Global warming's first victims?

5.30pm

Polar bears will become extinct in the wild within 60 years as a result of global warming, a new report will reveal this week.

By 2060 climate experts believe Arctic pack ice will have melted to such an extent that all of the existing population of 22,000 polar bears will starve as the animals they feed on, such as seals, become harder to find.

Twenty years after that, in 2080, forecasters from the Norwegian Polar Institute believe that the last of the Arctic pack ice will disappear completely.

The forecasts make gloomy reading for groups such as the Worldwide Fund for Nature (WWF), which drew attention to the bears' plight in 1999.

Now, the WWF says that the species is "living on borrowed time" and that climate changes "is the No. 1 risk" to them. It is calling on political leaders – and particularly the US – to sign up for the Kyoto Protocol which would slow global warming by reducing greenhouse emissions.

Polar bears need the springtime Arctic pack ice as a support for their homes and to enable them to travel large distances in search of prey such as ringed seals.

But that ice has thinned by 40 per cent in the past 20 years, from an average thickness of 4.8m in 1980 to 2.7m today, according to Peter Wadhams, professor of ocean physics at Cambridge University, who is currently working on an Arctic climate and ice prediction study for the European Union.

"There will come a point when the ice will be too thin for the bears to use," he said. "At that point, the population will crash."

Rangers in northern Canada have already observed a growing number of hungry polar bears foraging for food at human-occupied buildings and towns, despite attempts to scare them off with various scare tactics from dogs to "cracker shells".

Because the ringed seals which make up the bears' main food source live on or under the pack ice, as that thins it reduces the areas from which the bears can hunt.

Thin or broken ice is harder and more tiring to walk over, meaning that the bears have to travel further to get the same amount of food. For cubs, that can mean the difference between life and death.

The bears are too specialised to live entirely on land; they rely on the pack ice for their camouflage and because the Arctic environment reduces the number of animals competing for the same food sources.

On land, there are other better-suited predators competing for the available food.

A 1999 study found that average weights of both male and female polar bears was declining, and that female bears are having fewer cubs. At that stage though significant population decline had not started.

The latest study says that the sea ice season in western Hudson Bay has been reduced by about three weeks over the last 20 years.

The scientists say the shorter season could be caused by a long-term warming trend.

The largest population of breeding polar bears presently lives between Norway and Greenland, but the ice cover there could be gone by 2050, according to the University of East Anglia.

The rest of the ice cover will follow in the next 10 to 30 years.

- INDEPENDENT

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