"Who would ever have believed that human beings would be stupid enough to blow themselves off the face of the Earth? [...]
The war started when people accepted the idiotic principle that peace could be maintained by arranging to defend themselves with weapons they couldn't possibly use - without committing suicide. Everybody had an atomic bomb, and counter-bombs, and counter-counter bombs. The devices outgrew us; we couldn't control them [...] Somewhere, some poor bloke probably looked at a radar screen and thought he saw something. He knew that if he hesitated one-thousands of a second his own country would be wiped off the map. So, he pushed a button - and the world went crazy [...]"

A short but important scene from the 1959 post-apocalyptic film On the Beach, by Stanley Kramer. Starring Gregory Peck, Fred Astaire, Anthony Perkins, Ava Gardner. The film is based on Nevil Shute's 1957 novel of the same name.

After a global nuclear war the whole northern hemisphere is devastated due to nuclear fallout. The only habitable areas are in the far reaches of the southern hemisphere, but air currents are slowly carrying the fallout south.