Fast Arctic thaw threatens people, polar bears

Global warming is heating the Arctic almost twice as fast as the rest of the planet in a thaw that threatens the livelihoods of millions of people and could wipe out polar bears by 2100, says an eight-nation report.

The biggest survey of the Arctic climate, by 250 scientists, said the accelerating melt could be a foretaste of wider disruptions from a build-up of human emissions of heat-trapping gases in the Earth's atmosphere.

The "Arctic climate is now warming rapidly and much larger changes are projected", says the Arctic Climate Impact Assessment funded by the United States, Canada, Russia, Denmark, Iceland, Sweden, Norway and Finland.

Arctic temperatures are rising at almost twice the global average and could leap 4C to 7C by 2100, roughly twice the global average projected by UN reports.

Siberia and Alaska have already warmed by 2C to 3C since the 1950s.

Possible benefits such as more productive fisheries, easier access to oil and gas deposits or transarctic shipping routes would be outweighed by threats to indigenous peoples and the habitats of animals and plants.

Sea ice around the North Pole, for instance, could almost disappear in summer by the end of the century, it said. The extent of the ice has already shrunk by 15 to 20 per cent in the past 30 years.

"Polar bears are unlikely to survive as a species if there is an almost complete loss of summer sea-ice cover," the report said. On land, creatures such as lemmings, caribou, reindeer or snowy owls were being forced north into a narrower range.