Polar bears are suffering from painful 'ice balls' stuck on their feet

Mighty polar bears, the iconic symbols of Arctic snow and ice landscapes, are developing a peculiar problem. It’s not the lack of food or the shrinking ice caps — these are well-known, and devastating, problems.

No, it’s something entirely unexpected and strangely ironic for a creature at home in the ice and snow — buildup of painful “iceballs” stuck on between the toes and on the bottoms of polar bears’ feet.

Icy polar bear paws

Researchers from the University of Washington recently discovered lacerations, hair loss, ice buildup and skin ulcerations primarily affecting the feet of adult polar bears, and other parts of their bodies.

Some even had ice blocks up to a foot (30 centimeters) in diameter stuck to their foot pads, leading to deep bleeding cuts that impaired their ability to walk.

This bizarre phenomenon was first documented in a study published the journal Ecology.

Unexpected response to climate change

The researchers, in their quest to understand this strange occurrence, propose a few theories.

They suggest that the transition from a chronically below-freezing climate to one riddled with unpredictable freeze-thaw cycles is to blame for the icing injuries.

“In addition to the anticipated responses to climate change for polar bears, there are going to be other, unexpected responses,” said lead author Kristin Laidre, a senior principal scientist at the UW Applied Physics Laboratory and a professor in the UW School of Aquatic and Fishery sciences.

“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.”

Polar bear feet covered in ice balls

Kristin Laidre and co-author Stephen Atkinson undertook a decade-long study, from 2012 to 2022, of two polar bear populations living above 70 degrees north latitude.

In the Kane Basin population, nestled between Canada and Greenland, they found evidence of icing-related injuries in 31 of the 61 polar bears observed.

In East Greenland, the second population under observation, 15 of the 124 polar bears exhibited similar injuries.

Two bears in particular from separate locations in Greenland in 2022 had massive ice balls stuck to their feet.

“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.”

Recent phenomenon

Researchers, alongside Indigenous subsistence hunters, have been monitoring these two polar bear populations since the ’90s.

However, they have never reported these types of injuries before, indicating it is a recent, and worrying, phenomenon.

Polar bears, adept at navigating icy terrains, have small bumps on their foot pads that provide grip on slippery surfaces.

These bumps, larger than those on other bear species, like brown and black bears, ironically makes it easier for wet snow to freeze and accumulate on their paws.

This problem, interestingly, is also prevalent amongst sled dogs in the north, as well as Newfoundland dogs in the Rockies.

Solving the polar bear ice balls mystery

Laidre and her colleagues hypothesize three possible reasons for the increasing ice buildup — all linked to climate warming.

The first is more rain-on-snow events creating moist, slushy snow that clumps onto their paws, which then freezes solid once temperatures drop.

The second possibility is frequent warm spells causing surface snow to melt and refreeze into a hard crust. The heavy polar bears break through the ice crust, injuring their paws on its sharp edges.

Finally, both populations inhabit “fast ice,” areas connected to the land where freshwater glaciers meet the ocean.

Warming in these environments leads to thinner sea ice, which allows seawater to infiltrate the snow. This damp snow then freezes onto the bears’ feet, causing injuries.

However, both populations seldom swim long distances in spring, which would help thaw and dislodge any accumulated ice from their feet, due to the warmer water temperature compared to the air.

Unknown consequences

While the bears are undoubtedly affected by this new challenge, the researchers are wary about drawing broader conclusions about the overall health of the two populations.

“We’ve seen these icing-related injuries on individual polar bears,” Laidre said. “But I would hesitate to jump to conclusions about how this might affect them at a population level. We really don’t know.”

There is no doubt that the surface of Arctic sea ice is transforming as the climate changes and temperatures continue rising.

“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. All these things can create challenging surface conditions for polar bears to travel on,” adds fellow researcher Melinda Webster.

Bridging knowledge and action

The new data on polar bears presents a clear call-to-action for the scientific community and policymakers alike.

As this newly emerged issue of ice balls on polar bears’ feet demonstrates the more nuanced impacts of climate change, it is vital that comprehensive research continues to predict and uncover other unforeseen consequences.

Collaborative efforts among scientists, indigenous communities, and governments are necessary to develop mitigation strategies that can help protect these emblematic creatures.

By sharing indigenous knowledge and integrating it with cutting-edge scientific research, there lies a hopeful path toward addressing these complex climate challenges.

Future directions

Looking forward, researchers acknowledge the imperative need for a more robust climate monitoring framework across the Arctic.

This involves deploying advanced technologies such as satellite imagery and drone surveillance to observe environmental changes continuously.

Furthermore, expanding interdisciplinary research, which unites climatology, ecology, and data science, can yield refined predictive models.

By interpreting these dynamic climate patterns more accurately, scientists can better anticipate ecological impacts and propose timely interventions.

Current discoveries, like those outlined by Kristin Laidre and her colleagues, pave the way for these future endeavors, ensuring that the Arctic’s ecological tapestry is preserved for generations to come.

Saving polar bears feet from ice balls

When asked what might be done to help these magnificent creatures, Laidre has a succinct response: “We can reduce greenhouse gas emissions and try to limit climate warming.”

With the Arctic warming at twice the rate of the global average, this unexpected and worrying ailment faced by the polar bears serves as a stark reminder of the far-reaching effects of climate change.

The damage, it appears, reaches far beyond what we can see and predict. It’s another urgent call to action for us to tread more lightly on this beautiful planet we call home.

The study is published in the journal Ecology.

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