Yes, at least five that we know of, which is why there is debate whether the current global warming/changing weather patterns is caused by mankind or just a naturally occurring event that occurs once in awhile. Either way, global warming is something not to be dismissed regardless of what is causing it. A new ice age would be devastating to humans. I doubt we would go extinct, but many people would die.
But how would we survive? Dome cities? Going underground?
We survived the most recent one... ---
Muscles Chicago Bears | Chicago Blackhawks | Chicago Bulls | Chicago Cubs | NIU Huskies