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 debris from space impacting the Earth. Its effects were widespread, causing unseasonal weather, crop failures, and famines worldwide.
Documentary evidence 
The Roman historian Procopius recorded of 536, 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
Further phenomena 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)
- Crop failures
- "A dense, dry fog" in the Middle East, China, and Europe
- Drought in Peru, which affected the Moche culture
Scientific evidence 
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. Similar patterns are recorded in tree rings from Sweden and Finland, in California's Sierra Nevada and in rings from Chilean Fitzroya trees. Ice cores from Greenland and Antarctica show evidence of substantial sulfate deposits around 533–534 ± 2 years, evidence of an extensive acidic dust veil.
Possible explanations 
It has been conjectured that these changes were due to ashes or dust thrown into the air after the impact of a comet or meteorite, or after the eruption of a volcano (a phenomenon known as "volcanic winter"). 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, Indonesia.
In 1999, David Keys in his book Catastrophe: A Quest for the Origins of the Modern World (supported by work of the American volcanologist Ken Wohletz), suggested that the Indonesian volcano Krakatoa exploded at the time and caused the changes. It is suggested that an eruption of Krakatoa attributed to the year 416 by the Javanese Book of Kings actually took place at this time–there is no other evidence of such an eruption in 416.
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 caused the haze. The spherules found in the ice may 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 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.
Historic consequences 
The 536 event and ensuing famine have been suggested as an explanation for the sacrifice, by depositing hoards of large amounts of gold by Scandinavian elites at the end of the Migration Period, possibly to appease the angry gods and get the sunlight back.
David Keys' book speculates that the climate changes may have contributed to various developments, such as the emergence of the Plague of Justinian, the decline of the Avars, the migration of Mongolian tribes towards the West, the end of the Persian Empire, the rise of Islam, and the fall of Teotihuacán. In 2000, a 3BM Television production (for WNET and Channel Four) capitalized upon Keys' book. This 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 are not widely accepted at this point. Reviewing Keys' book, the 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" and that "Nonetheless, both the global scope and the emphasis on the 6th century AD as a time of wide-ranging change are commendable, and the book contains some fascinating and 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."
See also 
- Great Famine of 1315–1317
- Kuwae, a South Pacific volcano implicated in events surrounding the Fall of Constantinople in 1453.
- Minoan eruption
- Plague of Justinian
- Year Without a Summer, 1816
- Abbott, D. H.; Biscaye, P.; Cole-Dai, J.; Breger, D.; Biscaye; Cole-Dai; Breger (12/2008). Magnetite and Silicate Spherules from the GISP2 Core at the 536 A.D. Horizon. "American Geophysical Union, Fall Meeting 2008". AGU Fall Meeting Abstracts 41: 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.
- 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.
- 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 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".
- Procopius. History of the Wars, Books III and IV: The Vandalic War. Dewing H.B. ISBN 1-4346-0550-7.
- Gaelic Irish Annals translations
- Documents of Ireland
- The Annals of the Four Masters
- Ochoa, George; Jennifer Hoffman; Tina Tin (2005). Climate: the force that shapes our world and the future of life on earth. Emmaus, PA: Rodale. p. 71. ISBN 1-59486-288-5.
- Rosen, William (2007). Justinian's flea: Plague, Empire and the Birth of Europe. London: Jonathan Cape. ISBN 0-224-07369-9.
- Keys, David Patrick (2000). Catastrophe: an investigation into the origins of the modern world. New York: Ballantine Pub. ISBN 0-345-40876-4.
- Baillie, M.G.L. (1994). "Dendrochronology Raises Questions About the Nature of the AD 536 Dust-Veil Event." The Holocene fig. 3 p. 215.
- 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 0-7134-8352-0.
- Rigby, Emma; Symonds, Melissa; Ward-Thompson, Derek (February 2004). "A comet impact in AD536?". Astronomy and Geophysics 45 (1): 1.23. Bibcode:2004A&G....45a..23R. doi:10.1046/j.1468-4004.2003.45123.x.
- Wohletz, Ken, Were the Dark Ages Triggered by Volcano-Related Climate Changes in the 6th Century?
- Stothers R.B. (26 January 1984). "Mystery cloud of AD 536". Nature 307 (5949): 344–5. Bibcode:1984Natur.307..344S. doi:10.1038/307344a0.
- Keys (2000), page 385
- "Comet smashes triggered ancient famine". New Scientist. 7 January 2009.
- Dull, R., J.R. Southon, S. Kutterolf, A. Freundt, D. Wahl, P. Sheets; Southon; Kutterolf; Freundt; Wahl; Sheets (13–17 December. 2010). "Did the TBJ Ilopango eruption cause the AD 536 event?". AGU Fall Meeting Abstracts 13: 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, and 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). Bibcode:2008GGG.....902S02K. doi:10.1029/2007GC001791.
- Morten Axboe (2001). "Året 536". Skalk (4): 28–32.
- Axboe, M. (1999). "The year 536 and the Scandinavian gold hoards". Medieval archaeology 43: 186–8.
- Dark, Ken (November 1999). "Review of David Keys' Catastroph". British Archaeology (49).
- Gao, Chaochao; Robock, Alan; Self, Stephen; Witter, Jeffrey B.; J. P. Steffenson, Henrik Brink Clausen, Marie-Louise Siggaard-Andersen, Sigfus Johnsen, Paul A. Mayewski and Caspar Ammann (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". Journal of Geophysical Research 111 (D12107): 11. Bibcode:2006JGRD..11112107G. doi:10.1029/2005JD006710.
Further reading 
- Arjava, Antti (2006). "The Mystery Cloud of 536 CE in the Mediterranean Sources". In Gerstel, Sharon E. J. Thresholds of the Sacred: Architectural, Art, Historical, Liturgical, and Theological Perspectives on Religious Screens, East and West 59. Washington, DC: Dumbarton Oaks Research Library and Collection. pp. 73–94. ISBN 0-88402-311-7.
- Axboe, Morten (2001). "Amulet Pendants and a Darkened Sun". In Bente Magnus. Roman Gold and the Development of the Early Germanic Kingdoms: Aspects of Technical, Socio-Political, Socio-Economic, Artistic and Intellectual Development, ... Historie Och Antikvitets Akademien, 51). Almquiest & Wiksell Intl. ISBN 91-7402-310-1.
- Baillie, M.G.L. (1994). "Dendrochronology Raises Questions About the Nature of the AD 536 Dust-Veil Event". The Holocene 4 (2): 212–217. doi:10.1177/095968369400400211.
- Baillie, Michael (1995). A Slice Through Time: Dendrochronology and Precision Dating. London: Batsford. p. 93. ISBN 0-7134-7654-0.
- Farhat-Holzman, Laina (Thursday, 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 1-84171-074-1.
- Keys, David Patrick (2000). Catastrophe: An Investigation into the Origins of the Modern World. New York: Ballantine Pub. ISBN 0-345-40876-4.
- 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 0-224-07369-9.
- Salzer, Matthew W.; Hughes, Malcolm K. (2007). "Bristlecone Pine Tree Rings and Volcanic Eruptions Over the Last 5000 Yr". 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 0-06-621285-5.