teBy Shelby Traynor
Collage by Alex Hanson
The fall of the Ptolemaic Kingdom in 30 BC was nothing if not dramatic: there was unrest and uprising in Egypt, the death of Queen Cleopatra VII, and the surge of the Roman Empire. According to researchers addressing the European Geosciences Union General Assembly in April, volcanic eruptions probably had a hand in the fall of the Ptolemaic dynasty as well. That’s right, volcanoes.
A team of volcanologists and historians, including Joseph Manning of Yale and Francis Ludlow of Trinity College Dublin, got together to compare notes. When they studied historical accounts alongside data from ice cores in Greenland and Antarctica (samples acting as chemical roadmaps to the past), they found the timing of eruptions—and the fallout from said eruptions—coincided with the unrest in the Ptolemaic Kingdom.
For the Egyptian Kingdom, unrest meant starvation and famine. Researchers suspect volcanic eruptions disrupted rainfall—less rain in the Ethiopian highlands, and therefore less water being drained into the Blue Nile, meant there just wasn’t enough rainfall to irrigate crops. Which meant the Roman Empire, taking advantage of the recent death (Suicide? Murder?) of Cleopatra, essentially strolled into Egypt and took the metaphorical wheel.
History is ripe with impactful volcanic eruptions: an 1815 eruption in Indonesia sent New England and Europe into The Year Without Summer (also known as The Poverty Year, The Summer that Never Was, and Eighteen Hundred and Froze to Death), an 1883 eruption blocked out the sun in Java and Sumatra, and a cloud of ash hovered menacingly over southern Chile after an eruption in 2015.
Volcanic eruptions can have a huge and polarising impact on climate—volcanos are like shortcuts to the Earth’s mantle, and when they erupt they release all kinds of materials: lava, gas, ash, and revenge. That last one hasn’t been scientifically verified.
In some cases, during particularly nasty periods of volcanism, eruptions can produce a warming effect. And it happens for much the same reason as the world at large has come to expect: greenhouse gases, such as carbon dioxide and water vapor. However, with the run-of-the-mill volcanic activity we usually experience, the emissions are laughably small in comparison to what we create driving our cars down the freeway—according to a 2009 US Geological Survey, volcanoes worldwide clock up about 200 million tons of carbon dioxide a year. In comparison, our automotive and industrial activities generate about 24 billion tons of carbon dioxide.
Most of the time, volcanic eruptions produce a cooling effect. Particles of dust and ash, small enough to travel high into the stratosphere, shield the Earth from sunlight. Sulfur dioxide spits forth, eyes set on the stratosphere, combining with water to form sulfuric acid aerosols which mute the sun’s radiation. The subsequent cooling effect can last months to years.
Back to 30 BC Egypt—the masses are starving and revolting, Cleopatra has been bitten by an asp, and Octavian’s Roman army is approaching. According to researchers, the cooling effect associated with volcanic eruptions means there are fewer clouds. It’s possible volcanic fallout is interacting with the Intertropical Convergence Zone, a low pressure belt that is supposed to bring monsoon rains to the Nile, but isn’t.
By matching historical and climatic data, researchers found that eight out of nine traceable uprisings in the Ptolemaic Kingdom were linked to volcanic eruptions and fallout. The instability contributed to the toppling of a Kingdom and the installment of an Empire, changing history and shaping the world we live in now.
Volcanic eruptions have had a hand in climate and history in the past. If history really does repeat itself, eruptions will probable have a similar say in the future (I’m looking at you Yellowstone).