New research shows that permafrost soils hold massive quantities of mercury — nearly twice as much as is held in all other soils in the world, plus the mercury in the oceans and the atmosphere —

Just what exactly is permafrost? And what is happening now that it's warming up? To find out, we enter the Arctic Circle's secret world of ice and frozen history.

Snow is melting sooner and coming in later on the North Slope, and that, in turn, is having an affect on other ecological variables.

The size of a large caribou herd in Alaska's Arctic region has dropped by more 50 percent over the last three years, and researchers who have tentatively ruled out hunting and predation as significant factors for the decline are trying to determine why.

Climate-induced habitat changes on Alaska's North Slope such as coastal erosion and permafrost thaw have produced more food for migrating brant, a study says.