Polar bears are a potentially endangered species living in the circumpolar north. They are animals which know no boundaries. They pad across the ice from Russia to Alaska, from Canada to Greenland and onto Norway's Svalbard archipelago. No adequate census exists on which to base a worldwide population estimate, but biologists use a working figure of 20,000 to 25,000 bears with about sixty percent of those living in Canada.
In areas where long-term studies are available, populations are showing signs of stress due to shrinking sea ice. Canada's Western Hudson Bay population has dropped 22% since the early 1980s. The declines have been directly linked to an earlier ice break-up on Hudson Bay. A long-term study of the Southern Beaufort Sea population, which spans the northern coast of Alaska and western Canada, has revealed a decline in cub survival rates and in the weight and skull size of adult males. Such declines were observed in Western Hudson Bay bears prior to the population drop there. Another population listed as declining is Baffin Bay. According to the most recent report from the Polar Bear Specialist Group, the harvest levels from Nunavut when combined with those from Greenland (which were thought to be much lower than they actually are) has resulted in this shared population being in a non-sustainable harvest situation, meaning the population is at great risk of a serious decline. The harvest is thought to be several times above what is sustainable.
Some Native communities in Canada have been reporting increasing numbers of polar bears on land. Traditional hunters believe this indicates an increased population, although the increased presence on land may, in fact, be related to shrinking sea ice and changes in the bears' distribution patterns. Data is needed to understand the change. The U.S. Fish and Wildlife Service states, "In the declining polar bear population of Canada's Western Hudson Bay, extensive scientific studies have indicated that the increased observation of bears on land is a result of changing distribution patterns and a result of changes in the accessibility of sea ice habitat."
Climate change is the main threat to polar bears today. A diminishing ice pack directly affects polar bears, as sea ice is the platform from which they hunt seals. Although the Arctic has experienced warm periods before, the present shrinking of the Arctic's sea ice is rapid and unprecedented.
In the 1960s and 1970s, hunting was the major threat to the bears. At the time, polar bears were under such severe survival pressure from hunters that a landmark international accord was reached, despite the tensions and suspicions of the Cold War. The International Agreement on the Conservation of Polar Bears was signed in Oslo, November 15, 1973 by the five nations with polar bear populations: Canada, Denmark (Greenland, Norway, the U.S., and the former U.S.S.R.
The polar bear nations agreed to prohibit random, unregulated sport hunting of polar bears and to outlaw hunting the bears from aircraft and icebreakers as had been common practice. The agreement also obliged each nation to protect polar bear denning areas and migration patterns and to conduct research relating to the conservation and management of polar bears. Finally, the nations agreed to share their polar bear research findings with each other. Member scientists of the Polar Bear Specialist Group now meet every three to four years under the auspices of the IUCN World Conservation Union to coordinate their research on polar bears throughout the Arctic.
The Oslo agreement was one of the first and most successful international conservation measures enacted in the 20th century. Its legacy continues today, with member scientists from each nation continuing to work together in face new threats to the bears including climate change, pollution, industrial activities, and poaching.