A female polar bear (R) and her two two-year cubs stand at Cape Blossom on the Isle of Vrangel in this 2002 archive picture. Russia's polar bears are adapting their behaviour to overcome the "catastrophic effects" of global warming, but new migration routes are pushing them dangerously close to humans, a leading researcher said. Picture taken in 2002.

The polar bear population that stretches from eastern Russia to the U.S. state of Alaska has fallen from an estimated 4,000 to around 1,500 as ice fields melted in the past 20 years, said Nikita Ovsyanikov, the top polar bear expert at the Academy of Sciences.

[Agencies]