Why 536 was ‘the worst year to be alive'
Glacier cores reveal Icelandic volcano that plunged Europe into darkness
15 NOV 2018 BYANN GIBBONS
Ask medieval historian Michael McCormick what year was the worst to be
alive, and he's got an answer: "536." Not 1349, when the Black Death wiped
out half of Europe. Not 1918, when the flu killed 50 million to 100 million
people, mostly young adults. But 536. In Europe, "It was the beginning of one
of the worst periods to be alive, if not the worst year," says McCormick, a
historian and archaeologist who chairs the Harvard University Initiative for
the Science of the Human Past.
A mysterious fog plunged Europe, the Middle East, and parts of Asia into
darkness, day and night—for 18 months. "For the sun gave forth its light
without brightness, like the moon, during the whole year," wrote Byzantine
historian Procopius. Temperatures in the summer of 536 fell 1.5°C to 2.5°C,
initiating the coldest decade in the past 2300 years. Snow fell that summer in
China; crops failed; people starved. The Irish chronicles record "a failure of
bread from the years 536–539." Then, in 541, bubonic plague struck the
Roman port of Pelusium, in Egypt. What came to be called the Plague of
Justinian spread rapidly, wiping out one-third to one-half of the population of
the eastern Roman Empire and hastening its collapse, McCormick says.
Historians have long known that the middle of the sixth century was a dark
hour in what used to be called the Dark Ages, but the source of the
mysterious clouds has long been a puzzle. Now, an ultraprecise analysis of
ice from a Swiss glacier by a team led by McCormick and glaciologist Paul
Mayewski at the Climate Change Institute of The University of Maine (UM) in
Orono has fingered a culprit. At a workshop at Harvard this week, the team
reported that a cataclysmic volcanic eruption in Iceland spewed ash across
the Northern Hemisphere early in 536. Two other massive eruptions
followed, in 540 and 547. The repeated blows, followed by plague, plunged
Europe into economic stagnation that lasted until 640, when another signal in
the ice—a spike in airborne lead—marks a resurgence of silver mining, as the
team reports in Antiquity this week.
To Kyle Harper, provost and a medieval and Roman historian at The
University of Oklahoma in Norman, the detailed log of natural disasters and
human pollution frozen into the ice "give us a new kind of record for
understanding the concatenation of human and natural causes that led to the
fall of the Roman Empire—and the earliest stirrings of this new medieval
economy."
Ever since tree ring studies in the 1990s suggested the summers around the
year 540 were unusually cold, researchers have hunted for the cause. Three
years ago polar ice cores from Greenland and Antarctica yielded a clue.
When a volcano erupts, it spews sulfur, bismuth, and other substances high
into the atmosphere, where they form an aerosol veil that reflects the sun's
light back into space, cooling the planet. By matching the ice record of these
chemical traces with tree ring records of climate, a team led by Michael Sigl,
now of the University of Bern, found that nearly every unusually cold summer
over the past 2500 years was preceded by a volcanic eruption. A massive
eruption—perhaps in North America, the team suggested—stood out in late
535 or early 536; another followed in 540. Sigl's team concluded that the
double blow explained the prolonged dark and cold.
Mayewski and his interdisciplinary team decided to look for the same
eruptions in an ice core drilled in 2013 in the Colle Gnifetti Glacier in the
Swiss Alps. The 72-meter-long core entombs more than 2000 years of
fallout from volcanoes, Saharan dust storms, and human activities smack in
the center of Europe. The team deciphered this record using a new ultra–
high-resolution method, in which a laser carves 120-micron slivers of ice,
representing just a few days or weeks of snowfall, along the length of the
core. Each of the samples—some 50,000 from each meter of the core—is
analyzed for about a dozen elements. The approach enabled the team to
pinpoint storms, volcanic eruptions, and lead pollution down to the month or
even less, going back 2000 years, says UM volcanologist Andrei Kurbatov.
Darkest hours and then a dawn
A high-resolution ice core record combined with historical texts chronicles
the impact of natural disasters on European society.
530
530
550
640
650
660
540
540
550
560
570
580
590
600
610
620
630
640
650
660
536
Icelandic volcano erupts, dimming the sun for 18
months, records say. Summer temperatures drop by
1.5°C to 2.5°C.
536–545
Coldest decade on record in 2000 years. Crops fail
in Ireland, Scandinavia, Mesopotamia, and China.
540–541
Second volcanic eruption. Summer temperatures
drop again by 1.4°C–2.7°C in Europe.
541–543
The “Justinian” bubonic plague spreads through the
Mediterranean, killing 35%–55% of the population
and speeding the collapse of the eastern Roman
Empire.
640
After declining in the mid-500s, a surge in atmo
-
spheric lead signals an increase in silver mining
because of economic recovery.
660
A second lead peak reflects silver mining, proba
-
bly at Melle, France, tied to a switch from gold to
silver for coins and the beginnings of the medieval
economy.
(GRAPHIC) A. CUADRA/SCIENCE; (DATA) C. P. LOVELUCK ET AL.,
ANTIQUITY 2018; M. SIGL ET AL., NATURE 2015; M. MCCORMICK
In ice from the spring of 536, UM graduate student Laura Hartman found two
microscopic particles of volcanic glass. By bombarding the shards with x-
rays to determine their chemical fingerprint, she and Kurbatov found that
they closely matched glass particles found earlier in lakes and peat bogs in
Europe and in a Greenland ice core. Those particles in turn resembled
volcanic rocks from Iceland. The chemical similarities convince geoscientist
David Lowe of The University of Waikato in Hamilton, New Zealand, who says
the particles in the Swiss ice core likely came from the same Icelandic
volcano. But Sigl says more evidence is needed to convince him that the
eruption was in Iceland rather than North America.
Either way, the winds and weather systems in 536 must have been just right
to guide the eruption plume southeast across Europe and, later, into Asia,
casting a chilly pall as the volcanic fog "rolled through," Kurbatov says. The
next step is to try to find more particles from this volcano in lakes in Europe
and Iceland, in order to confirm its location in Iceland and tease out why it
was so devastating.
A century later, after several more eruptions, the ice record signals better
news: the lead spike in 640. Silver was smelted from lead ore, so the lead is a
sign that the precious metal was in demand in an economy rebounding from
the blow a century before, says archaeologist Christopher Loveluck of the
University of Nottingham in the United Kingdom. A second lead peak, in 660,
marks a major infusion of silver into the emergent medieval economy. It
suggests gold had become scarce as trade increased, forcing a shift to silver
as the monetary standard, Loveluck and his colleagues write in Antiquity. "It
shows the rise of the merchant class for the first time," he says.
Still later, the ice is a window into another dark period. Lead vanished from
the air during the Black Death from 1349 to 1353, revealing an economy that
had again ground to a halt. "We've entered a new era with this ability to
integrate ultra–high-resolution environmental records with similarly high
resolution historical records," Loveluck says. "It's a real game changer."
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