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Loss of habitat is the greatest threat to biological diversity, and 85 per cent of the species on the 2006 Norwegian red list are threatened by changes in habitat. Highly-specialized species appear to be the most vulnerable. The polar bear is one such species, and the extent and sustainability of sea ice is essential for its survival. The global population of polar bears consists of roughly 20,000-25,000 individuals spread between 19 sub-populations. However, polar bears wander across enormous distances, so there are no major genetic differences between these populations. On Svalbard, for instance, polar bears live mainly in areas where there is sea ice, and most of them are therefore found along the eastern coast and in the fjords in the north. The most important hibernation areas on Svalbard are located on the islands of Kongs?ya, Svensk?ya, Edge?ya, Nordaustlandet and Hopen. However, because the sea ice is retreating as a result of climate change, polar bears have stopped hibernating on Hopen. This is an indication that these hugely important hibernation areas are under direct threat from global warming.
In 2006, the polar bear was categorized as vulnerable on the World Conservation Union red list. Because of the polar bear's specialization for living on the marine sea ice, it is particularly vulnerable to large-scale changes in its habitat. A low reproduction rate and a long generation time means that this species is poorly equipped for tackling rapid changes in its habitat like those currently being experienced in the Arctic. Based on extremely conservative forecasts about the future extent of the sea ice, scientists have estimated that two thirds of the polar bear population could become extinct by 2050. If the sea ice continues to retreat at the speed witnessed during the last few years, the situation will become even more?critical. (Adapted from )