The 8.2-kiloyear abrupt cooling event
- Date
- c. 6200 BCE
- Category
- Environment & climate
- Region
- Global (North Atlantic origin)
- Era
- Prehistory
- Significance
The 8.2-kiloyear event was the most pronounced abrupt climate fluctuation of the early Holocene, a sudden cooling that began around 8,200 years before present (c. 6200 BCE) and lasted roughly 150 years.
It was triggered by a massive pulse of glacial meltwater, most likely from the final collapse of the Laurentide Ice Sheet over Hudson Bay and the catastrophic drainage of the proglacial lakes Agassiz and Ojibway into the North Atlantic. This freshwater influx weakened the Atlantic Meridional Overturning Circulation by more than half, disrupting the transport of heat to higher latitudes and producing temperature drops of roughly 1 to 5 degrees Celsius, including a fall of about 3.3 degrees in Greenland recorded in the GISP2 ice core. The cooling was accompanied by widespread aridification across the Northern Hemisphere, weakened Asian and African monsoons, and a permanent rise in global sea level of several metres. Evidence preserved in ice cores and speleothems from Eurasia, the Mediterranean, South America, and southern Africa shows the event was globally synchronous, and it coincided with demographic disruption among Mesolithic and early Neolithic communities, including aridification in the Near East that may have spurred Mesopotamian irrigation agriculture.
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Related environment & climate events
- The Pleistocene–Holocene boundary and the start of the Holocenec. 11,700 years ago (c. 9700 BCE)
- End of the African Humid Period and Desertification of the Saharac. 3500–2700 BCE
- Late Pleistocene megafaunal extinctions and the overkill-vs-climate debatec. 15,000 – 10,000 years ago
- The Last Glacial Maximum and human refugiac. 26,500 – 19,000 years ago
- The Toba super-eruption and the disputed 'volcanic winter'c. 74,000 years ago
- The Younger Dryas cold reversalc. 12,900 – 11,700 years ago
Further reading
The wider story
A New Green History of the World
The classic accessible account of how environment and climate have shaped human history.
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