Genetic detectives figure the human gene pool was very tiny 75000 thousand years ago. Something horrible nearly made mankind extinct. A supervolcano like the one at Yellowstone erupted at about that time period. Thanks to a handful of people, both private and government, that have special places set aside for nuclear war I don't think extinction will happen this time, but the next eruption event at Yellowstone is already due by noting it past history of eruptions. The last time it went off Kansas was covered by ash at least 10 feet thick.
We now have both. It will be a little tough for a year or two. But we'll be okay.
By the way, the last time Yellowstone blew, the ash only cover everything west of the Mississippi in the U.S. If your east of the Smokey Mountain, you'll probably be okay.
It will not be the end of the world, it will just be a very bad day for anyone caught in the blast.
That was TOBA (click the link and read, they say less than 1,000 humans survived.)