An aggregated climate teleconnection index linked to historical Egyptian famines of the last thousand years

Abstract

Variations in the Nile River water level have been historically associated with social development of the Egyptian civilization, particularly through times of famine. In addition, the Nile River water levels have been strongly linked to variations in climate teleconnections, specifically El Niño/Southern Oscillation, the North Atlantic Oscillation (NAO), and the Pacific Decadal Oscillation. In this paper, we demonstrate that the cumulative effects of these three teleconnections link strongly to the occurrence of famine in Egypt. To create a cumulative response, we employed a principal component analysis (PCA) of the reconstructions of these three climate teleconnections that yielded a composite accounting for 61% of the total variance in the three datasets. We compared that analysis to a new compilation of drought and famine in Egypt. Analysis reveals 8 of 10 major famines in Egypt over the last thousand years correspond to low points or downward movements in a detrended composite eigenvector of the three major climate teleconnections discussed. This Southern Oscillation Index–NAO (SOI-NAO) eigenvector has a statistically significant discrimination between the occurrence of famine and non-occurrence of famine (t = 2.56; p = 0.013). Additionally, the composite climate eigenvector correctly identifies 50 out of 80 events (63%) of lesser incident years mentioned in other Arabic texts. While this climate composite teleconnection analysis alone does not explain all famine events in Egypt over the last thousand years, the relative strength of linkage suggests that potential exists to account for even older (e.g. Egyptian Empire) famines as climate reconstructions extending further back in time become available.