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, and/or debris from space impacting the Earth. Its effects were widespread, causing unseasonal weather, crop failures, and famines worldwide.
The Byzantine 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
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 90kg/km2 around AD 536, evidence of an extensive acidic dust veil. JJA temperature anomaly shows 1.67℃ cooling in 536 AD, and lasted for 10 years.
It has been conjectured that these changes were due to 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, Indonesia.
In 1984, R. B. Stothers postulated that this event might have been caused by the volcano Rabaul in what is now New Britain island near Papua New Guinea. More recent high-precision 14C dating shows the eruption is now thought to have occurred in the interval AD 667–699.
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, 535–536, there being no other evidence of such an eruption in 416. GeoB 10043-3 presents an unbroken sequence of sediment for at least 2000 yr, providing an opportunity to test for the presence of tephra from a proposed very large AD 535 eruption of either Krakatau or another (as yet undiscovered) volcano in Sunda Strait. Taking reservoir corrections into account, AD 535 corresponds to a depth of ~33 cm in GeoB 10043-3, but the first ash below the 1883 tephra in this core is at 225–232 cm. Hence, although GeoB 10043-3 contains a clearly visible ~5-cm-thick ash layer from the 1883 Krakatau eruption, there is no evidence for an AD 535 event, which supposedly involved tephra volumes many times larger. Thus, for a proposed Sunda Strait eruption many times larger than the 1883 event, the absence of significant tephra deposition in a well-dated core just 130 km downwind seems so improbable that it effectively rules out any possibility that such an eruption took place.
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.
In 2015, M. Sigl found volcanic glass in depths of 327.17–327.25 m from NEEM-2011-S1, which corresponding to the sulfate spike at 536 CE. The chemical of glass does match with Edziza complex, Aniakchak, and Mono/Inyo crater. Geochemistry of tephra indicated multiple North American volcanoes as likely candidates for a combined volcanic signal, and may not related to Tierra Blanca Joven.
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 may have been deposited as a sacrifice to appease the 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 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. 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.
- 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 (December 2008). "Magnetite and Silicate Spherules from the GISP2 Core at the 536 A.D. Horizon". 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
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- 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.
- Sigl, M (2015). "Timing and climate forcing of volcanic eruptions for the past 2,500 years". Nature. doi:10.1038/nature14565.
- Wohletz, Ken, Were the Dark Ages Triggered by Volcano-Related Climate Changes in the 6th Century?
- 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.
- Stothers R.B. (26 January 1984). "Mystery cloud of AD 536". Nature 307 (5949): 344–5. Bibcode:1984Natur.307..344S. doi:10.1038/307344a0.
- Mckee, CO (2015). "A revised age of ad 667–699 for the latest major eruption at Rabaul". Bulletin of Volcanology. doi:10.1007/s00445-015-0954-7.
- Keys (2000), page 385
- Southon, J (2013). "Planktonic foram dates from the Indonesian ARC: Marine 14C reservoir ages and a mythical AD 535 eruption of Krakatau". Radiocarbon. doi:10.2458/azu_js_rc.55.16384.
- "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.
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