Scientists who work with polar bears are already seeing the effects of human-caused global warming on some polar bear populations. So far these changes, while serious, have been gradual.
But natural variation within the climate system, combined with the chronic loss of ice already taking place, is likely soon to create massive sea ice losses in some parts of the Arctic in a single year--with a catastrophic impact on the polar bears living there.
To help managers plan for such a crisis,
an international team of 12 scientists--including Dr. Andrew Derocher, professor of biological sciences at the University of Alberta, and Dr. Steven C. Amstrup, PBI's chief scientist--have published a paper in Conservation Letters that provides an overview of available management options.
"We've known for years that a crisis is coming," says Derocher, senior author of the paper and a scientific advisor to PBI. "The sea ice habitat that polar bears depend on for their survival is
declining, and freeze up and break-up patterns have changed as the Arctic has warmed. So far, the decline has been mostly linear. But modeling shows that a single bad ice year with a prolonged ice-free period could have a devastating impact on already stressed populations."
"Ultimately, the only way to save polar bears is to save their sea ice habitat by reducing the greenhouse gas emissions that cause global warming," says PBI chief scientist, Dr. Steven C. Amstrup.
"Eventually, all years will be bad for sea ice and the bears that depend on it, unless we take action on climate change. But in the nearer term, wildlife managers need to plan for individual bad ice years that will precede the ultimate loss of arctic ice. And the time to do so is now--not during a crisis when starving polar bears are stranded onshore."
Unfortunately, the media focus has largely missed the paper's point with headlines like "Scientists recommend feeding polar bears." But the authors emphasize that they are not recommending specific actions. Rather, given the expected public and political pressure, the paper reviews anticipated management options, including some drastic measures such as supplementary feeding, relocations, or various kinds of rescue. While not recommending one policy over another, they point out the pros, cons, and costs that will confront managers when a crisis comes.
Why explore such options? Amstrup says that public pressure will be enormous for managers to do something in the face of a catastrophe. "People will respond emotionally to the sight of starving polar bears," he says. "Because the only real solution, addressing climate change, will not offer immediate relief of the symptoms, we felt it was important to inspire managers to begin to think about on-the-ground responses so they can be prepared."
"If we do gain control of carbon emissions," he adds, "these actions may help preserve more bears in more areas than would otherwise have been the case."
The scientists also stress that the success of rehabilitation, short-term housing of problem bears, and other possible interventions will depend on the degree of advance planning done by managers and policy makers.
While the identified strategies could help some polar bears in the short term, stopping climate change is the only long-term solution for polar bears and their threatened sea ice habitat, the authors say.
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