Oslo  - Threats to polar bear populations, mainly due to climate change, were the topic of a three-day meeting that opened Tuesday in the northern Norwegian city of Tromso.

"Climate change has superceded hunting as the main threat to polar bears. We have to act to protect the habitat of the polar bear," Norwegian Environment Minister Erik Solheim said in his opening remarks.

"Global warming has to be stopped if we are to succeed," he added.