From the beginning of the 16th century until the 19th century, the earth was unusually cool. This time is also called the Little Ice Age. Until now, natural causes were assumed for the Little Ice Age as well as for the warm weather period of the 12th century. Now it looks like this cooling was at least partly man-made.
Researchers at University College London claim the fluctuation is linked to CO2 levels in the air. Just as increasing CO2 levels heat up the atmosphere today, back then a decrease in carbon dioxide would have led to cooling.
Today, CO2 is increasing because we burn fossil fuels on a large scale; back then, the bound biomass increased massively. The nitrogen in the air migrated into plants.
And they have found a terrible explanation for the reduction in CO2 levels in the atmosphere. The aphorism comes from Lichtenberg: “The American who first discovered Columbus made a nasty discovery.” In fact, within a short period of time, Europeans wiped out most of the indigenous Americans. Through direct violence, through introduced diseases and because the Indians could not tolerate the slave labor that the new masters forced them to do,
A team of scientists now says that European colonization caused a huge swath of Native American agricultural land to simply disappear and be covered by fast-growing trees. “The great extinction of the indigenous peoples of the Americas led to the abandonment of so much land that the resulting uptake of terrestrial carbon had a noticeable impact on the atmosphere and global surface temperatures,” writes Alexander Koch in the study, published in “Quaternary Science Reviews ” was published.
To arrive at this thesis, the scientists first tried to determine population numbers. Accordingly, at the end of the 15th century, around 10 percent of the world’s population at the time lived in the whole of America, that is, 60 million people. A hundred years later, five to six million remained. Co-author Professor Mark Maslin says the actual cooling was about twice as great as if it were caused by natural processes alone. “To get cooling on that scale, you need that genocide-generated increase in CO2.”
In addition to remembering the genocide, the study has another not very hopeful implication. If you convert the increase in biomass back then, for which the area of France was converted into jungle, into today’s combustion rates of fossil fuels, it corresponds to the global CO emissions of a little more than two years.
This means that reforestation projects are important for the local climate. They will not be able to stop climate change caused by CO2 emissions. That much area is not available to produce biomass on this scale.
Quellen: Quaternary Science Reviews
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