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.

nn_3c13b502505985Images:  Timetoast.com & learnQuebec.ca


  1. If this theory is true then it must be pretty warm in Canada now with over 35M folks here now ..

    Where are the carbon credit due Canada as we are a carbon sink due to VAST FORESTS, one of the if not the highest number of trees per capita anywhere in the world ?

    Clearly deforestation is a huge issue .. in EU, North America and esp Asia and S-America ..

    1. I’m not certain about Canada’s forests but BC’s forests are not a carbon sink. They’ve been emitting more carbon than they’ve been sequestering in recent years. That seems likely to get worse as our summers get hotter and dryer and our forests burn harder and faster. A feedback loop that climate scientists have been warning us about for decades.

      Your sudden acknowledgement of the carbon problem is heartening. But nature doesn’t care what Christie Clark wants you to believe.

    2. Your ipso is missing a few factos. Like the fact that Canadians are among the biggest carbon emitters on the planet. By what metric do we get to lay claim to the carbon sink benefits of trees we didn’t plant, nurture, or plan for? Are we as willing to add volcanic emissions to our per capita output then? Does Mt. St. Helens count against my lifetime total, or are we restricting emissions and telling them to stay on the US side of the 49th?

      I didn’t think so.

      1. How much km of biking to offset one volcano eruption of Mount St. Helen’s (or Hawaii’s venting at the moment) size ?

        As always, the hype is OFF THE CHARTS .. for example oceans’ alleged “massive” rise flooding coastlines and devastating cities and condos developments in FL and New York .. who not google

        judith curry ocean rise

        to see that it maybe a meter (or 3 feet) .. likely far less in the next 100 years !!

        1. https://www.scientificamerican.com/article/how-do-volcanoes-affect-w/

          “There is no doubt that volcanic eruptions add CO2 to the atmosphere, but compared to the quantity produced by human activities, their impact is virtually trivial: volcanic eruptions produce about 110 million tons of CO2 each year, whereas human activities contribute almost 10,000 times that quantity.”


          “The eruptions considered to be large enough to affect the Earth’s climate on a scale of more than 1 year are the ones that inject over 100,000 tons of SO2 into the stratosphere.[67] This is due to the optical properties of SO2 and sulfate aerosols, which strongly absorb or scatter solar radiation, creating a global layer of sulfuric acid haze.[68] On average, such eruptions occur several times per century, and cause cooling (by partially blocking the transmission of solar radiation to the Earth’s surface) for a period of several years.”

          Seems to me, Thomas, that we’ve seen flooding coastlines and devastation in New York and New Orleans among other places *without* 3 feet of sea level rise, due to more intense hurricanes which will only get more intense.

          Many conservatives are unable to understand the severity of what is barreling at us with intense slow motion because it is not in their nature. Conservatism is all about holding humanity back by pining for the good old days. We’d have never left the trees. We’d never have figured out agriculture or electronics or flight. You’re not one of those are you?

          Thankfully there are progressives who progress. Don’t get left behind.

        2. “How much km of biking to offset one volcano eruption of Mount St. Helen’s (or Hawaii’s venting at the moment) size ?”

          You’ve managed to utterly miss the point yet again. I repeat– if we claim the unearned carbon benefits of trees as a counter to our emissions, why aren’t you including natural sources of emissions on the other side of your GHG bookkeeping?

          You’ve gone from denying climate change exists, to minimizing its impacts, to misrepresenting the speed of recent change. All this with nothing to indicate any expertise or basic research to understand the topic, save linking to questionable sources, often with clear ‘follow-the-money’ biases at play.

          Nothing would better serve the readers of Price Tags quite so well on this topic as you typing less and reading more Mr Beyer. Free advice. Worth every penny.

Leave a Reply

Your email address will not be published. Required fields are marked *