How Polar Bears Struggle as Climate Change Alters Their Environment

A new study has highlighted the struggles of polar bears as climate change alters their environment, forcing them into a losing diet battle. With Arctic sea ice diminishing due to climate change, polar bears are compelled to shift their diets to land during parts of the summer. The study, focused on Hudson Bay polar bears, examines their ability to maintain their body weight in the face of changing circumstances.

As Arctic sea ice continues to shrink, polar bears are spending more time on land during the summer, affecting their traditional feeding habits. The research, published in the journal Nature Communications, reveals that despite efforts to find alternative food sources on land, polar bears are losing weight and expending more energy than they consume.

Researchers found that 19 out of 20 bears studied experienced an average weight loss of 47 pounds (21 kilograms) over three weeks. This amounts to an average loss of about 7% of their body mass in just 21 days, emphasizing the significant impact of climate change on their ability to sustain themselves.

Polar bears typically rely on high-fat seals, particularly during the spring when seal pups are abundant and easy prey. However, the lack of sea ice in areas like Hudson Bay has led to polar bears spending more time on land, where alternative food sources, such as berries, eggs, sea birds, and even caribou antlers, are found.

"Regardless of which behavior strategy the bears were using, they all lost weight at similar rates, which highlighted that those bears were more active," the study’s lead author Anthony Pagano, a U.S. Geological Survey wildlife biologist, said. "Basically, they were compensating for their higher activity levels through the terrestrial foods they were eating, but they weren't getting any net benefit from that."

The research also highlights the crucial role of sea ice in polar bears' feeding habits, as they rely on it to access their primary prey—ice seals. The study suggests that, given the current pace of climate change, polar bears may struggle to adapt to a land-based diet, raising concerns about their long-term survival.