For the first time, scientists have documented polar bears suffering from severe ice injuries to their feet in the warming Arctic. The study, published October 22 in Ecology, found bears with ice blocks up to one foot (30 centimeters) in diameter frozen to their foot pads, causing deep lacerations and mobility issues.
Summary: A groundbreaking University of Washington study reveals polar bears in the high Arctic are developing painful ice-related foot injuries due to changing climate conditions, with some bears struggling to walk due to massive ice buildup on their paws.
Estimated reading time: 6 minutes
“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,” said lead author Kristin Laidre, a senior principal scientist at the UW Applied Physics Laboratory and professor in the UW School of Aquatic and Fishery Sciences.
Widespread Injuries in Arctic Populations
The research, conducted between 2012 and 2022, focused on two polar bear populations above 70 degrees north latitude. In the Kane Basin population between Canada and Greenland, researchers found that 31 of 61 polar bears showed evidence of icing-related injuries. In East Greenland, 15 of 124 bears exhibited similar problems.
“I’d never seen that before,” Laidre said, describing two severely affected bears in Greenland. “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.”
Climate Change’s Unexpected Effects
Researchers identified three potential causes for the increasing ice injuries, all linked to climate warming:
- More frequent rain-on-snow events creating slushy conditions
- Warm spells causing surface snow to melt and refreeze into sharp crusts
- Thinner sea ice allowing seawater to seep into surface snow
“The surface of Arctic sea ice is transforming with climate change,” said Melinda Webster, a research scientist at UW’s Applied Physics Laboratory. “The sea ice has less snow in late spring and summer, and the snow that does exist is experiencing earlier, episodic melt and more frequent rain.”
When asked about solutions, Laidre’s response was direct: “We can reduce greenhouse gas emissions and try to limit climate warming.”
Glossary of Terms
- Fast Ice: Sea ice that’s connected to the land
- Freeze-thaw Cycles: Alternating periods of freezing and melting temperatures
- Rain-on-snow Events: Rainfall occurring on existing snow cover
- Foot Pads: The cushioned bottom of an animal’s paw
- Sea Ice: Frozen seawater that forms in polar regions
- Subsistence Hunters: Indigenous people who hunt for food and survival
Quick Quiz
- How large were the ice blocks found attached to some polar bears’ paws?
- What percentage of Kane Basin polar bears showed evidence of ice-related injuries?
- What unique feature of polar bear paws makes them more susceptible to ice buildup compared to other bears?
Answer Key:
- Up to 1 foot (30 centimeters) in diameter
- 31 out of 61 bears (approximately 51%)
- They have larger bumps on their foot pads that help with traction but make it easier for wet snow to freeze and accumulate
Original Research:
Ecology: DOI 10.1002/ecy.4435
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