I thought of something today at work, well, it's something I had kinda thought about before, but...
The setting is in our future, but not too far, like the 22nd century. The planet has been devastated by a global war, the "Terran War", but all that is remembered about the conflict is that it was West vs. East. The thing about that though is that the magnetic poles had already flipped themselves back in 2012, so it's your guess as to the combatants. The only thing known for sure is that our current inhabited world was irradiated, the ice caps melted, and the only livable area left was Antarctica. The survivors eventually gathered there and started a new culture. What's interesting is that after the ice covering on Antarctica had melted, it revealed the remnants of an advanced race that had lived there millions of years ago. They had some pretty advanced technology, some of which remains, but they were definitely not human. Oh and by this time there is a colony on Mars that could house about 20,000 people, but they haven't been heard from since the war.