The largest volcanic eruption in recorded history, which killed over seventy thousand people directly and caused the 'Year Without a Summer' of 1816 — disrupting agriculture across the Northern Hemisphere, driving famine and migration from Europe to North America, and demonstrating for the first time that a single geological event could alter global climate.
A mountain in Indonesia erupted in 1815. The following year, it snowed in New England in June. Crops failed across Europe. Tens of thousands starved. Mary Shelley, stranded indoors by the cold and rain, wrote Frankenstein. The connection between a tropical volcano and a cold summer in Switzerland is one of the most consequential causal chains in modern history.