Found the cause of mass cataclysms in the first millennium of our era

We are talking about global warming and droughts that occurred in approximately the same time period.

For that,

To understand the cause of these disasters, the researchers analyzed data on tree rings that grew in nine subarctic and high-mountain regions of the Northern Hemisphere.

Based on the results of the first stage, they found that there are seven areas where the most clearly visible changes in the temperature regime of huge adjacent territories.

According to Doctor of Biological Sciences Olga Churakova, tree rings are a unique archive by which one can understand changes in temperature conditions. 

Warming peaks in the Northern Hemisphere werein the 280s, 990s and 1020s of our era, when the impact of volcanoes during the long periods preceding these decades on the planet's climate was minimal. It was found that 536, 541 and 542 AD were anomalously cold, when the eruption of an unknown volcano led to a global cooling in the North Atlantic, European, East Asian regions, including Siberia.

Olga Churakova, Doctor of Biological Sciences          

Based on this, researchers have identified the main cause of the cataclysms—the eruptions of stratospheric volcanoes. 

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