European colonization of the Americas resulted in the killing of so many native people that it transformed the environment and caused the Earth’s climate to cool down, new research has found.
Settlers killed off huge numbers of people in conflicts and also by spreading disease, which reduced the indigenous population by 90% in the century following Christopher Columbus’s initial journey to the Americas and Caribbean in 1492.
This “large-scale depopulation” resulted in vast tracts of agricultural land being left untended, researchers say, allowing the land to become overgrown with trees and other new vegetation.
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The regrowth soaked up enough carbon dioxide from the atmosphere to actually cool the planet, with the average temperature dropping by 0.15C in the late 1500s and early 1600s, the study by scientists at University College London found.
“The great dying of the indigenous peoples of the Americas resulted in a human-driven global impact on the Earth system in the two centuries prior to the Industrial Revolution,” wrote the UCL team of Alexander Koch, Chris Brierley, Mark Maslin and Simon Lewis.
The drop in temperature during this period is known as the “Little Ice Age”, a time when the River Thames in London would regularly freeze over, snowstorms were common in Portugal and disrupted agriculture caused famines in several European countries.