A genetically distinct and isolated population of polar bears has been documented living in southeastern Greenland.
Scientists who have studied and tracked the bears have determined that they survive despite having limited access to sea ice — something critical for polar bears — and instead rely on freshwater ice provided by the Greenland ice sheet.
A study describing these animals was published this Thursday (16) in the journal Science.
“We wanted to research this region because we didn’t know much about polar bears in southeastern Greenland, but we never expected to find a new subpopulation living there,” said lead author Kristin Laidre, a polar research scientist at the University of Applied Physics Laboratory. of Washington in a statement.
“We knew there were some bears in the area from historical records and indigenous knowledge. We just didn’t know how special they were.”
an icy need
Traveling far and wide, the 19 known populations of polar bears rely on sea ice to hunt their prey, such as seals, and sit near vents to capture them. The calories provided by seals can help them store energy for months when food and sea ice are scarce.
Global warming is causing sea ice to rapidly melt and disappear as the Arctic warms more than twice as fast as the rest of the planet. When the sea ice disappears, polar bears must move on land, which gives them fewer opportunities for food.
Meanwhile, southeastern Greenland’s polar bears tend to stay close to home, so they’ve adapted to their environment in a unique way. Although isolated due to the Greenland ice sheet, mountains, open water and fast-flowing coastal currents, polar bears have access to freshwater ice and some limited access to sea ice, which helps them capture seals.
Bears can use sea ice between February and late May. For the rest of the year, they hunt seals using freshwater ice as it separates from the larger ice sheet.
“Polar bears are threatened by the loss of sea ice due to climate change. This new population gives us some insight into how the species might persist in the future,” said Laidre, also an associate professor of aquatic and fisheries sciences at the University of Washington.
“But we need to be careful when extrapolating our findings, because the glacier ice that supports the bears of southeastern Greenland is not available in most parts of the Arctic.”
The southeastern environment of Greenland is a unique, small-scale climate refuge where bears can survive, and similar habitats can be found along the coast of Greenland and the Norwegian island of Svalbard.
“These types of glaciers exist elsewhere in the Arctic, but the combination of fjord shapes [entrada de mar entre montanhas rochosas], the high ice production of glaciers and the large reservoir of ice that is available in the Greenland ice sheet is what currently provides a constant supply. of glacier ice,” study co-author Twila Moon, deputy principal scientist at the US National Snow and Ice Data Center in Boulder, Colorado, said in a statement.
“In some ways, these bears provide a glimpse into how Greenland bears might fare in future climate scenarios,” Laidre said.
“Sea ice conditions in southeastern Greenland today resemble what is predicted for northeastern Greenland at the end of this century.”
The new study is made up of 30 years of historical data from the east coast of Greenland and seven years of new data from the southeast coast. The latter is a remote region with sharp mountains, heavy snow and unpredictable weather, making study difficult.
The research team spent two years consulting with polar bear hunters, who hunt for survival rather than sport, in eastern Greenland. Hunters were able to share their knowledge and contribute samples for genetic analysis.
The researchers, working with the Greenland Institute of Natural Resources in Nuuk, Greenland, were able to study and track the bears using helicopters as the researchers flew over the sea ice, estimating that there are a few hundred bears living in the remote area. This is similar to other small polar bear populations elsewhere.
Female southeastern Greenland polar bears are less frequently observed than female polar bears in other regions.
The smaller animals also have fewer young, which could be related to trying to find mates as they travel through the fjords and surrounding mountains. But researchers won’t be sure until they have more data from long-term monitoring of these mammals.
Bears travel on ice within fjords or climb mountains to reach neighboring fjords. Of the 27 bears tracked during the study, half of them accidentally floated about 120 miles south on average, trapped in small ice floes caught in Greenland’s strong eastern coastal current.
Once the bears had the chance, they simply jumped off the ice and walked back to the fjord they call home. Created by glaciers, fjords are long, narrow and deep inlets found between high cliffs.
“Even with rapid changes happening in the ice sheet, this area in Greenland has the potential to continue producing glacial ice, with a coastline that could look like today, for a long time to come,” Moon said.
The researchers caution, however, that this habitat may not be enough for other polar bears suffering from the climate crisis.
“If you’re concerned about preserving the species, then yes, our findings are hopeful – I think they show us how some polar bears can persist under climate change,” Laidre said.
“But I don’t think the glacier habitat will support large numbers of polar bears. There just isn’t enough. We still expect to see major declines in polar bears across the Arctic under climate change.”
Uncertain future
Researchers believe that southeastern Greenland’s polar bears evolved in isolation for several hundred years. The first known reference to bears at this location dates to the 1300s, and the first written record of the animals among the region’s fjords is from the 1830s, according to the study’s authors.
“The status of polar bears remains unknown. Researchers don’t know if the population is stable, increasing or decreasing, but closer monitoring could reveal what the future holds for this unique population,” Laidre said.
Due to isolation, polar bears are so genetically distinct that researchers propose that polar bears from southeastern Greenland be considered the 20th subpopulation of the species.
Ultimately, that determination rests with the International Union for Conservation of Nature, which helps oversee protected species. And the government of Greenland will make all the decisions about protecting the bears.
“Preserving the genetic diversity of polar bears is crucial in the future under climate change,” said Laidre. “Officially recognizing these bears as a separate population will be important for conservation and management.”
Meanwhile, sea ice continues to decline in the Arctic, which greatly reduces survival rates for most polar bear populations going forward.
“Climate action is the most important thing for the future of polar bears,” said Laidre.
Source: CNN Brasil
