No Arctic tipping point?

摘要

It Will be little consolation to hungry polar bears in northern Manitoba, Canada, who have had to wait weeks longer than usual for sea ice to form on Hudson Bay, but their habitat is not irreversibly doomed. It could be saved -if we cut greenhouse gas emissions. Polar bears only hunt from ice platforms at sea. The worry has been that the Arctic will hit a tipping point beyond which there will be no ice in summer, causing the bears to starve. Thats because the dwindling ice reflects less heat into space, causing it to warm up faster and melt away. Steven Amstrup of Polar Bears International in Bozeman, Montana, and colleagues ran a climate model for 2000 to 2100.