Charlemagne´s Omen: Dark skies, climate change and solar storms around 800 AD
A new study of two Austrian historians fathoms atmospheric and climatic phenomena surrounding major political upheavals in early medieval Europe.
The coronation of Charlemagne as Roman Emperor on 25 December 800 is often interpreted as the end of a “Dark Age” that had begun in Western Europe after the fall of the Western Roman Empire in the 5th century AD. Charles' claim to the imperial title was legitimized with the deposition of the Eastern Roman Emperor Constantine VI in Constantinople in August 797 and the following reign of his mother Irene (who, as a woman, was not considered a legitimate “emperor” by some coevals). According to the most important chronicle, the fall of Constantine, who was also blinded, was accompanied by a “darkening” of the sun, which lasted 17 days and indicated divine displeasure at the attack on the emperor.
Research has so far mostly dismissed this description as a literary invention or as an exaggerated representation of a solar eclipse that took place shortly before or after the blinding. Johannes Preiser-Kapeller from the Department for Byzantine Research at the Institute for Medieval Research at the Austrian Academy of Sciences and Ewald Kislinger from the Department for Byzantine and Modern Greek Studies at the University of Vienna did not find this explanation convincing. In almost two years of detective work, they not only examined all available written evidence for the period around 797 from Ireland to Syria and from the Rhineland to southern Italy for clues, but also the latest natural scientific findings, including data obtained from ice cores in Greenland and from more than 1000 years old tree rings in northern Scandinavia and the Swiss Alps.
They not only encountered evidence of solar eclipses, but also of massive solar storms that caused the northern lights to appear far to the south in what is now southeastern Turkey. In addition, fires, earthquakes and epidemics (among humans and cattle) ravaged Europe and the Mediterranean region in these decades (see also the chronological overview below). Massive volcanic eruptions, in turn, repeatedly contributed to cold anomalies that led to crop failures and even the freezing of the Bosphorus around Constantinople. The ash particles ejected into the atmosphere by such eruptions also sometimes obscured sunlight for weeks or months; this was probably also the physical background for the darkening described for the fall of Emperor Constantine VI in 797.
Charlemagne benefited not only from the weakening of imperial power in Constantinople, but also from the apocalyptic mood felt by some of his contemporaries, heightened by spectacular natural events, which seemed to call for a “strong man” to renew the Roman Empire “darkened” in the East. In addition, the Byzantine Empire had lost some of its legitimacy in the eyes of Western Christianity as a result of measures taken against the veneration of the holy images (“iconoclasm”) under Irene’s predecessors. This dynamic interplay between political upheavals, atmospheric and climatic phenomena and their interpretation could only be explored by Preiser-Kapeller and Kislinger through the interdisciplinary analysis of historical and natural archives.
Their findings are published open access online in the scientific journal Medieval Worlds (nr 17, December 2022) under the title “The sun was darkened for seventeen days (AD 797). An interdisciplinary exploration of celestial phenomena between Byzantium, Charlemagne, and a volcanic eruption”, https://doi.org/10.1553/medievalworlds_no17_2022s3.
Overview map of the volcanic and atmospheric phenomena around the year 800 and the available historical and scientific data (J. Preiser-Kapeller, OEAW, 2022)
Selected political events, portents and natural phenomena in the 8th to 9th century AD
|
Time |
Event or phenomenon |
(Possible) physical background |
|
726 |
Large volcanic eruption on Thera (Santorini) in the southern Aegean, said to have motivated Emperor Leon III to take first measures against the veneration of sacred images |
|
|
746, March-April |
Veiling of the sun in Syria and Mesopotamia |
Atmospheric turbidity (after a volcanic eruption or dust storms) |
|
747 or 748, April |
Birth of Charlemagne |
|
|
747, August |
Veiling of the sun in Syria and Mesopotamia for 5 days |
Atmospheric turbidity (after a volcanic eruption or dust storms) |
|
747/747 |
Last outbreaks of the First Plague Pandemic in Constantinople and in the Caliphate |
|
|
ca. 752 |
Birth of Eirene |
|
|
754 |
Ecclesiastical Council of Hiereia near Constantinople, chaired by Emperor Constantine V, adopts measures against the veneration of sacred images |
|
|
762/764 |
Sulphate peak in ice cores in Greenland |
Major volcanic eruption |
|
763-764, Winter |
Extreme winter cold across Europe, freezing of parts of the Black Sea and the Bosporus around Constantinople |
Climate anomaly after a volcanic eruption |
|
764, March |
“Falling of stars” in Constantinople |
Meteorite shower? |
|
767, Summer |
Severe drought around Constantinople |
|
|
768, 9 October |
Accession to power of Charlemagne in the Frankish Kingdom |
|
|
769 |
Wedding of Eirene to Leon (IV), son of Emperor Constantine V |
|
|
771, 14 January |
Birth of Constantine VI |
|
|
773/774 |
Charlemagne conquers the Lombard Kingdom in Northern Italy |
|
|
774/775 |
Sightings of auroras a far south as Amida in northern Mesopotamia |
Massive outbreak of the sun ("774/775 event") |
|
775, 14 September |
Death of Emperor Constantine V, accession to the throne of Leon IV |
|
|
780, 8 September |
Death of Emperor Leon IV, accession to the throne of Constantine VI and of Eirene (as co-empress) |
|
|
787, 16 September |
Solar eclipse, partially visible in Constantinople |
|
|
787, 24 September-23 October |
Second Council of Nicaea, presided by Constantine VI and Eirene, the veneration of sacred images is permitted again |
|
|
787/800 |
Volcanic eruptions of Vesuvius near Naples and Monte Pilato on the Liparic Islands |
|
|
790, February |
Discord of Constantine VI and Eirene, earthquake in Constantinople |
|
|
790, October |
Constantine VI has Eirene confined to the Palace of Eleutherios, fire in Constantinople |
|
|
792, August |
Emperor Constantine VI orders the blinding of his paternal uncles after an attempted coup |
|
|
792, 25 December |
Rebellion of the army corps of the Armeniacs against Constantine VI, fire in Constantinople |
|
|
792-794 |
Periods of bad weather and crop failures in the Frankish realms |
Climate anomaly (maybe after a volcanic eruption?) |
|
795, September |
Constantine VI separates from his first wife Maria and marries Theodote |
|
|
796, April-May |
Earthquakes in Crete and later in Constantinople |
|
|
ca. 796 |
Ammonium peak in ice cores in Greenland |
Large scale wildfires in North America? |
|
797, 3 March |
Solar eclipse, partially visible in Constantinople |
|
|
797, July-798, July |
Planet Mars not visible on the night sky in the Frankish realms |
Conjunction of Mars |
|
797, August |
Blinding of Emperor Constantine VI in Constantinople, “darkening of the sun” for 17 days |
Atmospheric turbidity after a volcanic eruption |
|
799, 25 April |
Blinding of Pope Leo III in Rome |
|
|
799/800 |
Sulphate peak in ice cores in Greenland |
Major volcanic eruption |
|
800 |
Severe summer cold registered in tree rings in Scandinavia and Switzerland, frost in June in the Rhineland, extreme drought in the Empire of the Uyghurs (Mongolia) |
Climate anomaly after a volcanic eruption |
|
800, 25 December |
Coronation of Charlemagne as Emperor of the Romans in Rome by Pope Leo III |
|
|
800-801, Winter |
Storms in England, mild winter in the Rhineland, severe winter in Catalonia |
Climate anomaly after a volcanic eruption |
|
801, Spring |
Epidemics among cattle and humans in England and the Rhineland |
|
|
802, October |
Overthrow of Empress Eirene by Nikephoros I, bad weather in Constantinople |
|
|
803, 9 August |
Death of Eirene in exile on Lesbos |
|
|
809/810 |
Severe epidemic among cattle and horses in the Empire of Charlemagne; death of the elephant conveyed to Charlemagne by Caliph Harun ar-Rashid |
|
|
812, 14 May |
Solar eclipse, partially visible in Constantinople |
|
|
813, 4 May |
Solar eclipse, partially visible in Constantinople |
|
|
814, 28 January |
Death of Charlemagne in Aachen |
|
|
822 |
Sulphate peak in ice cores in Greenland, extreme cold weather in Ireland |
Climate anomaly after a volcanic eruption (Katla on Iceland) |
From: Johannes Preiser-Kapeller and Ewald Kislinger, “The sun was darkened for seventeen days (AD 797)”. An interdisciplinary exploration of celestial phenomena between Byzantium, Charlemagne, and a volcanic eruption. Medieval Worlds 17/2022, https://doi.org/10.1553/medievalworlds_no17_2022s3