Today, 20% of Earth's land surface is locked up in a deep freeze.
Even as glaciers and sea ice have captured the most headlines, growing concern is now focused on the transformation of permafrost, soils that are frozen year-round.
As permafrost thaws in the Arctic, huge pockets of methane -a potent greenhouse gas - could be released into the atmosphere.
As warmer air thaws Arctic soils, as much as 55 billion tons of methane could be released from beneath Siberian lakes alone, according to Walter’s research.
That would amount to 10 times the amount currently in the atmosphere.
Methane emissions from Arctic lakes were a major contributor to a period of global warming more than 11,000 years ago
Methane levels in the atmosphere have tripled since preindustrial times.
Human activities, including rice cultivation, cattle raising and coal mining, account for about 70% of releases, according to recent studies.
Natural sources, like tropical wetlands and termites, make up the rest. But those estimates had not incorporated the bubbles Walter was probing on an autumn morning on the Seward Peninsula.
Nowhere is the evidence of a heating planet more dramatic than in the polar regions.
Over the last 50 years, the Arctic has warmed twice as fast as the rest of the globe. Last summer 08, for the first time in recorded history, the North Pole could be circumnavigated. Ice sheets on Greenland and West Antarctica are melting rapidly. Polar bears and emperor penguins are threatened with extinction.
The upper 3 meters -- about 10 feet -- of permafrost stores 1.9 trillion tons of carbon, more than double the amount in the atmosphere today
We are seeing thawing down to 5 meters," says geophysicist Vladimir Romanovsky of the University of Alaska. "A third to a half of permafrost is already within a degree to a degree and a half [Celsius] of thawing."
If only 1% of permafrost carbon were to be released each year, that could double the globe's annual carbon emissions.
http://www.latimes.com/news/la-na-global-warming-methane22-2009feb22,0,234694.story?page=1&track=ntothtml
cesky www.zi.ma/otep
