The Black Death may have been triggered by a medieval volcanic eruption
A volcanic eruption in 1345 may have set off a chain reaction that eventually led to the arrival of the Black Death in Europe, according to the latest research. The cooling and rainy years that followed the eruption caused agricultural decline, and together with increased grain imports, the pathogen responsible for the plague also reached the continent.
A new study suggests that a previously unknown volcanic eruption around 1345 triggered the climate changes that ultimately led to the devastating European plague epidemic known as the Black Death, Live Science reports.
Researchers claim that the eruption resulted in a cool and cloudy period in the Mediterranean region, which in turn reduced agricultural output. Due to shortages, Italian merchants began importing grain from the Black Sea region – and with it came the bacterium that causes bubonic plague.
A climatic turning point after 1345
Martin Bauch, a historian at the Leibniz Institute in Leipzig, and Ulf Büntgen of the University of Cambridge mainly sought to answer why the plague reached Europe specifically in 1347, and why it entered via Italy.
Historical sources record reduced sunlight, dense cloud cover and an extraordinary lunar eclipse between 1345 and 1349 in both Asia and Europe.
Palaeoclimatological analyses indicate that sulphur levels in polar ice also increased, pointing to an eruption in the tropics. Although the exact location remains unknown, the impact was enormous – bringing cooling followed by prolonged periods of rain.
Cold summers and poor harvests
European tree-ring studies show that between 1345 and 1347 summers were colder, and autumns far wetter, leading to soil erosion and flooding. Historical accounts clearly indicate that harvests of grapes and grain declined, especially in Italy.
Because of the shortages, Italian commercial fleets transported grain across the Black Sea to avoid famine. This, however, carried an unexpected consequence.
The Black Death arrived “as a stowaway”
The grain ships also brought the bacterium Yersinia pestis to Europe, most likely through fleas living in grain dust. The first human cases of plague were recorded in Venice only weeks after the last grain shipments arrived.
The spread of the infection followed a familiar pattern: rodents were infected first, and when they died out, fleas passed on to other mammals and eventually to humans.
A chance – yet fatal – coincidence
Although the devastation of the Black Death was immense – claiming perhaps up to 60% of Europe’s population – researchers argue the outbreak resulted from a combination of coincidence and long-term processes.
The volcanic eruption triggered short-term climate change, while the Italian grain-supply network created a pathway for the infection. According to Monica H. Green, a specialist in plague studies, the research offers groundbreaking new information about the 1345 eruption and sheds more light on why the outbreak occurred precisely at that time.
What can we learn from it?
Although events of such magnitude are rare, researchers warn that the likelihood of zoonotic diseases emerging continues to rise due to global warming and the intensification of global trade. Understanding past pandemics may therefore help us prepare for those of the future.
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