Mega Volcanic Eruptions in 536 and 540 CE and Aftermath Caused the Collapse of Multiple Societies and Massive Deaths

"...the volcanoes decreased average global temperatures by as much as 3.6 degrees Fahrenheit. Crops in northern Europe and elsewhere failed, likely triggering starvation and disease."

I zeroed in on that 36 degrees F decrease in temperature, because a few days ago, I read an article at The Washington Post about the recent average 2 degrees Centigrade increase in temperatures in the United States - which equates to 3.6 degrees F.  If a drop of less than 4 degrees F caused massive crop failures and famines around the globe, triggering societal collapses in one area after another and roving groups of bandits and invaders looking for food, water and animals - what do you think a 3.6 degrees F rise in temperature on average may do to crop production, local ecosystems and their plants and animal life?  

The "disease" the quote above refers to is the plague of Justinian, which killed "tens of millions of people" starting in 541, arguable the worst year of the combined sustained impact of the catastrophic volcanic eruptions in 536 and 540.

This scares the bejesu out of me!  The climate change in the 6th century CE was "mini" (it lasted about 10 years) compared to what we can expect to get worse and deepen from now into the foreseeable future - and beyond that. 

If you want to read the articles I did, here they are:

"2 Degrees Centigrade Beyond the Limit
Extreme Climate Change Has Arrived in America"
Steven Mufson, Chris Mooney, Juliet Eilperin and John Muyskens
Photography by Salwan Georges
August 13, 2019"
The Washington Post Online

"The Global Cooling Event of the Sixth Century.  Mystery No Longer?"
Dr. Tim Neufield, Princeton University
May 1, 2016
Historical Climatology Blog
(This is the first article I read about the period in the 6th century CE called the "Mini-Ice Age."  It can get a little bit technical in places, but not overly so).  

"Colossal volcano behind 'mystery' global cooling finally found"
Michael Greshko
August 23, 2019
National Geographic Online
(While this article does not pinpoint the location of the massive volcanic eruption that occurred in 536 CE, it does refer to it.  The article itself is about the eruption in 540 CE and how researchers eventually narrowed the eruption site down to a volcano in Central America).  

Volcano Responsible for "Little Ice Age" May Have Been Identified

This is fascinating!

From Science Now

Source of Mysterious Medieval Eruption Identified

1 October 2013 4:45 pm

 

About 750 years ago, a powerful volcano erupted somewhere on Earth, kicking off a centuries-long cold snap known as the Little Ice Age. Identifying the volcano responsible has been tricky. Now, using geochemical, stratigraphic, and even historical data, a team of scientists has fingered a likely culprit: Indonesia’s Samalas volcano, part of the Rinjani Volcanic Complex on Lombok Island.

The Little Ice Age has been abundantly depicted in contemporary accounts of advancing mountain glaciers that destroyed villages and paintings of ice-skating on frozen Dutch canals or on London’s River Thames, but the date of its actual onset was uncertain. Chilling of the Northern Hemisphere was pronounced: cold summers, incessant rains, floods, and resulting poor harvests, according to medieval records.

That a powerful volcano erupted somewhere in the world, sometime in the Middle Ages, is written in polar ice cores in the form of layers of sulfate deposits and tiny shards of volcanic glass. These cores suggest that the amount of sulfur the mystery volcano sent into the stratosphere put it firmly among the ranks of the strongest climate-perturbing eruptions of the current geological epoch, the Holocene, a period that stretches from 10,000 years ago to the present. A haze of stratospheric sulfur cools climate by reflecting solar energy back into space.

In 2012, a team of scientists led by geochemist Gifford Miller of the University of Colorado, Boulder, strengthened the link between the mystery eruption and the onset of the Little Ice Age by using radiocarbon dating of dead plant material from beneath the ice caps on Baffin Island and Iceland, as well as ice and sediment core data, to determine that the cold summers and ice growth began abruptly between 1275 and 1300 C.E. (and became intensified between 1430 and 1455 C.E.). Such a sudden onset, they noted in Geophysical Research Letters in 2012, pointed to a huge volcanic eruption injecting sulfur into the stratosphere and starting the cooling. Subsequent, unusually large and frequent eruptions of other volcanoes, as well as sea-ice/ocean feedbacks persisting long after the aerosols have been removed from the atmosphere, may have prolonged the cooling through the 1700s. [I wonder how many people died from famine and/or malnutrition either directly or indirectly, e.g., a person weakened by chronic hunger might have a compromised immune system compared to someone well fed.] 

Volcanologist Franck Lavigne of the Université Paris in and colleagues now think they’ve identified the volcano in question: Indonesia’s Samalas. One line of evidence, they note this week in the Proceedings of the National Academy of Sciences, is historical records. According to Babad Lombok, records of the island written on palm leaves in Old Javanese, Samalas erupted catastrophically before the end of the 13th century, devastating surrounding villages—including Lombok’s capital at the time, Pamatan—with ash and fast-moving sweeps of hot rock and gas called pyroclastic flows.
The researchers then began to reconstruct the formation of the large, 800-meter-deep caldera that now sits atop the volcano. They examined 130 outcrops on the flanks of the volcano, exposing sequences of pumice—ash hardened into rock—and other pyroclastic material. The volume of ash deposited, and the estimated height of the eruption plume (43 kilometers above sea level) put the eruption’s magnitude at a minimum of 7 on the volcanic explosivity index (which has a scale of 1 to 8)—making it one of the largest known in the Holocene. The eruption, the authors note, was on the scale of the Tambora eruption of 1815, and more powerful than Krakatoa in 1883.

The team also performed radiocarbon analyses on carbonized tree trunks and branches buried within the pyroclastic deposits to confirm the date of the eruption; it could not, they concluded, have happened before 1257 C.E., and certainly happened in the 13th century.

It’s not a total surprise that an Indonesian volcano might be the source of the eruption, Miller says. “An equatorial eruption is more consistent with the apparent climate impacts.” And, he adds, with sulfate appearing in both polar ice caps—Arctic and Antarctic—there is “a strong consensus” that this also supports an equatorial source.

Another possible candidate—both in terms of timing and geographical location—is Ecuador’s Quilotoa, estimated to have last erupted between 1147 and 1320 C.E. But when Lavigne’s team examined shards of volcanic glass from this volcano, they found that they didn’t match the chemical composition of the glass found in polar ice cores, whereas the Samalas glass is a much closer match. That, they suggest, further strengthens the case that Samalas was responsible for the medieval “year without summer” in 1258 C.E.

Irish Monks' Annals of Weather Changes Confirmed by Modern Research

This is just fascinating!  From BBC News.

June 6, 2013
Ancient Irish texts show volcanic link to cold weather
By Matt McGrath Environment correspondent, BBC News

Researchers have been able to trace the impact of volcanic eruptions on the climate over a 1200 year period by assessing ancient Irish texts. The international team compared entries in these medieval annals with ice core data indicating volcanic eruptions.

Of 38 volcanic events, 37 were associated with directly observed cold weather extremes recorded in the chronicles. The report is published in the journal Environmental Research Letters.

In the dim light of the Dark Ages, the Irish literary tradition stands out like a beacon. At monastic centres across the island, scribes recorded significant events such as feast days, obituaries and descriptions of extreme cold and heat. These chronicles are generally known as the Irish Annals and in this report, scientists and historians have looked at 40,000 entries in the texts dating from AD431 to 1649.

The researchers also looked at the Greenland Ice Sheet Project (GISP2) ice-core data.

When volcanoes erupt, they produce sulphate aerosol particles which down the centuries have been deposited on and frozen in ice sheets, leaving an extremely accurate temporal record of the event.

Walking on water

Scientists say these particles reflect incoming sunlight and can cause a temporary cooling of the Earth's surface. In a country with a mild maritime climate like Ireland, these colder events would have a significant impact.

"When the weather that is cold enough to allow you to walk over a lake in Ireland, it is pretty unusual," lead author Dr Francis Ludlow, from Harvard University, told BBC News. "When it happened, it was remarkable enough to be recorded pretty consistently."

The scientists in the team identified 48 volcanic eruptions in the time period spanning 1,219 years. Of these, 38 were associated closely in time with extreme weather events identified in the Irish texts.

"These eruptions occur and they override existing climate patterns for a period of two or three years," said Dr Ludlow.  "And it is clear from the sources that they cause a lot of devastation among societies at the time - whether it was the mass mortality of domestic animals or humans, or indirectly by causing harvest failure."

The end is nigh

The research team believe the texts are accurate as the annals also record solar and lunar eclipses which can be compared with other contemporary sources.

The keen recording of weather though had another motivation.

"A lot of these scribes are working in monasteries, in some time periods they are interpreting these weather events as divine omens or portents as signals of the coming of the last days," said Dr Ludlow.  "That was one of their motivations so we are able to use the records that were created for a completely different purpose that the scribes would never have conceived."

The researchers say that one expected effect of volcanic eruptions that occur in tropical regions is to make for milder winters in northern latitudes.

But in this study, they found several instances of these type of eruptions causing extremely cold winters in Ireland. The team believes their work shows the complex nature of volcanic impacts on climate, and they say there are lessons for the future in the ancient texts.

"That tells us a lot about what sort of weather we might expect in the British Isles when the next big eruption goes off," said Dr Ludlow.  "We might want to buy a bit more salt for the roads."