Polar bear 'extinct within 100 years'

The bears face pollution and climate threats

By Helen Briggs BBC News Online science reporter

The polar bear could be driven to extinction by global warming within 100 years, warns an ecology expert.

The animal, which relies on sea ice to catch seals, is already starting to suffer the effects of climate changes in areas such as Hudson Bay in Canada.

As the sea ice disappears, so will the polar bears

Prof Andrew Derocher

Scientists say Arctic sea ice is melting at a rate of up to 9% per decade. Arctic summers could be ice-free by mid-century.

Dr Andrew Derocher, of the University of Alberta, Edmonton, has used the data to assess the impact on the Arctic's top predator.

Top carnivore

He believes the polar bear could disappear in the wild by the end of the century unless the pace of global warming slows.

He told BBC News Online: "Polar bears are a species whose whole life history is dependent on having sea ice.

Polar bears are being tracked for research

"As the sea ice changes in distribution and pattern we can expect this to have fundamental changes on the ecology of polar bears.

"As the sea ice disappears, so will the polar bears."

Polar bears are uniquely adapted to survival in the Arctic. They are the world's largest land predator, feeding mainly on seals.

They use the sea ice as a floating platform to catch prey and they travel across it on their way to their dens.

British polar expert Dr Peter Wadhams of the University of Cambridge says the bear faces a gloomy future unless it is able to change its habits.

"It could be that a polar bear could adapt to a new habitat and adopt habits like the brown bear in Alaska which hunts salmon in streams and other small animals on land," he said.

Fragile ecology

Scientists believe that Ursus maritimus, the "sea bear", evolved about 200,000 years ago from brown bear ancestors.

Whether it can "change its spots" and behave more like a brown bear is another matter.

Lynn Rosentrater, climate scientist in the WWF International Arctic Programme, thinks it unlikely.

There have been cases of polar bears scavenging in bins for food in summer, she said, but the animals need seal fat to get through the winter.

"In the absence of sea ice the whole basis of polar bear ecology ceases to exist," she explained.

Polar bears are currently found in Arctic regions of Alaska, Canada, Russia, Greenland and Norway.

Populations in southern limits such as Hudson Bay are at most risk of dying out.

Bears stand most chance of surviving, in isolated groups, in the western Arctic or the Canadian archipelago.

Photos courtesy of Andrew Derocher.