As the Arctic warms, some polar bears are suffering injuries from painful ice buildup on their paws: study

Some polar bears living in the far north suffer ice-related injuries, which in some cases seriously affect their mobility and may be linked to a warming Arctic.

Researchers observing polar bears in two different populations in northern Canada and Greenland found that some had hair loss, cuts and sometimes severe ice buildup on their paws.

Two bears had ice blocks up to 30 centimeters in diameter around their paws, resulting in deep lacerations.

“The bears were clearly in a lot of pain,” Christine Laidre, a University of Washington professor and lead author of the paper, told CBC News.

The observations were made by researchers between 2012 and 2022 while studying a population of bears in the Kane Basin, which lies between Nunavut and Greenland, as well as another population in East Greenland. Their results were published last week in the scientific journal Ecology.

Ice build-up bothers some bears

Among bears in the Kane River Basin, 31 of the 61 bears they observed had injuries related to ice accumulation, including cuts, scars, and hairless areas caused by getting wet, freezing again, and fur being torn off.

In the East Greenland population, the prevalence of injuries was lower, with 15 of 124 bears observed exhibiting similar injuries. But the two worst cases of icing occurred in bears in Greenland; It took researchers more than 30 minutes to remove ice from the hind legs of two euthanized bears.

“Bears that developed ice had difficulty walking and running,” Laidre said.

Injuries were most common among adult males, who are heavier than females or cubs and tend to travel longer distances.

Laidre cautioned that they don’t have enough data to indicate a trend for these populations or to suggest it’s happening more broadly.

However, she said, this is the first time such injuries have been reported among these two polar bear populations.

When researchers consulted with Inuit hunters in nearby communities in Nunavut and Greenland, most said they had never seen ice buildup on polar bears this strong before.

Andrew Desrochers, a University of Alberta professor who has studied polar bears for more than 40 years, says ice ball injuries happen to other animals in the Arctic. But this is “an unusual event,” he said.

“Normally the damage that occurs is nowhere near as severe as what was seen in these situations,” he told CBC News.

If a polar bear were to suffer such an injury in the spring, it could be “really catastrophic” to its chances of survival, he said. “You will have to gain weight in the spring. And if you can’t move and hunt efficiently, that will have negative consequences.”

Factors that may cause injury

According to the researchers, changing temperatures in the Arctic are one of the main factors that may contribute to these injuries.

“It could get so warm in the Arctic that the sea ice will turn into rain instead of snow. And that can create wet conditions that, if they freeze again, can cause injury,” Laidre said.

In addition to more rain on the snow, increased cycles of temperature fluctuations can also cause the snow surface to melt enough to become slushy and then refreeze soon after.

“These bears have lived in extremely stable and extremely cold environments throughout their evolutionary history,” Laidre said. “Polar bears in such high Arctic populations are not accustomed to freeze-thaw cycles, and that’s what we think we’re seeing here on our paws.”

The third scenario is that these two bear populations are uniquely susceptible to ice formation due to where they live.

Polar bears in other regions may engage in longer ocean swims, which may help melt ice buildup. The researchers noted that bears in these two regions live near glaciers and thick ice, so they do not have to navigate open water frequently or for long periods of time.

This is the most likely cause of these particular injuries, Desrochers said.

“Personally, I think these are just unlucky bears in an unusual place,” he said.

But Laidre says the source of Arctic temperature fluctuations that contribute to ice formation is clear to her.

“These injuries are due to warmer conditions,” she said. “Given that (these injuries) have never been seen before, they’re new, and we have all these changes, it’s likely climate change.”

Laidre said the field research, which was supported by the governments of Canada and Nunavut as well as Greenland, shows the value of ongoing monitoring of polar bear populations. This is the only way researchers will be able to see if there is any trend in these injuries that could affect bears at the population level, she said.

As a species, polar bears cover a vast area, with some populations traveling near the North Pole and others hanging out around Churchill, Maine. But there is one problem—changes in sea ice—that affects all populations, regardless of location, Derocher said.

And the problem has a clear link to climate change, he said.

“There is a very strong correlation between global greenhouse gas emissions and sea ice loss,” he said.

People who are concerned about the health of polar bears should push for action on climate change, not just climate awareness, Laidre said.

“The way to help polar bears is to reduce greenhouse gas emissions and slow or stop warming in the Arctic and the globe.”