What event or combination of events could bring about the fall of civilization?

I’m not talking about the end of human life, but the end of human civilization or society as we know it.

I can think of two single events that could do this, one would be a comet strike, and the other would be a Yellowstone eruption.

A comet strike that would be the equivalent of a super volcano [caldera] eruption could lead to a end of civilization as we know it. It depends on where it hits. If it strikes Earth in the Atlantic Ocean so many coastal cities would be destroyed that I think the world would not be able to cope with its effects.

A Yellowstone Eruption I believe would result in worldwide food shortages because of the effects on the American Midwest bread basket, and other longer term effects from global weather patterns as a direct result of such an eruption, would cause society to collapse within six months to a year from such an event.

Do you think we will see something like this happen?

Sorry mods I meant to post in skunk works



[edit on 26-11-2007 by LDragonFire]

reply to post by LDragonFire


Two more:
Nasty virus/plague
Nuclear War