Study Forecasts Poor Future for Polar Bears

An adult male polar bear pauses at the edge of the Chukchi Sea (Photograph U.S. Geological Survey).

By Xander Zellner for National Geographic Polar Bear Watch

An adult male polar bear pauses at the edge of the Chukchi Sea (Photograph U.S. Geological Survey).

A recent study found that greenhouse gas emissions remain the number one threat posed to polar bears. The study, released on June 30 by the U.S. Geological Survey, predicts a decline for polar bear populations across all four ecoregions of the Arctic by the end of the century.

From Canada to Russia, polar bear populations in all of the ecoregions are at risk. Using sea-ice projections from the Intergovernmental Panel on Climate Change, researchers compared future polar bear populations under two different scenarios. The first projects a stabilized climate with reduced carbon emissions, the second with emissions continuing at their current rate. In both cases the projection for polar bears isn’t good. The study builds on previous scientific work from 2010 and 2007.

Todd Atwood, a USGS biologist and lead author of the study, said he and his team compared greenhouse gas emissions to other polar bear population stressors, such as conflict with humans, exposure to contaminants such as oil, gas, and mining activity, and parasitic foods and disease. “Everything else paled in comparison,” Atwood said.

“[Greenhouse gas emissions] are responsible for the rise in ambient temperature, and without sea-ice habitats, polar bears have no access to prey,” Atwood said.

When sea ice melts during the summer, polar bears are forced to retreat onto land, where seals, their traditional prey, are unavailable and other rich food sources—such as walruses or bird eggs—are too few to maintain populations.

The study projected that all four ecoregions will see significant decreases in polar bear populations. The Archipelago ecoregion, which, at a higher latitude, retains its ice for a longer period, is likely to be the last polar bear stronghold. Atwood said it’s —> Read More