Volcanic ash layers suggest eruptions may have messed with crop-dependent monsoons, leading to an era of revolt
A series of volcanic eruptions may have helped bring about the downfall of the last Egyptian dynasty 2,000 years ago.
By suppressing the monsoons that swelled the Nile River each summer, triggering flooding that supported the region’s agriculture, the eruptions probably helped usher in an era of periodic revolts, researchers report online October 17 in Nature Communications. That upheaval ultimately doomed the dynasty that ruled Egypt’s Ptolemaic Kingdom for nearly 300 years until the death of Cleopatra.
To piece together this puzzle, Yale University historian Joseph Manning and his colleagues first compared records of Nile River heights dating back to A.D. 622 with volcanic eruptions recorded in ice cores from Greenland and Antarctica that date back 2,500 years. Ash layers in the ice cores, corresponding to “eruption years”, were linked to years of less extensive