:max_bytes(150000):strip_icc():focal(923x502:925x504)/Lava-flow-from-stromboli-volcano-120825-728cc62ac9a4402aa59ac856318f5fe5.jpg?w=800&resize=800,500&ssl=1 "Volcanic eruption led to the Black Death, new research suggests")
A study suggests that a volcanic eruption might have set off the Black Death
Recent studies suggest that a colossal volcanic eruption during the mid-14th century might have triggered a series of events culminating in the Black Death, one of the most lethal pandemics in human history. By integrating climate data from tree rings, ice cores, and historical documents, researchers are illuminating how environmental and societal elements converged to form an ideal scenario for the plague.
Researchers have long studied the Black Death, which ravaged Europe between 1347 and 1351, claiming the lives of at least 25 million people—roughly half of the continent’s population at the time. While the role of the plague bacterium, Yersinia pestis is well established, the conditions that allowed the disease to spread so rapidly have remained less clear. The new study, published in Communications Earth & Environment, suggests that an unusual combination of volcanic activity, climate disruption, and trade networks may have been critical in sparking the pandemic.
A fiery volcanic ignition
The research team identified evidence pointing to a significant volcanic eruption around 1345, approximately two years before the first documented outbreak of the Black Death. Although the precise location remains uncertain, the eruption—or possibly a cluster of eruptions—likely occurred in the tropics. The resulting volcanic haze would have partially blocked sunlight across Europe and the Mediterranean region, triggering cooler temperatures and successive years of poor harvests.
This sudden climatic downturn would have caused widespread crop failures, prompting Italian city-states such as Venice and Genoa to import large quantities of grain from the Black Sea region. While these shipments alleviated immediate famine concerns, they inadvertently became a conduit for disease. Fleas carrying Yersinia pestis, which primarily infect rodents, traveled aboard these ships and ultimately transmitted the plague to humans.
“The bacterium responsible for the plague infects fleas that typically live on rats. When these primary hosts perish, the fleas then target humans,” stated Martin Bauch, a historian specializing in medieval climate and epidemiology at the Leibniz Institute in Germany and coauthor of the study. “Fleas are capable of surviving on grain dust for extended periods, enabling them to withstand lengthy sea voyages before arriving in populated regions.”
Indicators of climate found in tree rings and ice cores
To trace the environmental conditions preceding the Black Death, the researchers examined thousands of tree ring samples collected across Europe, including both living trees and naturally preserved dead wood. Tree rings provide a high-resolution record of past climate conditions: wider rings indicate favorable growth conditions, while narrower rings point to colder, drier years.
The data indicated a significant climatic decline in 1345 and 1346, aligning with a volcanic cooling event. Corroborating this, ice core samples from Greenland and Antarctica exhibited sulfur anomalies from the same timeframe, further implying a major volcanic eruption. “The alignment of tree ring and ice core evidence suggests an environmental shock capable of impacting agriculture throughout Europe,” stated Ulf Büntgen, a professor of environmental systems analysis at the University of Cambridge and coauthor of the study.
The aftermath of the eruption seems to have resulted in a precarious situation in the Mediterranean. Diminished crop yields increased dependence on imported grain, which enabled the introduction of plague-carrying fleas into densely populated urban centers.
The impact of commerce and human endeavors
Italian ports played a crucial role in the spread of the Black Death. Cities like Venice and Genoa, heavily dependent on grain imports from the Black Sea, became entry points for the bacterium. The grains were stored in central granaries before being distributed throughout the region, providing a mechanism for rapid dissemination of plague-infected fleas.
Historical records, including administrative documents, letters, and contemporary accounts, corroborate the timeline suggested by the climate data. These sources describe food shortages, famine, and the urgent movement of grain across trade networks in the years preceding the Black Death. The integration of environmental and documentary evidence allowed the research team to construct a comprehensive narrative linking a volcanic eruption to societal disruptions and the onset of the pandemic.
Bauch stated, “To fully grasp the timing of the Black Death in 1347 and 1348, one must consider the famine and economic pressures brought about by these unusual years.”
Understanding the mechanics of transmission
The study underscores the complex interplay of natural and human factors in historical pandemics. Rat fleas, the primary vectors of Yersinia pestis, thrived in grain stores and could endure months without direct contact with rodent hosts. Once ships carrying contaminated grain reached Mediterranean ports, the fleas began infecting local rodent populations and subsequently humans.
Bauch and Büntgen emphasize that this sequence illustrates a broader principle: pandemics often arise from the convergence of environmental, economic, and biological factors. In the case of the Black Death, a volcanic eruption, poor harvests, and trade routes created the conditions necessary for a pathogen to devastate Europe.
“This is a reminder that historical pandemics were not solely biological events,” Büntgen said. “They were the outcome of intricate interactions between climate, ecology, and human society.”
Differences in regional impact
The research additionally sheds light on why certain regions in Europe were impacted more significantly than others. Although Venice and Genoa suffered intense outbreaks because of their reliance on imported grain, other prominent cities, such as Rome and Milan, were largely unaffected. These cities were encircled by local grain-producing areas, which diminished the necessity for external deliveries and curtailed exposure to plague-carrying fleas.
The uneven mortality across Europe, with some regions losing up to 60% of their population while others remained largely intact, reflects this combination of environmental and societal variables. The findings highlight the importance of local geography and economic practices in shaping the impact of pandemics.
Implications for historical and modern understanding
Experts who were not part of the study have commended its multidisciplinary approach. Mark Welford, a geography professor at the University of Northern Iowa, observed that the research highlights the link between climate events and disease dynamics. Likewise, Mark Bailey, a professor of late medieval history at the University of East Anglia, emphasized how the study illustrates the impact of climate-induced famine and changing trade patterns in enabling the Black Death.
Alex Brown, an associate professor of medieval economic and social history at Durham University, emphasized the study’s broader relevance. “This research illustrates the importance of understanding interactions between humans, animals, and the environment,” Brown said. “It provides insights not only into historical pandemics but also into contemporary strategies for pandemic preparedness.”
By integrating paleoclimatic evidence, historical documentation, and epidemiological insights, the study offers a more nuanced understanding of the Black Death. It underscores that the pandemic was not simply the result of a single pathogen but arose from a cascade of interconnected events, beginning with a volcanic eruption that altered climate, agriculture, and trade patterns.
A glimpse into history
This research provides a compelling example of how multidisciplinary approaches can illuminate historical events. The combination of tree rings, ice core chemistry, and archival evidence allows scientists to reconstruct the environmental and societal context of one of history’s most devastating pandemics.
As researchers continue to explore the intersection of climate, trade, and disease, studies like this may reshape our understanding of how natural events influence human history. The Black Death serves as a cautionary tale: pandemics are often the product of complex, interwoven factors, and recognizing these dynamics is essential for preparing for future global health crises.
The latest research presents a credible scenario where a volcanic eruption initiated a series of environmental and societal upheavals that enabled the Black Death to proliferate throughout Europe. By analyzing both natural and human systems, scientists have delivered an unparalleled viewpoint on how remarkable alignments of climate, trade, and biology can lead to a devastating pandemic, imprinting a lasting mark on society, economy, and culture.
