CLIMATE

The Cold Snap in the Middle of the Thaw

~12,900 to 11,700 years ago

Phanerozoic · Cenozoic · Quaternary · Pleistocene · Late Pleistocene

Two thousand years into the warming that ended the last ice age, the North Atlantic went back to near-glacial cold within decades and stayed there for more than a thousand years. Then it warmed again just as abruptly. Greenland ice cores date both turns to within a decade, which is why this is the best-dated climate reversal in the record.

Why it matters

Here is the proof that climate can turn over inside one human lifetime, and it did so while people were already settling into the first villages. The usual explanation is a flood of meltwater shutting down the North Atlantic circulation, but which route the water took, and whether there was enough of it, is still argued.

Dating & uncertainty

The event itself is dated to the decade in ice cores. Its cause is not settled: a flood of meltwater is the standard explanation, but by which route, and whether the flood was large enough, is still argued.

Sources

1. Bakke et al. (2009), Nature Geoscience · Rapid oceanic and atmospheric changes during the Younger Dryas cold period
2. Condron & Winsor (2012), PNAS · Meltwater routing and the Younger Dryas
3. Keigwin et al. (2018), Nature Geoscience · Deglacial floods in the Beaufort Sea preceded Younger Dryas cooling

Earth history as one day

23:59:59.75245 ms before midnight

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