Climate change hits hard on Arctic inhabitants. Its impact doesn’t stop before the king of the Arctic, the polar bear. Polar bears need sea ice because their prey mainly lives on it. Shifts in the timing and duration of ice cover, especially the possible lengthening of ice-free periods, may impact polar bears under projected warming before the end of the 21st century. This is the result of an international study published just recently in the journal PLOS One.

Polar bears are highly adapted for a life on the ice and need the sea ice for their hunts on seals.
Polar bears are highly adapted for a life on the ice and need the sea ice for their hunts on seals.

Sea ice across the Arctic is declining and altering physical characteristics of marine ecosystems, and polar bears are vulnerable to these changes in sea ice conditions. However, there are still many open questions and it has been shown that large regional differences exist regarding sea ice developement. Thus, the question also arises to which extent the various polar bear populations will fare in the next decades. The researchers led by Stephen Hamilton from the University of Alberta have glanced into the future of Canadian polar bears. To this end, the scientists used sea ice projections for the Canadian Arctic Archipelago from 2006-2100 and metrics developed from polar bear energetics modeling to gain insight into the conservation challenges for polar bears facing habitat loss.

Although polar bears spend a lot of time in the water, they rely on ice floes for recovering. These floes will disappear in the near future forcing the bears to remain on land or drown.
Although polar bears spend a lot of time in the water, they rely on ice floes for recovering. These floes will disappear in the near future forcing the bears to remain on land or drown.

Shifts away from multiyear ice to annual ice cover throughout the region, as well as lengthening ice-free periods, may become critical for polar bears before the end of the 21st century with projected warming. Each polar bear population in the Archipelago may undergo 2-5 months of ice-free conditions, where no such conditions exist presently. Under business-as-usual climate projections, polar bears may face starvation and reproductive failure across the entire Archipelago by the year 2100. "We predict that nearly one-tenth of the world's polar bear habitat, as much as one-quarter of their global population, may undergo significant habitat loss under business-as-usual climate projections," said Stephen Hamilton.

Quelle: Stephen Hamilton, PLOS One, www.plosone.org