Tambora: The Eruption that Changed the World 
by Gillen D’Arcy Wood.
Princeton, 293 pp., £19.95, April 2014, 978 0 691 15054 3
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When​ an Icelandic volcano looks as if it’s about to blow, the flurry of anxiety in our age of entitlement is focused on the potential disruption to European airspace and whether or not flights will be cancelled. In August, we were reassured – if that’s the word – that Bárðarbunga, unlike Eyjafjallajökull four years ago, wouldn’t be allowed to interfere with anyone’s holiday plans, which is to say with any airline’s revenue stream, however much debris it blasted into the atmosphere. The eruption of Mount Laki in June 1783 presented Benjamin Franklin with a more serious problem. As Gillen D’Arcy Wood recounts, Franklin was in Paris the following spring, negotiating peace terms with the British. ‘The makeshift US capital in Annapolis, Maryland, was snowbound, preventing assembly of congressional delegates to ratify the treaty, while storms and ice across the Atlantic slowed communications between the two governments.’

Between negotiations, Franklin wrote a paper for the Manchester Philosophical Society entitled ‘Meteorological Imaginations and Conjectures’, in which he suggested that the cold weather was the result of a ‘dry’ fog high in the atmosphere over Europe and North America which blocked the sun’s rays. ‘The cause of this universal fog is not yet ascertained,’ but one possible source was the ‘vast quantity of smoke, long continuing to issue during the summer from Hecla in Iceland, and that other volcano which arose out of the sea near that island, which smoke might be spread by various winds over the northern part of the world’. He got the name of the volcano wrong, but was otherwise more or less correct, not least in saying that the winds spread the ‘smoke’ only over the northern part of the world. Volcanic activity in Iceland can affect the weather in the North Atlantic, but the way the winds blow means the rest of the planet is unaffected. Volcanoes in the tropics, as Wood’s book makes plain, are another matter entirely.

The eruption of Tambora on the island of Sumbawa in the Indonesian archipelago on 10 April 1815 was the most powerful volcanic explosion of the past thousand years, twice the magnitude of Krakatoa’s nearly seventy years later. Technically speaking, Tambora’s 1815 eruption, which threw out 160 km3 of ash and rock (that’s more than enough to fill the Dead Sea or Lake Tahoe; it takes nine months for an equivalent volume of water to go over Niagara Falls), was ‘mega-colossal’, with a ranking of 7 on the logarithmic Volcanic Explosivity Index. There have been only five confirmed eruptions with a vei of 7 (more than 100 km3 of ejecta) in the last five thousand years: the others were Santorini around 1650 bc, Taupo Volcano on New Zealand’s North Island in 230 ad, Baekdu Mountain on the Chinese-North Korean border in 969 and Mount Rinjani, a hundred miles or so west of Tambora, in 1257. By comparison, Vesuvius in 79 ad, Krakatoa in 1883 and Pinatubo in 1991 had a vei of 6 (more than 10 km3); Mount St Helens in 1980 had a vei of 5 (more than 1 km3); Eyjafjallajökull in 2010 had a vei of 4 (more than 0.1 km3). The vei goes up to 8 (‘apocalyptic’, with more than 1000 km3 of ejecta), but there hasn’t been one of those since the Oruanui eruption of the Taupo Volcano 26,500 years ago.

As recently as twenty years ago, Tambora’s 1815 eruption could be dismissed as not especially consequential. In Volcanoes: Crucibles of Change (1997), Richard Fisher, Grant Heiken and Jeffrey Hulen devote only half a sentence to it: ‘The dust cloud … lasted less than two years, and its effects upon the environment, though harmful to people, were short-lived.’ But Wood, who intends no hyperbole in his subtitle, makes a convincing case for Tambora’s role in causing ‘the most catastrophic sustained weather crisis of the millennium’. Wood’s isn’t the first book on Tambora’s aftermath, but it is the first to treat the event ‘as a three-year episode of drastic climate change’: flood, drought and famine across Europe and Asia; a political shift to the right in post-Napoleonic Europe; the first cholera pandemic; the rise of the international opium trade; the renewal of the doomed quest for the Northwest Passage; the formulation of ice age theory; the ‘first major westward expansion in US history’ and ‘the United States’ first major economic depression’; not to mention several major works of Romantic literature (Mary Shelley’s Frankenstein, Percy Shelley’s ‘Mont Blanc’, Keats’s ode ‘To Autumn’, Byron’s ‘Darkness’).

One of the ways of investigating long-ago eruptions is by looking at the density of sulphate deposits buried deep under the ice in Greenland and Antarctica. The ice core data also show evidence of a colossal (vei 6) eruption six years before Tambora. It must have been somewhere in the tropics, because the ash cloud reached both poles, but beyond that the location of the ‘1809 Unknown’ remains a mystery. For Tambora, however, there are eyewitness accounts. Stamford Raffles, then the lieutenant-governor of Java, wrote about the eruption in a footnote to his History of Java (1817):

at the distance of three hundred miles, it seemed to be awfully present. The sky was overcast at noon-day with clouds of ashes, the sun was enveloped in an atmosphere, whose ‘palpable’ density he was unable to penetrate; showers of ashes covered the houses, the streets, and the fields to the depth of several inches; and amid this darkness explosions were heard at intervals, like the report of artillery or the noise of distant thunder.

Several months later, having heard reports that the people on Sumbawa were starving, their crops destroyed and water supplies poisoned by the eruption, Raffles dispatched a Royal Navy ship loaded with (not nearly enough) rice under the command of Lieutenant Owen Phillips. ‘The extreme misery to which the inhabitants have been reduced is shocking to behold,’ Phillips wrote. ‘There were still on the roadside the remains of several corpses, and the marks of where many others had been interred: the villages almost entirely deserted and the houses fallen down.’ One of the people he met was the raja of Sanggar, ‘himself a spectator of the late eruption’, whose kingdom at the foot of the volcano had been annihilated. The raja told Phillips what had happened:

three distinct columns of flame burst forth near the top of the Tomboro [sic] mountain … and after ascending separately to a very great height, their tops united in the air in a troubled, confused manner. In a short time, the whole mountain … appeared like a body of liquid fire … The fire and columns of flame continued to rage with unabated fury, until the darkness caused by the quantity of falling matter obscured it … Stones … fell very thick … some of them as large as two fists … ashes began to fall, and soon after a violent whirlwind ensued, which blew down nearly every house in the village … The sea rose nearly twelve feet higher than it had ever been known to do before … sweeping away houses and every thing within its reach … there were certainly not fewer than twelve thousand individuals in Tomboro and Pekáté at the time of the eruption, of whom only five or six survive.

That’s five or six individuals, not five or six thousand. At least fifty thousand more people died of starvation and disease across Indonesia. And the indirect global death toll, according to Wood, reached into the millions.

Yunnan, in southern China, saw its population increase sixfold in the second half of the 18th century, from three to twenty million, thanks to what Wood calls ‘advanced technologies of irrigated land management and fertilisation’ applied to ‘an environment of pliable soil and sunny weather’. In the summer of 1815, however, because of Tambora’s ash cloud, the sun didn’t come out. The wind blew from the north instead of the south-west. Heavy rains flooded the wheat, barley and bean fields. The rice paddies could have survived the rain, but not the cold. Snow, frost and freezing fog enveloped the land in July and August. Villagers were reduced to eating soil. The conditions persisted for three years. Wood doesn’t give an estimate for how many people died, but ‘mortality’ was ‘high’. The emperor, two thousand miles away in Beijing, blamed ‘provincial officials’ for mismanaging the crisis.

Wood quotes extensively from the poems of Li Yuyang, who had studied at a Confucian academy in Kunming, Yunnan’s capital, but failed the imperial examinations and by 1815 was working in the rice fields. In one of his poems he describes starving parents selling their children in the streets of Kunming: ‘Stop crying and go with him … because to buy you he must feed you.’ Another poem tells the story of Magistrate Liu, a provincial official who returned the alienated children to their families – Wood calls him ‘heroic’, though many of the children he saved from slavery must have died of starvation soon afterwards.

The climate and the harvests recovered in 1818. By 1820, reports were reaching Beijing of a ‘sudden explosion in opium production’ in Yunnan. Poppies were ‘as good as money and more reliable than food’, Wood writes. A hundred years later, ‘Yunnan was growing almost nothing but opium’ and ‘importing most of its rice from Southeast Asia’. Wood concedes that the evidence linking the growth in poppy production to the food shortages caused by Tambora’s eruption is circumstantial – there’s nothing to say the farmers wouldn’t have switched crops anyway – but it’s compelling all the same.

The disruption that Tambora’s ash cloud brought to Yunnan’s climate began hundreds of miles to the south-west, in the Bay of Bengal. The monsoon season usually starts in May, as the land heats up faster than the ocean and the colder, higher-pressure air blows in from the sea (the same thing happens on a much, much smaller scale in Torquay or Scarborough on warm summer mornings), bringing storm clouds and heavy rains. Three-quarters of Kolkata’s annual rainfall – and more than twice as much as drizzles on London in a year – pours down between June and September. Without the monsoon, as Wood says, ‘the land would be uninhabitable.’ That year aerosol particles from Tambora, lingering in the stratosphere above the Bay of Bengal, blocked out enough sunlight to alter the weather pattern, ‘inhibiting evaporation from the ocean and deflating the temperature differentiation of land and sea’. The ‘crippling monsoonal break’ of 1816, Wood writes, ‘is the longest in the historical record of the Asian subcontinent’.

Crops failed, wells dried up. When the rains came, too late, in September, they were ‘ruinously extreme’, bringing floods to the Ganges delta. The rains were early the next year: ‘On 21 March, an unprecedented hailstorm destroyed the spring grain crop and tore up orchards of dates, bananas and papaya all across the fragile alluvial plain.’ Two months later, people were dying of cholera. The disease had always been endemic in Bengal, but the unseasonal outbreak in May 1817 was also unusually virulent – and this, too, appears to have been a consequence of Tambora’s eruption. It spread across India, reaching Bombay within a year, then travelled southeast to Burma, Siam and Java in 1819-20, north to the Philippines, Japan and China, west to Persia, Russia, Europe and across the Atlantic, reaching North America and the Caribbean in 1832 (opinion is divided on whether this was a single epidemic or two separate ones, the second beginning in Bengal in 1826). The disease was carried by traders, pilgrims and armies – Wood begins his account of the first cholera pandemic with a description of British forces dropping dead in central India in November 1817 – but conquest and commerce aren’t enough to explain its unprecedented spread.

Genetic research into Vibrio cholerae – the pathogen’s genome was sequenced in 2000 – suggests that it underwent significant mutations shortly before the 1817 outbreak. The bacteria can be found harmlessly in waters around the world: more than two hundred serogroups of v. cholerae have been identified, and only two of them (O1 and O139) produce the toxin that causes catastrophic diarrhoea. O139 first appeared, in southeastern India and the Bay of Bengal, in 1992; before that, cholera outbreaks were caused by two biotypes of O1. One of them, known as El Tor, has been largely responsible for the seventh cholera pandemic, which began in 1961 and is ongoing. Before that, outbreaks were traced to the classical biotype. Recent research has shown that dramatic changes in its habitat can lead – as you might expect – to the emergence of new varieties of the bacteria. ‘A truly bizarre monsoonal anomaly such as the Tamboran Asian weather regime of 1815-18,’ Wood writes, ‘would certainly have been sufficient for the evolution of a new microbial strain.’

One of the British soldiers who survived the cholera outbreak in India was Thomas Medwin, Shelley’s cousin. After returning to Europe, he joined the Shelley circle in Pisa in 1820. ‘They could not have imagined the geophysical teleconnections between the wet, stormy summer of 1816 they had spent together in Geneva and the chilling war stories of cousin Thomas.’ Mary Shelley is Wood’s lodestar, or the hub of his ‘geophysical teleconnections’, a familiar reference point as he tracks Tambora’s devastation across the globe: the poppy cultivation in Yunnan, for example, is introduced with an account of her sister Fanny Godwin’s death by opium overdose.

In the summer of 1816 – or rather, between the months of May and September, since 1816 was the ‘year without a summer’ – Shelley and Mary Godwin (they married six months later), their infant son, William, and Godwin’s stepsister, Claire Clairmont, were staying at a house on the shore of Lake Geneva. Byron and Polidori were up the hill at the Villa Diodati. During what Richard Holmes in his biography of Shelley calls ‘a spell of bad weather in the last fortnight of June’, the two households stayed up late into the night at the Villa Diodati, telling ghost stories and discussing galvanism as the lightning struck outside. Godwin dreamed of Dr Frankenstein, ‘the pale student of unhallowed arts kneeling beside the thing he had put together’. It’s one of the most reimagined episodes in English literary history.

Less celebrated is the effect of that ‘spell of bad weather’ – which went on a lot longer than the last fortnight of June – on harvests across Europe. Luke Howard, a chemist in Tottenham who in his Essay on the Modification of Clouds (1803) had distinguished the cirrus, stratus and cumulus types, began keeping a detailed record of London’s weather in 1807. He maintained it until 1819, publishing his findings as The Climate of London, which ‘offers hard evidence’, Wood says, ‘of the altered weather patterns across western Europe produced by Tambora’s eruption’. Temperatures had already dropped thanks to the ash cloud from the 1809 Unknown eruption. Recent research suggests that the 1810s were the coldest decade of the last five hundred years. Between 1807 and 1815, according to Howard’s measurements, the average daily temperature in London was 50°F (10ºC). In 1816 it was 38°F (under 4°C). Across the country there were ferocious thunderstorms, hailstorms, gales, darkness at noon, snow on Helvellyn in July.

Howard travelled on the Continent in the summer: ‘From the sources of the Rhine among the Alps, to its embouchure in the German ocean, and through a space twice or thrice as broad from east to west, the whole season presented a series of storms and inundations.’ Further north, however, in Scandinavia and around the Baltic, they were praying for rain. ‘Crop yields across the British Isles and western Europe,’ Wood writes, ‘plummeted by 75 per cent and more in 1816-17.’ There were food riots, authoritarian clampdowns, and mass starvation. In Ireland, the famine was compounded by a typhus epidemic – lice spread quickly between people who’d sold most of their clothes and shared blankets to keep warm as there was no dry peat to burn – that killed around 100,000 people. In Switzerland, officials closed the borders to grain exports, which meant they were closed to imports, too. Tens of thousands of people died.

The extreme cold and wet presented other dangers. In the spring of 1818, the Dranse de Bagnes river in southwest Switzerland was blocked by a natural dam of ice, holding back a vast body of water. As the ice began to melt in the warming weather, and the amount of water accumulating behind the dam increased, it was only a matter of time before it burst, inundating the valley below. (The Icelandic term for floods of this kind, Wood says, is jökulhlaups; in French they’re known as débâcles.) To avert disaster, a tunnel was dug by hand through the ice to let the water out more gradually. When the dam eventually burst – a process unfortunately accelerated by the water streaming through it – the temporary lake had been reduced by a third. The débâcle, though not quite as disastrous as it would have been without any intervention, still laid waste to the valley. The engineer in charge of digging the tunnel was called Ignace Venetz. His guide in the Val de Bagnes was a chamois hunter, Jean-Pierre Perraudin. Perraudin had long been convinced that the valley had once been filled with ice; it was the only way, he thought, to explain many of the rock formations, and the presence of huge boulders in places where they had no business being. Venetz was persuaded. In 1821, he wrote a paper in which he ‘developed the outlines of modern glacial theory and periodic Ice Ages … Climate change has driven a historical cycle of glaciation,’ Wood paraphrases, ‘which in turn has left its indelible mark on the geological formation of the Alps and by implication the European continent.’

The climate crisis​ brought on by Tambora’s eruption came to an end in 1818, when ‘normal crop-growing conditions returned’ to Europe, which ‘enjoyed a return of bumper harvests’. Wood has a refreshingly literal-minded take on Keats’s ode ‘To Autumn’, arguing that it ‘celebrated the return of sunny English harvesting’. This would be more persuasive if the poem had been written in September 1818 rather than, as it was, a year later. Wood’s literary criticism can be a bit hit-and-miss. He’s sniffy, for example, about Madame de Staël’s ‘magmatic style’ in Corinne (1806): ‘The river of fire flowing from Vesuvius was revealed by the darkness of night, and it seized and bound the imagination of Oswald.’ But this – the translation is Emily Baldwin and Paulina Driver’s from 1906 – is restrained by the standards of some of Wood’s own prose: ‘The mountain itself began to glow as streams of boiling liquefied rock coursed down its slopes … whole villages … had already been consumed within a vortical hell of flames.’ (At the other extreme he describes Napoleon in April 1815 as being ‘back in Paris and up to his usual tricks’.) His material is interesting enough not to need such pyroclastics; happily, it’s interesting enough not to be smothered by them, either.

Keats’s brother George was one of the tens of thousands who left Europe for the United States during the Tambora emergency, sailing from Liverpool in the summer of 1818. North America ‘in 1817-19 witnessed its first significant wave of refugee European migration in the 19th century’, Wood writes. Many of them were heading for the Midwest. The eastern seaboard experienced its share of terrible weather: it snowed in New England on 6 June 1816, ‘an iconic day in the history of American weather’, and there were frosts throughout the summer, which ‘laid waste to staple crops and fruit stocks’ from Maine to the Carolinas (including Thomas Jefferson’s at Monticello). But the cold and storms didn’t cross the Appalachians: ‘Farming territories from the Ohio Valley to Illinois produced bumper crops and sold their bounty at record prices.’ The price of land shot up, too. The Midwestern farmers exported a lot of their grain to Europe. When the European weather recovered, the bottom fell out of the American market. Prices dropped by nearly three-quarters between 1817 and the early 1820s. In April 1819, Jefferson, having decided to sell off some of Monticello to pay his debts, found that ‘the value of property had fallen to less than a year’s rent’.

Further north, speculation of a different sort was fuelled by Tambora’s disruption to weather patterns. In 1817, William Scoresby, a whaling captain, told Joseph Banks, the president of the Royal Society, that he had ‘found about two thousand square leagues of the surface of the Greenland Sea, between the parallels of 74° and 80° north, perfectly void of ice, which is usually covered with it’, and that if he’d been hunting for the Northwest Passage rather than whales, ‘I have little doubt but that the mystery … might have been resolved.’ Tambora’s overall suppression of global rainfall had reduced the flow of freshwater into the sea sufficiently to alter the ocean currents, increasing the flow of warm waters from the tropics to the Arctic. By the time the first Royal Navy expeditions reached the west coast of Canada in 1818, however, the ice had returned, though that didn’t deter the Admiralty from pouring resources into decades of fruitless searching for the Northwest Passage, which led to yet more deaths.

The temporary melting of Arctic ice two hundred years ago is often cited by 21st-century climate change deniers, who point to it as a reason not to worry too much about the disappearing ice caps now, ignorant as they are (wilfully or otherwise) of its particular cause. The story of Tambora’s eruption and its aftermath is, for Wood, a ‘cautionary tale’. ‘If a three-year climate change event in the early 1800s was capable of such destruction … then the future impacts of multidecadal climate change must be truly off the charts.’ According to the latest report from the Intergovernmental Panel on Climate Change, published at the beginning of November, the effects of global warming may soon be ‘severe, pervasive and irreversible’. Now, as in 1815, we are all living under the volcano, but this time the air won’t clear after three years.

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