Scientists have proposed a startling new explanation for the rapid spread of the Black Death, the pandemic that wiped out between a third and half of Europe's population in the mid-14th century. Research points to a colossal volcanic eruption as the catalyst for a perfect storm of events that unleashed the plague.
The Climate Clue Hidden in Ice and Trees
An international team of researchers from Cambridge and Germany has pieced together a compelling narrative from environmental evidence. Their study, published in Communications Earth & Environment, identifies sooty particles trapped in the ice sheets of Antarctica and Greenland.
These particles indicate at least one major eruption from an unknown tropical volcano around the year 1345. This event would have shrouded the planet in a dense haze of ash and sulphur, cooling the climate.
This theory is supported by historical accounts of unusually cloudy skies and dark lunar eclipses from the period. Furthermore, analysis of tree rings shows three consecutive years of stunted growth immediately following the suspected eruption, pointing to cool, wet conditions that devastated harvests.
From Famine to Pandemic: A Deadly Chain Reaction
Dr Martin Bauch, a historian of medieval climate and co-author of the study, explained the critical sequence. The volcanic-induced climate shift led to widespread crop failures and famine across Europe and the Mediterranean in the years before the plague arrived.
"That large-scale pattern can only have a climatic explanation and the volcano is a good one because the impact would last two or three years," Dr Bauch told Sky News. "It all fits together."
This famine drove powerful Italian maritime states like Venice, Genoa, and Pisa to seek new grain supplies. They turned to the Mongols of the Golden Horde around the Black Sea in 1347. According to the research, ships carrying this vital grain also carried an unintended cargo: fleas infected with the Yersinia pestis bacterium, likely from wild gerbils in central Asia.
Once in European ports, the infected fleas jumped to local rat populations and other mammals, triggering the devastating pandemic. "These powerful Italian city states... ultimately, these would inadvertently lead to a far bigger catastrophe," said Dr Bauch.
A Historical Warning for a Globalised World
The researchers describe the Black Death as a tragic consequence of early globalisation, where trade networks designed to solve a crisis instead imported a greater one. Professor Ulf Buentgen from Cambridge University, another study author, highlighted the modern relevance.
"Although the coincidence of factors... seem rare, the probability of zoonotic diseases emerging under climate change and translating into pandemics is likely to increase in a globalised world," he stated. "This is especially relevant given our recent experiences with Covid-19."
The study underscores how a convergence of climatic, agricultural, and societal factors can create the ideal conditions for a pandemic, offering a sobering lesson from history as the world faces contemporary climate and health challenges.
