Manmade climate change is not only a thing of the last hundred years, according to new research from scientists at the Ecole Polytechnique Federale de Lausanne (EPFL). The Roman Conquest, expansion of civilization in China, the Black Death, and the discovery of America, amongst other historical landmarks, have all had large impacts on the climate.
“Humans didn’t wait for the industrial revolution to provoke environment and climate change. They have been having an influence for at least 8000 years,” said Jed Kaplan, a Swiss National Science Foundation professor at EPFL, who along with his colleague Kristen Krumhardt, have developed a computer model that reveals an obvious linkage between population increase and deforestation.
For the first time, this model provides scientists with an accurate idea of human impact on the environment, not just into the future, but well back in time as well.
As a civilization, humanity needs food, and early on the only source of food came from farms. Techniques were rudimentary and any advance was years away, so as a result, “for each individual,” it was necessary to clear a very large area of forest,” explains Kaplan, to have enough farmland to feed everyone.
As time went by, we did reinvent our techniques, implementing irrigation, developing better tools, designing better seeds, and using more effective and environmentally friendly fertilizer. These improvements were a critical factor in the history of our environment, as with the improvements came a way to counterbalance the blooming population and minimize – and in some areas counteract – the pressure that population growth put on the environment.
As a result, the relationship between population levels and agricultural land-use is not solely proportional, as had been previously assumed. In the Middle Ages, we had fewer forests than we do today because we needed more land to farm. However since then, our population has increased more than fivefold.
Previous models implied that the same area of land was required to feed a European living in the fifth century as was needed in the 20th century. This doesn’t fit, though, because there have been improvements in our techniques that need to be included in models.
The New Model
The new mode designed by Kaplan and Krumhardt shows a large increase in carbon emissions which corresponds to the expansion of civilizations in China and around the Mediterranean, some two-thousand years ago. Forests had a good chance to reclaim land that had been taken from them during periods such as the fall of the Roman Empire and the Black Death.
In fact, Kaplan brings to the table an entirely unprovable and definitely bold new hypothesis, as a result from his research, which he believes explains the significant decrease in emissions which began in the 16th century.
“Thanks to the reports of the early explorers, we know that the forests were less abundant on the American continent. Then the settlers gradually eliminated the indigenous population.” Threatened with extinction, these populations effectively deserted the forested areas, which – by taking up the carbon in the atmosphere – in turn set off the legendary frosts of the 19th century. “Of course, it’s only a hypothesis”, he concludes, “but given the data we have gathered, it’s entirely plausible”.
Lastly, Kaplan’s model does not contradict previous ones in one very important area; the massive increase in emissions which began at the start of the industrial era. “We are just saying that our influence on the climate began a lot earlier than we thought. In 6000 BC, we were already accumulating significant quantities of carbon in the atmosphere, even though it was nothing compared to the situation today,” Kaplan said.