There's a variety of reasons people cite, from nuclear war to the second coming of Jesus, to whatever the Mayans had in mind.
The U.S. had among the highest doomsayers, with around 22%, while Western Europeans seemed to have the lowest. Younger, less educated, and poorer people had overall less optimistic views about the world's chances.
I know there are plenty of crazy conspiracy theorists out there, and plenty of reasons to be concerned about a global war escalating to mutually assured destruction. Still, it surprises me that that many people genuinely think the world as we know it won't make it through our lifetimes.
Do you think doom is impending? Will it be in 2012, or sometime in the coming decades? What do you think the cause will be?