Warming Temperatures Are Causing Some Polar Bears To Sustain New Types Of Ice-Related Paw Injuries In The High Arctic

In some parts of the high Arctic, polar bears are sustaining ice-related paw injuries due to a warming environment.
When researchers surveyed the health of two populations of polar bears, they found lacerations, skin ulcerations, and signs of hair loss and ice buildup, mostly on adult bears’ feet.
Two bears had ice blocks up to one foot in diameter stuck on their feet. The ice blocks caused deep, bleeding cuts in their footpads, making it difficult for them to walk. It was the first time that polar bears were seen to have such injuries.
A team led by researchers from the University of Washington offered a number of theories for why the changing sea ice patterns are causing ice buildup and injuries in polar bears.
“In addition to the anticipated responses to climate change for polar bears, there are going to be other, unexpected responses,” said Kristin Laidre, the lead author of the new study.
“As strange as it sounds, with climate warming, there are more frequent freeze-thaw cycles with more wet snow, and this leads to ice buildup on polar bears’ paws.”
Laidre and colleagues were studying two polar bear populations living above 70 degrees north latitude between 2012 and 2022 when they saw the injuries.
A total of 61 polar bears make up the Kane Basin population, which is located between Canada and Greenland. They discovered that 31 of the 61 polar bears showed signs of ice-related injuries, such as cuts, scarring, and hairless patches.
In the second population, 15 of 124 polar bears in East Greenland had similar injuries. In 2022, two Greenland bears had large ice blocks stuck to their feet.

Mario Hoppmann – stock.adobe.com – illustrative purposes only, not the actual polar bear
“I’d never seen that before,” Laidre said. “The two most affected bears couldn’t run—they couldn’t even walk very easily. When immobilizing them for research, we very carefully removed the ice balls.”
“The chunks of ice weren’t just caught up in the hair. They were sealed to the skin, and when you palpated the feet, it was apparent that the bears were in pain.”
Since the 1990s, researchers have been studying these two polar bear populations, but no injuries of this kind have been reported until now.
Polar bears have small bumps on their foot pads that help with traction on the slippery ice. However, the bumps make it easier for wet snow to freeze on the pads.
The research team believes that there are three reasons to blame for the increasing buildup of ice on the polar bears’ paws—and they all have to do with climate warming.
One possible reason is that there has been more rain, which creates wet, slushy snow that freezes onto paws once the temperatures drop.
Another possibility is that more warm spells are melting the surface of snow and then refreezing it into a hard crust.
The polar bears are heavy enough to break through this ice crust and end up cutting themselves on sharp edges.
The final possible reason is that warming has led to thinner sea ice at the edge of glaciers, allowing seawater to soak into the snow. The wet snow freezes onto the bears’ feet.
To help the polar bears and other animals facing challenging conditions, it is crucial to reduce greenhouse gas emissions to slow down climate warming.
The study was published in Ecology.
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