POLAR BEAR (Ursus maritimus)

RANGE:. Circumpolar Arctic.

The polar bear has become a central icon of the impacts of climate change on the Arctic—and for good reason. This top Arctic predator relies on sea ice for all its essential activities: hunting seals, seeking mates, moving long distances over the ice, and in Alaska, building dens to rear cubs. The rapid melting and earlier breakup of sea ice has pushed the polar bear onto the front lines of extinction.

Polar bears need sea ice to successfully hunt their main prey: blubbery, energy-rich ringed seals and bearded seals. Polar bears hunt by catching these seals at openings in the ice where seals surface to breathe, and by breaking into the snow caves of ringed seals on top of the ice. The shrinkage and early breakup of the sea ice leaves bears with a vastly diminished hunting ground and less time to hunt. As they struggle to find enough food, polar bears in two of the most well-studied populations—the Hudson Bay population of eastern Canada and the southern Beaufort Sea population of Alaska and western Canada—are in poorer body condition and are dying earlier, leading to declining populations. [ 1, 2, 3, 4, 5, 6] In the southern Beaufort Sea, scientists are finding that polar bears are starving, using unusual and desperate foraging behaviors to try to catch seals, and even resorting to cannibalism. [7, 8, 9]

Sea-ice loss has additional impacts on polar bears. As the sea ice dwindles, bears that would normally be on the ice are forced to come ashore. Although they are good swimmers, polar bears are drowning as they attempt to swim across greater expanses of open water. [10] Once stranded on land, polar bears have more contact with humans and are often killed in these encounters. As sea ice deteriorates, females in the southern Beaufort Sea are abandoning den sites on the ice and are building dens along coastal banks and barrier islands for giving birth and rearing young. [11] Females give birth to one or two tiny cubs, each weighing less than a kilogram (1 to 1.5 pounds), which rely on the insulation of the den for warmth. However, declining snow cover makes it difficult for females to build sturdy snow dens, and accelerating coastal erosion threatens to wash away den sites. [12]

As sea ice melts away, eight of the world’s 19 polar bear populations are declining. [13] If current emissions trends continue, scientists predict that two-thirds of the world’s polar bear population will be lost by 2050, while the rest will near extinction by the end of the century due to the disappearance of sea ice. [14] Unfortunately, polar bears are being overhunted in many of the regions in Canada where sea ice is predicted to last the longest and where polar bears have the best chance of surviving.