow's issue of the journal Science.

It's not clear whether this previously unknown source of atmospheric methane became active recently or represents a long-term source whose existence only now has come to light, several scientists say.

Scientists are keenly interested in filling in the blanks – how these emissions might change as the climate warms, writes Ed Brook, a geochemist at Oregon State University, in an e-mail exchange.

"I don't think we are looking at a future catastrophe, but we may be looking at some acceleration of the increase in methane in the atmosphere because of enhanced release from systems like this," explains Dr. Brook, who was not part of the research team.

Is this a new source?

Scientists have taken careful measurements of atmospheric methane for years. The newly discovered source, the Eastern Siberian Arctic Shelf, may already be accounted for in those measurements.

Yet during the past few years, atmospheric methane levels have increased after a period where concentrations stalled, says Andrew Weaver, a climate scientist at the University of Victoria in Canada. Recent studies have suggested that the resumed increase is tied to methane sources in the northern hemisphere.

The discovery of emissions from Siberia's continental shelf "is such a northern-hemisphere source," says Dr. Weaver, who also did not take part in the study. "This is a really important piece of science," he adds.

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