Melting permafrost could double C[O.sub.2].

• Position: Greenhouse Effect

For the past decade, much of the focus in the Arctic has centered on the rate at which ice melts and its ecological impact. Now, as Arctic ice continues to melt, carbon that has been stored in the frozen tundra for thousands of years is creeping up to the surface and exposed to a new element: sunlight. Researchers at the University of North Carolina, Chapel Hill, reveal that this exposed carbon could double the amount of greenhouse gases in the environment--and profoundly change the trajectory of the climate change debate.

"Organic carbon locked into permafrost stores more than twice the amount of carbon that is currently in the atmosphere, but it has always been frozen, so it has not participated in the carbon cycle for thousands of years. With the Earth getting warmer, that's all changing," says Rose Cory, assistant professor in the Department of Environmental Sciences and Engineering.

Cory and her team studied 27 melting permafrost sites in Alaska and identified seven thermokarst failures, large patches of the Arctic tundra that have melted. The melted ice causes the soil to collapse, creating either a large sinkhole or, if the slope is right, a landslide.

The researchers found...