Well, I really don't think that a nuclear weapon would be able to destroy a world-ending asteroid. They are simply too weak for that to be actually feasible. But I really like the idea of the world coming together and using its nuclear arsenal to accomplish something that is actually good, for a change.Of course that world without nuclear bombs would be a better place because sooner or later someone will use them and even the testing is not very environment friendly. I guess people are paranoid and even if they agree to this everyone would have some back up underground nuclear head. Another thing that crossed my mind is that if an asteroid would come to collide with earth we would be in need for a bomb of that power to try to destroy it. I am aware that nothing will prevent our stupidity to get to the world's end but it is a good idea and a start.