At the origin of Black Deaththe epidemic that caused tens of millions of victims in Europe between 1347 and 1353, there might be volcanic eruptions occurred a short time ago. A new study, published in the journal, supports this Communications Earth & Environmentby researchers at the University of Cambridge and the Leibniz Institute for the History and Culture of Eastern Europe (GWZO) in Leipzig, Germany. The eruptions would have resulted in a climate changeof which there is trace in tree rings, causing famines in Europe. The only solution was to import cereals from the Black Sea region, along with which the deadly plague bacterium.
The volcanic eruptions that led to the Black Death in Europe
Despite the in-depth research carried out over time on the bacterium of the Black Death, the reason why it suddenly arrived in our continent remained unclear for a long time. In the new study, researchers used written testimonies and climate data to reconstruct a complete picture of the origin ofepidemic. THE tree trunks in the Spanish Pyrenees have provided valuable information thanks to the so-called “blue rings“, whose particular color is due to chemical processes that occur in correspondence with a climate change. In this case the rings signaled unusually cold and humid summers in 1345, 1346 and 1347 across much of southern Europe. The phenomenon is confirmed in documents of the time, which also report a persistent haze. Furthermore, they have been found in cores extracted from the ice of Greenland and Antarctica high concentrations of sulfur corresponding to that period. These phenomena can be considered the effect of one or more particularly intense volcanic eruptions: the ash and gases emitted in large quantities are able to reflect and therefore partially block solar radiation, resulting in a drop in temperatures for a certain period of time.
The consequences of cooling caused by eruptions
The cooling has had negative consequences on crops, causing famines in Europe. In order to guarantee the survival of the population and avoid political unrest, Italian city-states such as Venice and Genoa began to import grain from the Black Sea region. With the wheat, however, also arrived in Italy rat fleas, infected with the plague bacterium Yersinia pestisnative to wild rodent populations in Central Asia.
The fleas they survived the long journey by feeding on wheat flour and, once disembarked, they passed first to rats and then to humans. The epidemic spread first in northern Italy, and then extend across trade routes to the rest of Europe. The most affected regions, in which more than 60% of the population died, were precisely those that had the greatest need to import cereals due to the lack of local crops.
The study shows how the beginning of the Black Death was consequence of the interaction between natural and social factorshighlighting the role of climate change and globalization in the spread of epidemics. Today is theincrease in global temperatures to represent a danger by encouraging the proliferation of viruses and bacteria. From some research, in particular, it has emerged that the spread of plague bacteria can also increase considerably with a minimal increase in temperatures.
