By Dan Shapley
Icon Of Environmental Movement Losing Ground -- Literally
They're the icon of the global warming issue, and there's another sign today that their time is limited. Polar bears, already stressed from long-distance swims made necessary by increasingly scarce ice, are moving from ice to land to give birth. It's a trend federal scientists, who conducted the study in Alaska, say is worrying, in part because pregnant bears have to wait as much as a month longer to start denning -- and that time costs energy and causes stress in animals already surviving in some of the world's harshest conditions.