Volcanic activity may have exacerbated the spread of the Black Death through medieval Europe, according to a study published in Communications Earth & Environment. The authors suggest that climatic cooling owing to volcanic activity, and a subsequent famine, led the Italian city states to import grain shipments from the Black Sea region that may have contained the plague bacterium, Yersinia pestis.
The Black Death spread throughout Europe between 1347 and 1353 CE and had a mortality rate of up to 60% in some regions. Despite its long-lasting effects on the region, the reasons for the timing of its onset and spread are not well understood.
Martin Bauch and Ulf Büntgen reviewed previously published tree ring data from eight regions across Europe, estimates of volcanic sulphur levels derived from ice cores collected in Antarctica and Greenland, and written accounts from the time. The combined evidence suggests that volcanic activity in an unknown location in the tropics around 1345 CE led to increased sulphur and ash levels in the atmosphere and wet and cold conditions throughout southern Europe and the Mediterranean region. Written evidence indicates that these conditions led to crop failures and famine in large parts of Spain, southern France, northern and central Italy, Egypt, and the Levant simultaneously. This led the Italian maritime city states — such as Venice and Genoa — to broker a ceasefire in an ongoing conflict with the Mongols of the Golden Horde and then import large amounts of grain from around the Black Sea in approximately 1347 CE. Although Venetian written sources report that this grain trade saved residents from starvation, the timing of grain ship arrivals and plague outbreaks in cities importing grain suggest that it may also have brought fleas infected with the plague bacterium. These infected fleas may then have been distributed in grain shipments to other parts of Italy such as Padua, exacerbating the spread of the Black Death across Europe.
The authors conclude that their findings provide a possible mechanism to describe the onset and spread of the Black Death in Europe.
