In its 4.5 billion-year history, life on Earth has been almost erased at least half a dozen times: shattered by asteroid impacts, entombed in ice, smothered by methane, and torn apart by unfathomably powerful megavolcanoes. And we know that another global disaster is eventually headed our way. Can we survive it? How? As a species, Homo sapiens is at a crossroads. Study of our planet’s turbu...