Mount Samalas

There was a big die-off in Northern Europe in 1258.

When archaeologists discovered thousands of medieval skeletons in a mass burial pit in east London in the 1990s, they assumed they were 14th-century victims of the Black Death or the Great Famine of 1315-17. Now they have been astonished by a more explosive explanation – a cataclysmic volcano that had erupted a century earlier, thousands of miles away in the tropics, and wrought havoc on medieval Britons.

Scientific evidence – including radiocarbon dating of the bones and geological data from across the globe – shows for the first time that mass fatalities in the 13th century were caused by one of the largest volcanic eruptions of the past 10,000 years.

It was a big famine, but it was a big famine caused by a Very Damn Big Volcano that threw sulfuric gases so high into the atmosphere that they veiled the whole planet and ruined the crops.

Mass deaths required capacious burial pits, as recorded in contemporary accounts. In 1258, a monk reported: “The north wind prevailed for several months… scarcely a small rare flower or shooting germ appeared, whence the hope of harvest was uncertain… Innumerable multitudes of poor people died, and their bodies were found lying all about swollen from want… Nor did those who had homes dare to harbour the sick and dying, for fear of infection… The pestilence was immense – insufferable; it attacked the poor particularly. In London alone 15,000 of the poor perished; in England and elsewhere thousands died.”

It was just one of those things – a bad year for the crops.

Surprisingly, perhaps, the volcano’s exact location has yet to be established.

This Guardian piece is from 2012. Last night I watched a new Nova about the famine, the mystery, and the solution of the mystery. It’s pretty fascinating. Step one was pinning down the chemical composition of the gas cloud via ice cores from Greenland – they did that and found a massive spike in 1257 that made the one from Krakatoa look puny. Step two was checking both poles – they did that and found the spike on both, which meant the volcano had to be near the equator. Step three was checking on Indonesia to see if there were any likely-looking culprits, and finding one on Lombok island. Step four was going there to check out the pumice fields around the volcano, which are much deeper than any others they knew of, indicating a huge pyroclastic flow. Final step was comparing a sample to the ones from the ice cores: bingo. The Mount Samalas eruption. At least three of the authors on that Nature article were talking heads on the Nova. Here’s the abstract:

Large explosive eruptions inject volcanic gases and fine ash to stratospheric altitudes, contributing to global cooling at the Earth’s surface and occasionally to ozone depletion. The modelling of the climate response to these strong injections of volatiles commonly relies on ice-core records of volcanic sulphate aerosols. Here we use an independent geochemical approach which demonstrates that the great 1257 eruption of Samalas (Lombok, Indonesia) released enough sulphur and halogen gases into the stratosphere to produce the reported global cooling during the second half of the 13th century, as well as potential substantial ozone destruction. Major, trace and volatile element compositions of eruptive products recording the magmatic differentiation processes leading to the 1257 eruption indicate that Mt Samalas released 158 ± 12 Tg of sulphur dioxide, 227 ± 18 Tg of chlorine and a maximum of 1.3 ± 0.3 Tg of bromine. These emissions stand as the greatest volcanogenic gas injection of the Common Era. Our findings not only provide robust constraints for the modelling of the combined impact of sulphur and halogens on stratosphere chemistry of the largest eruption of the last millennium, but also develop a methodology to better quantify the degassing budgets of explosive eruptions of all magnitudes.

Their version of my crude summary of Nova’s adventure storytelling version of how they figured it out:

The 1257 eruption of Mt Samalas, a part of the Rinjani volcanic complex (Fig. 1) on Lombok Island (Indonesia), has been recognized as the “mystery eruption”7 associated with the largest sulphate spike of the last 2.3 ky recorded in cores from both Arctic and Antarctic ice sheets8. This continuous four-phase eruption evacuated 40 ± 3 km3 of trachydacitic magma during tens of hours, producing plinian plumes that rose up to 43 km in the stratosphere and tephra fingerprinted up to 660 km from the source, thus standing as the most powerful eruption of the last millenium9. Archaeologists recently determined a date of 1258 for mass burial of thousands of medieval skeletons in London10, that could be linked in some respect to climatic perturbations in the Northern Hemisphere by the 1257 Samalas eruption. Indeed, medieval chronicles in Northern Europe7 document the occurrence of initial warming in the early winter of 1258 just following the eruption, that was followed by extensive wet and cold climatic conditions in 1259 that may have impacted crops and contributed to the onset and magnitude of famines at that time for some regions of the Northern Hemisphere. The 1257 Samalas eruption might also have contributed to the onset of the Little Ice Age11.

It’s damn interesting. Also tragic – a third of the population of London died.

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