Do you remember the Mount Saint Helens eruption in 1980? That shut down the Pacific NorthWest for 7-10 days, remember it well. These things HAPPEN, the question is the RATE, how MUCH volcanic dust is injected into the stratosphere for it to subsequently settle out over the ensuing 3-4 years. Do you remember the golden/yellow hue of the atmosphere after the Mount Pinatubo eruption?
Yellowstone is showing all the signs of an eruption with the increased activity and rising land/earthquakes. All it takes is a crack from the surface to the pluton magma chamber 5 miles down....is this the "wormwood" mentioned in the book of revelation, and the subsequent three and a half years of nuclear winter darkness that follows.
On the one hand is the "it never happens to ME" crowd and on the other hand is may 1980...
Toba(tuba) was 6,000 times bigger.
I'm not saying that the Yellowstone supervolcano will not explode again, I'm just saying that it may not be quite as bad as the last one was, because of the supposed movement of the magma chamber. Even an eruption 1/4th the size of the previous one would put a lot of people in a world of hurt for a long time!