- Tambora: The Eruption that Changed the World by Gillen D’Arcy Wood
Princeton, 293 pp, £19.95, April 2014, ISBN 978 0 691 15054 3
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.
The full text of this book review is only available to subscribers of the London Review of Books.