Polar bears can adapt to climate change

In south-east Greenland, researchers have discovered a new polar bear population that is better adapted to the changing climatic conditions than the previously known polar bears in the Arctic. The discovery gives hope that polar bears, who are particularly threatened by global warming, may be more resilient than feared.

In the trade magazine Science a research team led by Kristin Laidre from the University of Washington in Seattle presented the results obtained from the analysis of 36 years of movement data, as well as sophisticated habitat analyses, genetic data and natural history observations. For years, bears have been fitted with GPS collars, biopsied, caught and observed, and sea ice dynamics have been tracked by satellite.

The discovery of the genetically diverse polar bear population in south-east Greenland, isolated from other populations, is particularly interesting because these bears thrive in an area where sea ice already matches the conditions predicted for the high Arctic by the end of the 21st century .

Polar bears actually need pack ice, i.e. free-floating sea ice, in order to hunt seals in particular from the floes. A certain number of days a year when hunting is possible from these floes is considered crucial for the life of polar bears. If these days become too few because the floes melt earlier, or if the ice-free period in which the bears have to move ashore, to other areas or further north and fast, becomes too long (the limit is 100 to 180 days), their survival is threatened.

The current population of about a hundred animals in south-east Greenland does not seem to need pack ice to get by. Instead, the bears use freshwater ice at the ends of the glaciers as a platform for their hunt, even when there is no sea ice. Also, the population, which hunts year-round, appears to travel far less distance than their counterparts in other areas. For example, while a neighboring polar bear population in northeast Greenland travels over 2,000 kilometers, the bears from southeast Greenland only move about 400 kilometers, the researchers observed.

The adapted bears in Southeast Greenland are good news for conservation and the future of polar bears. Freshwater ice is not found in much of the Arctic, but it is found in Greenland and Svalbard. Ringed seals, the main prey of polar bears, also roam there all year round. In this way, these areas could act as refuges for the bears and secure their existence at least in the medium term.

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