MADRID, 5 Abr. (EUROPA PRESS) –
By observing the night skymedieval monks unknowingly recorded some of the largest volcanic eruptions in history, according to a study published in the journal ‘Nature’.
The research – carried out by an international team of researchers, led by the University of Geneva (UNIGE) – was based on European and Near Eastern chronicles from the 12th and 13th centuries, as well as data from ice cores and rings. of trees, to accurately date some of the largest volcanic eruptions ever seen.
Their results provide new data on one of the periods of greatest volcanic activity in Earth’s history, which, according to some, helped trigger the Little Ice Age, a long period of cooling that caused the advance of European glaciers.
It took researchers nearly five years to sift through hundreds of annals and chronicles from across Europe and the Near East, looking for references to total lunar eclipses and their coloration.
Normally, the Moon remains visible as a reddish orb because it is still bathed in sunlight that is deflected around Earth by its atmosphere. But after a very large volcanic eruption, there can be so much dust in the stratosphere — the middle part of the atmosphere that starts about where commercial airliners fly — that the eclipsed moon almost disappears.
Medieval chroniclers recorded and described all kinds of historical events, including the deeds of kings and popes, major battles, and natural disasters and famines. Equally noteworthy were the celestial phenomena that could herald such calamities.
Considering the Apocalypse, a vision of the end times that speaks of a blood-red moon, the monks paid special attention to the coloration of the moon. Of the 64 total lunar eclipses that occurred in Europe between 1100 and 1300, chroniclers had accurately documented 51. In five of these cases, they also documented the moon’s coloration. In five of these cases, they also reported that the moon was exceptionally dark.
Asked what led him to link the monks’ records of the eclipsed moon’s brightness and color to the volcanic penumbra, the paper’s lead author, Sébastien Guillet, Senior Research Associate at UNIGE’s Institute of Environmental Sciences, He explains that he was listening to music.
I was listening to the album ‘Dark Side of the Moon’ de Pink Floyd when I realized that all the darkest lunar eclipses occurred about a year after large volcanic eruptions –remember it’s a statement–. Since we know the exact days of the eclipses, the possibility of using the sightings to determine when the eruptions must have occurred was opened up.”
The researchers found that scribes in Japan equally took note of lunar eclipses. One of the best known, Fujiwara no Teika, wrote of an unprecedented dark eclipse observed on December 2, 1229: “the ancients had never seen it like this time, with the location of the Moon’s disk not visible, as if there had been disappeared during the eclipse… It was really scary.”
“Stratospheric dust from large volcanic eruptions was not only responsible for the disappearance of the Moon. It also cooled summer temperatures by limiting sunlight reaching the Earth’s surface. This, in turn, could ruin crops agriculture,” he says.
“We know from previous work that strong tropical eruptions can induce global cooling on the order of about 1°C in a few years,” explains Markus Stoffel, Senior Lecturer at UNIGE’s Institute of Environmental Sciences and last author of the study, a specialist in convert tree ring measurements into climate data, who co-designed the study–. They can also cause rainfall anomalies, with droughts in one place and floods in another.”
Despite these effects, people at the time could not imagine that bad harvests or unusual lunar eclipses had anything to do with volcanoes: the eruptions themselves were not documented, save for one.
“We only knew about these eruptions because they left traces in the ice of Antarctica and Greenland,” says Clive Oppenheimer, co-author of the study and professor in the Department of Geography at the University of Cambridge (United Kingdom). Uniting the information from the cores ice sheets and descriptions from medieval texts we can now make better estimates of when and where some of the largest eruptions of this period occurred.”
To take full advantage of this integration, Sébastien Guillet worked with climate modelers to calculate the most likely timing of the eruptions. “Knowing the season in which volcanoes erupted is essential, since influences the spread of volcanic dust and the cooling and other climatic anomalies associated with these eruptions“, he stresses.
In addition to helping to pinpoint the timing and intensity of these phenomena, what makes the results significant is that the interval between 1100 and 1300 is one of the periods of greatest volcanic activity in history, as evidenced by witnesses from the ice cores.
Of the 15 eruptions considered in the new study, one in the mid-13th century rivals the famous Tambora eruption of 1815, which sparked the “year without a summer” of 1816. The collective effect of medieval eruptions on Earth’s climate may have caused the Little Ice Age, when winter ice fairs were held on the frozen rivers of Europe.
“Improving our knowledge of these otherwise mysterious eruptions is crucial to understanding whether and how past volcanism affected not only the climate but also society during the Middle Ages,” concludes the researcher.