8.2 kiloyear event

The 8.2 kiloyear event was a sudden cold spell during the early Holocene, approximately 8,200 years ago, caused by the final catastrophic drainage of glacial Lake Agassiz into the North Atlantic. The freshwater pulse — estimated at 100,000 to 160,000 cubic kilometers — suppressed \u200bNorth Atlantic Deep Water formation, weakening the \u200bAtlantic Thermohaline Circulation and triggering a \u200bthermohaline catastrophe that cooled Greenland by roughly 3–6°C and disrupted precipitation patterns across the Northern Hemisphere for about 150 years.

The event is the best-documented example of how freshwater forcing can switch ocean circulation between stable modes. It demonstrates that the Holocene — often regarded as a period of climatic stability — was punctuated by abrupt transitions driven by the same bistable dynamics that concern contemporary climate scientists. See Younger Dryas and Paleoclimate.