12,900 YEARS AGO, THE ICE AGE CAME BACK IN ONE LIFETIME

About 12,900 years ago the world was finally thawing out of the Ice Age. Then, within a single human lifetime, it fell back into near-glacial cold that lasted around 1,200 years. This is the story of the Younger Dryas: what the Greenland ice records, what the hunters of that time faced, and why scientists still argue over what flipped the switch. Annual layers in Greenland ice and in the mud of a small German crater lake let scientists read this event almost year by year. In one of those records, Europe's winds changed from one year to the next. In central Greenland, the sudden temperature swings of that era reached roughly 9 to 14 °C. We meet the people who lived through it: reindeer hunters in a valley near Hamburg who left behind the oldest arrows ever found, and their bones of 650 reindeer; Clovis hunters in North America and the mysterious black layer that lies over the last mammoths; and early villagers along the Euphrates who had to decide whether to stay or move on. Then we go through the suspects one at a time. A comet, backed by a giant crater under the Greenland ice. A volcano in Germany as big as Pinatubo. And a glacial lake that, at its largest, was bigger than all the Great Lakes combined. You'll see what the newest dating, from tree rings to zircon crystals to seafloor mud, says about each of them. And one question carries through to the very end: why do geologists around the world care so much about one exact depth in a cylinder of ice kept in a freezer in Copenhagen? 00:00 A strange number in Greenland's ice 02:40 The warm world before the cold 06:35 The year the wind changed 12:50 Reindeer hunters and the oldest arrows 16:30 The black mat over the last mammoths 19:05 Suspect one: a comet from the sky 25:20 A crater under the ice and a volcano with an alibi 31:25 Suspect three: a giant lake and the ocean conveyor 37:25 Villages in the cold: did it lead to farming? 42:55 How the cold ended, and the answer in the ice #YoungerDryas #IceAge #EarthHistory