They had no clue that the observations they made of celestial objects when gazing up at the night sky as mediaeval monks did when they recorded them, but a group of scientists studying volcanology would benefit much from their remarks centuries later.
A new study illustrates how descriptions of lunar eclipses by monks and scribes were crucial in understanding some of the biggest volcanic eruptions on Earth. The study was published on Wednesday in the peer-reviewed journal Nature.
Researchers were able to determine the dates of about 10 volcanic eruptions that occurred between the years 1100 and 1300 using a combination of these mediaeval manuscripts and centuries’ worth of climate data.
Lead author Sébastien Guillet, senior research associate at the Institute for environmental sciences at the UNIGE, said in a press release, “I realised that the darkest lunar eclipses all occurred within a year or so of major volcanic eruptions while listening to Pink Floyd’s Dark Side of the Moon album.” Since we are aware of the precise dates of the eclipses, it is now possible to use the observations to determine when the eruptions must have taken place.
Finding a more precise chronology for these catastrophic occurrences, according to researchers, could help explain how volcanoes affect extreme climatic variability.
HOW VOLCANOS AND LUNAR ECLIPSES ARE LINKED
Why read about moon eclipses in literature to learn about volcanic eruptions? Well, many historical eruptions that occurred at that time were not documented.
We have evidence that they occurred, as scientists already determined that the 2,500-year interval between 1100 and 1300 was one of the most volcanically active times due to sedimentary traces found in ice shelves in Antarctica and Greenland.
A combination of records failing to survive, the Earth being less populated, and the vast dust clouds that spread for thousands of kilometres after a large enough eruption may be to blame for the lack of eyewitness accounts for the majority of these events. These clouds may have registered only as bad weather and not been noteworthy enough to be recorded.
Yet, researchers hypothesised that literature about eclipses would have included atmospheric dust that was less evident during the day.
The moon typically appears rust-red in the sky during a total lunar eclipse because light from the sun is still visible despite being mostly blocked by Earth’s shadow.
This meant that any historical accounts of eclipses that were darker than usual could have been caused by recent volcanic activity.
Five years were spent poring over mediaeval records in search of accounts of eclipses that sounded unusual.
Monks and scribes from all throughout Europe, the Middle East, and East Asia documented lunar eclipses in great detail, including the colour of the moon during these amazing occasions.
The fact that numerous religious writings utilised a blood-red moon to predict impending disasters, which would have been on the minds of ancient scribes and monks when they took great care to characterise the moon’s hue, was noticed by researchers as being helpful.
Based on the motions of the sun, Earth, and moon, scientists have been able to forecast lunar eclipses with mathematical certainty for centuries. These patterns imply that we have dates for eclipses that took place long before anyone was paying close attention to them.
We are aware of 64 total lunar eclipses that took place in Europe between 1100 and 1300. 51 of these 64 verified eclipses were extensively detailed in mediaeval texts.
Five of them mentioned how dark the moon was in the sky.
Early in December of 1229, a Japanese scribe also described an eclipse that was extremely dark and noted that “the old folk had never seen it like this time, with the location of the moon’s disc not visible, just as if it had disappeared during the eclipse… There was legitimate cause for concern.
VOLCANIC WINTERS CONFIRMED BY CLIMATE DATA
Researchers compared the darker eclipses mentioned in these ancient writings with available climate data to support the hypothesis that these eclipses may have been influenced by volcanic clouds.
According to Clive Oppenheimer, a professor in the University of Cambridge’s Department of Geography, “We only knew about these eruptions because they left evidence in the ice of Antarctica and Greenland. We can now more accurately predict when and where some of the largest eruptions of this era happened by combining the data from ice cores with the accounts from mediaeval manuscripts.
During large volcanic eruptions, the climate can be affected in a variety of ways that can leave observable traces on Earth’s climatic history. For instance, the legendary Mount Tambora eruption in 1815, which is now in Indonesia, was so powerful that it caused a year-long drop in world temperatures that is commonly referred to as the “Year Without a Summer.”
According to Markus Stoffel, the study’s last author and full professor at the Institute for Environmental Sciences at the UNIGE, “we know that big tropical eruptions can effect global cooling on the order of around 1 C over a few years.” They “may also result in anomalous rainfall patterns, with droughts in some areas and floods in others.”
Researchers were able to determine the precise dates of five significant eruptions as well as a number of other volcanic events by searching for these “volcanic winters” in climate records, as well as other climate markers connected to significant eruptions, and comparing them with written records of anomalous eclipses.
One of these was the projected eruption time of the 1257 eruption of the Samalas volcano in modern-day Indonesia, which researchers constrained to the spring/summer of that year, refuting a claim made by certain experts that it may have occurred in 1256.
With the help of this investigation, another eruption’s date was determined to fall between May and August of 1171, which is a relatively limited time window for an eruption that occurred more than 800 years ago.
Researchers noted that gaining a better understanding of historical volcanic eruptions helps us understand how volcanic eruptions affect the climate.
Understanding the season when the volcanoes erupted is crucial because it affects how the volcanic dust disperses, the cooling that results from these eruptions, and other climatic oddities, according to Guillet.
