Apocalypse how: Your guide to handicapping the end of the world
Method of destruction: Supervolcano
How that's going to work: A supervolcano, like the one buried beneath Yellowstone, erupts, vaporizing everything within a few hundred miles and throwing enough ash into the sky to ensure world-record levels of smog for decades, not to mention a new ice age. The lucky ones will be killed instantly Everyone else gets to hang around and fight to the death over who gets the last HEPA air purifier and space heater at Home Depot.
What it's going to look like:
(Only with a much better effects budget)
Why that probably won't happen: Actually, scientists say it's pretty likely, and they would know. Them and the Mayans, of course.
Odds: 5 to 2