Over the past two millennia, volcanoes have significantly affected the Earth's weather conditions. Scientists from Harvard even believe that the eruptions and the temperature fluctuations they provoked played a large role in changing the history of the whole mankind.
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As part of the new scientific work, the researchers studied samples of about 9 thousand dead and living trees, and the obtained data were used to create a complete record of climatic records. The calculations were carried out from 1 year A.D. e. The scientists compared the information received with the dates of large-scale volcanic eruptions. As it turned out, they were able to reduce the average temperature in the world by a few tenths of a degree Celsius, which is considered a fairly tangible decline, and this was most clearly seen in Eurasia and North America. Sulfur emitted by volcanoes was directed into the stratosphere, blocking the sun's rays, which, in turn, reduced the periods of growth of plants, which, coupled with a cold snap, caused crop failures.
In the years when volcanic activity was absent, the planet, on the contrary, became warmer. So, for example, in the 280s, 990s and 1020s, the summer weather was so hot that the temperature values were comparable to those of the first decade of the 21st century. But the 6th-7th centuries were marked by the Little Ice Age.
The researchers also found out: more or less constant warmth in the Medieval and Roman periods, when there were almost no major volcanic eruptions, coincided with the heyday and political stability of the countries. And the time, which was characterized by volcanic activity, was accompanied by conflicts and economic decline.
“Millions of people are being harmed by a major eruption that is reducing grain production. Crop failure results in famine, disease, conflict and displacement. We have traced a lot of evidence of this in historical records, ”said Harvard researchers.