Global warming is starting to have a big impact on some of the world’s animals. Scientists have found out that polar bears are becoming smaller because they do not get enough to eat.

A polar bear weighs only two thirds of what it used to weigh 30 years ago. It is harder for them to hunt their main source of food –seals. In open water polar bears can not catch them. They wait on the ice for them to come up for air, and then they snatch them. As theice sheets in the Arctic are melting away bears cannot get to their food so easily.

Other scientists say that instead of hunting seals, polar bears are now hunting each other in order to survive. Two years ago an American government study predicted that global warming would kill two thirds of the world’s polar bears by 2050. But if the melting of the ice sheets goes on at the current speed the Arctic Ocean could be completely ice-free in the next 20 years.