Agricultural human activities have increased the amount of carbon dioxide in the atmosphere.
Scientists from the U.S. conducted a comparative analysis of the modern climate era and of the same period in the previous and found a significant difference in the development of climatic conditions. According to the researchers, it is connected with activity of ancient farmers.
One of the study’s authors, William Ruddiman studied traces of methane and carbon dioxide in Antarctic ice 15 years ago. “I noticed that the concentration of methane started to decline about ten thousand years ago, but then five thousand years ago, the trend was reversed. A similar situation was and with carbon dioxide: its concentration is also decreased to ten thousand years ago, but went the mountain seven thousand years ago. It struck me as odd, and the only explanation that came to mind early agriculture”, – he said.
In the new study, the researchers built a computer simulation based on data derived from deposits of ice. In this model, they compared our own climatic era, the Holocene – the one that was 770 thousand years ago, which was called The Marine Isotope Stage 19c (MIS19c).
In the result, it was found that both era began with the same level of carbon dioxide and methane. While in MIS19c the amount of gas decreased in the Holocene, its concentration began to increase about five thousand years ago and reached a peak in 1850. Experts have deliberately limited the model of the nineteenth century, before the industrial revolution, to ignore the sharp jump of greenhouse gases after it.
According to the authors of the study, human activities over the last two thousand years has changed the development climate and prevent another ice age, and it is therefore difficult to predict what will happen next.
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