Twelve thousand eight hundred years ago, something slammed Earth’s climate to a halt, yet almost no one agrees on what caused it. Ice sheets that had been melting suddenly re-froze, plunging the planet back into near-glacial conditions for over a millennium.
About 12,800 years ago, near the end of the last ice age, a sudden cooling event interrupted a period of global warming. The temperature in Greenland fell by roughly 10 degrees Celsius, and cold conditions lasted for about 1,200 years before warming resumed. This period is known as the Younger Dryas, named after an Arctic wildflower whose pollen appears in lake sediments at the time of the cooling…