Obviously there are some events that could set back civilization, or even wipe out the human race. A comet striking the earth for example might wipe us out. A huge eruption such as Yellowstone could set us back quite a ways. I’m guessing another glacial ice advance would cause a huge disruption. And combined with the natural events would be the wars that would ensue to fight for the remaining resources.
My bet is on rapid global cooling. (Technically we are still in “the ice age”, and have experienced the longest warm period ever recorded in the glacial ice record.)
It is amazing how ignorant people are of past climate changes and the fact that we are still in a 2 million year old ice age.
A comet striking the earth for example might wipe us out.
—
Last time a comet struck Earth, it was not a single event, but an event that lasted over 100 years and burned off 10% of the Earth’s vegetation ; and we still survived.