That anthropocentric theory was presented a few days ago at the annual meeting of the Geological Society of America:
By sailing to the New World, Christopher Columbus and the other explorers who followed may have set off a chain of events that cooled Europe’s climate for centuries.
The European conquest of the Americas decimated the people living there, leaving large areas of cleared land untended. Trees that filled in this territory pulled billions of tons of carbon dioxide from the atmosphere, diminishing the heat-trapping capacity of the atmosphere and cooling climate, says Richard Nevle, a geochemist at Stanford University. …
Tying together many different lines of evidence, Nevle estimated how much carbon all those new trees would have consumed. He says it was enough to account for most or all of the sudden drop in atmospheric carbon dioxide recorded in Antarctic ice during the 16th and 17th centuries. This depletion of a key greenhouse gas, in turn, may have kicked off Europe’s so-called Little Ice Age, centuries of cooler temperatures that followed the Middle Ages.
This is all about global warming, of course. One of the fundamental problems with global warming alarmism is that the Earth’s climate has constantly been changing for many millennia, often far more dramatically than anything we have witnessed recently, and generally for reasons that can’t possibly be associated with carbon dioxide. So if Columbus caused the Little Ice Age, it perhaps supports the plausibility of humans being responsible for the current mild changes in the climate.
Ken Haapala, Executive Vice President, Science and Environmental Policy Project, is skeptical of the Columbus theory:
According to Michael Mann, cited in the article, the Little Ice Age did not exist. Although not uniform throughout the world, significant research indicates the Little Ice Age may have started about 200 years before Columbus sailed; thus, the causal relationship is somewhat difficult to establish.