Canada’s High Arctic Is No Longer a Safe Haven for Polar Bears
As climate change has accelerated, scientists have long believed that Canada’s far north would serve as polar bears’ last sanctuary.
No longer. New research from the University of Alberta has found that as their ice habitat disappears, polar bear populations in the Canadian Arctic Archipelago might be no better off than their southern counterparts.
The entire region’s polar bear population could face starvation and reproductive failure by 2100, crossing the “point of no return,” according to the study.
“The previous work on the long-term trends in polar bear habitat indicated that the high Arctic was a likely refuge for polar bears,” Andrew Derocher, a biology professor and coauthor of the study, said in an email.
The new study, published in the journal PLOS One and led by University of Alberta professor Stephen Hamilton, looks at bears in the 550,000-square-mile region north of the Canadian mainland. The archipelago’s narrow channels and 36,000-plus islands make it hard to obtain accurate readings of bear populations and sea ice levels.
The area is thought to be home to large populations of around 2,500 bears as well as small isolated groups of fewer than 300 bears.
“Some estimates are very old, from the late 1990s and early 2000s,” Derocher said. “Regardless, with the changes we’re seeing, viable populations are unlikely under the warming scenario we examined.”
Most of the high Arctic’s multiyear ice fields will devolve into annual ice fields, growing and receding with the seasons, according to the researchers' computer-generated climate models, which estimated a three-degree Celsius increase in temperatures by 2100. That means the growing amount of time the area will be free of ice could put a significant strain on the bears' survival rates, as they depend on ice fields to hunt seals.
“The very high reaches of the Arctic will still be cold in winter and some ice will form,” Derocher said. “The question is will it be around long enough in a year to allow polar bears to persist: Our analyses suggest it won’t be with the climate forcing we used.”
A similar pattern has already started in northeast Alaska, where polar bear populations have plummeted 40 percent, from 1,500 to 900, in the past decade. The reason? Greater sea ice melt triggered by climate change, scientists say.
Could polar bears adapt to a land-based existence, roaming the ice-free archipelago like their grizzly bear cousins to the south? Hardly, Derocher says. Polar bears have evolved as marine-based predators preying on seals. Land-based prey available in the region pales in comparison with the sustenance blubber-rich seals provide.
“Grizzly bears in the Arctic are tiny compared to polar bears,” Derocher said. “They hibernate in winter, and move over areas of 1,000 square kilometers. Polar bears are active in winter and move over areas of 300,000 square kilometers or more. If there is a bear species that will do well with warming in the Arctic, it is the grizzly.”