Agence France Presse: Some of Canada’s polar bear populations risk being wiped out within four decades because of climate change and human activity including hunting, the World Wide Fund For Nature warned Sunday. Canada, whose frozen north is home to two-thirds of all polar bears, is contributing to the creatures’ decline by failing to take action to curb its emissions of greenhouse gases, WWF-Canada official Peter Ewins said. "There is rapidly mounting evidence that many polar bear populations …