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 depend on for blubber-rich meals. The bears' fat reserves provide energy and insulation and allow mothers to produce rich milk for cubs.
Researchers weighed and measured 770 adults in Svalbard between 1992 and 2019 and found that bears had become significantly fatter. They believe Svalbard bears have adapted to recent ice loss by eating more land-based prey, including reindeer and walruses.
The discovery, published in Scientific Reports, is particularly puzzling given the impact of climate change in Svalbard. During the same period, global temperature rise has reduced the number of ice-free days per year in the region by almost 100 - at a rate of about four days each year.
Lead researcher Dr. Jon Aars highlighted, The fatter a bear is, the better it is, while expressing surprise that body condition remained stable despite profound sea ice loss.
The new findings could be linked to the bears recovering from past hunting pressures, and the increase in walrus and reindeer populations in recent decades appears to have provided the bears a temporary boost. However, researchers warn that this situation may not be sustainable as sea ice continues to diminish.
Dr. John Whiteman, chief research scientist at Polar Bears International, remarked that while these findings are positive in the short term, the overall long-term picture remains concerning. Svalbard's polar bears have significantly reduced survival in cubs related to increased ice-free days, suggesting that the effects of climate change vary greatly across different regions.
