Will the Arctic Prove (Polar) Bearable?

New research suggests possible hope for polar bears, but only if . . .

03-29-2011 // Roger Di Silvestro

 

Polar bear near Churchill by Mark Wexler
Polar Bears International, in Bozeman, Montana, recently ran climate models that examined possible trends from 2000 to 2100 and found that at current levels of greenhouse gas emissions, global warming will cause Arctic sea ice to melt away rapidly in the 2020s. Loss of the ice would be bad news for polar bears, which hunt only from the ice and would decline 66 percent by 2050 as the sea ice collapsed. However, a second model showed that sea ice would begin to recover after 2020 if greenhouse gases stopped rising by that year. In that case, the bears would decline only a little, suggesting that cutting back emissions could save the polar bear, says PBI’s Steven Amstrup.

 

Now the Bad News

On a more somber note, researchers at the University of Alberta have linked polar bear litter size in the Hudson Bay area with sea ice decline. Loss of sea ice reduces the hunting success of pregnant bears and can cause the hungry animals to abort their young. The estimated 900 bears that make up the Hudson Bay population compose the southernmost polar bear population, making these animals likely to be the first polar bears affected by global warming. In one study in the 1990s, 28 percent of food-deficient pregnant polar bears in the bay area failed to produce cubs. According to a report in Science Daily, if ice broke up a month earlier than it did in the 1990s, 40 to 73 percent of pregnant females in the area would fail to reproduce. Worse still, if ice broke up two months earlier, 55 to 100 percent of the pregnant females would abort.

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