It’s one of the most dramatic examples of climate change in Earth’s history, and scientists now say it happened almost entirely in one year’s time. 

A drastic cooling of the climate in western Europe happened exactly 12,679 years ago, scientists said, giving a hint of how abruptly the climate can change. The study, of pollens, minerals and other matter deposited in annual layers at the bottom of Lake Meerfelder Maar in Germany, pinpointed an abrupt change in sediments consistent with a sudden chill over just one year.

“Our data indicate an abrupt increase in storminess during the autumn to spring seasons, occurring from one year to the next at 12,679 years before the present,” they wrote in the journal Nature Geoscience.