Polar bears in northern Greenland are doing better at the moment | Polarjournal
The population of polar bears in the Kane Basin, a region between northwest Greenland and Nunavut, Canada, has grown from 225 to 360 animals over the past 30 years. But how long this trend will last is unknown and could reverse with the current pace of change. Picture: Michael Wenger

Polar bears are actually perfectly adapted to their Arctic environment. But the rapid climatic changes in the Arctic, together with hunting and pollution, have massively added to the decline of the King of the Arctic. In many regions, the population is declining very quickly. But at least in northern Greenland, in the Qaanaaq region, the population of bears has grown since the 1990s.

The polar bears in the Kane Basin, between Nunavut and Greenland, have not only become more numerous, but are also in a better physical condition than they were 30 years ago. In addition, at least female bears had more than doubled their home range between 1990 and 2010. The reason for this is the earlier start of spring ice melt in the region and the change from continuous ice cover to the almost complete opening of the water surface. This favors biological productivity and thus the food base of the bears. This is the conclusion of a study by an international research team, which recently published its findings in the journal Global Change Biology.

The Kane Basin is a 180 km wide and 130 km long site on the Nares Strait, which lies between Ellesmere Island and the northwest corner of Greenland. The sea ice here has shrunk from almost year-round cover to a seasonal, thinner blanket. This allows light and carbon dioxide to enter the water and boost productivity, which apparently has led to a bigger food availability for polar bears. The question, however, is how long. Picture: Michael Wenger

In their work, lead author Dr. Kristin Laidre of the University of Washington Seattle and the team examined not only the numbers of polar bears, but also their movements, their condition, the reproductive numbers and compared them to satellite images of ice cover between 1993 and 1997 and 2012 – 2016. They found that within the time frame, the ice had given way from a layer of perennial ice that had covered more than 50 percent of the region almost all year round to a layer of one- to two-year-old ice, and the time between melting and reforming of the ice had increased by an average of nearly two months. On the one hand, this means two months of longer fasting for polar bears, but also a longer time span for productivity. And it is seemingly this factor that currently outweighs the fasting time span, according to the study.

Polar bears need sea ice to hunt their main food, ring seals and bearded seals. Because only those seals really provide enough energy to survive the summer months. In the Kane Basin, higher productivity has now dampened the effect of the longer fasting period. According to the study, more bears spend their summer months on the east side of the region, as there are more glaciers and therefore more food. Also, there is no evidence that reproduction is currently impaired. Picture: Michael Wenger

“The positive benefits in the Kane Basin are likely temporary because, under unmitigated climate change, continued sea‐ice loss will eventually become a limiting factor.”

Dr Kristin Laidre, Laidre et al (2020) Global Change Biology

But polar bears don’t just have more food everywhere. The team’s research has shown that polar bears are increasingly spending their summer months on the Greenland side. The authors suspect that more food can be found there because of the glaciers. This means that at least now more food is available to the animals, also for the offspring. Despite the decline in sea ice, the researchers found no evidence that the polar bears had shown signs of impaired reproduction. But the researchers warn that this trend is unlikely to last. ” The positive benefits in hte Kane Basin are likely temporary because, under unmitigated climate change, continued sea‐ice loss will eventually become a limiting factor,” the authors write in conclusion of their study. So the reality will sooner or later catch up with the polar bears in northern Greenland, and it is only a matter of time before the polar bears in the Kane Basin will share the fate of their fellows in other polar regions.

Dr Michael Wenger, PolarJournal

Link to the study: Laidre et al (2020) Glob Chan Biol EPub Transient benefits of climate change for a high-Arctic polar bear subpopulation; https://doi.org/10.1111/gcb.15286

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