Polar bears have become the furry face of the climate crisis, and experts suggest that animals could be virtually extinct in a matter of decades as the Arctic sea ice they hunt melts.
But now researchers say they have found a group in southeast Greenland that survives despite the lack of sea ice for much of the year.
The team says polar bears, which appear to have been isolated from other groups for hundreds of years, have clung to the freshwater ice of glaciers that are discharged into the sea.
Researchers add that despite expectations of a sharp decline in the number of polar bears in the Arctic, the discovery offers some hope, especially as current conditions in south-eastern Greenland are similar to those ‘they were waiting in the high Arctic towards the end of the century.
“I think they can teach us something about where a small, rare number of polar bears could endure in an ice-free Arctic,” said Dr. Kristin Laidre, the first author of the University of Washington study she worked on. . with the Greenland Institute of Natural Resources.
Polar bear graphic
Writing in the journal Science, Laidre and colleagues report on their studies of the movement, genetics, and demographics of a polar bear subpopulation along the east coast of Greenland. two different groups, one of which lives above 64 degrees north. and the other below, in the southeast of the island.
The team says the latter meet the criteria for a new subpopulation of polar bears, increasing the number identified so far from 19 to 20, noting that the animals are the most genetically isolated polar bears in the Arctic. Its movements are limited by features such as mountainous terrain and the Greenland ice sheet to the west, open water to the east and the lack of adequate habitat in the south.
“They are geographically, genetically and demographically isolated, meaning they are not interacting with other bears,” Laidre said, though he stressed that the group is not evolving into a new species.
“From time to time, there is an immigrant who comes in and adds genetic diversity to the group,” Laidre added. “But because they are so geographically isolated, they don’t have much genetic input from other polar bears in other parts of the Arctic.”
At first glance, conditions in southeast Greenland may seem like an unlikely habitat for polar bears, as sea ice has been present for less than a third of a year. But as fjord glaciers move toward the ocean, the breaking ice can give rise not only to icebergs but aggregate in front of the glacier, providing what Laidre calls a “floating landscape” from the which they can hunt all year round.
“What we know about polar bears is that having sea ice for about 100 days a year is too little for bears to survive,” he said. “The reason they can do it in this isolated environment is that they have an additional ice platform.”
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It is not the first time that polar bears have been discovered to move along glacial fronts, but the team says the newly identified group, which is believed to have a few hundred forts, is unusual, as these features are essential for to their survival.
However, Laidre said these habitats were rare and likely to change with global warming, while the small genetic reserve of bears in south-east Greenland could be problematic if immigrant bears cease to appear.
Professor Andrew Derocher, a polar bear expert at the University of Alberta who did not participate in the study, said the research showed that polar bears in south-eastern Greenland comprised a different genetic group with isolation and inbreeding, although he said the lack of a fixed system. The definition made it difficult to tell if this was a new subpopulation.
“He suspects that as the climate continues to warm in the Arctic, this study reflects a pattern that will emerge much more often: declining abundance along with low immigration will result in genetically distinct groups of scattered polar bears. for the Arctic, which, with continued warming, will be eradicated over time, “he said.
“The low body condition and birth rate reported in south-east Greenland suggest that this group of bears is already living on the brink of persistence.”