The largest carnivore on land roams the icy north. Polar bears like this one spend much of their lives on sea ice rather than terra firma, stalking their favorite prey: seals. Superbly insulated against the cold, polar bears are uniquely suited for life on the ice—so they"re especially vulnerable to a warming planet. Their plight is the focus of Polar Bear Week, observed the first week of every November, bringing attention to these creatures who live far out of sight of most humans.