Canada's permafrost retreats amid warming trend

Wed Feb 17, 2010 4:50pm EST
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By Deborah Zabarenko, Environment Correspondent

WASHINGTON (Reuters) - The permanently frozen ground known as permafrost is retreating northward in the area around Canada's James Bay, a sign of a decades-long regional warming trend, a climate scientist said on Wednesday.

When permafrost melts, it can liberate the powerful greenhouse gas methane that is locked in the frozen soil. The amount of methane contained in permafrost around James Bay is slight compared to the vast stores of the chemical found in ancient, deep permafrost in the Yukon, Alaska and Siberia.

The southern edge of permafrost in the James Bay area has moved about 80 miles north of where it was 50 years ago, Serge Payette of Laval University in Quebec City said in a telephone interview.

It's a sign that warming is taking hold in this area that straddles the Canadian provinces of Quebec, Ontario and Manitoba. Payette said the sites he has studied have warmed by 3.6 degrees F (2 degrees C) in the last two decades.

And it shows what dying permafrost looks like.

"This is the end of the line for permafrost," Payette said.

To track the retreat, Payette and his colleagues looked at distinctive plant-covered mounds called palsas that form naturally over ice in the soil of northern peat bogs.

There were up to 90 percent fewer palsas in bogs around James Bay in 2005 than there were in 2004, the researchers found. And that was far fewer than those palsas shown in the area in aerial photographs taken in 1957, Payette said.   Continued...