Climate change in the Arctic may not just produce the fabled Northwest Passage; it may also release the vast stores of methane frozen in its tundra and lakes. New research in Siberia shows that methane from decaying plant and animal matter at the bottom of lakes is contributing 10 percent to 63 percent more of the powerful greenhouse gas to the atmosphere than previously estimated. And as more ground thaws, creating more such lakes, even more methane may be released--another potent example of the kind of positive feedback phenomenon that drives radical global warming. A paper detailing the finding appears in today's Nature.