A U.S. climate researcher is leading a team of 30 North American and European scientists in urging the polar bear be listed as a threatened species.

The researchers want U.S. Fish and Wildlife Service to list the polar bear as a threatened species because global warming is melting its sea-ice habitat.

"As scientists engaged in research on climate change, we are deeply concerned about the effect of Arctic warming on the polar bear habitat," University of Chicago climate scientist Pamela Martin said in a June 15 letter to U.S. government officials. "Biologists have determined that sea-ice is critical in the life cycle of the polar bear and the survival of the polar bear as a species."

The scientists say the ongoing and projected increased loss of sea-ice in the warming Arctic poses a significant threat to the polar bear.

The letter observes the Earth's global surface temperature is unstable and will remain so for years. Therefore, the scientists warned, the planet is committed to a trend in global warming for centuries.

Copyright 2006 by United Press International