Interesting article about how volcanoes contributed to unrest in Ancient Egypt. A series of eruptions led to less flooding in the Nile River Valley which led to food shortages.
Volcanic Eruptions May Have Contributed to Unrest in Ancient Egypt
Using climate modeling, a group of scientists have found that four closely timed volcanic eruptions around the world over 2,100 years ago might have led to less flooding of the Nile River, which would have deprived the valley of water needed for agriculture. A strain on farming could have contributed to revolts and social unrest seen in ancient Egypt at the time.
River flooding was "the lifeblood of a place like Egypt," said Joseph Manning, a historian at Yale University who specializes in Egypt's Ptolemaic period, which lasted from 305 to 30 B.C. Manning leads a broader Yale Nile Initiative that the modeling is a part of.Singh and his collaborators focused on 168 to 158 B.C., a period that Manning called "a pivotal decade in Mediterranean history." Rome had been amassing power in the region throughout the second century B.C. and won a crucial war against Macedonia in 168 B.C., putting "huge external pressure" on states such as Egypt, he said.
The researchers hypothesize that the four eruptions they studied occurred in modern-day Philippines, Iceland, Alaska and eastern Russia.Read the entire article at the link.In general, volcanic eruptions contribute volcanic ash and sulfate aerosols to the atmosphere that shade the planet from the sun's radiation, cooling Earth's atmosphere. Singh said northern hemisphere eruptions affect the movement of a tropical zone in the atmosphere that is a source of rain. The cooler northern hemisphere isn't able to pull this moisture-laden belt as far northward as usual during the monsoon season, so areas such as the Ethiopian highlands get less rain.
Rainfall in this region contributes to the Blue Nile River, a source of 80% of the Nile's water during the rainy season. Egypt itself gets little to no rainfall, so ancient Egyptians needed the river to flood to water their crops, which included wheat, barley, beans and lentils.