In brief
In a surprising twist, polar bears on the Norwegian islands of Svalbard have become fatter and healthier since the 1990s, despite a dramatic loss of sea ice due to climate change. Research shows these bears have adapted by diversifying their diet, which now includes more land-based prey like reindeer and walruses. However, experts warn that this trend may not last as ongoing ice loss challenges their long-term survival.
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.
While this is unexpected good news for these Arctic predators, the researchers think it is unlikely to last. As the sea ice continues to decline, bears will have to travel further to access hunting grounds, using more energy and depleting precious fat reserves. Experts think the new findings could be linked to the population recovering from hunting pressures and an increase in walrus and reindeer numbers in recent decades.
However, Dr. John Whiteman from Polar Bears International warned that the long-term picture is clear: bears need sea ice to survive. If ice loss continues unchecked, we know the bears will eventually disappear.
