evidence: While scientists have long known polar bears are threatened by global heating, this latest study published in Nature Climate Change is the first to identify when and where the bears will disappear. [...] But polar bears, which are the largest terrestrial carnivore on the planet, are vulnerable to extinction according the International Union for Conservation of Nature, which cites climate change as the main cause of their decline. The Arctic has been warming at double the rate of the global average for the past 25 years. Since the 1970s, sea ice has been melting by approximately 13% per decade, according to satellite records. Polar bears, which are not strong enough swimmers to catch seal in open water, have struggled to hunt as sea ice disappears. This is not the first time polar bears have faced extinction. In 1965, specialists warned that commercial polar bear hunting was pushing the species to extinction, leading to a worldwide restriction on commercial hunting in 1973. And though the ban led to a resurgence in bear population numbers, melting sea ice now threatens the lives of the estimated 26, 000 polar bears that remain today.