This project examines the link between explosive volcanic eruptions and the annual Nile river summer flooding in antiquity. Large volcanic eruptions can reduce average global temperatures and suppress average global precipitation. This is known to have had dramatic effects on annual rainfall on the Nile watershed in historic times. The human response to this annual flooding, and to its variability over the years, was the major driver of Egyptian history up to the completion of the high dam at Aswan in 1970.

A collaboration among historians, scientists, hydrologists, and statisticians, this four year project seeks to understand the coupling between the hydrological cycle and human society in Egypt during the Hellenistic era (305 BCE - 30 BCE), a well-documented period of economic, technological and social change with often violent rivalries between major regional powers. The results will also inform our understanding of best-practice responses to the changing climate in the modern world. The project will inform the broad public about human and natural systems and the complex interactions between them at diverse scales, through a traveling exhibition program developed at the Yale Peabody Museum of Natural History.

Years 1 Achievements

  • Constructed a database framework for entering historical data from the papyri.

  • Collected historical information on important eruptions that perturbed Nile river flow.

  • Compiled published price data from Egypt, Delos, and Babylon.

  • Formulated statistical analysis of historical data.

  • Compiled relevant paleoclimate and paleohydrological proxies to establish background climatic context of Nile river flood variability.

  • Configured boundary conditions for climate model.

  • Completed a control simulation for the climate of 2500 years ago.

Year 2 Achievements

  • PI Manning, Co-PI Ludlow, and Graduate Researcher Joe Morgan have completed the historical database of annual Ptolemaic-era Nile flood quality values

  • Co-PI Stine has been working with PI Manning on formulating the statistical analysis of historical data produced by PI Manning’s group. Co-PI Stine has also been extending our existing (Manning et al., 2017) analysis of volcanic impacts on Nile hydrology as identifiable via the Islamic Nilometer from 622 CE onward, in particular in identifying the impact of Southern Hemispheric explosive eruptions on the Nile summer flood. Initial results suggest, as expected by theory, that these eruptions induce a discernible increase in Nile summer flooding. This is the first time such a response has been seen in the literature.

  • Co-PI Marlon along with Project Manager Nadia Grisaru, have compiled relevant paleoclimate and paleohydrological proxies to establish the background climatic context of Nile river flood variability. Literature from dendrochronological records, ice cores, European glaciers, lake and marine sediment cores, speleothems, and other sources have been compiled and categorized. Detecting low-frequency variations in response to periods with one or more volcanic eruptions is being explored.

  • The climate modeling work, undertaken by Co-PI LeGrande, Co-PI Tsigaridis, and Postdoctoral Researcher Ram Singh, followed two separate paths, which will converge in the next two years:

    1. In order to investigate the sensitivity of the climate system to anthropogenic changes due to hydroclimatic shocks and to understand how such changes could have acted in tandem with the natural factors on the regional climate system to magnify the local climatic impacts, two scenarios were studied: one affecting the water level on the Nile, and another affecting the surrounding vegetation across the Nile basin.

    1. A preliminary analysis of the late-Holocene period (2.5 kya BP) control run was carried out. The simulation is in dynamic equilibrium, after 1000 years of simulation. This vegetation cover will serve as boundary conditions to the GISS model.

  • In collaboration with Prof. Benjamin Kelly (York University) and Gert Baetens (KU Leuven), we have also developed a multi-century chronology comprising hundreds of precisely dated petitions submitted by a range of social classes to authorities seeking redress for crimes committed and relief in times of socioeconomic stress.

  • Project Partner Stagge has begun generating a 1-dimensional hydraulic flood model using digital elevation data based on the post-processed MERIT-DEM, high resolution Nile centerlines, and recently published global land use/land cover data.

Year 3 ACHIEVEMENTS

  • Analysis and the integration of the paleoclimate proxy record into our work. 

  • The modelling has advanced considerably in Years 3 and 4.

  • We continue the work with statistical analysis of our historical database. 

  • We are already planning a major international conference to be held at Yale at the end of Year 4. We are hard at work with Peabody Museum staff about an exhibit based on  our work, and, we hope, a traveling exhibit as well, although that work has slowed both because of the major construction project at the Peabody and the COVID19 closures of museums. 

  • We continue working with the VICS group sponsored by PAGES in Bern on climatic and societal impacts of volcanic eruptions, and we are now coordinating our work with the new group in Basel working on Roman Egypt.

Year 4 ACHIEVEMENTS

  • A major climate model output paper led by Ram Singh has now been published in the special volcanic impacts issue of Climate of the Past. It received notice in Nature the week of February 3 2023.

  • We held our first in-person team meeting in New Haven, CT on October 26-28, 2023.

This project is made possible through funding awarded by the National Science Foundation. More information can be found under award #1824770, CNH-L: Volcanism, Hydrology and Social Conflict: Lessons from Hellenistic and Roman-Era Egypt and Mesopotamia. The opinions, findings, and conclusions expressed here by the authors do not necessarily reflect the views of the NSF.