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NotSanguine writes:

Ars Technica is reporting [arstechnica.com] on a new (published 5 April 2023) paper [nature.com] combining ice core, tree ring and textual analysis to "more accurately date medieval volcanic eruptions."

The primary author's inspiration to pursue this line of research included:

Sébastien Guillet, an environmental scientist at the University of Geneva in Switzerland, was rocking out to Pink Floyd's classic Dark Side of the Moon album one day when he made a prescient connection. The darkest lunar eclipses all occurred within a year or so of major volcanic eruptions. And astronomers know the exact days of those eclipses. So medieval historical accounts of lunar eclipse sightings should be able to help scientists narrow down the time frame in which major eruptions occurred during the High Medieval period spanning 1100 to 1300 CE. Guillet collaborated with several other scientists to conduct such a study, combining textual analysis with tree ring and ice core data. They described their findings in a new paper [nature.com] published in the journal Nature.

"Climate scientists usually identify past volcanic eruptions by measuring the acidity and amount of volcanic ash in cores drilled from polar ice, or by inferring abrupt temperature changes in tree ring records," Andrea Seim (University of Freiburg) and Eduardo Zorita (Helmholtz-Zentrum Hereon) wrote in an accompanying commentary [nature.com]. "However, these sources sometimes disagree, because the location, intensity, and timing of eruptions can produce varying results, as can circulation of the atmosphere. Guillet and colleagues' approach offers an independent—and perhaps even more direct—source of information about the timing of volcanic eruptions, which could resolve some of these disagreements."
[...]
Guillet's critical insight stems from the impact volcanic eruptions can have on the appearance of a lunar eclipse. If there are a lot of aerosols, the moon will appear dark during the eclipse; if aerosols are scarce, the moon will have a bright reddish appearance. So one should be able to estimate how much volcanic aerosols were in the atmosphere from medieval descriptions of the color and luminosity of the moon during lunar eclipses, and use that information to more accurately date medieval volcanic eruptions.

It's an interesting combination of science and analysis of historical writings to arrive at a better understanding of some of the forces acting on the climate in Medieval Europe.

N.B.: The Nature journal reference appears to be the full paper, not just an abstract.

References:
DOI: https://doi.org/10.1038/s41586-023-05751-z [doi.org]
Study Data/Code Availability: https://doi.org/10.5281/zenodo.6907654 [doi.org]

Original Submission