Polar bears could soon be declared a “threatened species,” as government officials warn that by 2050, two thirds of the world’s existing population could die out.

The U.S. Geological Survey released a report Friday that brings no good news for our children’s children and grandchildren: the world’s population of polar bears risks severe decimation within the following decades due to global warming.

As the bears’ indispensable ice sheets continue to melt, the carnivorous mammals will start to disappear. Polar bears depend on ice shelves, as they spend much of their lives here. They need sea ice as a platform for breeding and for hunting seals, their primary food.

Forced to swim out, they stand little chances of covering such long distances.

The study estimates that, by 2050, about 42 percent of “optimal polar bear habitat” could be lost in summertime. While the bears will not become extinct, they could disappear completely from Alaska, the study says.

“As the sea ice goes, so goes the polar bear,” said Steven Amstrup, lead biologist for the survey team.

The authors say the bears would be largely relegated to the Arctic archipelago of Canada, as well as to parts off the northern Greenland coast, where the sea ice usually persists even during the summertime.

It is up to the Fish and Wildlife Service to decide whether polar bears should be listed as a “threatened species,” protected under the Endangered Species Act. According to officials, this decision will be made by January 2008.

Various studies conducted by scientists have found that in some places, bears have adapted themselves to new foods such as snow geese and garbage, while in other parts there have been cases of cannibalism.

“It’s that declining sea ice that appears to be driving the results in our models,” said Amstrup. “As the sea ice goes, so goes the polar bear.”

Environmental groups that have been lobbying for polar bears to be declared a threatened species hope that this move will lead to governmental measures to decrease greenhouse gases.

Scientists however, have a somewhat bleaker perspective on the situation.

“Despite any mitigation of greenhouse gases, we are going to see the same amount of energy in the system the next 20, 30 or 40 years,” said Mark Myers, U.S. Geological Survey director.