A zombie apocalypse on the other hand, you'd have plenty of stable buildings to seek shelter in and to hunt for food and supplies. Zombies are pretty slow and easy to avoid (I don't consider the "fast" zombies in 28 Days Later to be zombies at all), and sure if you get bitten you'll be infected and doomed. But if you quickly amputate the infected area you should be OK, and you could always just wear protective clothing like thick leather jackets to make it less easy for zombies to bite you.
A real life zombie apocalypse is damn near impossible to take place. First off, the second it's discovered, everything around the thing would be quarantined. They can't spread their disease without biting anyway, so cutting them off from society is really easy.
Second, since they are basically already rotting dead meat, weather would be very harsh on them. Heat can actually cause them to explode, and cold would cause them to freeze in place. Meaning LA would probably be the only place on Earth zombies could ever exist.
Another point is, they can't heal themselves, ever. So if they're damaged slightly, they're not going to recover from it. Even if you shoot one of them in the leg, they're pretty much useless as they can no longer move, and thus no longer cause damage or spread the infection.
Unless there's some sort of airborne virus that is spread across an entire city, but then again, they could simply quarantine a city. They've been known to do crazy stuff like that, whoever "they" are..
Nuclear apocalypse is also pretty survivable if you're in the right place. Say you live on a country that's a remote island. Like Cuba or Hawaii. Unless you're directly targeted, you'll live. Sure, things will be tough as you won't have the outside support, and exports, and economy would suffer, but atleast you'd be alive. A majority of the world would not be targeted, as no ones going to waste a nuke on a neutral country. Out of the ashes, it's pretty easy for humanity to come back. Plus, there isn't any ridiculous stuff in real life like Super Mutants or anything.
We have absolutely nothing to worry about. Except for local dangers like rapists, murderers, and thieves. :cryvaultboy: