The Deadliest Volcanic Eruption in History

In 1815, Mount Tambora erupted on Sumbawa, an island of modern-day Indonesia. Historians regard it as the volcano eruption with the deadliest known direct impact: roughly 100,000 people died in the immediate aftermath.

But far more died over the next several years, due to secondary effects that spread all over the globe, says Gillen D’Arcy Wood, author of Tambora: The Eruption That Changed the World.

“What happened after Tambora is that there was three years of climate change,” he says. “The world got colder, and the weather systems changed completely for three years. And so you had widespread crop failure and starvation all from Asia to the United States to Europe.”

Volcanoes near the equator can cause global weather changes if their eruptions are powerful enough to release gases into the stratosphere. This gas gets trapped since it is too high to be washed away by rain, then travels along the equator and spreads out toward the poles. This decreases the amount of heat that passes through the stratosphere from the sun.

This doesn’t just affect whether you should put on a sweater or not; it has profound effects on the ecosystem you live in. With Tambora’s eruption, cooling temperatures led to decreased rainfall, failed crops, and mass starvation in many parts of the world.

It’s difficult to know how many people died because of starvation conditions, but “the death toll is probably about a million people, at least, in the years afterwards,” Wood says. “If you want to include the fact that Tambora unleashed a global pandemic of cholera … then the death toll goes into tens of millions.”