The Younger Dryas
The ice age returns for 1,200 years — then ends within a decade
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The leading explanation is that meltwater from the Laurentide ice sheet, pooled in the vast glacial Lake Agassiz, broke through and flooded into the North Atlantic. The fresh water weakened the thermohaline circulation that carries heat northward. Greenland ice cores show 10 degrees of warming within a few years at its close — the fastest climate change directly recorded in any archive. The event matters for two reasons: it demonstrates that the climate system has tipping points with abrupt transitions, and it coincides with the Natufians of the Levant beginning to cultivate grain.
For children
The ice had begun to melt and the world was warming. Then, abruptly, it turned cold again — almost as cold as during the ice age — and stayed that way for twelve hundred years. When it flipped back, it did so in under ten years. Greenland's ice cores record every single year.
Connects to
Part of Terra Saga — the story of Earth on a timeline. terrasaga.org