Melting sea ice in the Arctic will kill thousands of bears in coming years, the US says, and continued commercial trade must not be allowed to make the situation worseIt is a familiar story in the climate change debate. The US government is at odds with the rest of the world and, despite criticism, wants other countries to change their minds and fall in line behind Uncle Sam.This time, the tale comes with an unexpected twist. This weekend, the US will warn that the threat from climate change to the future survival of the polar bear is so great that the world must grant the animal the highest possible protection.At the annual meeting of the international body that regulates trade in animals, the US will push for a total ban on the sale and movement of polar bear products that are used for furs, rugs and taxidermy.