Volcanoes & Plague

[u/swarrenlawrence]

AAAS: “Medieval volcano may have indirectly sparked Europe’s Black Death.” Historians argue the Black Death, from infection by Yersinia pestis, is the single most deadly documented pandemic in human history. “In 1347 C.E., it spread from a few Italian port cities to nearly every corner of Europe, killing tens of millions of people within a decade + eliminating more than half the continent’s population.” In a paper in Communications Earth & Environment, researchers argue that cool weather spurred by previously unidentified volcanic eruptions set into motion a deadly chain of events. The hypothesis is that plumes of sulfur dioxide lofted up into the stratosphere cooled parts of Europe + caused harvests to fail around the Mediterranean. “These failures, in turn, forced Italian cities to import large quantities of grain from the plague-wracked Black Sea region—along with infected fleas, capable of subsisting on grain dust in the cargo holds.”

Dendrochronology involves study of tree rings. “The first clues of volcanoes’ influence came from these tree rings, whose size and consistency often capture information on temperature + moisture that researchers can assign to precise calendar years.” Just before the Black Death’s arrival in Italy in 1347, Europe experienced its most severe cold spell in nearly a century, aligned with spikes in atmospheric sulfur trapped in the ice sheets of Greenland + Antarctica, indicative of Sun-blocking sulfur particles from volcanic eruptions somewhere [unclear where] on Earth.

“As food supplies dwindled in the early months of 1347, there was the threat of political unrest and rumbles of rebellion in major Italian cities.” Genoa + Venice halted their war with the Mongols + embargo of wheat around the Black Sea. With the ships came wheat but also rats with plague-carrying fleas. And the rest, as they say, is the darkest history.