Are You Calling Me Fat? A Scientific Surprise in the Arctic

A surprising scientific finding is reshaping the conversation about polar bears: in at least one Arctic region, some bears are not wasting away; they are getting fatter. Yet researchers caution that this apparent resilience tells only part of the story. Across the Canadian Arctic, many populations face the opposite trajectory, with shrinking sea ice directly linked to weight loss, increased starvation risk, and long-term decline.

A new study published in Scientific Reports examined polar bears in the epicentre of Arctic expedition cruising, the Norwegian archipelago of Svalbard, and found that their body condition has improved despite rapid environmental change. Or to a non-scientist, the bears are getting fatter! 

Researchers analysed 1,188 body measurement records from 770 adult bears collected between 1992 and 2019, using a “body composition index” to track fat reserves. Over the same period, the number of ice-free days increased by roughly 100 days, yet the index rose after 2000.

Scientists describe the result as unexpected because the Barents Sea region has warmed dramatically, with temperatures rising in degrees since the seventies, forcing bears to adapt to changing hunting conditions.

One explanation for this weight gain is dietary flexibility. Recovering populations of Svalbard reindeer, bird eggs, and walruses may provide easy alternative prey, while shrinking ice can sometimes concentrate seals into smaller areas, temporarily improving hunting efficiency. 

The stability of the population has also surprised researchers. As ecologist Jon Aars noted, the region has experienced “much faster loss of sea ice than other areas having polar bears,” yet the bears benefit from limited hunting pressure, few competitors on land, and access to alternative food sources. So the bears get more time on land due to ice-melt, thus more time to eat alternatives. And if you've ever been to Svalbard, you'll know that their trusting reindeer are likely easy prey.

But even the scientists behind the research urge caution. The findings differ from observations elsewhere in the Arctic, where sea-ice loss has coincided with population declines. Nowhere is that contrast clearer than in Canada’s Western Hudson Bay, one of the most closely studied polar bear regions in the world. There, sea-ice loss has been directly linked to starvation and population decline, underscoring the uneven climate impacts across the Arctic.

More recent analyses suggest the decline may be even steeper. One report found the population has fallen by almost 50% between 1979 and 2021, with female bears losing 39 kilograms and one-year-old cubs 26 kilograms over the same period.

The underlying mechanism is increasingly well understood: shorter hunting seasons mean less time to build the fat reserves that sustain bears through summer. Researchers at the University of Toronto Scarborough directly linked population decline to an energy deficit caused by “a lack of food” as shrinking sea ice reduces hunting opportunities. Energetic studies support this conclusion, showing that stored energy in the Western Hudson Bay population declined from 1985 to 2018 in association with earlier ice breakup and longer open-water periods.

Taken together, the research reveals an Arctic defined less by uniform decline than by divergence. There are roughly 19–20 distinct polar bear subpopulations worldwide, and they are responding differently to the same planetary pressures.

What makes the Svalbard finding scientifically important is not that polar bears are suddenly safe, but that ecological outcomes are highly regional. Adaptation may be possible where prey is diverse, and ecosystems remain productive. In areas without those alternatives,  particularly parts of the Canadian Arctic, the loss of sea ice still translates into hunger.

Polar bears remain deeply dependent on sea ice for nearly every aspect of their life history, and climate-driven ice loss is widely considered the species’ primary long-term threat. The emerging lesson is one of nuance. Some bears are gaining fat today, but resilience in one region does not cancel decline in another. Instead, it highlights a species navigating a rapidly transforming Arctic, sometimes adapting, sometimes struggling, always dependent on a frozen platform that is steadily disappearing.

The unexpected finding that some Svalbard polar bears are growing fatter offers a nuanced backdrop for expedition cruise travel in the High Arctic, where the species remains the wildlife encounter most visitors hope for. Yet their presence also dictates how tourism operates: stricter regulations, greater viewing distances, controlled landings, and limits on ship activity all reflect a growing recognition that access must be balanced with protection.

While these bears appear relatively adaptable for now, scientists caution that this resilience is regional and should not obscure wider Arctic decline. For travellers, a polar bear sighting is therefore more than a highlight; it is a reminder that entering fragile environments carries responsibility. The future of expedition cruising should ultimately depend less on how close we can get to wildlife and more on how respectfully we are willing to observe it.