Fig. 1
Political and environmental setting with volcanic forcing history. a Eastern Mediterranean wet season rainfall (taking as example the December mean, mm, 1950–2000, at 30 arc-seconds resolution, worldclim.org, v1.4)66, indicative of Ptolemaic and Seleukid territories potentially capable of rainfed agriculture, with state boundaries c.275 BCE overlain: Ptolemaic (black line with diagonal dashes) and Seleukid (thick gray dashes)67. Key territories contested by these states are numbered with red Arabic numerals alongside indicative rectangles (1, Cyrenaica; 2, ‘Koile’ Syria; 3, Cyprus; 4, Lycia; 5, Caria) and are observed to focus on regions potentially capable of rainfed agriculture. Selected urban power bases are located with Roman numerals ((i), Babylon; (ii), Antioch; (iii), Seleukia; (iv), Alexandria; (v), Memphis; (vi), Thebes). b Ice-core-indicated dates of maximum aerosol forcing from volcanic eruptions with time-integrated (i.e., cumulative (Methods section)) forcing estimates for the Northern Hemisphere, 400 BCE to the present27. CMIP5 eruptions are those five twentieth century eruptions included in the Coupled Model Intercomparison Project Phase 5 (Methods)
