When they arrived in the Americas centuries ago, European colonists brought pestilence and death. Their arrival was so devastating, in fact, that it may have contributed to a period of global cooling, a study said.
The research, to be published in the March issue of the journal Quaternary Science Reviews, represents an ambitious attempt to show that, through a series of events, human activity was affecting the climate long before the industrial revolution and global warming.
The authors found that disease and war wiped out 90 percent of the indigenous population in the Americas, or about 55 million people, between the time Christopher Columbus arrived in the Bahamas in 1492 to 1600. The earth, they argue, then reclaimed the land that these populations left behind. In that era, carbon stored on land increased and carbon dioxide in the air decreased, supporting the hypothesis that colonization may have been to blame for contributing to what scientists refer to as the “Little Ice Age.”
“It was a drastic change in the Earth’s system,” said Alexander Koch, a Ph.D. candidate at the University College London Department of Geography.
Still, the effect that the authors describe pales compared to the toll modern humanity has taken — in the opposite direction. While the cascading effects of colonization reduced atmospheric carbon dioxide by about 3.5 parts per million over more than a century, atmospheric carbon dioxide today is increasing at a rate of about 2.3 parts per million each year.