Sébastien Guillet, an environmental scientist at the University of Geneva in Switzerland, was obsessed with Pink Floyd’s classics. dark side of the moon The album one day he made a visionary connection. The darkest lunar eclipses all occurred within a year of him from a massive volcanic eruption. And astronomers know the exact days of those eclipses. Medieval historical accounts of lunar eclipse sightings should therefore help scientists narrow down the timeframe in which major eruptions occurred during the High Middle Ages spanning 1100-1300 AD. Guillet collaborated with several other scientists on such a study, combining textual analysis with tree-ring and ice-core data. They describe their findings in a new paper published in Nature.
“Climate scientists typically identify past volcanic eruptions by measuring the acidity and ash abundance of cores drilled from polar ice, or by inferring rapid temperature changes in tree-ring records,” he said. , Andrea Seim (University of Freiburg) and Eduardo Zorita (Helmholtz-Zentrum) here) write in the accompanying commentary. “However, these sources are sometimes inconsistent because the location, intensity, and timing of eruptions, and atmospheric circulation, can lead to different outcomes. Guillet and colleagues’ approach to eruptions is an independent and Perhaps provides a more direct source: the timing of volcanic eruptions that could resolve some of these discrepancies.”
Large eruptions can release large amounts of sulfur dioxide into the atmosphere that are converted to aerosols in the stratosphere. This creates volcanic ash. That dust blocks incoming solar radiation and alters the Earth’s surface temperature, precipitation, and atmospheric circulation. Climate models suggest that this type of volcanic-induced cooling of about 1 degree Celsius, sustained over several years, could result in anomalous precipitation patterns. Massive flooding occurs in one area and drought in another. And as ocean temperatures cool and sea ice may expand, the effects could last for decades or more. In fact, there was speculation that a large volcanic eruption in the High Middle Ages may have contributed to the start of the Little Ice Age (c. 1300-1850).
Guillet’s key insight comes from the impact of volcanic eruptions on the appearance of lunar eclipses. A lot of aerosols will make the moon appear darker during the eclipse. If the aerosol is scarce, the Moon will take on a bright reddish appearance. Therefore, we should be able to estimate how much volcanic aerosol was in the atmosphere from medieval descriptions of the moon’s color and luminosity during lunar eclipses, and use that information to more accurately determine the dates of medieval volcanic eruptions. is.
“We only knew about these eruptions because they left traces in the ice of Antarctica and Greenland,” said co-author Clive Oppenheimer of the University of Cambridge. have allowed us to more accurately estimate when and where some of the largest eruptions of this period occurred.” This timing is important as it can influence cooling and other extreme weather events associated with eruptions.
Given that the biblical book of Revelation warns of a blood-red moon appearing in the apocalypse, medieval monks tended to pay special attention to the color of the moon when observing the night sky. But they weren’t the only ones, according to the author. Chinese and Korean astronomers have carefully recorded lunar eclipses in astronomical treatises and official dynastic histories. In the Arab world, lunar eclipses were recorded in universal chronicles, while Japanese observations of these events were recorded in courtiers’ diaries, chronicles, or temple records. One such account was that of the Japanese scribe Fujiwara Teika, who described a dark lunar eclipse he observed on December 2, 1229.
Regarding the recent total lunar eclipse, there used to be a total lunar eclipse, but people in the past did not see the position of the lunar disk like this time, and saw it as if it had disappeared during the total lunar eclipse. There was no. Moreover, it lasts for a very long time and changes rapidly. It was really scary.In fact in my 70 years I have never heard or seen [such a thing]official astronomers have dreaded it.
Of the 64 total lunar eclipses known to have occurred between 1100 and 1300, medieval chroniclers recorded 51, five of which were described as very dark. I was.Guier othersWe also examined 15 specific volcanic eruptions in detail. One of them he was equivalent to the Tambora eruption of 1815, which occurred in the middle of the 13th century and resulted in the “year without summer” of 1816.
Britt. rib. Bd./NY Pub. Lib./Asahi Shimbun
The authors dated several dark lunar eclipses of May 1110, January 1172, December 1229, May 1258, November 1258, and November 1276 to polar ice chronology. and associated with stratospheric dust veils resulting from large volcanic eruptions. Tree-ring records allowed them to narrow down the time even further. They found that five other eruptions were likely associated with aerosol dust veils only in the troposphere, and these did not appear to have a significant impact on climate.
Guier and others. Given that the visibility of lunar eclipses varies both geographically and meteorologically, we acknowledge the methodological limitations of our study. However, “our dataset provides a new, reliable and independent set of chronological tiepoints that can complement established age markers,” they concluded. As pointed out in , a better understanding of how this kind of perturbation affects climate will help scientists improve climate models in the future.
DOI: Nature, 2023. 10.1038/s41586-023-05751-z (About DOI).
