Polar Bears: The Arctic's Apex Predator Facing an Uncertain Future

The polar bear (Ursus maritimus) is the world's largest land carnivore and the undisputed apex predator of the Arctic ecosystem. Weighing up to 700 kilograms and measuring up to 3 metres in length, polar bears are supremely adapted to life on and around sea ice — hunting ringed and bearded seals through the ice, swimming between ice floes, and raising cubs in snow dens. They are also among the most visible casualties of Arctic climate change: as sea ice retreats earlier each spring and returns later each autumn, polar bears face longer fasting periods, reduced body condition, and lower cub survival rates.

Masters of the Sea Ice

Polar bears are classified as marine mammals — a designation that reflects their fundamental dependence on the ocean and its ice. Their primary prey — ringed seals (Pusa hispida) and bearded seals (Erignathus barbatus) — are hunted almost exclusively at the sea ice surface, where bears wait motionlessly at seal breathing holes for hours or even days before striking. This hunting technique, called still-hunting, requires extensive sea ice coverage and the presence of productive seal populations. Bears may travel thousands of kilometres annually across sea ice in search of optimal hunting areas.

The Sea Ice Crisis

Arctic sea ice extent has declined by approximately 13% per decade since satellite measurements began in 1979. For polar bears, the critical metric is not total ice extent but the timing and extent of sea ice in their specific subpopulation ranges. Across most of the Arctic, the ice-free season — when polar bears are forced ashore and cannot hunt — has lengthened substantially. In Hudson Bay, the ice-free period has extended by approximately three weeks since the 1980s. Bears that come ashore earlier and in poorer body condition produce fewer and lighter cubs, and experience higher mortality rates.

Polar Bear Subpopulations — Status by Region

Adaptation and Resilience

Despite the pressures of climate change, polar bears are not entirely without adaptive capacity. Some subpopulations have been observed switching prey when sea ice is unavailable — consuming bird eggs, vegetation, and carrion on land. Genetic studies have revealed that polar bears survived previous warm periods in Earth's history, suggesting some degree of evolutionary resilience. However, the current rate of warming is far faster than previous natural climate cycles, leaving limited time for adaptation. Most climate projections indicate that without significant reductions in greenhouse gas emissions, most polar bear subpopulations will face severe declines by 2100.