A paleoclimatologist, Professor Jack Hall, discovers that due to global warming, the polar ice caps are melting, which is lowering ocean temperatures. This triggers a massive climate shift which causes many natural disasters and eventually a new ice age. Too late everyone realizes this, and as they try to evacuate to the warmer south, for half of the northern USA, and Canada, it's already too cold to go outside. Meanwhile, Jack's son, Sam, is in Manhattan on a trip with some friends. Jack heads north to try and rescue his son, but the cold is a powerful adversary.