Historic volcanic eruptions and climate change impacts

The first telegram arrived in Singapore on a Monday in 1883, sent from the Dutch East Indies with urgent news: a volcanic island had obliterated itself in a catastrophic explosion. Within hours, the scope of the disaster became clear to readers across the world: over 36,000 people had died, mostly in tsunamis unleashed by the blast. For the first time in history, thanks to Victorian-era telegraph networks, humanity could watch a major natural disaster unfold and document its global effects in something approaching real time.

That eruption of Krakatau, between Java and Sumatra, became a turning point in our understanding of how historic volcanic eruptions shape climate and society. Since then, researchers have discovered that the world’s biggest volcanic events have repeatedly triggered famines, diseases, mass migration and the collapse of empires.

Why historic volcanic eruptions matter so much

The mechanism is surprisingly straightforward. When a massive volcano explodes, it hurls sulfur particles into the upper atmosphere. These particles reflect sunlight back to space, cooling the Earth. After Krakatau, the upper atmosphere was so laden with volcanic aerosols that summer temperatures in the Northern Hemisphere dropped by 0.6 degrees Celsius. The effect circled the globe within months, drifting volcanic particles so thick they painted vivid sunsets that contemporary artists, including possibly Edvard Munch, captured in their work.

The cooling itself was manageable. The problem came from what it did to harvests. Shorter growing seasons, unexpected frosts, torrential rains and droughts cascading across continents meant crop failures, starvation, and the collapse of food systems that societies had built around reliable weather patterns.

Historic volcanic eruptions also correlated with the emergence of epidemics. When crops failed and people weakened from malnutrition, disease spread faster. The Black Death, which killed roughly half of Europe’s population between 1346 and 1352, may have begun its journey across continents because of a chain of events set in motion by a volcanic eruption around 1345. Cold, wet summers in southern Europe damaged crops, forcing communities to import grain from the east. The grain ships arrived with rats carrying plague-infected fleas, according to research by Cambridge tree-ring specialist Ulf Büntgen and his colleagues.

Piecing together the evidence from ancient eruptions

The challenge for researchers studying historic volcanic eruptions has always been proof. A scribe in medieval Europe might write about a haze blocking the sun, but how do scientists know an eruption actually caused it? The answer lies frozen beneath the ice sheets of Greenland and Antarctica.

Polar ice cores preserve annual layers of atmospheric deposits like a book written in ice. Scientists can drill down through thousands of years and read the chemical signatures of volcanic ash and sulfur, revealing when major eruptions occurred. When researchers examined ice cores for the year 536, they found a distinctive sulfur signal matching historical accounts of bizarre weather that year: a haze that blocked the sun for 18 months, failed harvests, and the outbreak of what became the first documented global plague. Yet which volcano erupted remains unknown, because Iceland, the suspected location, was not yet populated and left no written record.

Better evidence emerged from historic volcanic eruptions pinpointed through detective work. The 1257 eruption of Samalas volcano in Indonesia was confirmed when researchers radiocarbon-dated ash and pumice around the volcano in 2013. Tree-ring studies revealed extensive cooling across North America and Eurasia from 1257 to 1259. In England, bad harvests led to starvation. In Japan, wet, cool summers destroyed rice production. Some scholars argue that this eruption helped trigger the climate stresses that contributed to an epidemic in China in 1259 that killed the last Mongol ruler, unraveling the Mongol Empire.

How did societies survive catastrophic volcanic eruptions in the past?

Not all regions suffered equally when historic volcanic eruptions triggered climate change. After the 1815 eruption of Tambora in Indonesia, which caused 1816 to be remembered as the “year without a summer,” Eastern Europe and western Russia actually experienced relatively good growing conditions. They produced surplus grain and exported it to struggling regions. Port cities with strong trade links, like London and Hamburg, had better access to imported food than inland areas. Those with transportation networks and trade connections proved more resilient.

Resilience, in other words, came from being connected. Isolated communities with no trade networks starved. Communities embedded in broader markets found alternative food sources.

Why this matters

Volcanologists are studying how historic volcanic eruptions reshaped societies because the lessons may apply today. We know that rapid climate shocks test the limits of human systems, and that some societies absorb those shocks better than others. The pattern observed in past centuries, where communities with trade networks survived better than isolated ones, mirrors contemporary debates about global supply chains and economic resilience.

• Historic volcanic eruptions provide a natural laboratory for understanding how societies respond to sudden, severe climate stress, knowledge that may inform how modern nations adapt to climate change
• Researchers have shown that major eruptions triggered global cooling, crop failures and epidemics that reshaped empires and drove mass migration, suggesting that climate shocks interact with existing social vulnerabilities in predictable ways
• The comparison between regions that thrived and regions that collapsed after historic volcanic eruptions reveals that access to trade networks and transportation infrastructure made societies significantly more resilient to environmental disaster

Clive Oppenheimer, a volcanologist at Cambridge, notes that climate shocks expose existing vulnerabilities in human society. Some crises pass without catastrophe; others strike when societies are already fragile. By studying how historic volcanic eruptions played out across different cultures and economic systems, researchers are building a clearer picture of how the modern world might weather the climate changes ahead. Thewealthora also covers markets and money, and these patterns have real implications for how institutions and economies prepare for future disruption.

Original reporting on this historic volcanic eruptions: Ars Technica.

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Originally reported by Ars Technica. Facts verified; analysis and wording are Thewealthora’s own.

Arpit Soni

The Thewealthora desk covers markets, money and personal finance, with zero jargon and every claim sourced.