Greenland’s polar bear population lives without sea ice

Researchers who studied and tracked the bears decided that they would survive despite having limited access to sea ice – which is critical for polar bears – and instead use freshwater ice from Greenland’s ice cover.

“We wanted to map this region because we did not know much about the polar bears in southeast Greenland, but we never expected to find a new subpopulation living there,” said study lead author Kristin Laidre, a polar researcher at the University of Washington’s Applied Physics Laboratory. in a statement.

“We knew there were some bears in the area from historical records and indigenous peoples. We just did not know how special they were.”

An icy necessity

When they travel far, the 19 known polar bear populations depend on sea ice to hunt their prey, such as ringed seals, and sit near breathing holes to catch the prey. The calories that seals provide can help them store energy for several months when food and sea ice are more in short supply.

Global warming causes sea ice to melt quickly and disappear as the Arctic heats up more than twice as fast as the rest of the planet. When sea ice disappears, polar bears have to move ashore, which gives them fewer opportunities for food.

Meanwhile, the southeastern Greenlandic polar bears tend to stay close to home, so they have adapted to the 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 somewhat limited access to sea ice, which helps them catch seals.

The bears can use sea ice between February and the end of May. The rest of the year they hunt seals by using freshwater ice when it detaches from the ice cover.

“Polar bears are threatened by sea ice loss due to climate change. This new population gives us some insight into how the species may persist into the future,” said Laidre, also an associate professor at the University of Washington in Aquatic and Fisheries Sciences.

“But we must be careful about extrapolating our findings, because the glacier that makes it possible for Southeast Greenland bears to survive is not available in most of the Arctic.”

An adult female polar bear (left) and two 1-year-old cubs cross a snow-covered glacier in freshwater in March 2015.

The environment in Southeast Greenland is a unique, small-scale climate refuge where the bears can survive, and similar habitats are found along the coast of Greenland and the Norwegian island of Svalbard.

“This type of glacier is found elsewhere in the Arctic, but the combination of the fjord shapes, the high production of glaciers and the very large ice reservoir available from the Greenland ice sheet is what today provides a steady supply. of the glacier, “said co-author Twila Moon, deputy director of the U.S. National Snow and Ice Data Center in Boulder, Colorado, in a statement.

“In a way, these bears provide an insight into how Greenland’s bears can cope with future climate scenarios,” said Laidre. “The sea ice conditions in Southeast Greenland today are similar to those predicted for Northeast Greenland at the end of this century.”

Air 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 southeast coast. The latter is a remote region with sharp mountains, heavy snow and unpredictable weather, making it difficult to study.

The research team spent two years consulting polar bear hunters, who hunt to survive, instead of sports, in East Greenland. The hunters could share their expertise and contribute samples for genetic analysis.

The researchers, in collaboration with the Greenland Institute of Natural Resources in Nuuk, Greenland, were able to study and track the bears using helicopters while the researchers flew over the sea ice, and estimate that a few hundred bears live in the remote area. This is similar to other small populations of polar bears elsewhere.

E-mail from the edge: Svalbard's polar bears send messages to researchers

The female polar bears in Southeast Greenland are more diminutive than the female polar bears in other regions. The smaller bears also have fewer cubs, which may be related to trying to find companions while traveling around the fjords and surrounding mountains. But scientists do not know for sure until they have more data from long-term monitoring of the bears.

The bears either travel over ice in fjords or climb over mountains to reach the neighboring fjords. Of the 27 bears tracked during the study, half of them accidentally floated about 120 miles (190 kilometers) south on average, trapped on small ice floes trapped within the strong East Greenlandic coastal current.

A fjord in southeast Greenland is shown filled with open water in April 2016.

When the bears had a chance, they just jumped off the ice and went back to the fjord they call home. The fjords are created by glaciers and are long, narrow, deep inlets found between high cliffs.

Polar bears become thinner and have fewer young.  Melting sea ice is to blame

“Even with rapid changes taking place on the ice sheet, this area of ​​Greenland has the potential to continue producing ice, with a coast that may look like today, for a long time,” said Moon.

However, researchers warn that this habitat may not be enough for other polar bears suffering in the wake of the climate crisis.

“If you’re concerned about conserving the species, then yes, our findings are hopeful – I think they show us how some polar bears can survive during climate change,” Laidre said.

“But I do not think glacier habitat will support a large number of polar bears. There is just not enough of it. We still expect to see large declines in polar bears across the Arctic during climate change.”

Uncertain future

The researchers believe that the southeastern Greenlandic polar bears have developed in isolation for several hundred years. The earliest known reference to bears in this place dates to the 14th century, and the first written registration of the animals among the region’s fjords is from the 1830s, according to the study authors.

The status of the polar bears is still unknown. Researchers do not know if the population is stable, growing or declining, but more monitoring can reveal what the future holds for this unique population, Laidre said.

Most polar bears may struggle to survive in the Arctic by 2100, the study finds

Due to their isolation, polar bears are so genetically distinct that researchers suggest that polar bears in southeastern Greenland should be considered the 20th subpopulation of the species.

Ultimately, this decision is up to the International Union for the Conservation of Nature, which helps to supervise protected species. And the Greenland government will make any decisions about protecting the bears.

Three adult polar bears can be seen using the sea ice during the limited time it is available in April 2015.

“Preserving the genetic diversity of polar bears is crucial going forward in climate change,” Laidre said. “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 the survival rate of most polar bear populations in the future.

“Climate action is the most important thing for the future of polar bears,” Laidre said.