Colonization of the Americas killed so many people that Earth cooled down when abandoned land became overgrown and sucked carbon dioxide from the atmosphere

Researchers estimate the arrival of Europeans in 1492 caused roughly 56 million deaths by the year 1600 due to disease, conflict, and slavery.

Mass deaths, in turn, resulted in the reforestation of landscapes that were left abandoned.

As swathes of agricultural land became overgrown, the new trees and foliage absorbed higher levels of carbon dioxide from the atmosphere, sparking what’s now casually referred to as a ‘little Ice Age’.