May 12, 2009

Now they ask?


Just how endangered is the polar bear?

US President Barack Obama has controversially opted to keep George Bush's rules on polar bear protection. In a nutshell, the Bush administration agreed to classify the bear as an endangered species, but specifically exempted protecting it from 'activities outside the bear's range, such as emission of greenhouse gases'.

If they'd gone with the letter of the Endangered Species Act, the US government could have been sued for failing to control the carbon emissions which are believed to be warming the Arctic and destroying the polar bear's natural habitat of sea ice. As Interior Secretary Ken Salazar put it: 'The Endangered Species Act is not the proper mechanism for controlling our nation's carbon emissions.' And he has a point.

So far, so last week's news. The polar bear is the poster beast of climate change and as such is on the list of threatened species for nearly every country with Arctic territory. Sea ice has shown a shrinking trend and the concern is that if it disappears completely, so will the polar bear.

But actually how endangered is Ursus maritimus? The problem here is that they are fiendishly difficult to count. In a lifetime, each bear can range over tens of thousands of square kilometres of the coldest, most intensely hostile terrain on Earth. By necessity, counts are done by a number of inexact methods, including aerial survey, capture-recapture and anecdotal sightings.
Of the 19 sub-populations of polar bears known to exist, we think that five have declined, five are stable and two have increased, but tellingly seven populations have rendered insufficient data to make a call. Total numbers are pegged at around 20,000 - 25,000, which nonetheless represents a massive increase since unregulated hunting ceased in the Seventies.

As Bjorn Lomberg pointed out, if we want to protect polar bear populations, we could simply try shooting even fewer of them, at a saving of 250 or more bears a year.

Perhaps more importantly, we are forgetting that the polar bear is a tough and adaptable creature that fossil evidence shows has already survived a much warmer period than the one we're going through now. This is probably why there is little evidence to support the popular misconception that lots of polar bears are drowning.

The 'drowning' thesis was a speculative conclusion based on sightings of four carcasses 'presumably, drowned' seen floating in the Alaskan Beaufort Sea during aerial surveys in September 2004. You could just as easily speculate that they were killed by the big storm that preceded the survey, because when it comes to swimming, a predator like the polar bear knows its limits, even if we don't know ours.

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