As the Arctic warms, some polar bears are being injured by painful ice buildup on their paws: study

Some polar bears living in the far north are turning up with ice-related injuries that, in some cases, seriously affect their mobility and may be connected to the warming Arctic.

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

Two bears had developed ice blocks up to 30 centimetres in diameter around their paws, causing deep lacerations. 

"It was clearly very painful for the bears," Kristin Laidre, a professor at the University of Washington 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, and another population in East Greenland. Their findings were published last week in the scientific journal Ecology. 

Among the Kane Basin bears, 31 of the 61 bears they observed had injuries related to ice buildup, including cuts, scars and hairless patches created when hair would get wet, refreeze and be torn off.

In the East Greenland population, the prevalence of injuries was lower, with 15 of the 124 observed bears showing similar injuries. But the two worst cases of ice buildup were on bears in Greenland; it took researchers more than 30 minutes to chisel the ice buildup off of the rear paws of two sedated bears.

"The bears with the ice buildup, they had trouble walking and running," Laidre said.

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

Laidre cautioned that they don't have enough data to point to a trend for these populations, or to suggest that this is happening more broadly.

However, she said, it is the first time these types of injuries have been reported among these two polar bear populations. 

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

Andrew Derocher, a professor at the University of Alberta who has studied polar bears for more than 40 years, said injuries from ice balls do occur to other animals in the Arctic. But it's an "unusual event," he said.

"Typically, the damage that occurs is nowhere near as severe as what was observed in these situations," he told CBC News.