WolfishMusings: There is always the danger of a nuclear weapon being used (again). There is also a danger of an epidemic that will destroy civilization. There is also the danger of an asteroid hitting Earth or the Sun going Nova. There is also the danger of Earth being visited by hungry aliens who think we are non-sentient but with a good taste.
Science Fiction is an interesting genre, but you should realize that it is fiction. If you are really worried about the end of the world, stop posting on YWN and concentrate on spending your minutes on Torah and Mitsvos.