be ice-free in summer by 2040, but they also predict that half a million square kilometres of sea ice could remain until at least 2100.This ice will lie next to the northern coasts of Greenland and the Canadian Arctic archipelago, the region where the oldest and thickest ice now occurs. This region will therefore offer at least a limited sanctuary for species that prefer, or rely on, year-round sea ice. Projections published in February indicate that by the middle of the century optimal polar bear habitat will have disappeared across most of the Arctic, but will persist north of the Canadian Arctic archipelago and Greenland.
The continued existence of this habitat lays the foundation for the long-term survival of ice-dependent species. But to ensure they do survive, we urgently need to draw up a management plan. As ice-covered areas open up, the Arctic will experience more human activity than ever before.
New developments in shipping, tourism and resource extraction, for example, will put pressure on ecosystems already struggling to adapt to environmental changes. We need to start an international assessment now, before Arctic countries establish their development schemes.
The management plan will have to extend to cover the "ice shed" that delivers ice to the region. Our research indicates that, in the past, some of the ice was formed locally, but some of it also drifted in from the central Arctic and as far away as the continental shelf waters of northern Alaska and north-eastern Russia. Even when most of the sea ice is gone in the summer, ice formed in the winter will be transported by wind and ocean currents into this region.
Because sea ice is dynamic, we will need an international system of monitoring and managing the remaining habitat and the areas that supply its ice. If we are able to do this successfully, we could maintain a viable habitat for polar bears and other species for decades into the future.
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