New research suggests that volcanic eruptions may have triggered climate cooling and famine that pushed Italian city-states to import grain from the Black Sea—unknowingly bringing plague-infected fleas with it.
Volcanic Cooling and the Conditions for a Medieval Pandemic
Research published today (December 4) in Communications Earth & Environment proposes that volcanic activity may have intensified the movement of the Black Death across medieval Europe. According to the authors, a period of cooling that followed this activity created widespread food shortages. Italian city-states responded by bringing in grain from the Black Sea region, and those shipments may have carried the plague-causing bacterium, Yersinia pestis.
The Black Death moved through Europe between 1347 and 1353 CE and killed up to 60% of people in some areas. Although its deadly impact is well documented, the reasons behind the specific timing of its arrival and rapid expansion remain unclear.
Evidence From Climate Records and Historical Accounts
To investigate this question, Martin Bauch and Ulf Büntgen examined earlier studies of tree ring data from eight European regions, measurements of volcanic sulfur collected from Antarctic and Greenland ice cores, and historical writings from the same period. Together, these sources point to a major tropical volcanic event around 1345 CE that increased sulfur and ash in the atmosphere. The resulting wet and cold weather affected large areas of southern Europe and the Mediterranean.
Written records describe extensive crop failures and famine during this period in Spain, southern France, northern and central Italy, Egypt, and the Levant. These hardships pushed Italian maritime powers, including Venice and Genoa, to negotiate a temporary ceasefire with the Mongols of the Golden Horde so they could secure grain from the Black Sea region around 1347 CE.
Grain Shipments and the Spread of Plague
Venetian sources claim that these grain imports prevented large-scale starvation. However, the timing of arriving grain ships and the appearance of plague in the cities that received them suggest another consequence. Fleas carrying Yersinia pestis may have been transported along with the grain. These fleas could then have traveled onward to places such as Padua as the shipments were redistributed, contributing to the wider spread of the Black Death through Europe.
A New Explanation for the Black Death’s Emergence
The authors conclude that their findings offer a potential explanation for how the Black Death began and moved through Europe, linking climatic disruption, famine, and the movement of grain during a critical moment in medieval history.
Reference: “Climate-driven changes in Mediterranean grain trade mitigated famine but introduced the Black Death to medieval Europe” by Martin Bauch, and Ulf Büntgen, 4 December 2025, Communications Earth & Environment.
DOI: 10.1038/s43247-025-02964-0
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5 Comments
Could… but will it?
I didn’t know that fleas liked grain! 🙂
Seriously, I think that what we have here is a spurious correlation — a coincidence. I think that while famine may have triggered desperate measures to venture into areas that were formerly inaccessible because of the conflict with the Mongols, it was most likely the sailors and the ship’s cats and rats that were the actual vectors for the fleas. It makes for an interesting fire-side story, but I’m not sure about the importance of the speculations.
The bottom line is that a previously unknown disease (actually the concept of “disease” was not known to the victims) that was easily transmissible, was introduced and spread rapidly because there was nothing that the people could do to treat their condition. Once the 60% of the population that was most susceptible (and unlucky) were eliminated, the remaining people probably had some natural genetic resistance and the rate of transmission decreased.
I would guess that if 2/3 of of a European population were dead and that original population were no greater than 100 million there would be increased distances between villages of the living and hence any disease would have less of chance of spanning the increased gaps even if people were not too scared to travel the greater distances on foot. 5 miles is 2 hours walk; 10 miles is 4 hours; why bother? The distance between mediaeval villages explains the assorted accents and dialects in the UK.
Bad enough to illustrate an article about the 14th century Black Death with a plague doctor mask, which, if the ever were in actual use, date from the 17th century, but to use an AI generated image on top of that is unforgivable. Do better.
I agree totally. Next, AI generated accident victim pictures?
AI is going to be used in very dangerous, detrimental, and destructive criminal enterprises.