Discoveries

June 29, 2022

Icy Hope

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Rising temperatures have been threatening the habitats of polar bears for years as the floating slabs of ice they used to hunt began to disappear.

Now, a research team has discovered a group of genetically distinct polar bears living in southeastern Greenland that have been isolated for around 200 years, creatures who eschew sea ice and use glaciers to hunt instead, Live Science reported.

The discovery has upended the way scientists think about polar bears and the looming danger for them as the climate warms.

Until now, scientists had identified 19 known subpopulations of polar bears living in the Arctic Circle. Among them was one population that spans a 1,988-mile stretch of the eastern coast of Greenland.

But new genetic analysis and decades of tracking data showed that these were actually two separate populations each living in the southeast and northeast of the icy landmass, according to a new study.

The team explained that the newly found group, the southeastern bears, numbering about 300, were the most genetically diverse out of all the 20 populations.

But what struck researchers was that this population had seemed to adapt to the warming climate because of its choice of location.

Polar bears need to use sea ice as platforms to stalk their prey from above. Sea ice usually forms during the autumn period and melts by spring. Polar bears can normally survive between 100 and 180 days without food during the summer months.

But the newly found population’s region experiences more than 250 days a year without sea ice – conditions that mimic those predicted for the Arctic by the end of the 21st century.

The authors added that a few northeastern bears –described as “immigrants” – had also acclimated to the warmer environment.

Currently listed as vulnerable to extinction, polar bears number around 36,000 in the wild.

Kristin Laidre, a wildlife scientist at the Polar Science Center at the University of Washington and lead researcher on the study, told Live Science that while the study offers some hope for the world’s largest land predator, it doesn’t mean widespread relief for the bears because this type of glacier ice is only found near a small fraction of other polar bear populations.

“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,” she said. “Loss of Arctic sea ice is still the primary threat to all polar bears.”

This story originally appeared in the June 29, 2022 newsletter, Back to the Future.