In a hypothetical worst case, a Yellowstone super-eruption could spread ash across North America, disrupting power, transport, water and food supplies; sulfur dioxide aerosols could temporarily cool the climate. The scenario is not a forecast of an imminent eruption.
The article points to a massive eruption in the Yellowstone region about 631,000 years ago. Its timeline, based on volcanic research from UK scientists, starts with an unusual earthquake cluster, then adds ground uplift and changes in geysers and gas emissions. In the scenario, scientists announce an 85%–92% chance of a catastrophic eruption within three weeks; an evacuation zone extending about 62 miles beyond the park would affect roughly 200,000 residents and thousands of visitors.
In the scenario, Billings could receive feet of ash, while Salt Lake City and Boise could get inches. Airports across North America could remain closed or severely disrupted because ash can damage aircraft engines; crop and livestock losses could push food prices higher worldwide. Health systems would face pressure, and communities could still be rebuilding farms, transport and water systems years later.
