The extreme weather events of the years 535-536 — encompassing strangely low-temperatures, with snow even falling during the summer months in some locations; widespread crop-failures and famine; greatly diminished levels of sunlight; and accompanying geopolitical problems — were the most severe and long-lasting such occurrence of the last 2000 or so years in the Northern Hemisphere.

While it’s currently thought that the event was caused by an extensive atmospheric dust veil formed either, via a large volcanic eruption in the tropics, or the disintegration of a large amount of space-debris in the upper atmosphere, nothing is known for sure.

Evidence does point towards the volcanic explanation though — owing to the presence of substantial sulfate deposits in glaciers around the world corresponding to the years in question.

While you may have never heard of this event before, that’s simply because you’re fortunate enough not to have lived then — and, for that matter, to be descended from some of the people that didn’t die during those years of extreme temperature-fluctuations, crop-failures, famine, flooding, limited sunlight, etc.

And while you may now be thinking, “well that’s unfortunate but it’s just weather people can simply pick up the pieces once things settle down”, it’s probably worth reminding yourself that there’s a good reason many old stories concerning the collapses of empires and civilizations often make mention of natural disasters and/or strange weather — the two often go hand-in-hand, with natural disasters often serving as a trigger for the release of built-up social/geopolitical pressures.

Contemporary Accounts — Byzantines, Moche (Peru), Chinese, Irish, Arabs, Etc

There are a fair number of contemporary accounts of the events (the ones specific to region where they originate). Probably the most interesting of these is the account of the famous Byzantine historian Procopius recorded in “History of the Wars“.

In that recounting, Procopius, while discussing the wars with the Vandals, noted that “during this year (536) a most dread portent took place. For the sun gave forth its light without brightness… and it seemed exceedingly like the sun in eclipse, for the beams it shed were not clear.”

There are a great many of notable accounts though, including:

• The Gaelic Irish Annals, which record: “A failure of bread in the year 536 AD” (the Annals of Ulster) and “A failure of bread from the years 536–539 AD” (the Annals of Inisfallen).
• Accounts in China mentioning very low temperatures, with snow occurring even during some of the summer months (and apparently causing widespread problems with crops).
• Severe drought — accompanied by strange weather — accounted by the Moche culture in what is now Peru.
• Accounts of crop failures, and a “dense, dry fog”, throughout Europe and the Middle East — as well as the aforementioned China.

Tree Ring Analysis + Ice Core Analysis

Tree-ring analysis work done by the dendrochronologist Mike Baillie — of the Queen’s University of Belfast — has shown that there was “abnormally” low growth in Irish oaks in the 536 growing season. This was followed by a partial recovery and then another drop in growth in 542.

Tree-ring analysis of tree-stands in Sweden, Finland, California, and Chile, all confirm these findings.

Ice core analysis backs this work up as well — with ice cores taken from Antarctica and Greenland both showing the presence of very large sulfate deposits around 533–534 ± 2 years. Which is exactly what you’d expect to find if there was a large volcanic eruption duringt his time,

While it’s not completely clear which volcano is responsible, the best current evidence points towards the Ilopango caldera in what is now El Salvador.

In 2010, Robert Dull, John Southon and colleagues presented evidence suggesting a link between the Tierra Blanca Joven (TBJ) eruption of the Ilopango caldera in central El Salvador and the AD 536 event. Although earlier published radiocarbon evidence suggested a two-sigma age range of AD 408–536, which is consistent with the global climate downturn, the connection between AD 536 and Ilopango was not explicitly made until research on Central American Pacific margin marine sediment cores by Steffen Kutterolf and colleagues showed that the phreatoplinian TBJ eruption was much larger than previously thought.

The radioactive carbon-14 in successive growth increments of a single tree that had been killed by a TBJ pyroclastic flow was measured in detail using Accelerator mass spectrometry; the results supported the date of AD 535 as the year in which the tree died. A conservative bulk tephra volume for the TBJ event of ~84 km3 was calculated, indicating a large Volcanic Explosivity Index 6+ event and a magnitude of 6.9. The results suggest that the Ilopango TBJ eruption size, latitude and age are consistent with the ice core sulphate records of Larsen et al. 2008.

Geopolitical & Social Effects

The extreme weather events of 535-536 have been (at various times) implicated in the decline of the largest city in the world at the time — Teotihuacán, in what is now Central America — owing to the effects of extreme drought, crop-failures, desertification, and the social problems that reliably accompany those things.

It’s also been suggested that the events are the reason that at this time huge stashes of gold were buried in the ground throughout Scandinavia by the elites of the time. Perhaps as an offering of some kind to the Nordic gods of the time?

Other connections suggested by historians include: the decline of the Avars; the migration of the Mongolian tribes westwards; the setting of the stage for the rise of Islam; the fall of the Gupta Empire; the migration and spread of various Turkic tribes; and the fall of the Sassanid Empire.

Given how long ago all of this occurred though, and the fact that only fragments of the records of the times have survived to the present, it’s impossible to know exactly in what way the events of 535-536 played into and affected the human-constructed world of the time. But there’s no doubt that it had an effect — and a very pronounced one at that, on many peoples and cultures.

Image Credit: Public Domain