Scientists have identified a distinct subpopulation of polar bears in southeastern Greenland. It survives by hunting from glacier-breaking ice in areas where there is little sea ice.
This finding suggests that a small number of bears may survive as warming continues and much of the sea ice they normally depend on disappears. However, researchers and other polar experts remain at significant risk to the entire Arctic polar bear population, mitigating only by reducing greenhouse gas emissions to curb global warming. I warned that it would be done.
A subpopulation believed to have hundreds of animals was identified during a multi-year study of what was believed to be a single bear population along the 1,800-mile east coast of Greenland. I did. Analysis of satellite tracking movements, tissue samples, and other data revealed that bears in the southeast were physically and genetically isolated from other bears.
“This was a completely unexpected discovery,” said Christine Reidre, a biologist at the University of Washington, who has been studying marine mammal ecology in Greenland for 20 years. Dr. Raidre Papers on subgroups It was published in the journal Science on Thursday.
Southeastern Greenland is particularly far away, with narrow fjords bordered by steep mountains. At the end of the inland, there are glaciers that often end in water. The other end is the open ocean with a strong southerly current. “These bears are geographically very isolated,” said Dr. Reidre. “They have evolved to become real residents because they are the only way to live there.” Researchers estimated that this subpopulation had been quarantined for at least hundreds of years.
Overall, there are an estimated 26,000 polar bears in 19 officially designated subpopulations around the Arctic Circle. As seals sunbathe on ice and come in for air through their breathing holes, animals live on seasonal sea ice and hunt their main prey, seals. However, the rapid warming of the Arctic associated with anthropogenic greenhouse gas emissions has reduced the extent and duration of sea ice coverage.
Some subpopulations, especially those in Alaska and the southern Bofort Sea off the coast of Canada, have already diminished because bears do not sustain enough ice to hunt enough food for themselves and their offspring. doing. Polar bear experts say that if the world continues to warm, polar bears could become nearly extinct by the end of this century.
Southeastern Greenland is relatively warm, with less sea ice coverage than many other polar bear-dwelling areas, with an average of about 100 days a year of ice to live and hunt. “We know that there are too few polar bears to survive,” said Dr. Reidre. These are the types of conditions that may spread elsewhere in the Arctic later this century.
Dr. Raidre and her colleagues discovered that bears in southeastern Greenland were hunting from sea ice while they were around it.But when it’s gone, the bear has other ice to hunt: drop the calf from the iceberg to the fjord, as the iceberg and gradually smaller chunks, and it’s freshwater ice that lasts most of the year.
Bears hunt from this mixture of floating ice, called glacier melange, in the same way they hunt from sea ice. “It gives them an extra and unusual ice platform not found in many other places,” said Dr. Reidre, allowing them and their descendants to catch enough seals to survive and thrive. did.
However, such habitats are rare, said Twila Moon, a scientist at the National Snow and Ice Data Center in Boulder, Colorado, who analyzed fjord sea ice and glacier ice cover as part of her research. I am.
“There are limited areas in the Arctic where we can see substantial and consistent production of glacier melange,” said Dr. Moon. In addition to some parts of Greenland, the Norwegian archipelago of the Svalbard Islands has glaciers that end in water.
Therefore, these special conditions may allow some bears to survive as sea ice continues to shrink, but overall, animals remain under threat of climate change.
“We expect polar bears to decline significantly across the Arctic Circle under the current warming trajectory,” said Dr. Reidre. “And this study doesn’t change that.”
Steven Amstrup, chief scientist at Polar Bears International, a conservation group that was not involved in the study, said the study was “really exhaustive” and “pointed to a very discrete group of bears.” ..
It is up to a group of experts to decide whether it constitutes the 20th official subgroup. United Nations for Nature Maintenance. “I don’t know if it will benefit this group of bears in terms of bear safety and future overall welfare,” said Dr. Amstrup.
He said he agreed with the researchers, as he said, “this is not some kind of relief for polar bears.” For one thing, he said, warming retreats and extinguishes all types of ice, including glaciers. Therefore, Greenland’s fjord glaciers do not end in water and produce glacier melange forever. The study “shows a temporary benefit to these bears,” he said.
“They can survive now, even though the ice-free days are too long in terms of sea ice,” Dr. Amstrap added. “But in the future, that will change unless we stop the global greenhouse gas growth.”