Climate change on track to wipe out polar bears by 2100

Climate change is starving polar bears into extinction, according to research published Monday that predicts the apex carnivores could all but disappear within the span of a human lifetime.

In some regions they are already caught in a vicious downward spiral, with shrinking sea ice cutting short the time bears have for hunting seals, scientists reported in Nature Climate Change.

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Their dwindling body weight undermines their chances of surviving Arctic winters without food, the scientists added.

"The bears face an ever longer fasting period before the ice refreezes and they can head back out to feed," Steven Amstrup, who conceived the study and is chief scientist of Polar Bears International, told AFP.

On current trends, the study concluded, polar bears in 12 of 13 subpopulations analysed will have been decimated within 80 years by the galloping pace of change in the Arctic, which is warming twice as fast as the planet as a whole.

The threat is not rising temperatures per se but the top-of-the-food-chain predators' inability to adapt to a rapidly shifting environment.

"If somehow, by magic, sea ice could be maintained even as temperatures increase, polar bears might be fine," Amstrup said by email.

"The problem is that their habitat is literally melting."

Half of Earth's land-based megafauna are classified as threatened with extinction, but only polar bears are endangered primarily by climate change. But that status may not be unique for long, and should be seen as a harbinger of how climate will impact other animals in the coming decades, the authors warned.