NEWS of the calamity reached Britain in November 1815 when The Times published a letter from a merchant in the East Indies. “We have had one of the most tremendous eruptions that ever perhaps took place anywhere in the world,” he wrote. The source of the blast was Mount Tambora on Sumbawa, an island neighbour to Lombok and Bali. People heard the thunderous roar 850 kilometres away.
A couple of local captains sailed to Sumbawa to see what had happened. “They found the sea for many miles around the island so completely covered with trunks of trees, pumice stone and etc as to impede the progress of the two ships,” the merchant recorded. For two days after the eruption the island was shrouded in darkness. “The crops of paddy have been utterly destroyed over a good part of the island. Great numbers have perished and more die daily.”
And that, so far as The Times was concerned, was that. The news by then was already seven months old. The explosion of Tambora was consigned not so much to history as to oblivion. It took another 160 years before scientists began to appreciate the gargantuan scale of what had happened on the night of 10 April 1815. Nothing like it has happened for the past ten thousand years. Think of another volcanic eruption – Vesuvius, Krakatoa, Mount Saint Helens – all were damp squibs next to Tambora.
The idea that volcanoes can have a global impact only seriously emerged in 1883, when a near neighbour of Tambora’s blew its top. Krakatoa exploded with less physical force than Tambora, but with immeasurably more impact on the public’s imagination in Europe. By then, the East Indies were no longer months away by sailing ships – they had been replaced by steamers – and telegraph cable networks were starting to make instant communication possible.
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Krakatoa alerted scientists to the possible links between climate and distant volcanic rumbles. French researchers in Montpelier tending the first instrument for continuously measuring solar intensity noted a 20 per cent decline in the months after Krakatoa. New compilations of average temperature in the northern hemisphere revealed a dip. The cause was a thin veil of volcanic dust and ash that had spread round the world, and which took several years to rain out. This much and more appeared in 1888 in a report on Krakatoa by the Royal Society in London.
Yet, even then, Tambora languished in obscurity. It was not reassessed until the 1970s, after glaciologist Claus Hammer of the University of Copenhagen found a layer of acidic ash in Greenland ice cores. The ash appeared in snow that fell in the years following 1815 and the only eruption that could have left such a mark was Tambora. This, combined with widespread scientific discussion of Krakatoa on its centenary in 1983, led to a flurry of papers on the “forgotten eruption” of Tambora and finally to a conference in 1989.
The eruption ripped 1400 metres from the top of the mountain. The summit was replaced by a crater about 6 kilometres across and more than a kilometre deep. Haraldur Sigurdsson of the University of Rhode Island, the foremost authority on the eruption, estimates that to have made such a hole Tambora must have exploded with the force of a billion tonnes of TNT, or 60 000 Hiroshimas. It shot more fine particles into the upper atmosphere than any event in recorded history and altogether threw out between 100 and 200 cubic kilometres of pumice, rock and ash, says Alan Robock, a meteorologist at the University of Maryland. That’s 150 times as much as Mount Saint Helens ejected in 1980 and seven times as much as Krakatoa. On the geologists’ Volcanic Explosivity Index, which runs from zero to eight, Tambora scored seven.
The blast had a devastating effect on the people of Sumbawa. Records from the time, unearthed in recent years, show two towns and 8000 inhabitants were engulfed by lava. Thousands of people fled to neighbouring islands, but found prospects there were also bleak. All the vegetation died on Lombok and Bali. Epidemics and famine in the months after the eruption killed some 82 000 on the three islands. Between a third and a half of all the people killed by volcanic eruptions around the world in the past 500 years perished in the islands around Tambora that summer.
The fallout spread far and wide. Contemporary Chinese records reveal that 2000 kilometres to the north in the South China Sea, the skies above Hainan Island went so dark with ash that the Sun disappeared. Frosts destroyed crops and half the trees died. China experienced exceptionally cold and stormy weather, with terrible harvests in 1816 and 1817.
Events elsewhere in the world took on a new significance as the extent of the eruption emerged. In Europe and North America, 1816 was dubbed “the year without a summer”. Temperatures in Britain dropped by about 2 °C and it rained or snowed almost every day. Prices on the London Grain Exchange hit record highs.
Wagons roll
Across the Atlantic in New England, 1816 was the coldest in 200 years. There was snow every month and frost repeatedly destroyed corn crops. “Farmers would plant crops, they would die, they’d plant them again and it ruined the harvest then, too,” says Robock. “That was the beginning of a lot of migration out to the Midwest of the US because people couldn’t survive in the east.”
But not all the consequences of Tambora were bad. The appalling weather famously upset the poet Lord Byron and his guests Mary and Percy Bysshe Shelley as they holidayed on the shores of Lake Geneva. They became so caught up in the gloom that they spent the summer reading ghost stories. Mary Shelley wrote Frankenstein, and Byron wrote a poem called Darkness which, according to Robock, “sounds like the beginning of a nuclear winter”.
I had a dream, which was not all a dream.
The bright sun was extinguish’d, and the stars
Did wander darkling in the eternal space,
Rayless, and pathless, and the icy earth
Swung blind and blackening in the moonless air;
Morn came and went – and came, and brought
no day,
And men forgot their passions in the dread
Of this their desolation; and all hearts
Were chill’d into a selfish prayer for light.
The English landscape painter William Turner became famous in the art world for his sunsets. But only much later did it become clear that he was painting skies full of dust from Tambora. The glowing images he saw were caused by sunlight scattering off volcanic dust.
Perhaps the eruption’s biggest benefit came eventually to Sumbawa and its neighbours. Ash from Tambora boosted the fertility of soils on the islands. Bali became a rice exporter and the value of the ash is still being reaped in the paddy fields today.
