On June 6, 1816, snow fell on Albany, New York. A few days later, the ground froze hard in the hills of New Hampshire, and farmers across New England went out to find their young corn black with frost. In Ireland, it rained for weeks on end. In Switzerland, a group of young English writers stayed indoors through a gloomy summer and told each other ghost stories, and one of them came up with Frankenstein. People at the time had no idea what was wrong with the weather. The answer was a mountain on the other side of the world that had blown itself apart the year before.
The loudest sound in recorded history
Mount Tambora sits on Sumbawa, an island in what is now Indonesia and was then part of the Dutch East Indies. Before 1815 it was one of the tallest peaks in the region, around 14,000 feet high, and it had been quiet for centuries. Inside, though, a chamber of magma was slowly cooling and building pressure.
It began to rumble in 1812. On April 5, 1815, it erupted with explosions heard hundreds of miles away. On Java, soldiers who heard the booms thought a battle had broken out nearby and set off to look for it. Then, on the evening of April 10, came the main event. According to accounts gathered afterward, three columns of fire rose from the mountain and merged. Pumice stones up to 8 inches across rained down, followed by ash. Avalanches of hot gas and rock, called pyroclastic flows, poured down every side of the mountain into the sea and wiped out the village of Tambora. Tsunamis up to about 13 feet high struck nearby coasts.
The blasts were heard on Sumatra, more than 1,600 miles away, where people again mistook them for gunfire. Ash fell more than 800 miles from the volcano. When it was over, the mountain had lost about a third of its height, and its top had collapsed into a crater about 4 miles across. Scientists rate the eruption a 7 on the Volcanic Explosivity Index, a scale that runs to 8, and it is the largest eruption in recorded history. By most estimates it threw out at least 10 times as much material as Mount Pinatubo did in 1991.
For the people of Sumbawa and the neighboring island of Lombok, it was a catastrophe. Roughly 10,000 people are thought to have died almost immediately. Far more died in the months that followed, as ash smothered crops and fouled drinking water. Estimates of the total death toll range from about 60,000 to more than 90,000, most of them from hunger and disease.
Why a volcano can cool the planet
Volcanic ash falls out of the sky within days or weeks, so ash alone could not have changed the weather a year later. The real culprit was gas. Tambora’s eruption column punched more than 25 miles up, well into the stratosphere, the calm layer of air above the weather. Along with ash, it carried enormous amounts of sulfur dioxide.
Up there, sulfur dioxide reacts with water vapor to form tiny droplets of sulfuric acid. There is no rain in the stratosphere to wash them out, so they can linger for a year or more while high winds spread them around the globe. The droplets act like a thin veil that reflects a bit of incoming sunlight back to space. Less sunlight reaching the ground means a cooler surface. Scientists can still see the evidence in ice cores from Greenland and Antarctica, where snow that fell in 1816 contains a spike of sulfate that stands out in the record.
The same thing happened on a smaller scale after Pinatubo erupted in the Philippines in 1991. Its sulfur haze cooled the planet by about 1 degree Fahrenheit over the next 15 months, according to NASA. Tambora was far bigger, and it went off near the end of the Little Ice Age, a centuries-long cool spell, after several other large eruptions earlier in the decade. Average global temperatures dropped by an estimated 0.7 to 1.3 degrees Fahrenheit, and some regions got much colder than that.
Snow in June, frost in August
In the spring of 1816, people in the eastern United States noticed a strange haze they called a dry fog. It dimmed and reddened the sun so much that sunspots could be seen with the naked eye, and neither wind nor rain cleared it away. That haze was the sulfur veil.
Then the cold came. In May, frost killed crops in the higher country of Massachusetts, New Hampshire, Vermont, and upstate New York. On June 6, snow fell in Albany and in Dennysville, Maine. Near Quebec City, about a foot of snow piled up between June 6 and 10. A Salem doctor named Edward Holyoke, visiting Franconia, New Hampshire, wrote on June 7: “Exceedingly cold. Ground frozen hard, and squalls of snow through the day. Icicles 12 inches long in the shade of noon day.”
The summer never really recovered. Warm spells came and went, and temperatures could swing from summer heat to near freezing within hours. Frost returned in July and again in August, killing what corn and beans had survived. A newspaper in Norfolk, Virginia, complained in July that “we have not yet had what could properly be called summer,” and that the air was “so chilling as to render the fireside a desirable retreat.” A Massachusetts diarist named Sarah Snell Bryant summed up the season in two words: “Weather backward.”
The cold was only part of the problem. With no railroads and few good roads, a farm family could not simply buy grain from somewhere else. Prices jumped. The price of oats rose from 12 cents a bushel in 1815 to 92 cents in 1816. Even Thomas Jefferson, retired at Monticello in Virginia, lost much of his corn crop, and the bad harvest deepened his debts.
Europe’s last great famine
Europe had it worse. It was still recovering from the Napoleonic Wars, and harvests had already been poor for several years. The summer of 1816 brought cold and relentless rain. Summer temperatures in Europe were the coldest on record between 1766 and 2000, and in Ireland it is said to have rained almost without a break for eight weeks. Wheat, oats, and potatoes failed across much of Britain and Ireland, and food ran short in France, Switzerland, and the German lands.
Food prices soared, and hungry crowds gathered outside bakeries and grain markets. Food riots broke out in city after city, and historians describe 1816 and 1817 as the most violent stretch on the continent since the French Revolution. Typhus followed the hunger, spreading out of Ireland and killing more than 65,000 people between 1816 and 1819. The historian John D. Post called the crisis “the last great subsistence crisis in the Western world.”
Not everywhere suffered. Scandinavia, eastern Europe, and western Russia had fairly normal harvests, and Russia’s emperor was able to send grain west. In Asia, though, the effects were serious. The monsoon was disrupted, the Yangtze Valley flooded, and a severe famine struck China’s Yunnan province.
The haze also changed the look of the sky. Long, brilliant orange and red sunsets were seen in London in 1815. A 2007 study of paintings made between 1500 and 1900 found that artists tended to use more red in their sunsets after big eruptions. The glowing skies of J. M. W. Turner and the moody, hazy light in Caspar David Friedrich’s paintings from these years are often mentioned as examples.
A ghost story contest on Lake Geneva
The most famous side effect of the cold summer started with a rainy holiday. In June 1816, the poet Lord Byron rented the Villa Diodati, a grand house above Lake Geneva in Switzerland. Nearby stayed Percy Bysshe Shelley, 18-year-old Mary Godwin, who would soon marry him and become Mary Shelley, and her stepsister Claire Clairmont. Byron’s young doctor, John Polidori, was there too.
Storms and constant rain kept them indoors. They read a collection of German ghost stories aloud, and Byron challenged everyone to write a scary story of their own. Mary later recalled the season as “wet, ungenial,” with “incessant rain.” One night, she lay awake and pictured a young scientist kneeling beside the creature he had built and brought to life. That image became Frankenstein, published in 1818.
Polidori’s contribution grew into The Vampyre, published in 1819, which helped create the elegant, aristocratic vampire that later fed into Dracula. Byron wrote a bleak poem called “Darkness,” about a world where the sun has gone out. He said it was inspired by a day when the birds went to roost at noon and candles had to be lit as if it were midnight.
A bicycle, a westward move, and a new science of fertilizer
The cold summer left other marks. Across Europe, the failed harvests left tens of thousands of horses starved or slaughtered. In Mannheim, in the German state of Baden, an inventor named Karl Drais began working on a way to get around without them. In June 1817 he showed off his Laufmaschine, or running machine. It had two wheels in a line, a seat, and handlebars to steer, but no pedals. Riders pushed along the ground with their feet, and it could roughly double walking speed. Historians still debate how much the horse shortage drove the idea, but Drais’s machine is now regarded as the first bicycle.
In the United States, the failed harvests pushed many New England farmers to give up on their rocky hillside fields. Thousands moved west to Ohio, Indiana, Illinois, and western New York in search of better soil and a kinder climate. The historian L. D. Stillwell estimated that Vermont lost 10,000 to 15,000 people in 1816 and 1817, wiping out seven years of population growth. Among the families who left Vermont was that of the young Joseph Smith, who moved to Palmyra, New York, where he later founded the Latter Day Saint movement.
In Darmstadt, Germany, a boy named Justus von Liebig lived through the famine. He grew up to be one of the great chemists of the century, studied what plants need to grow, and helped introduce mineral fertilizers. Some historians connect his childhood hunger to the problem he chose to work on.
Why nobody connected the dots
What strikes many people about the Year Without a Summer is that almost nobody at the time linked the cold to the eruption. News of Tambora traveled only as fast as a sailing ship, and few people in Europe or America ever heard of it. Some people blamed the dark spots they could see on the dimmed sun. The idea that a volcano could chill the whole planet had been floated before, most famously by Benjamin Franklin after a huge Icelandic eruption in 1783, but it did not become accepted science until after Krakatoa erupted in 1883, in an age of telegraphs and newspapers, and turned sunsets red around the world.
Tambora wasn’t the only volcano to kill far from its crater. Lake Nyos in Cameroon did it in a very different way, with a silent cloud of carbon dioxide rather than a global veil of sulfur, as we wrote about in the night Lake Nyos exhaled.
The bottom line
Mount Tambora’s 1815 eruption killed tens of thousands of people on the islands around it, then spent the next year quietly reaching across the planet. A thin haze of sulfur droplets high in the stratosphere trimmed the sunlight just enough to bring snow to New England in June, ruin harvests across Europe and Asia, and set off famine, disease, and mass migration. Along the way, it gave us Frankenstein, a fresh kind of vampire, and the first bicycle. Volcanoes this large are rare, but scientists study 1816 closely because it shows how much a single eruption can matter to a world that depends on each year’s harvest.
Ride the running machine, or read the whole story
Strider 12 Sport Balance Bike — Karl Drais’s pedal-free running machine lives on as the balance bike. This one has a 6.7-pound steel frame, flat-free foam tires, and a seat and handlebars that adjust without tools, and it’s made for kids roughly 1 to 4 years old who are learning to balance before they pedal.
Tambora: The Eruption That Changed the World — Gillen D’Arcy Wood’s readable history of the 1815 eruption and the three years of global climate chaos that followed, from famine in China’s Yunnan province and cholera in Bengal to the cold summer on Lake Geneva.