Struggling against the waves, this polar bear faces almost certain death after becoming lost at sea in the Arctic.

It is one of a group of nine to have plunged into the ocean after the ice float they lived on melted.

The bears were spotted miles from their normal hunting ground by U.S. government oil survey scientists flying over Alaska's Chukchi Sea.

They said the creatures' homing instinct has sent them north towards the edge of the polar cap instead of 60 miles south towards the nearest land.

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Scientists found this polar bear swimming in Alaska's Chukchi Sea and fear it and eight others will drown in an impossible 400 mile swim back to shore

However, because of global warming, the ice cap has melted so much that it is around 400 miles away - too far for the bears to reach.

Although one group of polar bears is known to have swum 100 miles, they arrived at their destination exhausted, with several drowning along the way.

Animal charity, the World Wide Fund for Nature, said it was considering asking the U.S. government to send a ship, like a modern Noah’s Ark, to rescue some of the bears.

Yesterday, researchers also warned they feared the annual ice-melt has passed its 'tipping point', where not enough freezes each winter to make up for the previous summer's melt.

Senior scientist Dr Mark Serreze said: ‘The summer melting used to slow down by the beginning of September.

'We thought it was slowing this year, but it’s suddenly sped up instead.'

Professor Richard Steiner, of the University of Alaska, said: 'Polar bears need sea ice, sea ice is decaying, and the bears are in very serious trouble.'

Experts with WWF, the World Wide Fund  for Nature, fear the bears can’t make it.

Polar bears are strong swimmers but would not be able to make it that far.

In May, the US Department of the Interior listed polar bears as threatened under the Endangered Species Act because the Arctic ice they hunt on is melting so quickly.

Margaret Williams, Director of WWF’s Alaska office, said: ‘The Arctic is a vast ocean and to find nine bears swimming in one area is extremely worrying because it means that dozens more are probably in the same predicament.’   

Her colleague, WWF polar bear biologist  Geoff York, said: ‘As climate change continues to dramatically disrupt the Arctic, polar bears and their cubs are being forced to swim longer distances to find food and habitat.’

The Chukchi Sea off Alaska’s northwest coast is home to one of  two populations of Alaska polar bears.