Scientists analyzed the body size of hundreds of bears between 1995 and 2019 in the Norwegian archipelago of Svalbard, a region experiencing climate change up to four times faster than the global average.
Polar bears in Svalbard, Norway’s Arctic archipelago, have increased their body size and are better able to resist the accelerated climate change affecting the region than expected, according to a study.
“The increase in their physical condition during a period of significant sea ice loss was a surprise”, Jon Aars, from the Norwegian Polar Institute, main author of the article published on Thursday in the journal Scientific Reports, told Agence France-Presse (AFP).
Aars believes this result can be explained by a diversification in the bears’ diet.
Scientists analyzed the body size of hundreds of bears between 1995 and 2019 in the Norwegian archipelago of Svalbard, a region experiencing climate change up to four times faster than the global average.
Some areas of the Barents Sea have registered a warming of almost 2°C per decade in the last 40 years, researchers pointed out.
As a consequence of these climatic conditions, the sea ice that serves as a habitat for polar bears, estimated at between 1,900 and 3,600 individuals throughout the Barents Sea, according to a 2004 census, is retreating.
Scientists therefore expected to find thinner bears, as in other regions of the world affected by similar ice retreat, but the result was surprising.
The index measuring bears’ body condition, after an initial decline between 1995 and 2000, “subsequently increased during a period of rapid sea ice loss,” the researchers concluded in their study.
“This result may seem surprising because it contradicts the conclusions of studies carried out in other polar bear populations, such as in Hudson Bay, where physical condition has drastically decreased due to global warming,” researcher Sarah Cubaynes, who was not directly involved in this study, but has also worked with bear populations, explained to AFP.
A decrease in these measures, which take into account body size and fat reserves, would have been considered an indicator of future demographic problems for these animals, as in other regions.
“When conditions deteriorate, with less access to food, we initially expect bears to become leaner, accumulating less fat, before the situation worsens further and survival and reproduction decline significantly,” said Jon Aars.
The authors of the investigation therefore highlighted the importance of not extrapolating observations from one region to another.
The situation of Svalbard’s polar bears is governed by a “complex relationship” between their habitat, the ecosystem and their energy gains and expenditures, they highlighted.
To explain their resilience, the authors suggested that the bears managed to diversify their diet, which until then consisted mainly of seals.
They may have been able to more easily hunt reindeer and walruses, whose populations have prospered again after being overexploited by humans.
The concentration of a particular seal species may also have increased when sea ice was less abundant, requiring less effort from bears to hunt them.
“A plausible hypothesis would be that bears are able to maintain their physical condition, although at the cost of producing fewer cubs,” added Sarah Cubaynes, suggesting a possibility not mentioned in the study.
Although the adaptation of the polar bears studied appears to be “good news”, researchers are less optimistic about the future, believing that Svalbard’s bears will likely be affected by climate change in the near future.
“We believe they still depend on their ability to hunt seals on the ice,” which will prove more difficult, warned Jon Aars.
