The ozone layer impact of lunar eclipses and climate on the Northern Hemisphere volcanoes. An analysis of meteorological data from Dome C

The strength of Guillet and co- workers study lies in its precision with which it estimated the timing of volcanic eruptions, from year to month to event. Seim and Zorita were not involved in the research.

Depending on the time of year, the moon passes between 5 and 25 km above the surface of the Earth. Upper tropospheric aerosols (5–10 km) may affect the brightness of the Moon18 but their residence time is on the order of a few weeks1,18. Dark lunar eclipses thus more probably indicate high turbidity of the stratosphere after large volcanic events16,17,18. We assume that lunar eclipses of reddish or coppery colour are the result of HMP eruptions which mean that aerosol veils were mainly confined to the troposphere and had limited climatic impacts. Our approach was evaluated against sulfur records from Dome C (Antarctica) to see if it provided a proxy to distinguish between eruptions that hit the ozone layer and those that did not.

They then examined tree-ring records sensitive to summer temperatures in the Northern Hemisphere, in which an unusually cold summer is indicated by reduced wood formation. The authors combined these records with climate simulations and found that five eruptions had a significant impact on the climate. The remaining eruptions seem to have had less effect.

The Roman Catholic Monk John Sacrobosco, lunar eclipses in Europe, the Middle East and East Asia (II): Supplementary Dataset S1

The resulting struggles are clear in the writings of a monk known as John, who chronicled sunspots and a solar eclipse from his post at Worcester Cathedral in England at the start of the High Medieval Period. John did not understand the Islamic methods for calculating lunar eclipses. Once more-sophisticated translations and recalculations had been produced, they formed the basis of textbooks on astronomy. One such book was written by Johannes de Sacrobosco in around 1220, and immediately became widely used (Fig. 2). How could there be any more doubts about the timing of lunar eclipses?

Such studies certainly became more accurate when Latin translations of Islamic astronomical texts and planetary tables were made available in Europe from around 11507. These texts used different calendars and referenced dates that were meaningless to the original compilers. They talked about the observations that were far away from northern Europe. Users unfamiliar with the Islamic calendar were not helped by early translations.

The answer is related to the fact that the solar year didn’t match up with the Julian calendar. Sacrobosco stated that Easter was being celebrated on the wrong day because of the accumulated error which had reached 11 days. Church leaders were aware of the problem, but feared there would be serious resistance to changing the calendar11. The timing of phases of the Moon was therefore out of step with the calendars of major religious institutions.

Historical source criticism and the eight-millennium catalogue of lunar eclipses were used to assess the reliability of each observation. The eclipses reported in historical sources were visible in Europe, the Middle East and East Asia using the maps visibility and local circumstances tables provided by both catalogues. Second-hand reports are those that a given author did not witness, but instead drew information on from another source. Frequent duplication occurred in Western and Eastern Christian sources owing to common underlying source materials and the scribal practices of copying, synthesizing and piecemeal updating of annals and chronicles. A table listing all lunar eclipses records for which information about the colour of the Moon could be retrieved is presented in Supplementary Dataset S1. An extended version of Supplementary Dataset S1 containing all descriptions of total lunar eclipses from Europe, the Middle East and East Asia considered in this study (with or without reference to colour), along with the eclipse visibility maps, can be accessed from the Zenodo repository: https://doi.org/10.5281/zenodo.6907654.

Historical observations of lunar eclipse brightness are recognized as a valuable proxy for SAOD following large volcanic eruptions7,16,17,18,19. However, precautions are necessary to use this proxy appropriately:

SAOD time series cover a 56 month time frame before and after the eruption. For eruptions that release more sulfur than Pinatubo, the residence time of aerosols is not certain, and the time window for SAOD 0.1 differs depending on the aerosol model selected. We determined the probability of the SAOD being exceeded on the basis of agreement between the time series. If the time series indicated exceedance of the threshold in a given month, the probability was very high. Likewise, probability was considered ‘high’ or ‘medium’ if at least three or two, respectively, datasets agreed and as ‘low’ if only one dataset indicated threshold exceedance (step 2.2). SAOD time series provide, for each eruption, the most probable time interval [Month min: Month max] during which a dark lunar eclipse can be observed after an eruption. Reciprocally, we can assume that the most probable eruption date falls within the time interval [Month max: Month min] before the date of the dark lunar eclipse (step 2.3).

Our study relies on state-of-the art reconstructions that efficiently capture post-volcanic summer cooling but several avenues may improve the peak cooling detection and refine the timing of HMP eruptions:

Totality should preferably have been observed in good weather conditions (that is, clear, dark sky), not too near the horizon and not too close to dawn or dusk16.

Moon eclipses in Europe from 1100 to 1300 – Preliminary results of a case study on the Little Ice Age and its effects on climate

Reports should be contemporary with the event and preferably by an eyewitness. These conditions are not always met for the medieval sources available (see Supplementary Dataset S1 for more information).

“Clear in the morning. Heavy rain and flooding occurred after the hour of the Snake. People were drowned when houses were swept away. At the hour of the Horse [11 am–1 pm] the weather began to clear. The moon was not visible during the hour of the Rat.

The research, published in Nature on 5 April, corroborates data extracted from ice cores and could help scientists to understand the run-up to the cold period known as the Little Ice Age, as well as the effects of a controversial technique proposed for manipulating the climate.

According to the study, which was published in the journal Nature, there were 64 total lunar eclipses in Europe between 1100 and 1300. In six of these cases, these documents also reported that the moon was exceptionally dark — in May 1110, January 1172, December 1229, May 1258, November 1258 and November 1276.

Solargeoengineering: a proposal for the explanation of dark eclipses and the disappearance of the moon during the 1229 December 2, 1229 eclipse

The effects of a proposal known as solargeoengineering, in which particles were injected into the sky to reflect sunlight back into space, might be better understood if we know more about the past. Some scientist argue that such efforts could serve as an emergency backstop to cool the planet and avert the worst effects of runaway global warming.

For Guillet, who spent a decade poring over historical records in his free time before finishing the project during pandemic lockdowns, the study is also a nod to the medieval observers whose accounts historians have long used to document social and political trends. If they can provide accurate records about political and social events, why isn’t it about natural events?

They wrote that the orb on top of the moon was more unusual than usual and that the moon seemed to disappear completely from the sky.

“The old folk had never seen it like this time, with the location of the disk of the Moon not visible, just as if it had disappeared during the eclipse… It was truly something to fear,” wrote Japanese poet Fujiwara no Teika, of an unprecedented dark eclipse observed on December 2, 1229.

What the chroniclers could not have known was this: An exceptionally dark eclipse is associated with the presence of a large amount of volcanic dust in the atmosphere, according to Sébastien Guillet, a senior research associate at the Institute for Environmental Sciences at the University of Geneva.

Guillet believes medieval manuscripts contain an important source of information about a string of large but little-understood volcanic eruptions on Earth.

Guillet said the eruptions were more powerful that some of the most well-known volcanic eruptions in recent history. One of the largest volcanic eruptions of the past millennium was the 1257 Samalas eruption.

Researchers believe volcanic eruptions took place before the dark eclipses based on their effect on the lunar eclipses.

“We only knew about these eruptions because they left traces in the ice of Antarctica and Greenland,” said study coauthor Clive Oppenheimer, a professor at the University of Cambridge, in a news release.

These sources sometimes conflict because volcanic eruptions have different effects on weather patterns depending on their location and intensity, said Eduardo Zorita, a senior lecturer at the University of Freiburg’s Institute of Forest Sciences.