Nuclear war. Climate change. Pandemics that kill tens of millions. These are the most viable threats to globally organized civilization. They’re the stuff of nightmares and blockbusters-but unlike sea monsters or zombie viruses, they’re real, part of the calculus that political leaders consider everyday. And according to a new report from the U.K.-based Global Challenges Foundation, they’re much more likely than we might think. In its annual report on “global catastrophic risk,” the nonprofit debuted a startling statistic: Across the span of their lives, the average American is more than five times likelier to die during a human-extinction event than in a car crash. Partly that’s because the