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How a volcanic eruption in 1815 darkened the world

In April 1815, the most powerful volcanic blast in recorded history shook the planet in a catastrophe so vast that 200 years later, investigators are still struggling to grasp its repercussions. It played a role, they now understand, in icy weather, agricultural collapse and global pandemics – and even gave rise to celebrated monsters.

Around the lush isles of the Dutch East Indies – modern-day Indonesia – the eruption of Mount Tambora killed tens of thousands of people. They were burned alive or killed by flying rocks, or they died later of starvation because the heavy ash smothered crops.

More surprising, investigators have found that the giant cloud of minuscule particles spread around the globe, blocked sunlight and produced three years of planetary cooling. In June 1816, a blizzard pummeled upstate New York. That July and August, killer frosts in New England ravaged farms. Hailstones pounded London all summer.

A recent history of the disaster, “Tambora: The Eruption that Changed the World,” by Gillen D’Arcy Wood, shows planetary effects so extreme that many nations suffered waves of famine, disease, civil unrest and economic decline. Crops failed globally. “The paper trail,” said Wood, a University of Illinois professor of English, “goes back again and again to Tambora.”

The gargantuan blast – 100 times bigger than Mount St. Helens’ – and its ensuing worldwide pall have been the subject of increasing study over the years as scientists have sought to comprehend not only the planet’s climatological past but the future likelihood of such global disasters.

Before it exploded, Tambora was the tallest peak in a land of cloudy summits. It lay atop the tropic isle of Sumbawa. Long dormant, the mountain was considered a home to gods. Villages dotted its slopes.

On the evening of April 5, 1815, flames shot from its summit and the earth rumbled for hours. Five days later, the peak exploded in a deafening roar of fire, rock and boiling ash that was heard hundreds of miles away. Flaming rivers of molten rock ran down the slopes, destroying tropic forests and villages. Days later, still raging but by then hollow, the mountain collapsed, its height diminished by a mile.

The repercussions were global, but no one realized that the widespread death and mayhem arose from an eruption halfway around the world. What emerged was regional folklore. New Englanders called 1816 “eighteen hundred and froze to death.” Germans called 1817 the year of the beggar. These and many other local episodes remained unknown or unconnected.

It was scientists who began to stitch together the big picture, especially the peculiar link between fiery volcanism and icy weather. An overarching goal was to separate natural climate fluctuations from those of human origin. One after another, studies came back to New England and its frigid summer of 1816.

The exploding mountain heaved some 12 cubic miles of earthen matter to a height of more than 25 miles. While coarse particles soon rained out, finer ones traveled the high winds in a spreading cloud. “It passed,” Wood wrote, “across both south and north poles, leaving a telltale sulfate imprint on the ice for paleoclimatologists to discover more than a century and a half later.”

The global veil, high above rain clouds, reflected much sunlight back into space. So the planet cooled.

By 1816, Switzerland, landlocked and famously rugged, was beginning to reel from the bad weather and failed crops. Starving mobs stormed bakeries after bread prices soared. The book recounts a priest’s distress: “It is terrifying to see these walking skeletons devour the most repulsive foods with such avidity.”

A cholera pandemic in 1817 began in India and globally killed tens of millions of people.

Wood closes with a portrait of the eastern United States in 1816, focusing first on upstate New York. One day that June, four young classmates walked to school, most barefoot. Then a blizzard struck. Dismissed early, the children ran for their lives as the snow rose to their knees. They succeeded in reaching warm cabins and fires.

The countless victims and occasional beneficiaries of Tambora’s fury were oblivious to the volcanic roots of their circumstances, Wood noted, making the challenge of writing about it formidable and “occasionally mind-bending.”

More generally, he said, the revelation of global volcanic ruin – a portrait 200 years in the making – offers a kind of meditation on the difficulty of uncovering the subtle effects of climate change, whether its origins lie in nature’s fury or the invisible byproducts of human civilization.