Possible impacts of climatic warming on polar bears

Abstract

If climatic warming occurs, the first impacts on Ursus maritimus will be felt at the southern limits of their distribution, such as in James and Hudson bays, where the whole population is already forced to fast for four momths when the sea ice melts during the summer. Prolonging the ice-free period will increase nutritional stress on this population until they are no longer able to store enough fat to survive the ice-free period. Early signs of impact will include declining body condition, lowered reproductive rates, reduced survival of cubs, and an increase in polar bear-human interactions. In the High Arctic, a decrease in ice cover may stimulate an initial increase in biological productivity. Eventually, however, it is likely that seal populations will decline wherever the quality and availability of breeding habitat are reduced. Rain during the late winter may cause polar bear maternity dens to collapse, causing the death of occupants. Human-bear problems will increase as the open water period becomes longer and bears fasting and relying on their fat reserves become food stressed. If climatic warming occurs, the polar bear is an ideal species through which to monitor the cumulative effects in arctic marine ecosysteme because of its position at the top of the arctic marine food chain. -from Authors