Scientists studying and tracking bears have found that they survive despite limited access to sea ice – something crucial to polar bears – and instead use freshwater ice supplied from Greenland’s ice sheet.
“We wanted to explore this region because we didn’t know much about polar bears in Southeast Greenland, but we never expected to find a new subpopulation living there,” said lead author Christine Leidre, a polar research scientist at the University of Applied Laboratories. physics in Washington, in a statement.
“We knew there were some bears in the area from historical records and local knowledge. We just didn’t know how special they were.”
Ice necessity
Traveling far away, the 19 known populations of polar bears rely on sea ice to hunt their prey, like ringed seals, and sit near breathing holes to catch their prey. Calories provided by seals can help them store energy for months when food and sea ice are scarcer.
Global warming is causing sea ice to melt and disappear as the Arctic warms more than twice as fast as the rest of the planet. When sea ice disappears, polar bears have to move on land, which gives them less food opportunities.
Meanwhile, polar bears in southeastern Greenland tend to stay close to home, so they have adapted to the environment in a unique way. Although isolated due to Greenland’s ice cover, mountains, open waters and fast-flowing coastal currents, polar bears have access to freshwater ice and limited access to sea ice, which helps them catch seals.
Bears can use sea ice between February and the end of May. For the rest of the year, they hunt seals using freshwater ice as it detaches from the ice sheet.
“Polar bears are threatened by the loss of sea ice due to climate change. This new population gives us some idea of how the species can be preserved in the future, “said Leidre, also an associate professor of water and fisheries at the University of Washington.
“But we need to be careful about extrapolating our findings, because the glacial ice that makes it possible for bears to survive in southeastern Greenland is not available in much of the Arctic.
The environment of south-east Greenland is a unique, small-scale climatic refuge where bears can survive, and similar habitats can be found off 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, high ice production and the very large ice reservoir available from Greenland’s ice sheet is what currently provides a stable supply. from icy ice, “said study co-author Tuila Moon, deputy lead scientist at the National Snow and Ice Data Center in Boulder, Colorado.
“In a sense, these bears give an idea of how Greenland’s bears can cope with future climate scenarios,” Leidre said. “Sea ice conditions in Southeast Greenland today are similar to what is forecast for Northeast Greenland by the end of this century.
Aerial research
The new study consists of 30 years of historical data from the east coast of Greenland and seven years of new data from the south-east coast. The latter is a remote region with sharp mountains, heavy snow and unpredictable weather, which makes it difficult to study.
The research team spent two years consulting with polar bear hunters who hunt for survival, not sports in East Greenland. The hunters managed to share their experience and bring samples for genetic analysis.
Researchers at the Greenland Institute of Natural Resources in Nuuk, Greenland, were able to study and track bears by helicopter while researchers flew over sea ice, estimating that several hundred bears lived in the remote area. This is similar to other small populations of polar bears elsewhere.
Female polar bears in southeastern Greenland are smaller than female polar bears in other regions. Smaller bears also have fewer cubs, which may be related to attempts to find mates as they travel the surrounding fjords and mountains. But researchers will not know for sure until they get more data from long-term observation of bears.
Bears either travel on ice in fjords or climb mountains to reach neighboring fjords. Of the 27 bears tracked during the study, half of them accidentally sailed an average of about 120 miles (190 kilometers) south, stranded on small ice floes caught within the strong coastal current of East Greenland.
Once the bears had a chance, they just jumped off the ice and headed back to the fjord, which they call home. Created by glaciers, fjords are long, narrow, deep sea bays located between high cliffs.
“Even with the rapid changes in the ice sheet, this area of Greenland has the potential to continue producing glacial ice, with a coastline that may look similar to today, for a long time,” Moon said.
However, researchers warn that this habitat may not be enough for other polar bears suffering as a result of the climate crisis.
“If you’re concerned about conserving the species, then yes, our findings are encouraging – I think they show us how some polar bears can continue in climate change,” Leidre said.
“But I don’t think the glacier habitat will support a huge number of polar bears. There just aren’t enough of them. We still expect to see a big drop in polar bears in the Arctic due to climate change. “
Uncertain future
Researchers believe that polar bears in southeastern Greenland have evolved in isolation for several hundred years. The earliest known mention of bears in this place dates back to the 1300s, and the first written record of animals among the fjords in the region dates back to the 1830s, according to the study’s authors.
The condition of the polar bears remains unknown. Researchers do not know if the population is stable, growing or declining, but more monitoring could reveal what the future holds for this unique population, Leidre said.
Due to their isolation, polar bears are so genetically diverse that researchers suggest that polar bears from southeastern Greenland be considered the 20th subpopulation of the species.
Ultimately, this decision depends on the International Union for Conservation of Nature, which helps to monitor protected species. The Greenlandic government will make all decisions regarding the protection of bears.
“Preserving the genetic diversity of polar bears is crucial for the future of climate change,” Leidre said. “The official recognition of these bears as a separate population will be important for conservation and management.”
Meanwhile, sea ice continues to shrink in the Arctic, significantly reducing the survival rate of most polar bear populations in the future.
“Climate action is the most important thing for the future of polar bears,” Leidre said.
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