A volcanic eruption around 1345 may have set off a domino effect that sparked Europe’s deadliest pandemic, the Black Death, researchers propose.
Spanning tree-ring and ice-core records, the study suggests that the eruption triggered a climate shock, which cascaded into a series of events that brought the disease to medieval Europe.
The scenario goes like this: volcanic ash and gases injected large quantities of dust into the atmosphere, blocking sunlight and causing sharp, multi-year temperature drops. That climate downturn led to widespread crop failures across the Mediterranean.
To prevent famine, major Italian city-states turned to grain imports from regions near the Black Sea. In doing so, they inadvertently ferried plague-carrying fleas into Europe, enabling the outbreak to take hold.
Experts describe this as a “perfect storm”—a climate shock, food insecurity, and global trade all intertwining to create ideal conditions for disease spread in a warmer, more connected world.
“While the exact combination of factors behind the Black Death may be unusual, the likelihood that zoonotic diseases could emerge and trigger pandemics in a changing climate and a globalized system is probably increasing,” noted Dr. Ulf Büntgen of the University of Cambridge.
He also pointed to contemporary parallels, noting the relevance of recent experiences with Covid-19.
The Black Death ravaged Europe in 1348–1349, killing up to half of the population. The disease was caused by the bacterium Yersinia pestis, transmitted by wild rodents such as rats and by fleas.
Researchers trace the outbreak’s origins to Central Asia, with the disease spreading outward through trade networks.
In this new study, a collaboration between the University of Cambridge and the Leibniz Institute for the History and Culture of Eastern Europe (GWZO) in Leipzig fills a missing link in the narrative.
By analyzing tree rings and ice cores from the period, they reconstructed climate conditions and found evidence of a volcanic event around 1345 that cooled the climate for several years.
The resulting agricultural shortfalls then forced Italian city-states to import grain from the Black Sea region, unintentionally introducing the bacterium into Europe.
According to Dr. Martin Bauch, a medieval climate and epidemiology historian at GWZO, the climatic episode intersected with a fragile food-security system, creating a “perfect storm.”
For more than a century, these northern Italian powerhouses had built extensive long-distance trade networks across the Mediterranean and the Black Sea, establishing an efficient system to avert famine. Ultimately, though, these very structures may have contributed to a catastrophe on a continental scale.
The study’s findings are published in Communications Earth & Environment.
