Permafrost in name only — thaw adds to warming

http://www.msnbc.msn.com/id/41625347/ns/us_news-environment/

By Miguel Llanos Reporter
msnbc.com msnbc.com
updated 2 hours 1 minute ago 2011-02-17T21:38:03

The permafrost capping the top of the world is irreversibly thawing and within two decades will release more carbon than it now absorbs, scientists calculate in a new study that makes this dire prediction: Up to 60 percent of Earth's permafrost will have thawed out by 2200.

Why care if you don't live in Siberia, Alaska or northern Canada, where thawing permafrost has already buckled roads and swallowed structures?

Because permafrost — which is ground that's been frozen continuously for two or more years — holds enormous amounts of carbon in the form of frozen plant matter, and adding more of that to the atmosphere would raise temperatures even higher, scientists say.

"The amount we expect to be released by permafrost is equivalent to half of the amount of carbon released since the dawn of the Industrial Age," Kevin Schaefer, lead author and a scientist at the National Snow and Ice Data Center, said in a statement. "That is a lot of carbon."

Here's another way to look at it: The carbon predicted for release through 2200 is about one-fifth of the total amount in the atmosphere today.

Earlier studies have estimated the carbon released from the "active layer" of soil a few inches above the permafrost — soil that freezes and thaws in winter and summer.

But "ours is the first study to estimate how much carbon could be released from thawing permafrost and when," Schaefer told msnbc.com.

If anything, the estimate is very conservative, Schaefer says, because it doesn't include a known "feedback" mechanism: that permafrost carbon release will certainly add to warming, which in turn will accelerate the thawing and then even more carbon emissions.

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