Extreme weather events of 535–536
The extreme weather events of 535–536 were the most severe and protracted short-term episodes of cooling in the Northern Hemisphere in the last 2,000 years. The event is thought to have been caused by an extensive atmospheric dust veil, possibly resulting from a large volcanic eruption in the tropics or in Iceland. Its effects were widespread, causing unseasonable weather, crop failures, and famines worldwide.
The Byzantine historian Procopius recorded in 536 CE in his report on the wars with the Vandals, "during this year 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".
- "A failure of bread in the year 536 AD" – the Annals of Ulster
- "A failure of bread from the years 536–539 AD" – the Annals of Inisfallen
The mid 10th-century Annales Cambriae record for the year 537:
- "The Battle of Camlann, in which Arthur and Medraut fell, and there was great mortality in Britain and Ireland." [a] 
Further phenomena were reported by a number of independent contemporary sources:
- Low temperatures, even snow during the summer (snow reportedly fell in August in China, which caused the harvest there to be delayed)
- Widespread crop failures
- "A dense, dry fog" in the Middle East, China and Europe
- Drought in Peru, which affected the Moche culture
Tree ring analysis by dendrochronologist Mike Baillie, of the Queen's University of Belfast, shows abnormally little growth in Irish oak in 536 and another sharp drop in 542, after a partial recovery. Ice cores from Greenland and Antarctica show evidence of substantial sulfate deposits in around 534 ± 2, which is evidence of an extensive acidic dust veil.
It has been conjectured that the changes were caused by ashes or dust thrown into the air after the eruption of a volcano (a phenomenon known as "volcanic winter"), or after the impact of a comet or meteorite. The evidence of sulfate deposits in ice cores strongly supports the volcano hypothesis; the sulfate spike is even more intense than that which accompanied the lesser episode of climatic aberration in 1816, popularly known as the "Year Without a Summer", which has been connected to the explosion of the volcano Mount Tambora in Sumbawa.
In 1999, David Keys suggested that the volcano Krakatoa exploded at the time and caused the changes. It is suggested that an eruption of Krakatoa described as occurring in 416 by the Javanese Book of Kings actually took place in 535–536, there being no other evidence of such an eruption in 416.:385
In 2009, Dallas Abbott of Columbia University's Lamont–Doherty Earth Observatory in New York published evidence from Greenland ice cores that multiple comet impacts may have caused the haze. The spherules found in the ice might originate from terrestrial debris ejected into the atmosphere by an impact event.
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 536 event. Although earlier published radiocarbon evidence suggested a two-sigma age range of 408–536, which is consistent with the global climate downturn, the connection between 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 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 suggested that the Ilopango TBJ eruption size, latitude, and age are consistent with the ice core sulphate records of Larsen et al. 2008. However, a more recent study, examining other evidence, now dates the eruption to the year 431 C.E.
A 2015 study further supported the theory of a major eruption in "535 or early 536", with North American volcanoes considered a likely candidate. It also identified signals of a second eruption in 539–540, likely to have been in the tropics, which would have sustained the cooling effects of the first eruption through to around 550.
In 2018, Harvard University researchers suggested the cause was a volcanic eruption in Iceland that erupted in early 536. However, the author of the previous study said to Science magazine that the evidence is insufficient to discard the North America hypothesis.
The 536 event and ensuing famine have been suggested as an explanation for the deposition of hoards of gold by Scandinavian elites at the end of the Migration Period. The gold was possibly a sacrifice to appease the gods and get the sunlight back. Mythological events such as the Fimbulwinter and Ragnarök are theorized to be based on the cultural memory of the event.
A book written by David Keys speculates that the climate changes contributed to various developments, such as the emergence of the Plague of Justinian (541–549 AD), the decline of the Avars, the migration of Mongolian tribes towards the West, the end of the Sassanid Empire, the collapse of the Gupta Empire, the rise of Islam, the expansion of Turkic tribes, and the fall of Teotihuacán. In 2000, a 3BM Television production (for WNET and Channel Four) capitalized upon Keys' book. The documentary, under the name Catastrophe! How the World Changed, was broadcast in the US as part of PBS's Secrets of the Dead series. However, Keys and Wohletz' ideas lack mainstream acceptance. Reviewing Keys' book, British archaeologist Ken Dark commented that "much of the apparent evidence presented in the book is highly debatable, based on poor sources or simply incorrect. [...] Nonetheless, both the global scope and the emphasis on the 6th century AD as a time of wide-ranging change are notable, and the book contains some obscure information which will be new to many. However, it fails to demonstrate its central thesis and does not offer a convincing explanation for the many changes discussed".
The historian Andrew Breeze in a recent book (2020) argues that the King Arthur and the Battle of Camlann are historical, happening in 537 as consequence of the famine associated with the climate change of the previous year.
- Tierra Blanca Joven eruption
- 1257 Samalas eruption
- Great Famine of 1315–1317
- 1815 eruption of Mount Tambora, largest ever recorded
- Justinian I, Roman emperor at the time
- Kuwae, a South Pacific volcano that erupted c. 1452–53
- Minoan eruption
- Year Without a Summer, 1816
- Volcanology of Iceland
- The battle is dated 539 in some editions.
- Abbott, D. H.; Biscaye, P.; Cole-Dai, J.; Breger, D. (December 2008). "Magnetite and Silicate Spherules from the GISP2 Core at the 536 A.D. Horizon". AGU Fall Meeting Abstracts. 41: 41B–1454. Bibcode:2008AGUFMPP41B1454A. Abstract #PP41B-1454.
- Larsen, L. B.; Vinther, B. M.; Briffa, K. R.; Melvin, T. M.; Clausen, H. B.; Jones, P. D.; Siggaard-Andersen, M.-L.; Hammer, C. U.; et al. (2008). "New ice core evidence for a volcanic cause of the A.D. 536 dust veil". Geophys. Res. Lett. 35 (4): L04708. Bibcode:2008GeoRL..3504708L. doi:10.1029/2007GL032450.
- Gibbons, Ann (November 15, 2018). "Why 536 was 'the worst year to be alive'". Science | AAAS. Retrieved November 16, 2018.
- Than, Ker (3 January 2009). "Slam dunks from space led to hazy shade of winter". New Scientist. 201 (2689): 9. Bibcode:2009NewSc.201....9P. doi:10.1016/S0262-4079(09)60069-5.
- Procopius; Dewing, Henry Bronson, trans. (1916). Procopius. vol. 2: History of the [Vandalic] Wars, Books III and IV. London, England: William Heinemann. p. 329. ISBN 978-0-674-99054-8.
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- Ochoa, George; Jennifer Hoffman; Tina Tin (2005). Climate: the force that shapes our world and the future of life on earth. Emmaus, PA: Rodale. ISBN 978-1-59486-288-5., gives this quote as "The Sun gave forth its light without brightness, like the moon during this whole year, and it seemed exceedingly like the Sun in eclipse".
- Cassiodorus; Hodgkin, Thomas, trans. (1886). The Letters of Cassiodorus. London, England: Henry Frowde. pp. 518–520. See: "25. Senator, Praetorian Praefect, to his deputy Ambrosius, an Illustris."
- Michel le Syrien; Chabot, J.-B., trans. (1901). Chronique de Michel le Syrien, Patriarche Jacobite d'Antoche [Chronicle of Michael the Syrian, Jacobite Patriarch of Syria] (in French). 2nd vol. Paris, France: Leroux. pp. 220–221. From pp. 220–221: "Or, un peu auparavant, en l'an 848, il y eut un signe dans le soleil. … , et le vin avait le goût de celui qui provient de raisins acides." (However, a little earlier, in the year 848 [according to the Greek calendar; 536/537 AD according to the Christian calendar], there was a sign in the sun. One had never seen it [before] and nowhere is it written that such [an event] had happened [previously] in the world. If it were not [true] that we found it recorded in most proven and credible writings, and confirmed by men worthy of belief, we would not have written it [here]; for it's difficult to conceive. So it is said that the sun was darkened, and that its eclipse lasted a year and a half, that is, eighteen months. Every day it shone for about four hours and yet this light was only a feeble shadow. Everyone declared that it would not return to the state of its original light. Fruits didn't ripen, and wine had the taste of what comes from sour grapes.)
- Gaelic Irish Annals translations
- Documents of Ireland
- The Annals of the Four Masters
- "Camlan | Robbins Library Digital Projects". Retrieved 2018-07-31.
- Ochoa, George; Jennifer Hoffman; Tina Tin (2005). Climate: the force that shapes our world and the future of life on earth. Emmaus, Pennsylvania: Rodale. p. 71. ISBN 978-1-59486-288-5.
- Rosen, William (2007). Justinian's flea: Plague, Empire and the Birth of Europe. London: Jonathan Cape. ISBN 978-0-224-07369-1.
- Keys, David Patrick (2000). Catastrophe: an investigation into the origins of the modern world. New York: Ballantine Pub. ISBN 978-0-345-40876-1.
- Stothers, R.B.; Rampino, M.R. (1983). "Volcanic eruptions in the Mediterranean before AD 630 from written and archaeological sources". Journal of Geophysical Research. 88: 6357–6471. doi:10.1029/JB088iB08p06357.
- Stothers, R.B. (16 January 1984). "Mystery cloud of AD 536". Nature. 307 (5949): 344–345. doi:10.1038/307344a0. S2CID 4233649.
- Rampino, M.R.; Self, S.; Stothers, R.B. (1988). "Volcanic winters". Annual Review of Earth and Planetary Sciences. 16: 73–99. doi:10.1146/annurev.ea.16.050188.000445.
- Arjava, Antti (2005). "The mystery cloud of 536 CE in the Mediterranean sources". Dumbarton Oaks Papers. 59: 73–94. doi:10.2307/4128751. JSTOR 4128751.
- Baillie, M.G.L. (1994). "Dendrochronology Raises Questions About the Nature of the AD 536 Dust-Veil Event." The Holocene fig. 3 p. 215.
- Wohletz, Ken, Were the Dark Ages Triggered by Volcano-Related Climate Changes in the 6th Century? Archived 2003-06-18 at the Wayback Machine
- MacIntyre, Ferren (2002). "Simultaneous Settlement of Indo-Pacific Extrema?". Rapa Nui Journal. 16 (2): 96–104.
- Baillie, M. G. L. (1999). Exodus to Arthur: Catastrophic Encounters with Comets. London: B.T. Batsford. ISBN 978-0-7134-8352-9.
- Rigby, Emma; Symonds, Melissa; Ward-Thompson, Derek (February 2004). "A comet impact in AD536?". Astronomy and Geophysics. 45 (1): 1.23–1.26. Bibcode:2004A&G....45a..23R. doi:10.1046/j.1468-4004.2003.45123.x.
- Stothers R.B. (26 January 1984). "Mystery cloud of AD 536". Nature. 307 (5949): 344–345. Bibcode:1984Natur.307..344S. doi:10.1038/307344a0. S2CID 4233649.
- "Comet smashes triggered ancient famine". New Scientist. 7 January 2009.
- Dull, R.; J.R. Southon; S. Kutterolf; A. Freundt; D. Wahl; P. Sheets (13–17 December 2010). "Did the TBJ Ilopango eruption cause the AD 536 event?". AGU Fall Meeting Abstracts. 13: V13C–2370. Bibcode:2010AGUFM.V13C2370D.
- Dull, R. A.; Southon, J. R. & Sheets, P. (2001). "Volcanism, ecology and culture: a reassessment of the Volcán Ilopango TBJ eruption in the southern Maya realm". Latin American Antiquity. 12 (1): 25–44. doi:10.2307/971755. JSTOR 971755.
- Kutterolf, S. A. Freundt; W. Peréz (2008). "Pacific offshore record of plinian arc volcanism in Central America: 2. Tephra volumes and erupted masses". Geochemistry Geophysics Geosystems. 9, Q02S02 (2): n/a. Bibcode:2008GGG.....902S02K. doi:10.1029/2007GC001791.
- Victoria C. Smith; et al. (2020). "The magnitude and impact of the 431 CE Tierra Blanca Joven eruption of Ilopango, El Salvador". PNAS. doi:10.1073/pnas.2003008117.
- Sigl, M.; Winstrup, M.; McConnell, J. R.; Welten, K. C.; Plunkett, G.; Ludlow, F.; Büntgen, U.; Caffee, M.; Chellman, N. (2015). "Timing and climate forcing of volcanic eruptions for the past 2,500 years". Nature. 523 (7562): 543–549. Bibcode:2015Natur.523..543S. doi:10.1038/nature14565. PMID 26153860. S2CID 4462058.. Archived copy
- Morten Axboe (2001). "Året 536". Skalk (4): 28–32.
- Morten Axboe (1999). "The year 536 and the Scandinavian gold hoards" (PDF). Medieval Archaeology. 43: 186–188.
- Ström, Folke: Nordisk Hedendom, Studentlitteratur, Lund 2005, ISBN 91-44-00551-2 (first published 1961) among others, refer to the climate change theory.
- Gunn, Joel D. (2000). The Years Without Summer: Tracing A.D. 536 and its Aftermath. British Archaeological Reports (BAR) International. Oxford, England: Archaeopress. ISBN 978-1-84171-074-7.
- Dark, Ken (November 1999). "Jumbling old events with modern myths". British Archaeology (49). Archived from the original on 2006-02-25. Retrieved 2020-07-14.
- Breeze, Andrew (2020). British Battles 493-937: Mount Badon to Brunanburh. London. pp. 13–24. JSTOR j.ctvv4187r.
- Gao, Chaochao; Robock, Alan; Self, Stephen; Witter, Jeffrey B.; Steffenson, J. P.; Clausen, Henrik Brink; Siggaard-Andersen, Marie-Louise; Johnsen, Sigfus; Mayewski, Paul A.; Ammann, Caspar (2006). "The 1452 or 1453 A.D. Kuwae Eruption Signal Derived from Multiple Ice Core Records: Greatest Volcanic Sulfate Event of the Past 700 Years" (PDF). Journal of Geophysical Research. 111 (D12107): 11. Bibcode:2006JGRD..11112107G. doi:10.1029/2005JD006710.
- Arjava, Antti (2006). "The Mystery Cloud of 536 CE in the Mediterranean Sources". Dumbarton Oaks Papers. 59. Washington, DC: Dumbarton Oaks Research Library and Collection. pp. 73–94.
- Axboe, Morten (2001). "Amulet Pendants and a Darkened Sun". In Bente Magnus (ed.). Roman Gold and the Development of the Early Germanic Kingdoms: Aspects of Technical, Socio-political, Socio-economic, Artistic and Intellectual Development, A.D. 1–500. Almquiest & Wiksell Intl. p. 51. ISBN 978-91-7402-310-7.
- Baillie, M.G.L. (1994). "Dendrochronology Raises Questions About the Nature of the AD 536 Dust-Veil Event". The Holocene. 4 (2): 212–217. Bibcode:1994Holoc...4..212B. doi:10.1177/095968369400400211. S2CID 140595125.
- Baillie, Michael (1995). A Slice Through Time: Dendrochronology and Precision Dating. London: Batsford. p. 93. ISBN 978-0-7134-7654-5.[permanent dead link]
- Farhat-Holzman, Laina (January 23, 2003). "Climate Change, Volcanoes, and Plagues – the New Tools of History". Good Times. GlobalThink.Net Research Papers. Archived from the original on 2007-09-27.
- Gunn, Joel (2000). The Years Without Summer: Tracing A.D. 536 and its Aftermath. British Archaeological Reports (BAR) International. Oxford, England: Archaeopress. ISBN 978-1-84171-074-7.
- Keys, David Patrick (2000). Catastrophe: An Investigation into the Origins of the Modern World. New York: Ballantine Pub. ISBN 978-0-345-40876-1.
- Levy, David (ed.), The Scientific American Book of the Cosmos, ISBN 0-312-25453-9, 2000, (Google Print, p. 186)[dead link]
- Rosen, William (2007). Justinian's Flea: Plague, Empire and the Birth of Europe. London: Jonathan Cape. ISBN 978-0-224-07369-1.
- Salzer, Matthew W.; Hughes, Malcolm K. (2007). "Bristlecone Pine Tree Rings and Volcanic Eruptions Over the Last 5000 Yr" (PDF). Quaternary Research. 67 (1): 57–68. Bibcode:2007QuRes..67...57S. doi:10.1016/j.yqres.2006.07.004. Retrieved 2010-03-18.
- Winchester, Simon (2003). Krakatoa: The Day the World Exploded, August 27, 1883. New York: Harper-Collins. ISBN 978-0-06-621285-2.