1258 volcanic eruption triggers global disaster

Fascinating piece in the Guardian on Facebook: "Mass grave in London reveals how volcano caused global catastrophe". The story begins:

Scientists search for the explosive source of a disaster that wiped out almost a third of Londoners 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.

The photo shows the huge excavation carried out by the team from the Museum of London Archaeology.

It's an interesting story, for it was the radio carbon dating of the bones to around 1250 that showed that the deaths could not have been caused by either the black death or the great famine of 1315-17. Another explanation had to be found.   

Writing 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 appears from further investigation including geological data from across the globe that this human catastrophe was cause by a huge volcanic eruption somewhere in the tropics up to eight times larger than that at Krakatoa (1883).  Now Krakatoa was a pretty big bang. I find it hard to imagine something up to eight times as large!

According to Volcanologist Bill McGuire:

"This was the biggest eruption in historic times. It may have brought the temperatures down by 4°c, a huge amount. Because it was somewhere in the tropics it meant that the winds of both hemispheres were able to carry these gases right across the planet. If you have a volcanic eruption at high latitudes, then the gases will stay in the northern hemisphere. But if you have an equatorial or tropical eruption that's big enough, then the sulphur gases can spread into both hemispheres and really encircle the whole planet in a sulphurous veil."

The reference to the global impact caught my eye, for this means that it would have affected Australia's Aboriginal peoples, including those living in New England. Intuitively, the relative impact wouldn't have been as great because of lower population densities. Still, it's interesting in the context of some of the thinking I have been doing about the patterns of Aboriginal life.