A volcanic eruption in the tropics around 1345 CE cooled the climate enough to trigger widespread crop failures across Europe and the Mediterranean. That famine forced Italian city states to import grain from the Black Sea region — and those ships may have carried the bacterium that caused the Black Death.
The Black Death killed an estimated 75 to 200 million people between 1347 and 1353, with mortality rates reaching 60% in some areas. Yet the precise trigger for how the pandemic began and spread so rapidly has remained unclear. A new study published in Communications Earth & Environment proposes a chain of events that connects climate, hunger, and trade in ways that finally make the timeline coherent.
The volcanic fingerprint in the ice
Researchers Martin Bauch and Ulf Büntgen pieced together evidence from tree rings across eight European regions, volcanic sulfur trapped in Antarctic and Greenland ice cores, and written records from the 1340s. The data converged on a single event: a major tropical eruption around 1345 CE that injected sulfur and ash into the atmosphere. The result was colder, wetter conditions across southern Europe and the Mediterranean — exactly where the plague would later arrive.
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Start Your News DetoxHistorical accounts from Spain, southern France, Italy, Egypt, and the Levant all describe the same crisis: widespread crop failures and famine. Cities couldn't feed themselves. In response, Venice and Genoa — then locked in conflict with the Mongol Golden Horde — negotiated a ceasefire specifically to secure grain shipments from the Black Sea region around 1347 CE.
Venetian records claim these imports prevented mass starvation. But the timing tells a darker story. The grain ships arrived in Italian ports like Genoa and Venice in 1347 — the same year the first documented plague cases appeared in those cities. The bacterium Yersinia pestis, carried by fleas living in grain stores, traveled with the shipments. As the grain was distributed to other cities, including Padua, the fleas went too, accelerating the plague's spread across Europe.
The eruption didn't cause the Black Death. But it set off a cascade: climate disruption → famine → desperate trade → pandemic. It's a reminder that the biggest historical events rarely have a single cause. They happen at the intersection of climate, economics, and biology — forces that still shape our world today.
