Volcano Driven Famine Brought Black Plague Bearing Fleas In Grain Shipments To Europe In 1347

Volcanic eruptions in 1345 CE, lead to crop failures from 1345 to 1347 in the Mediterranean. This led Italians to import grain from Mongols near the sea of Azov region (currently between Ukraine and Russia) in 1347, where a black plague infestation was already present, spreading the plague to Europe. The black plague then ran rampant across Europe from 1347 to 1353 killing an immense share of the population of Europe (up to 60% of some towns and villages). 

Several years of famine also probably weakened the immune systems of most Europeans, impairing their ability to fight to black plague bacteria and making its lethality rate greater.

This black plague pandemic actually started in "the arid foothills of the Tien Shan mountains west of Lake Issyk-Kul in modern-day Kyrgyzstan" in 1338, but it took nine more years for it to reach Europe. While the volcano induced famines in Europe sped its spread, arguably its eventual arrival in Europe, sooner or later, was almost inevitable.

Human history is pockmarked with periods of death and destruction on unimaginable scales. Of these calamitous epochs, one stands out: The Black Death. The mid 14th century scourge killed tens of millions of people in Europe, Asia, and Africa and changed the course of history—marking the tail end of the Middle Ages and ushering in the cultural reawakening of the Renaissance by disrupting society, the feudal system, and economies across the continent. 

Researchers have long known the Black Death’s central villain: the bacterium Yersinia pestis, which caused the bubonic plague that swept through towns and villages with a mortality rate of up to 60 percent. Experts also know this microbial agent was spread by fleas, borne on the backs of rodent pests and maybe domestic animals, and passed between humans through the air and bodily fluids. But historians have had a tougher time recreating the sequence of events that initially started the devastating pandemic. 

Now, a pair of scientists have found new clues hidden in tree rings. By looking at these rings in the Spanish Pyrenees—as well as details in historical accounts of the time—they suggest that heightened volcanic activity sometime around 1345 may have sparked a famine, kicking off the sequence of events that eventually led to the Black Death raging through Eurasia from 1347 and 1353. They published their findings today in Communications Earth & Environment. . . . 

Here is the model Bauch and his colleague Ulf Büntgen, a dendrochronologist at Cambridge University, propose. As yet unknown volcanic eruptions ejected huge amounts of ash and gases into the atmosphere around 1345, causing drops in annual temperatures that persisted for several years. The cross sections from living and relic trees that the researchers studied had “blue rings,” denoting abnormally cold and wet summer growth seasons, in 1345, 1346, and 1347. Additional accounts from the time considered by Bauch and Büntgen tell of abnormal cloudiness and dark lunar eclipses, further hints of volcanic activity. This sustained cooling could have caused widespread crop failure across the Mediterranean. 

The resulting food shortages drove merchants in the maritime republics of Venice, Genoa, and Pisa to increase imports of grain from the Mongols living around the sea of Azov in 1347. Along with shipments of grain coursing across established trade routes came plague-infested fleas. Once Y. pestis and the fleas that carried it landed in Europe, the pathogen jumped to rats, mice, and perhaps domesticated animals. Eventually the disease hopped to humans, and people began transmitting it in densely packed population centers. The rest is a dark part of history. 

“For more than a century, these powerful Italian city states had established long-distance trade routes across the Mediterranean and the Black Sea, allowing them to activate a highly efficient system to prevent starvation,” said Bauch. “But ultimately, these would inadvertently lead to a far bigger catastrophe.” 

From a Facebook post by Nautilus Magazine. 

The introduction to the published paper states:

Recent advances in paleogenetic research now demonstrate that the Black Death was caused by the bacterium Yersinia pestis, which is likely to persist in different forms in natural reservoirs, including wildlife rodent populations. Investigations of great gerbil (Rhombomys opimus) populations in Kazakhstan, for instance, have outlined how the bacterium can be transmitted from one mammalian host to another by hematophagous insect vectors, such as fleas. The zoonotic disease, however, only occasionally spills over to domestic mammals and humans, and so far three pandemics have been documented: The Justinianic plague from circa 541 to the second half of the 8th century CE; the second pandemic starting around 1338 CE in central Asia and later outbreaks in the Mediterranean region and Europe until the early 19th century CE; and the third plague pandemic that had its origin in the 1770s in China and is arguably still prevalent in endemic rodent populations in different parts of the world.

A combination of archaeological, historical and ancient genomic data proposes that the causal agent of the second plague pandemic most likely originated from the arid foothills of the Tien Shan mountains west of Lake Issyk-Kul in modern-day Kyrgyzstan. A genetically distinct strain of the bacterium was then transmitted along ancient trade routes and entered Europe via the northern Black Sea region in the early 1340s. While changes in long-distance maritime grain trade have been introduced as a possible explanation for the import of plague-infected fleas to Venice and other Mediterranean harbour towns in 1347 CE, this chain of arguments excludes alternative transmission pathways, such as human-to-human infection or the transport of rodents and goods. Intriguingly, the role climatic changes and associated environmental factors may have played in the onset and establishment of the Black Death remains controversial amongst scholars from the natural and social sciences and the humanities.

Despite an ever-growing understanding of the evolution, origin and transmission of Yersinia pestis during the second plague pandemic, it is still unclear if the bacterium was frequently re-introduced into Europe or if natural reservoirs of the bacterium ever existed there. Recent insights into plague ecology include aspects of prolonged flea survival without human and/or rodent hosts but feeding opportunities on grain dust during long-term food shipments. Empirical evidence from around 1900 CE may therefore be considered as a possible explanation of how Yersinia pestis could have arrived in medieval Italy. While there is so far no convincing argument to pre-date the beginning of the second plague pandemic into the 13th century CE, changes in socio-economic structures, political institutions and trade networks since the second half of the 13th century possibly impacted the course of the second plague pandemic.

Here, we show that interdisciplinary investigations into the entanglements between weather, climate, ecology and society well before the Black Death are essential to understand the exceptional level of spread and virulence that made the first wave of the second plague pandemic so deadly. Based on annually resolved and absolutely dated reconstructions of volcanically forced cooling, transregional famine, and changes in long-distance maritime grain trade from 1345–1347 CE, we argue that the onset of the Black Death most likely resulted from a complex interplay of natural and societal factors and processes. Although this unique spatiotemporal coincidence of many influences seems rare, our findings emphasise the increased likelihood of zoonotic infectious diseases to suddenly emerge and rapidly translate into pandemics in both, a globalised and warmer world with COVID-19 just being the latest warning sign.