Three adult polar bears in Southeast Greenland in April 2015. They are using the sea ice during the limited time when it is available.Photo: Kristin Laidre / University of Washington
Elizabeth Peacock, an assistant professor at the Emory University School of Medicine and a polar bear expert, wrote a perspective article to accompany Laidre’s research in the journal Science. She explained that some posts online have hinted that this isolated bear group could be a “thriving” population because they have found a new way to hunt. But Peacock she’s not confident that’s the case.
“Plasticity generally refers to an individual that has the ability to, you know, to use different behaviors… so, ‘I can figure out how to kill a walrus or I can figure out how to catch fish’,” she said. “Natural selection is about adapting over time… that assumes that polar bears have enough time to change what they’re doing to respond to natural selection.”
Unfortunately, the effects of climate change are happening faster than many polar bears can reproduce.
In her article, Peacock pointed to other known polar bear populations that have shown signs of plasticity, such as nesting farther inland away from depleting sea ice or hunting for different types of prey when their usual seal diet is not as abundant. There are questions as to whether glacier hunting will continue to be possible in the future, as ice melts in both poles. Polar bear generations are about 10 years long, but climate change is affecting ice at a rate much faster than that. Researchers are worried that this new behavior may not be passed down, because the climate crisis is rapidly depleting ice in the Arctic.
“We have NO IDEA if they are thriving. We know nothing about whether the population is stable or in trouble. This will require more research, ”Laidre said in an email. To actually determine how this population is faring in the face of climate change, scientists will have to study the survival of adult female polar bears by marking them and studying them over three or four years.
“Glacier ice may help small numbers of polar bears survive for longer periods under climate warming, and may be important to the species persistence (meaning preventing extinction), but it is not available for the vast majority of polar bears,” she said. “Future monitoring these bears can perhaps tell us a bit more about the future for the species.”