It is shown that the description of the lunar eclipse left in the ancient documents of the Middle Ages is the key to unraveling climate change due to volcanic activity
During the Middle Ages, from the mid-14th century to the mid-19th century, a cold period called the '
Lunar eclipses illuminate timing and climate impact of medieval volcanism | Nature
https://doi.org/10.1038/s41586-023-05751-z
'Like blood, then turned into darkness': how medieval manuscripts link lunar eclipses, volcanoes and climate change
How Pink Floyd inspired research into medieval monks and volcanology | Ars Technica
Large volcanic eruptions release large amounts of sulfur dioxide and dust into the atmosphere, which are converted to aerosols in the stratosphere. Aerosols and dust block the light and heat from the sun and change the surface temperature, precipitation, and atmospheric circulation of the earth. In addition, large-scale eruptions are said to cause seawater temperature drops and droughts, and large-scale volcanic eruptions in the Middle Ages are thought to have caused the Little Ice Age for over 500 years.
However, it has been difficult to identify the volcanic eruptions that triggered the Little Ice Age using conventional survey methods that measure the acidity and amount of volcanic ash in ice cores mined from Antarctica.
Therefore, the research team of Mr. Guile et al. devised a method to read and understand medieval manuscripts as a way to know the volcanic eruption that caused the Little Ice Age. The research team collected records of total lunar eclipses between 1100 and 1300, when volcanic eruptions that triggered the Little Ice Age occurred, from medieval manuscripts in Europe, the Middle East, and Asia. According to the research team, 187 lunar eclipses were recorded between 1100 and 1300.
When a total lunar eclipse occurs, light with long wavelengths such as red and orange in sunlight preferentially reaches the moon due to a phenomenon called ' Rayleigh scattering ' in which the wavelength of light is scattered by fine particles in the atmosphere. As a result, the moon appears reddish-brown during a total lunar eclipse.
Why does the moon turn red during a total lunar eclipse? -GIGAZINE
The image below shows the moon during a total lunar eclipse. If there is a large amount of aerosols in the atmosphere, the Moon appears dark red during a total lunar eclipse (left). On the other hand, when there are few aerosols, the moon appears to glow red (right). So the researchers estimated how much volcanic aerosol was in the atmosphere from medieval manuscript descriptions of the moon's color and luminosity during total lunar eclipses. In addition, by using aerosol information, we performed accurate dating of medieval volcanic eruptions that triggered the Little Ice Age.
According to the research team, medieval European monks tended to pay particular attention to the color of the moon. In China and Korea, there were descriptions of lunar eclipses in astronomical treatises and books summarizing the history of dynasties. In Japan, descriptions of lunar eclipses were left in the diaries and chronicles of officials who served in the Imperial Court, and in the records of temples.
One of the best explanations for the dark reddish moon that accompanies the amount of aerosols is given in Meigetsuki , left by Fujiwara no Teika on December 2, 1229. Although there have been eclipses, this is the first time in my experience that the position of the lunar disk cannot be seen, and it looks as if it has disappeared during the lunar eclipse. It was very long and the changes were extreme.'
Of the 64 total lunar eclipses that occurred between 1100 and 1300, 51 were described in manuscripts, five of which were described as ``the moon is very dark''. As a result of investigating 15 volcanic eruptions that occurred during that period, the research team speculated that it was the volcanic eruption that occurred in the middle of the 13th century that caused the Little Ice Age.
“Given that the visibility of the lunar eclipse varies geographically and meteorologically, there are limitations to this survey method,” Guillet said. 'We have a new and reliable method of research that allows us to base our research on established historical markers.'
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