Climate study predicts big thaw

ANCHORAGE, Alaska (AP) -- Climate change could thaw the top 11 feet of permafrost in most areas of the Northern Hemisphere by 2100, altering ecosystems across Alaska, Canada and Russia, according to a federal study.

Using supercomputers in the United States and Japan, the study calculated how frozen soil would interact with air temperatures, snow, sea ice changes and other processes.

The most extreme scenario involved the melting of the top 11 feet (3.35 meters) of permafrost, or earth that remains frozen year-round.

"If that much near-surface permafrost thaws, it could release considerable amounts of greenhouse gases into the atmosphere, and that could amplify global warming," said lead author David Lawrence, with the National Center for Atmospheric Research. "We could be underestimating the rate of global temperature increase."