A new study linking paleoclimatology — the reconstruction of past global climates — with historical analysis by researchers at Yale and other institutions shows a link between environmental stress and its impact on the economy, political stability, and war-fighting capacity of ancient Egypt.
The team of researchers examined the hydroclimatic and societal impacts in Egypt of a sequence of tropical and high-latitude volcanic eruptions spanning the past 2,500 years, as known from modern ice-core records. The team focused on the Ptolemaic dynasty of ancient Egypt (305-30 B.C.E.) — a state formed in the aftermath of the campaigns of Alexander the Great, and famed for rulers such as Cleopatra — as well as material and cultural achievements including the great Library and Lighthouse of Alexandria.
Using an interdisciplinary approach that combined evidence from climate modelling of large 20th-century eruptions, annual measurements of Nile summer flood heights from the Islamic Nilometer — the longest-known human record of environmental variability — between 622 and 1902, as well as descriptions of Nile flood quality in ancient papyri and inscriptions from the Ptolemaic era, the authors show how large volcanic eruptions impacted on Nile river flow, reducing the height of the agriculturally-critical summer flood.
The findings, published in the journal Nature Communications, show that integrating evidence from historical writings with paleoclimate data can advance both our understanding of how the climate system functions, and how climatic changes impacted past human societies.
“Ancient Egyptians depended almost exclusively on Nile summer flooding brought by the summer monsoon in east Africa to grow their crops. In years influenced by volcanic eruptions, Nile flooding was generally diminished, leading to social stress that could trigger unrest and have other political and economic consequences,” says Joseph Manning, lead author on the paper and the William K. & Marilyn Milton Simpson Professor of History and Classics at Yale.
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Image Souce: Department of Papyrology, Institute of Archaeology, University of Warsaw