Last month, the Polar Bear Specialist Group of the International Union for the Conservation of Nature (IUCN) – a global authority on wildlife conservation – released a new assessment of polar bears. The findings reveal the most up-to-date information for polar bear populations.
Polar bears across the Arctic are up against a huge problem: the loss of their habitat as the Arctic warms and sea ice disappears. The bears need sea ice for moving around, finding a mate and hunting. Until the summer sea ice stops shrinking, their survival is under threat.
- The world’s polar bear population is split into 19 subpopulations.
- Subpopulations are decided based on management needs and what biologists know about the movement and genetics of the bears.
- To measure how subpopulations are changing over time, scientists ask different questions like are there more, fewer, or roughly the same number of polar bears?
The field survey from the Chukchi Sea, found between Alaska and Russia, shows a stable subpopulation between 2008 and 2016. This means there’s more than a 66% chance that over that eight-year period the number of polar bears hasn’t experienced any significant changes. The Barents polar bear subpopulation located off the northern coasts of Norway and Russia, was also found to be stable between 2004 and 2015. Before this assessment, scientists didn’t have enough information to establish trends for either of these subpopulations. These groups of bears have stayed stable despite declining sea ice in both the Chukchi Sea and Barents Sea in recent decades.
Scientists think that the Chukchi Sea subpopulation was stable because it inhabits a very biologically productive area. In addition to having a lot of seals, Chukchi Sea bears often have access to walrus and whale carcasses that wash up on shore. For Barents bears, the likely explanation for stability is a little different. Polar bears from the Barents Sea subpopulation were hunted intensively for more than 100 years before hunting became illegal in Norway and Russia. The subpopulation is likely still in a recovery phase. However, continued sea ice loss will mean that at some point, this subpopulation will start to decline.
It will be important to keep surveying these subpopulations to better understand how polar bears are coping with this loss of their habitat, especially considering the record low ice cover in the Chukchi Sea in October 2019.
What’s the bad news?
The number of polar bear subpopulations experiencing recent decreases has gone from 1 to 4. In Canada, polar bears from Southern and Western Hudson Bay as well as the Northern Beaufort Sea have all experienced a fall in numbers. According to scientists, Southern Hudson Bay dropped by 17% and Western Hudson Bay dropped by 18% between 2011 and 2016.
These polar bears are also showing other signs of climate change-related stress. Because the ice is breaking up earlier there are declines in the survival rates of both young and old bears. The bears are also thinner.
However, local communities living among the polar bears note the opposite and report increasing numbers across Hudson Bay. This highlights the need for more monitoring and joint efforts to better understand what’s happening with these bears.
What does this new information mean for the future?
The polar bear subpopulation map above is a good illustration of the struggles polar bears are facing. The Arctic is vast, and the changes taking place are not uniform. In some regions, including the Last Ice Area, where summer sea ice is predicted to last the longest, polar bears appear to be doing well.
But in other regions the reality is troubling. There are also several grey areas on the map – literally and figuratively – where scientists just don’t have enough information to know what’s happening with polar bears. This is a risky situation to be in, because the Arctic is warming more than twice as fast as the rest of the planet and major changes can happen quickly.
While it’s important to note that these trends aren’t predictions of the future, we should use the subpopulations in the more southern regions as warning beacons, giving us a glimpse into a future that more and more polar bears may face.