Independent: Polar bears are shrinking, along with the ice on which they live — and are turning to cannibalism — as global warming increasingly stops them getting enough to eat. Scientists say the animals are now only two-thirds as big as they were 30 years ago as melting ice makes it harder for them to catch seals, and that they have begun to hunt each other instead. The news comes as Arctic nations agreed at a special summit in Norway last week to draw up an action plan to try to save …