Big Question For 2012: Is the Polar Bear Doomed?

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In September 1965, 46 participants convened in Fairbanks, Alaska, for the First Scientific Meeting on the Polar Bear. The impetus for that gathering was concern about the polar bear's fate, and whether the species could survive a growing human threat. That threat was commercial hunting, using airplanes to find and herd polar bears toward a waiting gunman — a 'sport' the New York Times lambasted as being "as sporting as machine-gunning a cow."

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The ultimate consequence of that meeting was the signing in 1973 of the International Agreement on the Conservation of Polar Bears and Their Habitat  and it marked the end of the era of commercial polar bear hunting. Another consequence was the stimulation of an ongoing, concentrated effort to improve scientific understanding of polar bears, given the recognition at the Fairbanks meeting that "scientific knowledge of the polar bear is far from being sufficient as a foundation for sound management policies." There was not, at the time, even certainty over whether there was one polar bear population or several, let alone how many bears in total there were throughout the Arctic (estimates varied between 5,000 and 25,000).

Forty-six years later, the global polar bear population is estimated at between 20,000 to 25,000, and for management purposes researchers divide those bears into 19 sub-populations. Of those 19, eight are believed to be declining, three stable, and just one increasing, and concern is again being expressed over the species' survival. The threat this time, of course, is from climate change.

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In several European languages, the polar bear is known as the "ice bear," because they are truly creatures of the sea ice. From their longer necks to their elongated heads, their small ears, their massive forepaws and their layer of blubber, everything that distinguishes polar bears from their close grizzly relatives is an adaptation to a life among the ice floes of the Arctic. But as temperatures rise, that habitat is disappearing, and in 2011 the only news on that front was bad news.

Sea ice extent in the Arctic reached its second-lowest level in the satellite record in 2011, fractionally higher than the record low set in 2007 – but whereas, four years ago, a "perfect storm" of conditions conspired to cause sea ice extent to plummet relative to the previous year, this time there was no such confluence of factors. Instead, sea ice in the Arctic appears to be reaching a state where it is increasingly struggling to recover each winter, the early stages of what has been dubbed a "death spiral." 

The reason for that is that the area or extent of sea ice tells only part of the story; of at least equal import is its thickness. Continued loss of the oldest, thickest ice has prevented any significant recovery of the summer minimum extent; first- and second-year ice made up 80% of the ice cover in the Arctic Basin in March 2011, compared to 55% on average from 1980 to 2000. As a result, the total volume of sea ice reached a new low for the second consecutive year. Furthermore, a Nature study published in late November showed the rate of Arctic sea ice decline was without precedent in at least 1,450 years.

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Not surprisingly, 2011 also brought new evidence of the impacts of that declining sea ice on polar bears. A study presented at the International Bear Association Conference in July provided the "first analysis to identify a significant multi-year trend of increased long-distance swimming by polar bears." The study's authors found that, over the course of the study, 20 different bears swam distances longer than 50 km (31 miles) during 50 separate occasions. The shortest such journey was 53.7 km (33.3 miles), and the longest, lasting just shy of an almost unfathomable 13 days, was 687.1 km, or 426 miles. According to study co-author Geoff York of World Wildlife Fund's Arctic Program, polar bears are being forced "to swim longer distances to find food and habitat.Climate change is pulling the sea ice out from under polar bears' feet."

Earlier in the year, a paper in the journal Nature Communications  concluded the size of a polar bear litter – and the likelihood of reproductive success – is strongly correlated to the amount of weight that a pregnant female is able to accumulate prior to entering the den. The greater the amount of fat, the larger the energy store to sustain her and her cubs. Of course, the less time the female has to eat, the less opportunity she has to build up that energy store – and, in parts of their range, polar bears have less time to eat than in the past, because sea ice melts earlier in summer and freezes later in fall. One such area is western hudson Bay in Canada, where polar bears are now forced to come ashore on average two weeks earlier than was the case in the early 1990s, and are predicted to be forced ashore a full month earlier by mid-century. They calculated that, under that latter scenario, as many as 73 percent of females would be unable to raise a litter, a prediction that serves "as another indicator that the western Hudson Bay population will probably not remain viable under predicted climatic conditions."

None of which means polar bears are necessarily doomed. Most predictions of sea ice demise predict an 'oasis' of ice off northwestern Greenland and northeastern Canada, and in December 2010, leading polar bear researcher and Polar Bears International chief scientist Steven Amstrup calculated that sea ice decline could be arrested and even reversed if greenhouse gas emissions were capped or reduced.

That, however, is a big 'if.' Concentrations of carbon dioxide in the atmosphere now exceed the 'worst-case' projections of the Intergovernmental Panel on Climate Change, and carbon emissions are actually increasing at record levels, with the jump from 2009 to 2010 almost certainly the largest in any year since the Industrial Revolution.

So are polar bears doomed? Not necessarily. But unless we see drastic changes in policy, behavior and energy use, the likelihood that anything more than a remnant population will be alive in, say, 2112, appears increasingly remote.