Did you know that in the century and a half after Christopher Columbus set foot in the New World in 1492, the invasion of the Spanish Conquistadors resulted in the deaths from all causes (i.e., introduction of smallpox and other diseases, mass slaughter, infrastructure collapse, etc.) of approximately 90% of the New World’s inhabitants by 1650? Those numbers do not include the genocide of the native Americans that occurred later. Quite a humanitarian historical legacy. The invasion was also an indirect contributor to the Little Ice Age.
A new study by researchers at University College London (UCL) published in the December 2018 Quaternary Science Reviews argues that the depopulation of the New World by the Spanish invasion partially caused the Little Ice Age. This story was reported in the Guardian newspaper in the UK on January 31, 2019, and subsequently picked up and reported by Mother Jones magazine.
Effectively, the mass depopulation of the western hemisphere set off a local chain reaction as these societies were primarily agrarian. The massive de-population resulted in less land being managed by the surviving populations. The UCL study indicated a land area approximately the size of France was left untended. As a result, vegetation over-grew the now untended, unmanaged land. (This is not dissimilar to what we see when land is abandoned today. Think of an empty lot in your neighborhood or a suburban lawn that has gone untended.) As a result, more carbon dioxide was pulled from the atmosphere by the increased vegetation and replaced with oxygen. (Photosynthesis is the process by which plants use sunlight to make food from carbon dioxide and water and release oxygen as waste.) The more plants, the less carbon dioxide in the air. Plants use carbon dioxide in the photosynthetic process. The less carbon dioxide in the air, the cooler the temperatures. Remember, carbon dioxide is a greenhouse gas. It traps heat. When carbon dioxide levels fall, temperatures fall. When carbon dioxide levels in the atmosphere rise, temperatures rise. This is the greenhouse effect. It is why scientists around the world are concerned with, and monitoring, the rise in the levels of greenhouse gases (like carbon dioxide and methane) in the atmosphere. Think for a moment about the implications of a tragic reduction in the area of the Amazon rain-forest and what it would mean for photosynthetic activity.
According to the Study, the drop in average temperatures (0.15 C) partially caused a man-made major climate event – the Little Ice Age (16th – 19th centuries). Per Wikipedia, the Intergovernmental Panel on Climate Change Third Assessment Report suggested that it consisted of regional events rather than a universal global one. It wasn’t a true Ice Age with mile high glacier movement but rather a significant extended cold period.
The Americas’ event was preceded by the Black Death in Eurasia, which wiped out between 75 to 200 million people in the middle of the 14th century. It is estimated to have resulted in the deaths of 30-60% of the population in Europe. As a result, it is possible that vegetative overgrowth similar to the the Americas could also have occurred in the prior century.
Regardless, the new Study is likely to be debated in more scholarly venues than this blog posting.
“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. They estimate that the Conquistadors’ were directly or indirectly responsible for the death of approximately 55 million human beings. Quite probably, the worst holocaust in history, and relatively unknown and/or ignored. Disgraceful.
I am reminded of the famous quote from George Santayana: “Those who do not remember the past are condemned to repeat it.”