I'm not sure how many of you seen the Preview over the TV for the History's channels tv series Life After People.
http://www.history.com/content/life_after_people/videos
Watching all those video's got me thinking, how many of those disasters were more likely then the others? Since I have a lack of faith in humanity as a whole I'd have to say a Nuclear Winter. Or Possibly some type of plague.
Note that if you don't want the show ruined then you probably shouldn't watch the little clips they give. But I think it's a show worth watching.
Discuss what you think is more possible to destroy human life? It could be something the show gives, or something else entirely.