In brief
A new study reveals that polar bears in Svalbard, Norway, have gained weight and improved their health since the 1990s, despite significant sea ice loss attributed to climate change. Researchers found that bears are adapting by hunting more land-based prey, such as reindeer and walruses, as sea ice becomes less accessible. This increase in body condition raises concerns over the sustainability of the bears' new diet amid ongoing climate challenges.
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 rely 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 think that Svalbard bears have adapted to recent ice loss by eating more land-based prey, including reindeer and walruses.
The discovery, published in Scientific Reports, was particularly puzzling because of the impact of climate change in Svalbard. During the same period that this research was carried out, 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.
The fatter a bear is the better it is, explained lead researcher Dr Jon Aars from the Norwegian Polar Institute. And I would have expected to see a decline in body condition when the loss of sea ice has been so profound.
Walruses have been officially protected in Norway since the 1950s, after they were hunted to near extinction. That protection has boosted their numbers, and apparently provided a new source of fatty food for polar bears. There are a lot more walruses around [for them to hunt] these days, said Aars. It is also possible that they are able to hunt seals more efficiently.
Experts caution that this positive trend may not last. As sea ice continues to decline, bears will have to travel further to access hunting grounds, using more energy and depleting precious fat reserves. Dr John Whiteman, chief research scientist at Polar Bears International, noted that while the short-term results are hopeful, continued ice loss spells long-term danger for polar bear populations.
