29. The Impact of the Mongol Invasions
In a nutshell, Genghis Khan’s Mongol conquests cooled Earth because so many people were killed that it resulted in reforestation. As the author of the study that examined, that put it: “It’s a common misconception that the human impact on climate began with the large-scale burning of coal and oil in the industrial era … Actually, humans started to influence the environment thousands of years ago by changing the vegetation cover of the Earth‘s landscapes when we cleared forests for agriculture”.
The Mongol invasions that swept across Asia, the Middle East, Russia, and Central Europe killed an estimated 40 million people. That was in a world whose population was about a twentieth of the one we live in today. If extrapolated to modern population figures, it would be the equivalent of more than four times the deaths of World War I and World War II combined. That massive body count meant there were significantly fewer people to engage in activities that emitted carbon. Most significantly, many regions were depopulated, and vast swathes of what had once been cleared and cultivated fields reverted to forests, whose trees and vegetation absorbed carbon dioxide from the atmosphere.