Polar bears threatened by melting Arctic ice

July 02, 2015 08:22
Substantial sea ice loss and expected declines in the availability of marine prey are the most important factors for the grim outlook for polar bear populations, according to US scientists. Photo: Arturo de Frias Marques/Wikipedia

Polar bears will see a population crash in most parts of the Arctic Ocean if global greenhouse gas emissions continue at current rates, according to a group of US scientists.

A study led by US Geological Survey (USGS) biologists showed that a worldwide failure to reduce the release of atmospheric pollutants tied to the burning of fossil fuels is likely to lead to "a greatly decreased state" for polar bear populations in Alaska and elsewhere, except for an Arctic region north of Canada where summer ice is known to persist longer, Reuters reported.

The world's 20,000 to 25,000 polar bears, which can stand as high as 11 feet (3.35 meters) and weigh as much as 1,400 pounds (635 kg), use floating sea ice as platforms for hunting ringed seals, for mating and to travel vast distances quickly and without expending crucial energy reserves on long-distance swimming, according to the US Fish and Wildlife Service.

The bears were protected in 2008 under the federal Endangered Species Act after US wildlife officials said climate changes threatened their survival in the first such listing of its kind.

USGS ecologists concluded that polar bears will face severe challenges in the next several decades even if climate warming stabilizes thanks to reductions in global emissions.

If releases are not reduced, the number of bears across the vast majority of the Arctic ice cap will sharply fall 25 years sooner than if greenhouse gas rates peak in 2040 and then decline through the end of the century, according to the study.

"Substantial sea ice loss and expected declines in the availability of marine prey that polar bears eat are the most important specific reasons for the increasingly worse outlook for polar bear populations," Todd Atwood, USGS research biologist and lead author of the study, said in a statement.

Atwood and his team found other stress factors, including oil and gas exploration and hunting by indigenous peoples, had little impact on them compared to the loss of sea ice.

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