Why Does Earth Freeze at All — And What Happens to Life Every Time It Does?

Seven hundred million years ago, Earth froze from pole to equator. Twice. The ocean was covered in ice a kilometer thick. Life survived — barely — and when the planet thawed, multicellular life exploded into existence within geological seconds. This episode covers the full story of ice on Earth: from Snowball Earth to the Pleistocene glacial cycles that created human intelligence, to the Last Glacial Maximum world of mammoths and three-kilometer ice sheets over Manhattan, to the most extraordinary fact in this entire story — that the species the ice ages created has now, in two centuries of industrial activity, altered the orbital pacing of glacial cycles that governed this planet for two and a half million years. We cancelled the next ice age. The geological record is unambiguous about what that means. SUBSCRIBE    / @chroniclesplanetearth   for deep science told from four billion years of evidence.