The bears hunt on a patchwork of glacial ice that breaks up in fjords, which are long and narrow coastal inlets where glaciers meet the ocean. According to the study, certain polar bears, at the very least, may be able to adapt to sea ice vanishing as climate change increases.
Still, that isn't a panacea for the species as a whole.
"Glacier ice may help small numbers of polar bears survive for longer periods under climate warming, but it is not available for the vast majority of polar bears," lead researcher Kristin Laidre, a wildlife biologist at the University of Washington's Polar Science Center, told Live Science in an email.
This is due to the fact that this sort of glacier ice is only present in the vicinity of a tiny percentage of other polar bear populations.
There were 19 recognized subpopulations of polar bears (Ursus maritimus) residing in the Arctic Circle until recently, according to biologists. One of these populations stretches 1,988 miles (3,200 kilometers) along Greenland's eastern coast. However, when researchers looked closely at this group to keep track of their numbers, they discovered that the bears were really divided into two distinct groups.
Bears from southeast Greenland did not travel over 64 degrees north latitude, while bears from the northeast did not pass the same line in the other way, according to researchers who reviewed 36 years of tracking data from bears fitted with GPS collars. Individual bears were genetically tested to confirm that the southeastern bears were unique from their northern counterparts.
"We present the first evidence for a genetically distinct and functionally isolated group of polar bears in southeast Greenland, which meet [the] criteria for recognition as the world's 20th polar bear subpopulation," the researchers stated in a new paper published in the journal Science on June 16.
According to the researchers, the new southeastern population has roughly 300 members, however identifying an exact figure is difficult. According to the researchers, the newly discovered group has the largest genetic diversity of the 20 Arctic communities, and genetic comparisons indicate that they have been separated from the northeastern population for roughly 200 years.
The International Union for Conservation of Nature (IUCN) Red List classifies polar bears as vulnerable to extinction, with just around 36,000 wild individuals remaining. However, other studies show that owing to the impacts of climate change, the species may go extinct by the end of the century.
Despite being the world's largest land predator, polar bears are classified as marine animals since they eat mostly seals and have a mostly aquatic diet. However, in order to search for food, the snow-white bears use sea ice as a platform from which to pursue their prey. Unfortunately, rising temperatures as a result of climate change are lowering the quantity of accessible sea ice, limiting their natural habitat.
In the Arctic, the amount of sea ice rises and wanes. During the fall, transient ice sheets emerge on the ocean's surface, which melt away in the spring. As the sea ice melts in the summer, polar bears can usually go between 100 and 180 days without eating.
Warming temperatures in the Arctic, on the other hand, mean that sea ice melts faster and freezes later, putting polar bears at risk of famine.
Because the fjords where the southeastern polar bears live are located on the southern tip of the Arctic Circle, the region is sea ice-free for more than 250 days per year.
According to the researchers, these sea ice conditions are similar to those forecast for the remainder of the Arctic by the end of the twenty-first century, making the fjords uninhabitable for polar bears.
The southeastern bears, on the other hand, appear to be doing fairly well without the sea ice.
The bears, according to the researchers, are taking advantage of glacial mélange, or ice that breaks off glaciers in the fjords and falls into the sea. The bears are expected to hunt on these freshwater ice patches in the same way they hunt on sea ice, allowing them to sustain themselves during the extended periods when sea ice is not there.
"This suggests that marine-terminating glaciers may serve as previously unrecognized climate refugia," the researchers noted.
The bears in the southeast also don't reside near any human settlements, and the location is thought to be too difficult to access for most hunters, providing them with an added layer of protection. The steep slopes of the fjords, on the other hand, can be difficult for polar bears to navigate, limiting their travel.
The birth rate among the new group is also exceptionally low when compared to previous communities, which experts believe is due to a lack of communication between possible partners.
The researchers utilized genetic data to identify two people who may be immigrants from the northeastern group in the new study. These migratory bears appear to have adapted successfully to hunting on glacial mélange, suggesting that when sea ice conditions worsen in other locations, other populations may be able to follow suit.
Other similar places in northern Greenland and Svalbard where glacial conditions may support polar bears were discovered by the researchers. However, for the vast majority of bears, migrating to these regions may be impossible.
Although the study offers some polar bears a ray of optimism, the researchers caution that this does not diminish the threat of climate change to the Arctic carnivores.
"Loss of Arctic sea ice is still the primary threat to all polar bears," Laidre added. "This study does not change that."
Sea ice will continue to melt over the Arctic, reducing the chances of most polar bears surviving, she noted.
