CLIMATE

The Coldest Century of the Holocene

~8,200 years ago

Phanerozoic · Cenozoic · Quaternary · Holocene · Northgrippian

The largest climate wobble of the last ten thousand years: about a hundred and sixty years of cold, one to three degrees across the northern hemisphere, recorded from Greenland ice to Californian stalagmites. It came as the last great ice-dammed lakes of North America emptied into the sea, though modelling now fits the duration better if the ridge of ice over Hudson Bay collapsed as well.

Why it matters

The ten thousand years in which farming, cities and writing were invented look calm only by comparison with the ice ages. This is where that shows: a century and a half of harder winters, in the middle of the interval we treat as the stable one.

Dating & uncertainty

The cooling lasted about 160 years and reached one to three degrees across the northern hemisphere. The trigger was long taken to be the sudden emptying of two ice-dammed lakes; modelling suggests the collapse of the ice ridge over Hudson Bay fits the duration better.

Sources

1. Matero et al. (2017), Earth and Planetary Science Letters · The 8.2 ka cooling event caused by Laurentide ice saddle collapse
2. Oster et al. (2017), Scientific Reports · Climate response to the 8.2 ka event in coastal California
3. Kendall et al. (2008), Geology · The sea-level fingerprint of the 8.2 ka climate event

Earth history as one day

23:59:59.84156 ms before midnight

if Earth’s 4.54 billion years were compressed into a single day