Perhaps we have a war. The bombs of the day don't emit radiation of any sort. They just emit heat. Of course, we've developed bunkers designed to withstand ginormous amounts of heat. So.... we're all underground while the bombs go off... We come up, and AAAAA WTF?!?? We're fucked now, because the bunkers can't withstand cold, and they're not waterproof.

What is it they say about silence being golden?