A Massive Volcanic Eruption in Alaska May Have Doomed the Roman Republic

The fall of the Roman Republic gave rise to the Roman Empire, making it one of the most significant events in Western history. According to a new study published in Proceedings of the National Academy of Sciences, it may have been hastened by a volcanic eruption on the other side of the world.

The year 43 BCE was a time of social unrest in ancient Rome. Julius Caesar had been assassinated a year earlier, sparking fights for political control that led to the fall of the Roman Republic and the Ptolemaic Kingdom. This was also a period of devastating climate change. Accounts from the era describe crop failure, famine, and disease plaguing the Mediterranean region as temperatures dropped. The new study from an international team of scientists connects these disasters to the massive eruption of an Alaskan volcano around the same time.

Researchers looked at Arctic ice cores containing millennia of geological data and found that a volcanic eruption—one of the largest of the past 2500 years—occurred in 43 BCE. Further analysis of the volcanic material inside the cores linked the event to the Okmok volcano in Alaska. Using Earth system modeling software, researchers digitally recreated the impact of the volcanic activity on a global scale. The model showed colder, rainier weather patterns in the Mediterranean for two years following the eruption, with seasonal temperatures dropping more than 10°F below normal in some places.

The connection between a volcanic eruption and climate change thousands of miles away isn’t hard to make. During violent eruptions, volcanoes spew debris and gases into the atmosphere. Such materials can block energy from the sun and absorb warmth from the Earth, disrupting the planet’s radiative balance and triggering a cooling trend.

The link between the 43 BCE eruption and the fall of Rome, however, is harder to prove. While data shows that the eruption spurred Mediterranean climate change at this time, written evidence showing that the harsh weather (and the death and hardship it caused) were behind the region’s political upheaval is sparse. Many factors contributed to Rome’s demise, and if this event played a role, it was in further destabilizing a kingdom that was already on the brink of collapse.

“ was killed on the Ides of March in 44 BCE by his rivals in the Senate, but rather than stabilizing the Republic, it instead launched a power struggle to see who would succeed Caesar,” Joseph R. McConnell, an environmental and climate scientist at the Desert Research Institute in Nevada and the study's co-author, tells Mental Floss. “Exactly when this power struggle was at its apex in 43 and 42 BCE, the Mediterranean experienced some of the worst weather of the past 2500 years as a result of the early 43 BCE Okmok volcanic eruption. While we can’t actually prove that the extreme weather and likely crop failures, food shortages, epidemic disease that resulted caused the downfall of the Republic 2000 years ago, it seems only logical that it must have played a significant role.”

Natural disasters triggering societal collapse have been a common story throughout history. Over a millennium before the Roman Republic ended, the Icelandic volcano Hekla erupted and caused cooling in Northern Europe. The large number of refugees that fled south as a result spelled ruin for the Eastern Mediterranean, which had been a thriving civilization up to this point. McConnell emphasizes that civilizations are no less vulnerable to cataclysmic disasters now than they were thousands of years ago—especially during politically volatile times.

“There are some interesting parallels to today, with democracies on the ropes and authoritarian wannabes on the rise, just like at the end of the Roman Republic,” he says. “Let’s hope our democratic institutions survive this time, because they didn’t 2000 years ago.”