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.
The Science article carries the implication that the sun was completely darkened. Yes, Procopius did write this, but he did not state how long the event lasted. The 18-months comes from the 12th century historian Michael the Syrian, who was probably citing the sixth century Historian John of Ephos, whom it is believed Michael faithfully quoted. This is Michael's quote
"In the year 848 [536/37 CE] there was a sign in the sun the like of which had never been seen and reported before in the world... So it is said that the sun became dark and its darkness lasted for one and a half years, that is, eighteen months. Each day it shone for about four hours, and still this light was only a feeble shadow. Everyone declared that the sun would never recover its original light. The fruits did not ripen, and the wine tasted like sour grapes."
Indeed, if we read the whole quote from Procopius it states
"And it came about during this year that a most dread portent took place. For the sun gave forth its light without brightness, like the moon, during this whole year, and it seemed exceedingly like the sun in eclipse, for the beams it shed were not clear nor such as it is accustomed to shed."
We must be careful here with what we take as meaning "like the sun in eclipse". We could of course jump to the image of the sun completely blocked out, but it is much more realistic to think of the reduced light levels of deep partial eclipses.
Even the length of the "darkness" may depend upon location. John of Lydos tells us in his work “On Portents” written around the 540s that:
“... the sun becomes dim... for nearly a whole year... the fruit was destroyed because of the bad time”.
Note again, that the sun is dim, not dark, and this lasted nearly a whole year.
So, in historical literature there is no mention of darkness day and night, merely that the sun was reduced in intensity.
On the topic of the Irish Annals the article states that "The Irish chronicles record "a failure of bread from the years 536–539."
This is a conflation of information from different chronologies. Failure of bread is indeed mentioned in the Irish Annals, but various dates are given for it. The Annals of Ulster give Failure of Bread in the years 536 and 539, Annals of Innisfallen 537 and the Annals of Tighernac 538. If we conflate these dates we get a prolonged event of 536-539, where there is a failure of bread every year. We do have two separate climatic events in 536 and 540, which seemingly matches the failure of bread in 536 and 539 (perhaps there is a slight mis-dating and the years should be 536/7 and 540).
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.
Note this is a workshop and that the results have yet to pass peer review. The Eruption in 547 doesnt appear to be that massive, judging by the sulphate signal in ice. It may have been detrimental because the climate was still recovering from the 536 and 540 eruptions.
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.
Mostly true, but it leaves out a very important point. In 2015 Sigl et al published the data that proved without doubt that there were two eruption signals in ice from Greenland dated to 536 and 540. In this publication they pointed out that 536 ice layer had at least 4 different tephra types. Chemical analysis found three of types of tephra shards to be similar to volcanic systems in the Aleutian arc (Alaska), Northern Cordilleran volcanic province (British Columbia), and Mono-Inyo Craters area (California). So it is possible that the 536 event may have been due to a multiple large explosive volcanic eruptions, so we cannot really blame a single eruption at the moment, though climate modelling based upon volcanic cooling calculated from the sulphur yield within the ice cores and an assumed eruption point in Alaska, does reproduce rather well the reconstructed European temperatures and historically recorded dust veil characteristics (Toohey et al. 2016).
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.
I agree with Michael Sigl, more evidence is needed. If the two shards are from Iceland, it doesn't necessarily mean that the volcano was the cause of the whole 536 event. The shards may have been transported to the Swiss glacier by tropospheric transport (i.e. on the weather systems), but this does not tell us that the Icelandic eruption was necessarily large enough to penetrate the tropospheric ceiling to the stratosphere where volcanic forcing of climate is far more efficient and prolonged.
To tell the truth I have issues with the researchers chronological dating of their Alpine ice core in which they claim to have found icelandic tephra in AD 536. From a recent paper )Loveluck et al 2018 [www.cambridge.org] by the authors they state the following:
The ultra-high-resolution time series allows the application of the Colle Gnifetti layer counting
procedure back to at least the beginning of the first millennium AD.The layer-counting
methodology had a theoretical error margin of ±72 years at c. AD 600, without absolute dating
markers to tie the chronology more closely (Bohleber et al. 2018). The chronology has been greatly refined and established to address the research questions of this paper by the use of three
absolute chronological markers that reduce this theoretical error-margin to an estimated ±10 years
or fewer. The first absolute marker is provided by the Black Death signal (see More et al. 2017).
More et al. (2017) have demonstrated that despite a theoretical error of 35–40 years, between 1330
and 1370, the total collapse in lead pollution in layer-counted deposits, from 1349 to 1353,
matches exactly the absolute chronology from textual sources for the Black Death epidemic,
especially in Britain—the probable source of the pollution record for that period.
The second absolute marker comes from the geochemical evidence of the massive eruption
of the Icelandic Eldgjá volcano between AD 934 and 939 (Thordason et al. 2001). The
discrete ICP-MS data from Colle Gnifetti present a large bismuth peak at AD 945, which
probably indicates the Eldgjá eruption. Although this also corresponds with a large sulphate
peak at Colle Gnifetti, sulphate cannot be used as a reliable volcanic marker there, as most of
it arrives in the form of gypsum (calcium sulphate) as dust (Schwikowski et al. 2004). A similar
contribution of sulphate from dust was encountered in the Mount Everest ice core, where
bismuth was also used as the independent volcanic marker (Kaspari et al. 2007: 1–2). The
identification of the large bismuth increase at c. AD 945 at Colle Gnifetti with the Eldgjá
eruption corresponds closely with its eruption interval, suggested as AD 934 in Alpine
tree rings and at 939 in the GISP2 Greenland ice core (Baillie & McAneney 2015: 112).
The occurrence of other Icelandic volcanic signals in the Colle Gnifetti core has also been
confirmed by the publication of Icelandic tephra recovered from it (Luongo et al. 2017),
and is further emphasised by the new discovery below.
The third absolute marker is provided by analysis of newly discovered tephra particles
from the Colle Gnifetti core that are chemically very similar to the tephra from the
NEEM-2011-S1 Greenland ice core—shard QUB-1859 (Sigl et al. 2015; see OSM S1).
The latter has been interpreted as tephra corresponding to the AD 536 volcanic event.
The NEEM-2011-S1 core is tied chronologically to the GICC05 Greenland ice core,
which fixes the NEEM-2011 and the Colle Gnifetti tephra to AD 536±2 (Sigl et al.
2013). The Colle Gnifetti annual layer-counting chronology places the AD 536-event tephra
at AD 500, suggesting a maximum error of 36 years at AD 536 in the initial chronology
(Bohleber et al. 2018). Recounting of the annual layers from the Eldgjá event to AD 536
has ascertained that, due to poorly defined annual layers, the counting error occurred between
c. AD 500 and 600. The current theoretical error margin between AD 600 and 700 is estimated
at a maximum of ±10 years, and less through the eighth and ninth centuries AD.
I cannot comment upon the first "absolute marker" but I can comment upon the second and third markers.
For the second marker they claim to have identified a marker from the Edgja eruption in their Alpine ice core. They seem to suggest that there is uncertainty in the eruption date of Eldgja giving the eruption interval between AD 934 and 939. As of 2015 we now have a precise and accurate date for tehe ruption of Eldgja in AD 539. This is because in layers of Greenland ice we have two volcanic tephra horizons, one from Edgja and another 7 years later from Changbaishan. In 2015 Sigl et al dated these two eruptions to 939 and 946 respectively, by linking ice cores to tree ring records via the AD 775 and 994 Miyake cosmic events. Later Oppenheimer et al dendrochronologically dated a tree killed by the Changbaishan eruption to the precise year of 946 by identifying the 775 event in the tree rings and counting the number of rings to the outside to arrive at 946. If they find a volcanic marker at 945 in their alpine ice core, and if it is Eldgja then it implies that their ice core is probably too young. Also, it is a dangerous exercise to attribute tree ring effects such as poor growth in Alpine trees in AD 934 to the climatic effects of any one specific eruption.
This brings us to the third "absolute marker". They try to synchronise their Alpine ice core with the NEEM ice core by supposed chemical similarity of tephra shards. They are confusing matters here with respect to the NEEM ice core. Yes the tephra shard QUB-1859 (which has been identified as coming from North America/Alaska) does now date to ice from AD 536 in the NEEM (Sigl et al 2015). In Sigl et al. (2013) the tehpra would have dated to 529 because the 2013 chronology was tied to the GICC05 time-scale which had a 7-year error in it. The 2015 timescale for NEEM is no longer ties to GICC05 and is completely independent of the GICC05 time-scale. For all intents and purposes the NEEM 2015 chronology is practically absolutely dated at AD 536.
I am not sure that the statement "newly discovered tephra particles from the Colle Gnifetti core that are chemically very similar to the tephra from the NEEM-2011-S1 Greenland ice core—shard QUB-1859" is sufficient to synchronise two geographically separate ice cores, particularly since in the above paper they do not seem to provide any quantitative data for others to check how similar the tephra shards are. Note that these are also the tephra shards that they are now claiming to be from Iceland, but which look to others to match Alaskan volcanic fields. So if the Alpine tephra shards are Icelandic, they may not actually date to 536. Even if they do, the 536 event looks to be more complex than a single massive eruption, given the 4 different tephra types found in NEEM.
|Why 536 was ‘the worst year to be alive’||1689||Race Jackson||18-Dec-18 23:09|
|Re: Why 536 was ‘the worst year to be alive’||314||JonnyMcA||20-Dec-18 16:15|
|Re: Why 536 was ‘the worst year to be alive’||177||Susan Doris||15-Jan-19 11:50|