Taken from another Google group:
http://news.nationalgeographic.com/news/2008/12/081219-methane-siberi...
December 19, 2008
Methane Bubbling Up From Undersea Permafrost?
Mason Inman in San Francisco, California
for National Geographic News
The East Siberian Sea is bubbling with methane, a powerful greenhouse
gas, being released from underwater reserves, according to a recent
expedition by a Russian team.
This could be a sign that global warming is thawing underwater
permafrost, which is releasing methane that has been locked away for
many thousands of years.
If these methane emissions from the Arctic speed up, it could cause
"really serious climate consequences," said study leader Igor
Semiletov of the Pacific Oceanological Institute in Vladivostok,
Russia.
Semiletov and colleagues have traveled along the Siberian coast this
year they covered 13,000 miles (22,000 kilometers) while monitoring
methane concentrations in the air and observing the seas.
"According to our data, more than 50 percent of the Arctic Siberian
shelf is serving as a source of methane to the atmosphere," Semiletov
said.
This vast shelf is about 750,000 square miles (2 million square
kilometers) about the same size as Greenland or Mexico and about 80
percent of it is covered with permafrost, Semiletov said.
He presented the findings from his group at an American Geophysical
Union meeting in San Francisco this week.
Not-So-Permanent Permafrost
Permafrost is basically dirt that's been permanently frozen for
hundreds or thousands of years, much of it since the last ice age.
Sea levels back then near the Siberian coast were about 325 feet (100
meters) lower than today, and the exposed ground froze solid down to
1,600 to 2,300 feet (500 to 700 meters) deep.
Over the past 10,000 years, sea levels rose to cover some of this
permafrost, and in recent years those seas have seen increases in
average temperatures.
"As a result, sub-sea permafrost has warmed up to minus 1 degree
Celsius [30 degrees Fahrenheit]," Semiletov said.
"It's very, very close to the thawing point."
Underneath the permafrost are stores of methane, the same as the
natural gas people use for cooking and heating.
There are also methane hydrates, a solid that forms when methane and
water mix in cold temperatures.
The hydrates release gas as they warm.
"It was assumed that these stores of methane have not been leaking,
because the sub-sea permafrost served as a lid keeping hydrates and
natural gas in place," Semiletov said.
But now global warming may be starting to release these stores of
methane into the atmosphere.
Drastic Increase
Regions farther from the Equator generally are experiencing more
warming, and the Arctic is warming fastest of all.
"Springtime air temperatures on the East Siberian Arctic shelf [have]
increased up to 5 degrees Celsius [9 degrees Fahrenheit]," Semiletov
said.
"It's a hot spot."
In comparison, the world as a whole has warmed about 1.25 degrees
Fahrenheit (0.7 degrees Celsius) since pre-industrial times.
If abrupt methane release became widespread, it could create a
feedback loop that would lead to even more drastic global warming.
"Our early observations in 1994 to 1999 didn't reveal a widespread
enhanced dissolved methane concentration" along the Siberian coast,
Semiletov said.
"With this newly obtained data, we suggest an increase of methane
release from the East Siberian Arctic shelf," he said.
"We have obtained a drastic increase of air methane in some
sites sometimes up to four times higher than the background [global
average]."
Vladimir Romanovsky, a permafrost expert at the University of Alaska,
Fairbanks, says the study is worrying.
"It has very serious implications for changes in greenhouse gases,"
Romanovsky said, and the releases described should be monitored more
closely. >end
Peace,
Doc
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