Conditions in the Arctic may become critical for polar bears by the end of the century, scientists have warned.

Longer ice-free periods due to global warming could rob a quarter of the polar bear population of their habitat, researchers fear.

The scientists base their findings on a study of historic and projected sea ice in the Canadian Arctic Archipelago from 2006 to 2100. Less ice is expected to remain in the region all year round as the planet warms.

Every bear population living among the islands was predicted to experience two to five months of ice-free conditions per year by the turn of the century.

Unless action is taken to curb global warming, polar bears may face starvation and reproductive failure, the scientists warn.

Canadian lead researcher Stephen Hamilton, from the University of Alberta, said: “We predict that nearly one-tenth of the world’s polar bear habitat, and as much as one quarter of their global population, may undergo significant habitat loss under business-as-usual climate projections.”

The findings are published in the online journal Public Library of Science One.