Climate Change and the Black Death’s Arrival in Europe

Researchers suggest that a climate disaster, which necessitated a shift in trade routes, might have facilitated the introduction of the plague into Europe, ultimately leading to the Black Death of the 14th century.

In a study published in the journal Communications Earth & Environment, scientists combined historical data with polar ice core analyses and European tree rings.

Martin Bauch of the Leibniz Institute in Germany and Ulf Büntgen from Cambridge University concluded that a mysterious volcanic eruption around 1345 released ash and sulfur into the atmosphere, cooling the climate and resulting in crop failures across the Mediterranean.

This crisis prompted major port cities to trade with the Golden Horde in Central Asia, inadvertently providing safe passage for Yersinia pestis, the bacterium behind the Black Death, into Europe.

While Italian city-states had developed effective food security measures, they ultimately couldn’t counter the devastation brought by the plague.

Bauch remarked, “It’s a mix of coincidences that lead to unexpected consequences. From a 14th-century viewpoint, one couldn’t predict that the very system that prevents starvation would lead to mass fatalities if the Black Death reached your city.”

Understanding the Black Death

The plague, caused by Yersinia pestis, was responsible for a catastrophic wave of illness across Europe from 1347 to 1351.

People bitten by infected animals like fleas or rodents would typically develop swollen lymph nodes, known as “buboes,” accompanied by fever, fatigue, and aches. If the bacteria spread to the lungs, it could evolve into pneumonic plague, a more lethal variant.

Thankfully, the advent of antibiotics has largely reduced the plague’s threat today. However, it does still pose a risk in parts of the world such as Madagascar, the Democratic Republic of Congo, and Peru, with occasional cases reported in the western United States and Central Asia.

Interestingly, Central Asia is believed to be the plague’s origin. A 2022 study pinpointed the initial strain of Yersinia pestis to outbreaks in the Tian Shan mountains, located near modern Kyrgyzstan, around 1338.

Through trade and migration, disease-carrying rodents and insects likely made their way into western Eurasia and Europe, spreading the plague.

Plague Arrivals and Environmental Impacts

The path the plague took to reach Europe has long sparked debate. In this recent study, Bauch and Büntgen outlined a possible route for how the disease entered the continent.

They posited that tree ring data from eight European regions, alongside volcanic sulfur found in polar ice cores, indicates that the 1345 volcanic eruption caused a significant cooling effect that impacted Mediterranean crops, leading to famine in southern Europe.

Historical records reveal that major Italian port cities, like Venice and Genoa, engaged in trade with the Mongol Golden Horde during this famine, importing grain via the Black Sea. While this alleviated local hunger, it likely introduced the plague, further spreading it through Italian states as grain trading expanded.

Utilizing environmental indicators like tree rings and ice cores allows historians and scientists to collaborate and comprehend how environmental transformations can trigger social and public health crises.

“Only tree rings provide the quality needed to piece together these events,” Bauch explained.

When scientific findings are integrated with historical data, researchers like Bauch and Büntgen can start to unravel the factors behind major events, including the Black Death.

Maria Spyrou, a paleopathologist at the University of Tübingen who previously identified the plague’s origins, noted that this recent study contributes further insight into how the plague infiltrated and spread through medieval Europe.

Spyrou mentioned that this investigation supports the idea of a mid-14th century emergence of the pandemic, aligning with genetic evidence indicating that ancestors of Black Death strains existed in both the Volga region and the Tian Shan mountains.

Yet, she observes that while this new route from the Black Sea to Europe offers clarity, there remains uncertainty about how the plague moved across Central Asia itself.

Bauch concurs, indicating that their study presents just one of the several theories regarding how the plague entered and spread throughout 14th-century Europe.