A study published in the journal Communications Earth & Environment suggests that a volcanic eruption may have played a crucial role in the rapid spread of the Black Death across medieval Europe. According to researchers, the cooling caused by this eruption led to crop failures and famine. In response to the crisis, Italian city-states began importing grain from the Black Sea region, and these shipments may have served as the entry point for the plague bacterium Yersinia pestis.

The Black Death swept through Europe between 1347 and 1353, with mortality rates in some regions reaching as high as 60%. While the consequences of the pandemic are well documented, the exact causes and circumstances of its outbreak remain unclear. To investigate this, researchers Martin Bauch and Ulf Büntgen analyzed tree ring data from eight European regions, measurements of volcanic sulfur in ice cores from Antarctica and Greenland, as well as written sources from the 14th century. All this evidence points to a powerful volcanic eruption in the tropics around 1345. This event increased the amount of sulfur and ash in the atmosphere, resulting in a colder and wetter climate in southern Europe and the Mediterranean.

Historical records indicate widespread crop failures and famine in Spain, southern France, northern and central Italy, Egypt, and the Levant during this period. These hardships forced Italian maritime powers such as Venice and Genoa to negotiate a truce with the Mongols of the Golden Horde to secure grain supplies from the Black Sea region around 1347.

Venetian sources claim that these shipments helped prevent mass starvation. However, the timing of the arrival of grain ships and the first outbreaks of plague in the cities receiving the grain suggests another possibility. Fleas carrying Yersinia pestis may have entered Europe along with the grain. As shipments moved to other cities, including Padua, these fleas could have contributed to the accelerated spread of the Black Death throughout Europe.

The authors of the study conclude that the combination of climatic upheaval, famine, and grain transport provides a plausible explanation for how the Black Death began and spread across Europe.