Summer is short in the Arctic Circle and by early October, the sea ice is beginning to return.Sea water starts to freeze at around minus two degree Celsius.But it will be some time before the ice is thick enough for polar bears to return to their hunting platform.For the bears, this is the toughest time of the year.Without the sea ice, it's almost impossible for them to catch seals.In autumn, the bears living around Canada's Hudson bay lie in the shores in large numbers waiting for the sea to freeze.These are the southern most polar bears on the planet and they deal with longer and hotter summers than any others.
