(ORDO NEWS) — An international team of geologists used tree rings, ice samples and the chronicles of medieval monks to pinpoint the exact dates of five powerful volcanic eruptions in the 12th and 13th centuries that supposedly triggered the so-called Little Ice Age.
“We only knew about these volcanic eruptions because their ash was preserved in the ice of Antarctica and Greenland.
By combining this geological data with information about lunar eclipses from medieval chronicles, we were able to get more accurate estimates of when and where the most powerful eruptions occurred in this period of time,” said Clive Oppenheimer, a professor at the University of Cambridge (Great Britain), quoted by the press service of the university.
The so-called Little Ice Age is a period of time between 1300 and 1850 AD, when average temperatures in Europe were about 0.5 degrees Celsius lower than in the previous millennium.
One of the reasons for this cooling is now considered to be that in the 12th-13th centuries, a record high level of volcanic activity was observed on Earth, the ash of which fell into the atmosphere and reflected sunlight and heat into space.
Professor Oppenheimer and his colleagues figured out exactly when the six largest volcanic eruptions occurred in this historical period by analyzing ash samples preserved in centuries-old ice deposits in Greenland and Antarctica, as well as studying records of lunar eclipses by medieval European monks and Asian chroniclers.
Volcanoes and lunar eclipses
Scientists have noticed that lunar eclipses become unusually dark in those months and years when powerful volcanic eruptions occur on Earth, throwing large amounts of ash into the atmosphere.
Guided by this idea, scientists studied ice samples that formed between 1100 and 1300 years in the southern and northern polar regions, and roughly determined the time when layers of volcanic ash fell into them.
The researchers compared these periods of time with the time when 64 total lunar eclipses occurred over these two centuries over Europe and the countries of East Asia.
It turned out that during this time, medieval monks and chroniclers witnessed six “bloody lunar eclipses” generated by large volcanic eruptions.
One of them – the explosion of the Indonesian island of Samalas in 1257 – was already known to historians and geologists.
The five other cataclysms that occurred in 1108, 1171, 1182, 1229, 1276 and 1286 were not previously known and were not mentioned in Western or Eastern chronicles.
Determining the exact dates of these eruptions, Professor Oppenheimer and his colleagues hope, will help geologists discover other traces of these cataclysms.
Their subsequent study will help geologists and climatologists more accurately assess the contribution of volcanoes to the start of the “Little Ice Age”, the researchers concluded.
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