August 8, 2021
Scientists have found that glaciers in southeastern Greenland harbor a previously unknown subgroup of polar bears. These bears have a unique ability to adapt to their environment, and they can provide an insight into the future of arctic warming.
Most polar bears rely on Arctic sea ice as a platform for hunting seals, mating and raising their cubs. As the planet warms and the sea ice decreases, the bear struggles to accomplish these basic life tasks. However, the researchers used satellite and ground-based data sources to find that polar bears in southeastern Greenland have adapted to life in places where sea ice is scarce for most of the year.
Instead of traveling long distances to hunt on sea ice, polar bears in southeastern Greenland live at home. They live and hunt in the fjords of the region, where glaciers overflow from land and flow into the sea. This unique population has been isolated from their counterparts in the high-latitude Arctic for so long that they have become genetically distinct.
Kristen Ryder, a polar scientist at the University of Washington, said: "Based on historical records and local knowledge, we know that there are some bears in this area. ”。“ We just don't know how special they are. ”
Ledley and his colleagues combined 36 years of activity, genetics and demographics to show that polar bears in southeastern Greenland are very different from those that live elsewhere off the island's east coast. Their findings were released on June 17th in the Sciences class.
In 2021
The map above, based on satellite telemetry data from 1993-2021, shows the habitat of the southeastern Greenland subpopulation (purple) and the adjacent subpopulation (orange) in northeastern Greenland. Polar bears spread 27,749 square kilometres (10,714 sq mi) of mountain and glacial coastal habitats in southeastern subpopulations; Bears in the northeast are found on most of the sea ice 671208 square kilometers (259155 square miles).
The team also used a medium-resolution imaging spectrometer to record the state of the fjord and offshore sea ice environment using NASA's Terra and Aqua Green satellites and data from the National Snow and Ice Data Center (NSIDC). They found that southeastern polar bears are cut off from sea ice two-thirds of the year. From late May to February, sea ice returns, and bears hunt from crushed ice floating in front of the glacier, a mixture known as Melanger.
"The ocean-terminating glaciers in southeastern Greenland are a pretty unique environment," said co-author Twila Moon, an NSIDC scientist. "These types of glaciers exist elsewhere in the Arctic, but the combination of fjord shape, high yields of glacial ice, and the huge ice reservoir on the Greenland ice sheet is the reason for the current stable supply of glacial ice."
One example is the Heimdall Glacier, pictured at the top of this page. Glaciers are part of the Timmiarmiut fjord system and are located within the habitat of the South-East Asia Group of Greenland. In April 2022 (left), there is still sea ice in front of the Heimdall Glacier; August 2021 (right), mainly the Mekong River and open waters. The images are with the Landsat 9 Land Imager-2 (OLI-2), as well as the Landsat 8 OLI.
Today, southeastern Greenland is similar to what researchers expected northeastern Greenland to look like at the end of the 21st century due to climate change. The adaptation of the southeastern polar bear may indicate how other polar bear populations may adapt to survive as global warming continues. But the authors warn that glacial ice can't feed many bears, and polar bear populations are likely to decrease.
Funding for the study came in part from NASA's Biodiversity and Ice Science Program, a collaboration that Moon said is important to support the group's interdisciplinary research. She added: "We believe these cross-collaborations are critical to solving many of the pressing research challenges associated with our rapidly changing world." ”