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On April 10, 1815, the Tambora Volcano produced the largest eruption in recorded history.(Photo: NASA)
Snow in June, freezing temperatures in July, a killer frost in August: "The most gloomy and extraordinary weather ever seen," according to one Vermont farmer.
Two centuries ago, 1816 became the year without a summer for millions of people in parts of North America and Europe, leading to failed crops and near-famine conditions.
While<span style="color: Red;">*</span>they didn't know the chill's cause<span style="color: Red;">*</span>at the time, scientists and historians now know that the biggest volcanic eruption in human history, on the other side of the world —<span style="color: Red;">*</span>Mount Tambora in Indonesia in April 1815<span style="color: Red;">*</span>— spewed millions of tons of dust,<span style="color: Red;">*</span>ash and sulfur dioxide<span style="color: Red;">*</span>into the atmosphere, temporarily changing the world's climate and<span style="color: Red;">*</span>dropping global temperatures by as much as 3<span style="color: Red;">*</span>degrees.
In addition to food shortages, the<span style="color: Red;">*</span>natural climate change caused disease outbreaks, widespread<span style="color: Red;">*</span>migration of people looking for a better home<span style="color: Red;">*</span>and religious revivals as people tried to make sense of it all.
The gloom spread to the literary world, too: that foul, frigid year inspired<span style="color: Red;">*</span>the plot of Mary Shelly's epic horror novel Frankenstein.
And it could happen again. Big volcanoes<span style="color: Red;">*</span>can erupt at anytime and with little warning,<span style="color: Red;">*</span>potentially changing the climate and giving a temporary reprieve to man-made global warming.
"We cannot reliably predict exactly when a volcano will erupt, or how powerful it will be, until the eruption is nearly upon us," said Nicholas P. Klingaman, co-author of<span style="color: Red;">*</span>the book<span style="color: Red;">*</span>The Year without Summer.
The eruption of Tambora, on April 10, 1815, on the island of Sumbawa in what's now Indonesia,<span style="color: Red;">*</span>was<span style="color: Red;">*</span>100 times more powerful than the 1981 Mount St. Helens blast, according to the U.S. Geological Survey, which ranked the eruption as a seven on its eight-level<span style="color: Red;">*</span>volcanic explosivity index.
The volcano spewed out<span style="color: Red;">*</span>enough ash and pumice to cover a square area 100 miles on each side of the mountain to a depth of almost 12 feet, according to the book,<span style="color: Red;">*</span>The Year without Summer,<span style="color: Red;">*</span>by Klingaman and his father,<span style="color: Red;">*</span>William K. Klingaman.
It was by far the deadliest volcanic eruption in human history, the Klingamans wrote, with a<span style="color: Red;">*</span>death toll of at least 71,000 people, up to 12,000 of whom<span style="color: Red;">*</span>killed directly by the eruption, according to the journal Progress in Physical Geography.
When a volcano erupts, it does more than spew clouds of ash, which can cool a region for a few days and disrupt airline travel. It also spews sulfur dioxide, NASA reports.
Sulphuric gases rise from the crater of Mt. Tambora on the island of Sumbawa, Indonesia. The eruption of Tambora in 1815 was the largest volcanic eruption in human history and resulted in a period of global cooling known as "the year without a summer."<span style="color: Red;">*</span>(Photo: Haraldur Sigurdsson, University of Rhode Island)
If the eruption is strong enough, it shoots that sulfur dioxide high into the stratosphere, more than 10 miles above<span style="color: Red;">*</span>Earth's surface.<span style="color: Red;">*</span>Up there, sulfur dioxide reacts with water vapor to form sulfate aerosols.
Because these aerosols float above the altitude of rain, they don't get washed out. Instead they linger, reflecting sunlight and cooling the Earth's surface, which is what caused the weather and climate impacts of Tambora's eruption to occur more than a year later.
Heavy snow fell in northern New England on June 7-8, with 18- to 20-inch high drifts. In Philadelphia, the ice was so bad<span style="color: Red;">*</span>"every green herb was killed and vegetables of every description very much injured,"<span style="color: Red;">*</span>according to the book American Weather Stories.
Frozen birds dropped dead in the streets of Montreal, and lambs died from exposure in Vermont,<span style="color: Red;">*</span>the<span style="color: Red;">*</span>New England Historical Society said.
On July 4, one observer wrote that "several men were pitching quoits (a game) in the middle of the day with heavy overcoats on." A frost<span style="color: Red;">*</span>in Maine that month killed beans, cucumbers and squash, according to meteorologist<span style="color: Red;">*</span>Keith Heidorn. Ice covered lakes and rivers as far south as Pennsylvania, according to the Weather Underground.
By the time August rolled around, more severe frosts further damaged or killed crops in New England.<span style="color: Red;">*</span>People reportedly ate<span style="color: Red;">*</span>raccoons<span style="color: Red;">*</span>and pigeons for food, the New England Historical Society said.
Europe also suffered mightily:<span style="color: Red;">*</span>the cold and wet summer led to famine, food riots, the transformation of stable communities into wandering beggars<span style="color: Red;">*</span>and one of the worst typhus epidemics in history, according to<span style="color: Red;">*</span>The Year without Summer.
Scientists’ best estimate<span style="color: Red;">*</span>is that the global-average temperature cooled by almost 2 degrees<span style="color: Red;">*</span>in 1816 said Nicholas Klingaman, who is also a meteorologist at the University of Reading in the United Kingdom.<span style="color: Red;">*</span>Land temperatures cooled by about 3 degrees, he added.
Eruptions on the scale of<span style="color: Red;">*</span>Tambora occur once every 1,000 years on average, but smaller events can still substantially impact the climate,<span style="color: Red;">*</span>Klingaman said. Krakatoa's 1883 eruption in Indonesia<span style="color: Red;">*</span>caused global cooling nearly five years later, even though it ejected less material into the atmosphere than Tambora.
Similarly, Pinatubo<span style="color: Red;">*</span>in 1991 in the Philippines caused global temperatures to cool by about 1 degree,<span style="color: Red;">*</span>Klingaman said.<span style="color: Red;">*</span>Eruptions of that magnitude — about one-sixth the size of the Tambora eruption —<span style="color: Red;">*</span>happen about once every 100 years.
"Any of those other volcanoes<span style="color: Red;">*</span>could erupt again, perhaps on a scale of Tambora or greater," said Mike Mills, an atmospheric chemist at the National Center for Atmospheric Research in Boulder, Colo.
The subject of how volcanoes affect climate is relatively new:<span style="color: Red;">*</span>Scientists didn't confirm the link between volcanic eruptions and global cooling until<span style="color: Red;">*</span>the 1960s and 1970s, Klingaman said.
A new area of research delves into how volcanic eruptions could interact with global warming, Mills said. The chemist says his own investigation found the role of volcano eruption in global climate change<span style="color: Red;">*</span>could be underestimated.<span style="color: Red;">*</span>And it could help explain why global warming appeared to temporarily slow down early this century when volcanic activity increased.
With global temperatures at record highs, a massive eruption today could halt man-made climate change. But the effect would be only<span style="color: Red;">*</span>temporary: Warming would pick up where it left off once all the stratospheric dust settled out, a process that could a few years or up to<span style="color: Red;">*</span>a decade, Weather Underground reported.
The fallout on the people affected by the event, though, could last far longer.<span style="color: Red;">*</span>The colorful, dusty skies from Tambora's<span style="color: Red;">*</span>epic blast inspired some<span style="color: Red;">*</span>of British artist<span style="color: Red;">*</span>J. M. W. Turner's<span style="color: Red;">*</span>most spectacular sunset paintings — some of which were painted decades after the eruption.
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