High-latitude eruptions cast shadow over the African monsoon and the flow of the Nile

[1] Nile River records indicate very low flow following the 1783–1784 Laki volcanic eruption, as well as after other high-latitude volcanic eruptions. As shown by climate model simulations of the Laki eruption, significant cooling ( 1 to 3 C) of the Northern Hemisphere land masses during the boreal summer of 1783 resulted in a strong dynamical effect of weakening the African and Indian monsoon circulations, with precipitation anomalies of 1 to 3 mm/day over the Sahel of Africa, thus producing the low Nile flow. Future high-latitude eruptions would significantly impact the food and water supplies in these areas. Using observations of the flow of the Nile River, this new understanding is used to support a date of 939 for the beginning of the eruption of the Eldgjá volcano in Iceland, the largest high-latitude eruption of the past 1500 years. Citation: Oman, L., A. Robock, G. L. Stenchikov, and T. Thordarson (2006), High-latitude eruptions cast shadow over the African monsoon and the flow of the Nile, Geophys. Res. Lett., 33, L18711, doi:10.1029/ 2006GL027665.