Polar Bear

The polar bear lives far to the north, within the Arctic Circle, and is closely tied to sea ice. Although it is known as the world’s largest land-based predator, it spends most of its life at sea, using the ice as a platform for hunting seals. Polar bears prefer areas with so-called seasonal ice – sea ice that melts in the summer and freezes again in winter – as these regions often have the richest food sources.

When seawater freezes, the salt is pushed out, forming tiny channels within the ice. Microscopic algae grow in these channels, forming the base of the entire Arctic food web. That’s why this type of sea ice is also where the largest numbers of seals are found, which is the polar bear’s most important prey.

In summer, when the ice melts, many polar bears are forced inland to the tundra. Here, they often fast for long periods while waiting for the ice to return. Pregnant females seek out coastal areas in late summer with deep snow or large piles of seaweed, where they dig dens to give birth and care for their cubs throughout the winter.
Because the polar bear is so dependent on sea ice, it is especially vulnerable to climate change. As temperatures rise, the ice melts earlier and more extensively, leaving polar bears with fewer hunting grounds and reduced access to food.