On the Beach (movie, 2000)

The world has finally managed to blow itself up and only Australia has been spared from nuclear destruction and a gigantic wave of radiation is floating in on the breezes. One American sub located in the Pacific has survived and is met with disdain by the Australians. The calculations of Australia's most renowned scientist says the country is doomed. However, one of his rivals says that he is wrong. He believes that a 1000 people can be relocated to the northern hemisphere, where his assumptions indicate the radiation levels may be lower. The American Captain is asked to take a mission to the north to determine which scientist is right.