The Volcano That Cancelled Summer: Tambora 1815

A volcano is heard a thousand miles away. Its haze cancels summer. Snow falls in June. Harvests fail across the Northern Hemisphere. Bread riots shake Europe. In a rainy Swiss villa, a ghost-story contest gives us Frankenstein. This is Tambora. Here's how it happened.

Start with a mountain. Tambora, on the island of Sumbawa, in what is now Indonesia. In 1815 it stands about 4,300 metres tall, among the highest peaks in the archipelago. On its slopes live traders and farmers, who speak a language found nowhere else, apparently unrelated to the island's others. In 1812 it begins to rumble, and sends up a dark cloud. Then, on the fifth of April 1815, it wakes up for real. The blast is heard on the island of Ternate, 1,400 kilometres away. Some who hear it take it for distant cannon fire. Nobody is under attack. It is a warm-up. Five days later, at seven in the evening, the mountain gets serious.

Around seven, the eruption intensifies. By eight, pumice is falling. By nine, ash. Then the towering column of ash collapses, and glowing avalanches of gas and rock, called pyroclastic flows, race down the mountain. They destroy the village of Tambora. Around ten at night, a tsunami about four metres high hits the coast at Sanggar. By morning, the mountain has lost about a third of its height, from roughly 4,300 metres to roughly 2,850. In its place is a vast crater, a caldera, six to seven kilometres wide. Two days later, floating cinders form a raft two feet thick that ships struggle to push through. Afterwards, Sir Stamford Raffles, the British governor of Java, collects eyewitness reports. One counts just twenty-six survivors in the province of Tambora, out of twelve thousand people. At its peak, the ash column had climbed more than forty kilometres, into the stratosphere, the calm layer of air above the weather. That is a seven on the scale volcanologists use. The most powerful eruption in recorded history. Four to ten times the energy of Krakatoa, if you have heard of Krakatoa. Most people have. Far fewer have heard of Tambora. For Sumbawa, the worst was over. For the rest of the world, it had barely begun. Up in the stratosphere, something invisible was starting to spread. And the first people to notice would be looking at the sunset.

The eruption left more than ash. It left sulfur gas, which turns into a haze of tiny droplets. Nobody knows exactly how much. Estimates run from ten to over a hundred million tonnes. High in the stratosphere, there is no rain to wash it out, so the haze spreads around the planet and lingers. Its main talent is reflecting sunlight back into space. In the northeastern United States, a persistent dry fog settles in. Later scientists identify it as a veil of sulfate particles. In London, sunsets blaze in unnatural colours in late June and early July 1815, and again that autumn. Some researchers link the glowing skies in paintings of the era, Turner's among them, to volcanic dust. Then comes the cooling. In the summer of 1816, the Northern Hemisphere is about half a degree Celsius cooler on average. Estimates run from 0.4 to 0.7. That sounds like nothing. Ask a farmer in New England, in May of 1816.

An average hides a lot of frost. In May 1816, frost kills most crops at higher elevations in Massachusetts, New Hampshire, Vermont and upstate New York. On the sixth of June, snow falls in Albany, New York, and in Maine. In late June, Cape May, New Jersey, sees frost five nights in a row. Between 1815 and 1816, the price of oats in the United States rises from twelve cents a bushel to ninety-two. Some call it the Poverty Year. Europe gets a different problem: rain. In Hungary, snow falls tinted brown. In northern Italy, it falls red. Dusseldorf receives almost thirteen inches between June and August. The English Midlands have a colder July than any in a record running from 1698 to 1952. The Paris Observatory logs a summer three degrees Celsius below normal. In July, The Times warns that the rain will flatten the corn. Across two continents, the summer of 1816 is wet, cold, and grey. And in one rented villa beside Lake Geneva, a group of young writers is shut in by the rain. One of them is about to change literature.

It is June 1816. Lord Byron, the most famous poet in Europe, has rented the Villa Diodati, above Lake Geneva. Nearby are the poet Percy Shelley, his partner Mary, later Mary Shelley, her stepsister Claire Clairmont, and Byron's physician, John Polidori. Mary describes the weather herself: 'It proved a wet, ungenial summer, and incessant rain often confined us for days to the house.' They read German ghost stories aloud. Then Byron says: 'We will each write a ghost story.' Everyone agrees. Most of them give up. Mary, eighteen, spends days with nothing. Then, in what she calls a waking dream, she sees 'the pale student of unhallowed arts kneeling beside the thing he had put together.' That image becomes Frankenstein. She wrote this account fifteen years later, in 1831, so treat it as her memory, not a diary. Polidori later turns a fragment of Byron's into The Vampyre. Byron writes Darkness, an apocalyptic poem about the end of the world. So did a volcano write Frankenstein? No. But the rain that kept them inside was part of the strange weather of 1816, which scientists link to Tambora. Inside the villa, that weather made stories. Outside, it was making famine.

The stories end. The hunger does not. Harvests fail across Europe, and by 1817 grain prices average about twice their level in 1815. In East Anglia in May 1816, around 1,500 rioters march behind a flag reading 'bread or blood', and loot mills. Food riots in 1816 and 1817 are the most violent in Europe since the French Revolution. In Gorizia, the Habsburg emperor writes that people live on lettuce and herb soup, and often have nothing to eat at all. Switzerland, among the worst-hit regions, goes through what is often called its last famine. In 1817, some thirty thousand Germans, Swiss and Alsatians end up stranded in Amsterdam, hoping to sail to America. Hunger brings disease. Typhus epidemics between 1816 and 1819 kill more than sixty-five thousand people. Further east, scientists have linked the disrupted monsoon to a new strain of cholera from Bengal. And historians link a famine in China's Yunnan province to the same cold. Tambora was not the only cause. The climate was already cooling, and after the Napoleonic wars, soldiers were coming home to no work. The volcano was the last push. And at least one man looked at the empty stables, and had an idea. Maybe.

Here is a story you may have heard. Harvests fail in 1816. Oats become scarce. Horses go hungry. And in 1817 a German baron, Karl Drais, builds a two-wheeled machine you push along with your feet, to replace the horse. The ancestor of the bicycle, born from a volcano. It is a great story. It is also a hypothesis. Drais's biographer, Hans-Erhard Lessing, argued for the link from circumstantial evidence. Other researchers say it is not proven. What we do know is that Drais's Laufmaschine, a running machine, appeared in 1817, and the press nicknamed it the Draisine. The rest is a maybe. The effects on people are better documented. Vermont's population is estimated to have fallen by ten to fifteen thousand in 1816 and 1817, and researchers link part of that emigration from New England to the failed harvests. But there is a question we have been avoiding. How many people actually died?

The honest answer is: nobody knows. A 1998 study counted about eleven thousand direct deaths, and forty-nine thousand from famine and disease. A 2003 review put the total at about seventy-one thousand. Some estimates reach about a hundred thousand. Behind the numbers are people we barely know. The language spoken on Tambora's slopes was lost in the eruption. In 2004 the volcanologist Haraldur Sigurdsson dug through three metres of ash and pumice, and found a house, two skeletons, bronze bowls and tools. He called the site the Pompeii of the East. Tambora is still active. Its last eruption was in 1967. In 1883, Krakatoa erupted. It was smaller. But thanks to the telegraph, the news spread faster than for earlier disasters. That is the next story. But first, remember how this one began. A volcano is heard a thousand miles away.