All scenarios / Earth systems
Supervolcano
Yellowstone's geysers are a very elaborate countdown.
What it is
A supervolcano eruption ejects more than 1,000 cubic kilometers of material. That's enough ash and sulfur to cool the global climate for years and devastate harvests. Yellowstone is the most famous example, but there are others, such as Toba in Indonesia and Campi Flegrei in Italy.
Why it ranks where it does
The USGS puts the annual probability of a caldera-forming eruption at Yellowstone at about 1 in 730,000. It says only about 5–15% of the magma chamber is molten, and that Yellowstone isn't "overdue", because volcanoes don't erupt on a schedule. Our score adds a small live bump from USGS earthquake data, but ordinary quakes are normal and don't signal an eruption.
Evidence on the board
- Live: USGS M4.5+ earthquakes this week. Super‑eruptions happen roughly every 100,000 years. USGS ↗
What the experts say
Toby Ord estimates the existential risk from supervolcanoes at about 1 in 10,000 per century, about 100 times his figure for asteroids. Super-eruptions are rare, but we currently can't deflect one the way we can deflect an asteroid.
Could we survive it?
The best-studied example is the Toba super-eruption in Sumatra about 74,000 years ago. Researchers once argued that it pushed early humans to the brink, but newer archaeological evidence from India and Africa suggests that people in many regions came through it fairly well. A modern super-eruption would bury nearby regions in ash and could cause several years of failed harvests worldwide, which makes food stockpiles and global trade the key defenses. It would be a catastrophe, but most researchers don't expect it to cause human extinction.
What would move the number
Up
- Sustained ground uplift and gas changes at a known caldera
- USGS raising its alert level
Down
- Continued normal monitoring readings
Live signals we track
The baseline above is set from the evidence as of October 13, 2026. On the live board, your browser adjusts it in real time using these feeds. Chatter can only nudge a score in proportion to its evidence, so attention alone can't make an unlikely scenario look likely.
- Public attention: daily Wikipedia pageviews for Yellowstone Caldera
- Public attention: daily Wikipedia pageviews for Supervolcano
- Online chatter: Hacker News stories mentioning "supervolcano" this week vs. the prior eight weeks
- Physical sensor: USGS M4.5+ earthquakes, past week
Sources
- USGS: Questions about supervolcanoes
https://www.usgs.gov/volcanoes/yellowstone/questions-about-supervolcanoes - USGS: Is Yellowstone overdue for an eruption?
https://www.usgs.gov/faqs/yellowstone-overdue-eruption-when-will-yellowstone-erupt - 80,000 Hours: Toby Ord's existential risk estimates
https://80000hours.org/articles/existential-risks/ - USGS
https://www.usgs.gov/volcanoes/yellowstone
Baseline scores are an editorial threat index from 0 to 100 that combines current reporting with published expert estimates. They're meant for comparing risks, not as actuarial forecasts. See how the numbers work.