NEW YORK TIMES: As Permafrost Thaws, Scientists Study the Risks

"A recent estimate suggests that the perennially frozen ground known as permafrost, which underlies nearly a quarter of the Northern Hemisphere, contains twice as much carbon as the entire atmosphere."

To read more, visit: http://www.nytimes.com/2011/12/17/science/earth/warming-arctic-permafrost-fuels-climate-change-worries.html?_r=1&emc=eta1