The world's largest, most active volcano system exists in the western US. 6,000 years ago, the Yellowstone Volcano erupted. Lava and pyroclastic flows covered 3,000-square miles with ash 3-feet thick. Fossils discovered as far away as Nebraska were foundto have died from inhaling the Yellowstone debris. If-or perhaps we should say when-it erupts again, the Yellowstone Mega-Volcano will create a global cataclysm beyond human comprehension. Everything within 150 miles-including the cities of Cody, Wyoming and Bozeman, Montana-will be hit by an 800-degree blast of heat and 200 miles-per-hour winds. Thousands will be killed. That's just the local effects. Half the US will be buried beneath a blanket of volcanic ash. Crops in the Midwest-the world's breadbasket-will be destroyed. And it will take years before crops can grow again. Starvation, epidemics, and social chaos won't be long in coming.