A group of polar bears in southeast Greenland have adapted to melting sea ice by chasing freshwater ice that pours into the ocean from glaciers.
The population – which is genetically distinct and adapted to its environment – could offer a glimpse into the future of polar bears in a warming Arcticthink the researchers.
Lead author Professor Kristin Laidre, a polar scientist at the University of Washington’s Applied Physics Laboratory, said: “We wanted to study this area because we didn’t know much about southeastern polar bears. from Greenland, but we did not expect to find a new subpopulation living there.
“We knew there were bears in the area based on historical records and Indigenous knowledge. We just didn’t know how special they were.”
The study is based on seven years of new data collected along the southeast coast of Greenland, plus 30 years of historical data across the entire east coast of the island.
The remote southeast region had been poorly studied due to its unpredictable climate, jagged mountains, and heavy snowfall.
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Recently collected genetic, movement and population data show how these bears use glacier ice to survive with limited access to sea ice.
Prof Laidre said: “Polar bears are threatened by loss of sea ice due to climate change. This new population gives us insight into how the species might persist into the future.
“But we have to be careful about extrapolating our findings, because the glacier ice that allows bears in southeast Greenland to survive is not available in most of the Arctic.”
The genetic difference between this group of bears and its closest genetic neighbor is greater than that observed for any of the 19 previously known populations of polar bears.
Co-author Beth Shapiro, a professor and geneticist at the University of California, Santa Cruz, said: “This is the most genetically isolated population of polar bears on the planet.
“We know that this population has lived separately from other polar bear populations for at least several hundred years, and that their population sizes throughout that time have remained small.”
Part of the reason the population is so isolated, the researchers say, is that the bears are hemmed in on all sides – by the sharp mountain peaks and the massive Greenland ice cap to the west, the open waters of the Denmark Strait to the east, and by the fast East Greenland Coastal Current which poses a hazard offshore.
Satellite tracking of adult females shows that unlike most other polar bears that travel far over sea ice to hunt, bears in southeast Greenland walk on ice inside protected fjords or climb mountains to reach the neighboring fjords above the Greenland ice cap.
Half of the 27 tracked bears accidentally floated an average of 120 miles south on small ice floes caught in the East Greenland Coastal Current, but then jumped off and headed back north on land to their fjord of origin.
Laidre said: “In a sense, these bears provide insight into how Greenland bears might behave under future climate scenarios.
“Sea ice conditions in southeast Greenland today resemble what is predicted for northeast Greenland by the end of this century.”
Bears in southeast Greenland only have access to sea ice for four months, between February and late May.
Sea ice provides the platform that most of the approximately 26,000 polar bears in the Arctic use to hunt seals.
For two-thirds of the year, polar bears in southeastern Greenland hunt seals off chunks of freshwater ice that break off the Greenland Ice Sheet.
Laidre warned, however, that longer-term monitoring is needed to know the future viability of bears in southeast Greenland and to understand what is happening to polar bear subpopulations as they grow. cut off from the rest of the Arctic by melting sea ice.
He said: “If you are concerned about the preservation of the species, then yes, our findings are hopeful – I think they show us how some polar bears could persist under climate change.
“But I don’t think glacier habitat will support large numbers of polar bears. There just aren’t enough of them. We still expect to see a significant decline in polar bears in the Arctic due of climate change.”
Watch: Polar bears fight for survival as sea ice disappears