Conclusion Global warming poses a special danger to the Arctic, a region in which wildlife and nature have formed a complex interrelationship. A major concern is the declining population of ringed seal, the polar bear's chief prey.
Unseasonable warmth causes the snow dens of the seal to collapse, leaving their pups vulnerable.
The warmth also shrinks the sea ice that is the bear's hunting ground, making it harder to find the seals during the short winter hunting season. A decline in its chief food source will result in a decline in polar bear populations, and biologists have already noted a drop in birth rates and suspect the bears' physical condition is worsening. Migratory birds are already being affected by the changing climate. Scientists studying the dates on which red-winged blackbirds arrive in northern Michigan found that warming temperatures have dramatically altered the birds' migration. They now arrive 21 days earlier than they did in 1960.