Cleopatra’s suicide and the fall of ancient Egypt is the stuff of legend. Shakespearean drama aside, there is often far more fuelling the collapse of an empire than political squabbling alone.
Now researchers have traced a domino effect of social upheaval and devastating climate change back to an erupting volcano, possibly as far as the other side of the globe.
A team of historians has linked evidence of volcanic events found in ice-cores with seasonal patterns of the Nile’s flooding, arguing this disruption to the life-blood of Egypt could have precipitated events that led to the culture’s decline.
Climate change and social upheaval often go hand in hand, leading to dramatic shifts in politics and economics that can see entire civilisations come and go.
So the idea isn’t an outlandish one. But even reasonable hypotheses need solid evidence.
“That’s the beauty of these climate records,” says researcher Joseph Manning from Yale University.
“For the first time, you can actually see a dynamic society in Egypt, not just a static description of a bunch of texts in chronological order.”
The team relied on previous research detailing the timing of significant volcanic eruptions over the past 2,500 years.
Volcanoes don’t have to be spewing lava into your backyard to be a problem. Ash and particles of sulphur can form aerosols that disperse through the stratosphere, reflecting sunlight in ways that can affect temperature and rainfall far from the eruption site.
To determine how Egypt’s seasonal weather might have been affected by any timely eruptions, the researchers turned to a monument known as al-Miqyas, or the Islamic Nilometer.
This stunning piece of architecture is a mix of art, water source, and historical record keeping.
The structure has preserved a record of the Nile’s summer peaks since the early 7th century, allowing the researchers to model a relationship between the river’s flow and years there was an eruption somewhere on the planet.
For details on the Nile’s cycle prior to this period of history, the team had to dig a bit deeper and interpret historical writings.
The results was a picture of the river’s heartbeat over the course of Egypt’s history, one that reflected the planet’s tectonic activity.
“When the Nile flood was good, the Nile valley was one of the most agriculturally-productive places in the ancient world,” says climate historian Francis Ludlow from Trinity College in Dublin.
“But the river was famously prone to a high level of variation.”
The Nile is famous today for being the world’s longest river, but for the ancient Egyptians it was the centre of everything.
Every summer, monsoons from the equator would wash over the Nile’s upper reaches, providing a source of water than would wash silt down the river.
Without this yearly delivery of fertile soil and water Egypt’s crops would falter, leading to food shortages. Not to mention a lot of unhappy customers.
Historical records indicate that one such period occurred during the rule of the Ptolemaic dynasty, which began with the death of Alexander the Great in 323 BCE.
In roughly 44 BCE, during the reign of Queen Cleopatra VII, a particularly severe volcanic eruption somewhere else in the world blasted a plume of ash and hot gases into the atmosphere, suppressing the monsoons and giving rise to a serious famine.
Clearly there was a lot going on in the world at this time, what with Rome marching all over Europe and the Mediterranean like it owned everything.
But Cleopatra’s rule wasn’t in any way helped by a food shortage that upset the economy and helped smooth the way for a plague or two as country folk swarmed into the cities.
Ultimately this social unrest made it much easier for Rome to pick up the pieces once Cleopatra tragically left the scene in 30 BCE, possibly poisoned if not bitten by an asp.
Volcanoes might also help explain another Ptolemaic mystery.
The Roman historian Justinus wrote of the war monger Ptolemy III, if he “had not been recalled to Egypt by disturbances at home, would have made himself master of all Seleucus’s dominions”.
What disturbances made it so important that one of the dynasty’s most successful rulers would give up trying to add more of what is today Iraq and Syria to his borders and trot back home?
It seems we could also blame a volcano for kicking off that social grumble as well.
We’re yet to see any volcanic interruptions to monsoons this century.
“But that could change at any time,” says Manning.
“The potential for this needs to be taken into account in trying to agree on how the valuable waters of the Blue Nile are going to be managed between Ethiopia, Sudan and Egypt.”
This research was published in Nature Communications.