Scientists expected the opposite, but polar bears in the Norwegian Arctic archipelago of Svalbard have become fatter and healthier since the early 1990s, all while sea ice has steadily declined due to climate change.
Polar bears rely on sea ice as a platform from which to hunt the seals that they require for their blubber-rich diets. Their fat reserves provide them with energy and insulation and help mothers to produce nutrient-rich milk for their cubs.
Researchers weighed and measured 770 adults in Svalbard between 1992 and 2019 and found that bears had become significantly fatter.
They attribute this change to the Svalbard bears adapting to recent ice loss by consuming more land-based prey, including reindeer and walruses.
The discovery, published in Scientific Reports, was particularly puzzling given the impact of climate change in the region, which has nearly halved the number of ice-covered days in recent decades.
Lead researcher Dr. Jon Aars from the Norwegian Polar Institute explained, The fatter a bear is the better it is, noting that he anticipated a decline in body condition with the severe sea ice loss.
Other researchers suggest the increase in walrus populations, which have been protected since the 1950s, may provide more hunting opportunities for bears. However, as sea ice continues to dwindle, bears may have to travel farther for food, threatening their energy reserves.
While this is relatively good news for Svalbard's polar bears in the short term, experts think it may be temporary as long-term ice loss scenarios predict serious challenges for polar bear populations.
Dr. John Whiteman from Polar Bears International emphasizes that body condition is just one factor in the complex survival dynamics of polar bears under climate change pressures.
