The polar bear (Ursus maritimus) is the largest land predator on Earth, uniquely adapted to the extreme conditions of the Arctic. These powerful marine mammals are positioned at the top of the Arctic food web, but their existence is threatened by the rapid warming of their environment. The crisis facing this species is a direct indicator of the wider climate emergency. The fate of the polar bear is linked to the state of the Arctic sea ice, which is disappearing due to the rise in global temperatures.
The Critical Role of Sea Ice
Sea ice is the primary habitat and hunting platform for polar bears. They rely on this frozen expanse to access their prey, the ringed and bearded seals, which surface at breathing holes in the ice. This hunting method allows the bears to accumulate the fat reserves necessary to sustain them through the warmer, ice-free summer months.
The seasonal cycles of ice formation and melt govern the bears’ ability to feed, migrate, and reproduce. Sea ice also serves as a corridor for traveling vast distances and a platform for mating. Warming temperatures are causing the ice to break up earlier in the spring and freeze later in the autumn, significantly extending the period polar bears must fast.
Scientists measure this habitat loss through “ice-free days,” tracking the number of days a region lacks sufficient ice for hunting. When the duration of this ice-free period exceeds a bear’s physiological threshold for fasting, their physical condition and survival rates decline. In the Western Hudson Bay region, the ice-free season has already extended by approximately three weeks compared to the 1980s, forcing bears onto land for longer periods without food.
Scientific Projections for Survival Timelines
The question of a specific “extinction year” does not have a single, definitive answer, as survival depends entirely on future greenhouse gas emissions. Scientific modeling provides a range of projections based on different climate scenarios. Under a high-emissions trajectory, known as Representative Concentration Pathway (RCP) 8.5, most polar bear populations are projected to face reproductive collapse by the end of the century.
This collapse is described as “functional extinction,” a point where the population’s reproduction rate fails to produce enough cubs to sustain the group. Studies combining sea ice projections with the bears’ energy requirements indicate that many populations will pass this critical threshold between the 2050s and 2100. Conversely, a scenario of moderate emissions reductions, such as RCP 4.5, would delay these declines, allowing more populations to persist longer, particularly in the northernmost parts of the Arctic.
The timeline for reproductive failure is directly tied to the number of ice-free days in a bear’s region. For the most vulnerable, southernmost subpopulations, failure is anticipated as early as the 2040s, as the fasting period exceeds the maximum duration a female can endure while sustaining a pregnancy. The only groups likely to survive past 2100, even under moderate mitigation, are those living in the Canadian Arctic Archipelago and northern Greenland, where sea ice is predicted to endure the longest.
Current Status of Polar Bear Subpopulations
Polar bears are managed as 19 discrete subpopulations distributed across the circumpolar Arctic. The health and stability of these groups vary widely, reflecting regional differences in sea ice loss and ecological productivity. The species is currently classified as Vulnerable on the IUCN Red List of Threatened Species due to the projected decline in global numbers driven by habitat loss.
The IUCN Polar Bear Specialist Group’s assessment in October 2023 indicated differing trends among the known groups. Of the 19 subpopulations:
- Two were reported as likely increasing.
- Five were considered likely stable.
- Three were assessed as likely decreasing.
- Nine were classified as data deficient due to insufficient recent information.
Populations in the Seasonal Ice Ecoregion, such as the Western Hudson Bay and Southern Beaufort Sea, are already showing stress. The Western Hudson Bay subpopulation, one of the most studied, experienced a population drop of 27 percent in just five years, based on a 2021 survey. Bears in these declining groups show physiological consequences, including lower body mass, reduced litter sizes, and poor cub survival rates.
Global Conservation Efforts
Addressing the fate of the polar bear requires a two-pronged approach, focusing on local management and global climate action. The five nations that share the polar bear’s range—Canada, Denmark (Greenland), Norway, Russia, and the United States—signed the 1973 Agreement on the Conservation of Polar Bears, which established a foundation for international cooperation. This agreement is reinforced by the Circumpolar Action Plan (CAP), which guides collaborative research and management efforts.
Local conservation strategies focus on managing human-bear conflict, which increases as bears are forced onto land to seek food. These efforts include developing polar bear patrols in Arctic communities and supporting research into bear movements and denning locations. Organizations like Polar Bears International and the IUCN Polar Bear Specialist Group track population health and provide scientific data to inform policy.
Despite these necessary local efforts, the long-term survival of the species rests on the successful mitigation of climate change. The most direct action for polar bear conservation is the immediate reduction of global greenhouse gas emissions, the sole driver of sea ice loss. Protecting regions like the “Last Ice Area,” where ice is projected to persist the longest, offers a refuge, buying time for the world to transition to a low-carbon economy.