Upheavals in the monsoon cycle and annual flooding of the Nile correlated with massive volcanic eruptions may have led to the destabilization of the last Ptolemaic dynasties of Egypt, according to a new study.
Illustration of massive volcanic eruption in ancient times
Could powerful volcanic eruptions have contributed to the weakening of the last dynasties of ancient Egypt? Those of the Ptolemies, whose ultimate sovereign, the famous Cleopatra VII, committed suicide in 30 BC after her naval defeat against Rome at Actium.
In ancient times, the Nile floods enriched the land and allowed crops to grow. Credits:Leemage/AFP
This is at least the thesis of Joseph G. Manning, historian at Yale University (United States), main author of a study which sees the beginnings of this collapse appear on different occasions on the banks of the Nile, and for the last reign, a decade earlier... Thus, a powerful volcanic eruption that occurred in 44 BC * would have induced climatic changes and, in fact, led to a change in the flow of the course of the Nile with catastrophic consequences. This would then have insufficiently flooded its nourishing shores on which the prosperity of Egypt depended. There would thus have been no harvest from the year 43 BC. J.C, and therefore not enough to feed the population of Egypt, nor to fill the granaries of the temples, even less to collect taxes...
Representation of Cleopatra VII. © Marthelot/Leemage/AFP
These years of political instability added to the pressure of the Romans could have contributed to ending 3000 years of history! These same mechanisms synchronizing a massive eruption and major political events would have been observed as early as 247 BC.
This hypothesis, developed in an article published in the journal Nature communication , sifts through the detailed history of the last 300 years of ancient Egypt (305-30 BCE). The researchers carried out computer simulations by combining climate data and historical events such as major popular uprisings. They have thus come to the conclusion that frequent massive volcanic eruptions recorded in a decade across the globe have led to a cessation of the monsoons and thus influenced the summer flooding of the Nile, the 6825 km of the great river being mainly fed by the rains from the equatorial plateau of East Africa and the Ethiopian highlands. The cause:large quantities of particles injected into the upper atmosphere (10-20 km altitude) during these explosive eruptions.
“At high altitudes, ash and sulfur oxidize and form small particulates, sulfate aerosols, which reflect solar radiation, leading to cooler temperatures “, explained to the daily New York Times Francis Ludlow, climate historian at Trinity College in Dublin, one of the signatories of the study. As the amount of water evaporating from the oceans is reduced, precipitation decreases. “Thus, a volcano eruption in the Northern Hemisphere can directly alter monsoon systems over Africa and the Ethiopian highlands “, he continued. It was analysis of ice cores from Greenland and Antarctica containing trapped sulfur from these ancient eruptions, combined with data from the Nilometer, an observational instrument that was used to annually monitor the Nile flood level, that enabled these scenarios to be established. For the researchers of this study, these volcanic eruptions did not directly cause the social upheavals themselves, but fed and exacerbated already existing tensions.
*Massive volcanic eruption identified by aerosols trapped in polar ice.