In school you may have read about the “Little Ice Age” that occurred in Medieval times and caused very cold temperatures in Europe. Now a group of scientists at University College in London England are advancing a theory that it was not volcanic activity or cyclical decreases in solar radiation that caused this cooling, but the impact of European colonization of America.
Researchers estimated from population data that 60 million people were living in the Americas at the end of the 15th century, representing a tenth of the world population. Within one hundred years of first European contact, that population “was ravaged by introduced disease (smallpox, measles, etc), warfare, slavery and societal collapse.”
First Nations were devastated, with an estimate of five to six million people remaining after the first century post European contact. Such a calamitous reduction in civilizations meant that land that was cultivated by First Nations was abandoned, and “repossessed” by the forest and bushland. The size of that cultivated land reclaimed by nature is estimated to have been 56 million hectares, “close in size to a modern country like France”.
The rewilding of these indigenous agricultural lands by trees and other vegetation “pulled down enough carbon dioxide (CO2) from the atmosphere to eventually chill the planet.”
“The Great Dying of the Indigenous Peoples of the Americas led to the abandonment of enough cleared land that the resulting terrestrial carbon uptake had a detectable impact on both atmospheric CO₂ and global surface air temperatures,” Alexander Koch and colleagues write in their paper published in Quaternary Science Reviews.
This suggests that human activities “affected the climate well before the industrial revolution began”. The study also indicates that using tree planting to take carbon dioxide out of the atmosphere has to be done on a grand scale~estimates from this research indicates that the huge reforestation resulted in a change of only 7 to 10 ppm, equivalent to two years of automobile emissions.
The term “Anthropocene” is being used to describe the epoch of humanity’s ecological impact on the earth. This study suggests that the label may need to also apply to the Great Dying in the Americas five hundred years ago.
You can read the full paper on this research here.
Images: Timetoast.com & learnQuebec.ca