The Stern Review, the U.K. government’s premier report on the economics of climate change, estimated a 0.1 percent risk of human extinction every year. That may sound low, but it also adds up when extrapolated to century-scale. The Global Challenges Foundation estimates a 9.5 percent chance of human extinction within the next hundred years.

And that number probably underestimates the risk of dying in any global cataclysm. The Stern Review, whose math suggests the 9.5-percent number, only calculated the danger of species-wide extinction. The Global Challenges Foundation’s report is concerned with all events that would wipe out more than 10 percent of Earth’s human population.

“We don’t expect any of the events that we describe to happen in any 10-year period. They might—but, on balance, they probably won’t,” Sebastian Farquhar, the director of the Global Priorities Project, told me. “But there’s lots of events that we think are unlikely that we still prepare for.”

So you're saying there's a 90.5 percent chance humans WON'T go extinct in the next 100 years?

That 9.5% doesn't alarm you?

It should but it doesn't because of that 90.5% chance of survival.