Black layers in rock to it's east show that Yellowstone erupts about every 600,000 years causing an ash fallout induced global winter. It's been 640,000 years since the last Yellowstone eruption, and the caldera is rising with higher earthquake activity. This will change most of the global climate to winter. The best place to be on earth when this super volcano blows...is in the southern hemisphere, within 10 to 20 degrees of the equator where it will remain somewhat warm and you can grow food.