New Study Links Hidden 14th-Century Volcanic Eruptions to Chain of Events That Brought the Black Death to Europe

Previously unknown volcanic eruptions may have triggered a cascade of events that eventually delivered the Black Death — the deadliest pandemic in recorded history — to medieval Europe, according to new research.

The bubonic plague outbreak, which ravaged Europe in the mid-1300s, killed tens of millions and wiped out up to 60% of the population in some regions. Yet how exactly it reached Europe, and why it exploded with such devastating force, has long remained a subject of debate.

Now, two researchers studying centuries-old tree rings say a volcanic eruption may have been the initial spark.

By analyzing tree rings from Spain’s Pyrenees mountains, the team found that southern Europe experienced unusually cold, wet summers between 1345 and 1347. Comparing this climate shift with contemporary written accounts, they concluded that diminished sunlight — likely caused by one or more volcanic eruptions in 1345 — produced widespread cooling.

The resulting climate shock devastated harvests, triggered crop failures, and pushed much of the region toward famine.

At first, powerful Italian trading states appeared to have a solution. “They had established long-distance trade routes across the Mediterranean and the Black Sea, allowing them to activate a highly efficient system to prevent starvation,” said Martin Bauch, a historian at Germany’s Leibniz Institute for the History and Culture of Eastern Europe.

“But ultimately, these would inadvertently lead to a far bigger catastrophe,” he added.

Grain ships — and deadly stowaways

City-states such as Venice, Genoa and Pisa relied on ships transporting grain from the Mongol-ruled Golden Horde in Central Asia, where the plague bacterium Yersinia pestis is believed to have originated.

Decades of earlier research suggest those ships also carried rats infected with plague-bearing fleas. When they arrived in Mediterranean ports, the disease soon followed. Between 25 and 50 million people died across Europe over the next six years.

The new study argues that the volcanic eruption — by driving abrupt climate change, crop collapse and increased reliance on long-distance grain imports — set in motion the chain of natural, economic and political events that allowed the plague to reach Europe on such a massive scale.

Study co-author Ulf Büntgen of the University of Cambridge said the findings carry modern-day relevance.

“Although the coincidence of factors that contributed to the Black Death seems rare, the probability of zoonotic diseases emerging under climate change and translating into pandemics is likely to increase in a globalized world,” he said. “This is especially relevant given our recent experiences with Covid-19.”

The research was published Thursday in Communications Earth & Environment.