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 much of the northern hemisphere, written in Greenland ice and, on the California coast, in a stalagmite that logged stormier, wetter winters at the same moment. 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 melt came instead from the collapse of the ice saddle linking the domes over Hudson Bay.

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 much of the northern hemisphere. The trigger was long taken to be the sudden emptying of two ice-dammed lakes; modelling suggests that the collapse of the ice saddle linking the domes over Hudson Bay accounts for 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