This feature first appeared in April 2024 on Londonist: Time Machine, our much-praised history newsletter. To be the first to read new history features like this, sign up for free here.
Volcanoes have killed more people in London than in Pompeii. Of course, there are caveats and a bit more to it, but it seems medieval London really did lose a huge portion of its population thanks to an eruption on the other side of the world.
“Numberless dead bodies were lying about in the streets. No one, indeed, could remember ever having before beheld such misery and such famine… Moreover, the dead lay about, swollen up and rotting, on dunghills, and in the dirt of the streets, and there was scarcely anyone to bury them.”
A description of London in 1258, by monk-historian Matthew Paris.
‘Unfortunate, but hardly exceptional,’ you might think. People died from plagues and famines all the time in medieval England. That may be true, but this visitation was different. It was caused by a volcano on the other side of the world.
Tropical menace
London’s problems started 7,808 miles away on the island of Lombok, in what is now Indonesia. The island was dominated by a central volcano called Samalas, one of the largest in the region. In 1257, it blew. You have only to look at the size of the caldera it left behind to imagine the scale of the eruption:
This was undoubtedly one of the most immense volcanic eruptions of recent millennia; it kicked out eight times more sulfur than Krakatoa.
Needless to say, the effects were devastating. According to local accounts, transcribed onto palm leaves, Lombok was transformed from an island paradise to an ash-covered wasteland. Thousands were killed, and the nearby city of Pamatan was buried beneath a pyroclastic flow. It has never been found. Somewhere below the dirt, a ‘Pompeii of the east’ awaits discovery.
So much ash was kicked up into the atmosphere that the effects were felt worldwide. A fine aerosol blanket spread over both hemispheres, reducing the amount of sunlight that reached the ground (see footnote). Global temperatures dipped for years. The inevitable result was widespread crop failures, famine, pestilence and death.
England was hit particularly hard. Accounts of the time, including those of Matthew Paris, speak of an unusually cold and rainy 1258. Loss of crops and livestock led to hunger, and with it came illness. Paris estimates that, by the middle of the year, some 15,000 of the poor had perished in the City of London alone. If accurate, that is an unspeakable loss for a city whose population can’t have been more than 50,000 — perhaps a similar proportion to the losses of the Black Death 90 years later.
It’s a bleak thought, but we can assume that a handful of very long-lived individuals had the misfortune to be born into London’s greatest ever famine, and die almost a century later in its greatest plague.
Paris’s morbid count may well be accurate. In the 1990s, a mass grave was discovered beneath Spitalfields Market, which would eventually yield over 10,000 skeletons. At first, archaeologists assumed they were victims of the Black Death, but subsequent radiocarbon dating suggested an earlier date, in the 1250s. The timing matches other pits around Britain and Europe, mass deaths that are now linked with some confidence to the volcanic eruption in Indonesia.
Multiple eruptions
Of course, nobody in London at the time had the slightest clue that the foul weather, famine and deaths were the after-effects of a volcanic eruption. Scientists and historians have only pieced this chain of events together in recent decades. But, it turns out, volcanoes have taken their toll on our city on numerous occasions. They deserve to feature alongside plague, war and great fires in London’s history books.
Another as-yet-unidentified volcanic eruption in 1452-53 is thought to have been a key component of the ‘Little Ice Age’, which lowered European temperatures into the mid-19th century. London’s Frost Fairs, held on the frozen winter Thames, were one of the happier consequences of this lengthy chill.
More confidently, the 1783 eruption of the Icelandic volcano Laki pumped millions of tonnes of sulfur dioxide and other gases into the atmosphere. Perhaps a quarter of Icelanders were killed in the aftermath, and the effects were also felt on the continent (and beyond). A thick haze settled over northern Europe. Thousands were killed from respiratory problems caused by the acidic gas. The haze dissipated by autumn, but the aftereffects contributed to a terrible winter in which many more people suffered. 10,000 people in Britain are estimated to have died.
1816 was known as ‘The Year Without a Summer’, probably caused by the eruption of Mount Tambora (also in Indonesia) the previous year. This led to failed crops across Europe. Ireland was particularly badly hit with thousands of deaths from famine and typhus.
In more recent times, many will remember the 2010 eruption of Eyjafjallajökull in Iceland. This volcano was much smaller than those related above, yet still had huge economic consequences for the wider world. An ash plume from that event closed London’s air space for five days, an unprecedented event in over 100 years of aviation. I took this photograph at the time, to record a sky without cloud or contrail:
The historical eruptions of 1257, 1783 and 1815 are a reminder that — long before globalisation — London lives could be turned upside-down or even extinguished by events on the other side of the world. You don’t have to know where your nearest volcano is to be killed by one.
Sooner or later, something the size of Samalas is sure to blow again. Could modern agriculture cope with the shock? Is London ready?
Footnote: The chief line of evidence for the volcanic winter comes from ice cores. A vertical column of ice from somewhere like Antarctica or Greenland contains hundreds of bands, each relating to one season of snowfall. It’s possible to count backwards and cross-check with other ice cores in order to date each band. By analysing air bubbles in any given band, you can work out the atmospheric conditions of the time — the amount of carbon dioxide, for example, or the presence of impurities. In this way, scientists have long known that something kicked out a lot of sulfates around 1257. The source was eventually identified as the Samalas volcano about a decade ago, using multiple lines of evidence.
