The volcanic winter of 536 was the most severe and protracted episode of climatic cooling in the Northern Hemisphere in the last 2,000 years. [1] The volcanic winter was caused by at least three simultaneous eruptions of uncertain origin, with several possible locations proposed in various continents. Most contemporary accounts of the volcanic winter are from authors in Constantinople [ citation needed ], the capital of the Eastern Roman Empire, although the impact of the cooler temperatures extended beyond Europe. Modern scholarship has determined that in early CE 536 (or possibly late 535), an eruption ejected massive amounts of sulfate aerosols into the atmosphere, which reduced the solar radiation reaching the Earth's surface and cooled the atmosphere for several years. In March 536, Constantinople began experiencing darkened skies and lower temperatures.
Summer temperatures in 536 fell by as much as 2.5 °C (4.5 °F) below normal in Europe. The lingering impact of the volcanic winter of 536 was augmented in 539–540, when another volcanic eruption caused summer temperatures to decline as much as 2.7 °C (4.9 °F) below normal in Europe. [2] There is evidence of still another volcanic eruption in 547 which would have extended the cool period. The volcanic eruptions caused crop failures, and were accompanied by the Plague of Justinian, famine, and millions of deaths and initiated the Late Antique Little Ice Age, which lasted from 536 to 560. [3]
The medieval scholar Michael McCormick wrote that 536 "was the beginning of one of the worst periods to be alive, if not the worst year." [4]
The Roman historian Procopius recorded in CE 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". [5] [6]
In 538, the Roman statesman Cassiodorus described the following to one of his subordinates in letter 25: [7]
In the entry corresponding to the year 535–536, the early 7th century Mandaean Book of Kings relates, "were you to request a tenth of a peck of grain in the land Gawkāy for five staters, we would look but it would not be found," [8] an exchange of 873 grams of grain for 43 grams of gold, reflecting the scarcity of grain during this time.
Michael the Syrian (1126–1199), a patriarch of the Syriac Orthodox Church, reported that during 536–537 the sun shone feebly for a year and a half. [9]
The Irish annals [10] [11] [12] recorded the following:
The mid-10th-century Annales Cambriae record for the year 537:
In Chinese sources include:
Further phenomena were reported by independent contemporary sources:
There are other sources of evidence regarding this period. [17] [18] [19] [20]
Tree ring analysis by the dendrochronologist Mike Baillie, of Queen's University Belfast, shows abnormally little growth in Irish oak in 536 and another sharp drop in 542, after a partial recovery. [21] 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. [22]
It was originally theorized that the climatic changes of CE 536 were caused by either volcanic eruptions (a phenomenon known as "volcanic winter") or impact events (meteorite or comet). [23] [24] [25]
In 2015, revision of polar ice core chronologies dated sulfate deposits and a cryptotephra layer to the exact year CE 536 (previously dated to CE 529 before revision). [26] This is strong evidence that a large explosive volcanic eruption caused the observed dimming and cooling, removing the need for an extraterrestrial explanation, [22] [26] but an impact event around this time period cannot be ruled out. [27]
The source of volcanic eruption remains to be found but several proposed volcanoes have been rejected:
Geochemical analysis of CE 536 cryptotephras distinguishes at least three synchronous eruptive events in North America. [26] Further analysis correlates one of the eruptions to a widespread Mono Craters tephra identified in northeast California. [26] [37] The other two eruptions most likely originated from the eastern Aleutians and Northern Cordilleran volcanic province. [26] [38]
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. [39] [40] Mythological events such as the Fimbulwinter and Ragnarök are theorised to be based on the cultural memory of the event. [41]
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), the decline of the Avars, the migration of Mongol tribes towards the west, the end of the Sasanian Empire, the collapse of the Gupta Empire, the rise of Islam, the expansion of Turkic tribes, and the fall of Teotihuacan. [16] In 2000, a 3BM Television production (for WNET and Channel Four) capitalised 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. [42]
However, Keys and Wohletz's 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 CE as a time of wide-ranging change are notable, and the book contains some obscure information that 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". [43]
The philologist Andrew Breeze in a recent book (2020) argues that some Arthurian events, including the Battle of Camlann, are historical, happening in 537 as a consequence of the famine associated with the climate change of the previous year. [44]
Historian Robert Bruton argues that this catastrophe played a role in the decline of the Roman Empire. [45]
1816 is known as the Year Without a Summer because of severe climate abnormalities that caused average global temperatures to decrease by 0.4–0.7 °C (0.7–1 °F). Summer temperatures in Europe were the coldest of any on record between 1766 and 2000, resulting in crop failures and major food shortages across the Northern Hemisphere.
A volcanic winter is a reduction in global temperatures caused by droplets of sulfuric acid obscuring the Sun and raising Earth's albedo (increasing the reflection of solar radiation) after a large, sulfur-rich, particularly explosive volcanic eruption. Climate effects are primarily dependent upon the amount of injection of SO2 and H2S into the stratosphere where they react with OH and H2O to form H2SO4 on a timescale of a week, and the resulting H2SO4 aerosols produce the dominant radiative effect. Volcanic stratospheric aerosols cool the surface by reflecting solar radiation and warm the stratosphere by absorbing terrestrial radiation for several years. Moreover, the cooling trend can be further extended by atmosphere–ice–ocean feedback mechanisms. These feedbacks can continue to maintain the cool climate long after the volcanic aerosols have dissipated.
Eldgjá is a volcano and a canyon in Iceland. Eldgjá is part of the Katla volcano; it is a segment of a 40 kilometres (25 mi) long chain of volcanic craters and fissure vents that extends northeast away from Katla volcano almost to the Vatnajökull ice cap. This fissure experienced a major eruption around 939 CE, which was the largest effusive eruption in recent history. It covered about 780 square kilometres (300 sq mi) of land with 18.6 cubic kilometres (4.5 cu mi) of lava from two major lava flows.
Grímsvötn is an active volcano with a fissure system located in Vatnajökull National Park, Iceland. The central volcano is completely subglacial and located under the northwestern side of the Vatnajökull ice cap. The subglacial caldera is at 64°25′N17°20′W, at an elevation of 1,725 m (5,659 ft). Beneath the caldera is the magma chamber of the Grímsvötn volcano.
Mount Takahe is a 3,460-metre-high (11,350 ft) snow-covered shield volcano in Marie Byrd Land, Antarctica, 200 kilometres (120 mi) from the Amundsen Sea. It is a c. 30-kilometre-wide (19 mi) mountain with parasitic vents and a caldera up to 8 kilometres (5 mi) wide. Most of the volcano is formed by trachytic lava flows, but hyaloclastite is also found. Snow, ice, and glaciers cover most of Mount Takahe. With a volume of 780 km3 (200 cu mi), it is a massive volcano; the parts of the edifice that are buried underneath the West Antarctic Ice Sheet are probably even larger. It is part of the West Antarctic Rift System along with 18 other known volcanoes.
Huaynaputina is a volcano in a volcanic high plateau in southern Peru. Lying in the Central Volcanic Zone of the Andes, it was formed by the subduction of the oceanic Nazca Plate under the continental South American Plate. Huaynaputina is a large volcanic crater, lacking an identifiable mountain profile, with an outer stratovolcano and three younger volcanic vents within an amphitheatre-shaped structure that is either a former caldera or a remnant of glacial erosion. The volcano has erupted dacitic magma.
The Minoan eruption was a catastrophic volcanic eruption that devastated the Aegean island of Thera circa 1600 BCE. It destroyed the Minoan settlement at Akrotiri, as well as communities and agricultural areas on nearby islands and the coast of Crete with subsequent earthquakes and paleotsunamis. With a Volcanic Explosivity Index (VEI) of 7, it resulted in the ejection of approximately 28–41 km3 (6.7–9.8 cu mi) of dense-rock equivalent (DRE), the eruption was one of the largest volcanic events in human history. Since tephra from the Minoan eruption serves as a marker horizon in nearly all archaeological sites in the Eastern Mediterranean, its precise date is of high importance and has been fiercely debated among archaeologists and volcanologists for decades, without coming to a definite conclusion.
Mount Churchill is a dormant volcano in the Saint Elias Mountains and the Wrangell Volcanic Field (WVF) of eastern Alaska. Churchill and its neighbor Mount Bona are both ice-covered volcanoes with Churchill having a 2.7-by-4.2-kilometre-wide caldera just east of its summit. There are sparse outcrops of lava flows and tephra, mostly dacite.
The Hatepe eruption, named for the Hatepe Plinian pumice tephra layer, sometimes referred to as the Taupō eruption or Horomatangi Reef Unit Y eruption, is dated to 232 CE ± 10 and was Taupō Volcano's most recent major eruption. It is thought to be New Zealand's largest eruption within the last 20,000 years. The eruption ejected some 45–105 km3 (11–25 cu mi) of bulk tephra, of which just over 30 km3 (7.2 cu mi) was ejected in approximately 6–7 minutes. This makes it one of the largest eruptions in the last 5,000 years, comparable to the Minoan eruption in the 2nd millennium BCE, the 946 eruption of Paektu Mountain, the 1257 eruption of Mount Samalas, and the 1815 eruption of Mount Tambora.
The 1808 mystery eruption is one or potentially multiple unidentified volcanic eruptions that resulted in a significant rise in stratospheric sulfur aerosols, leading to a period of global cooling analogous to the Year Without a Summer in 1816.
The 946 eruption of Paektu Mountain, a stratovolcano on the border of North Korea and China also known as Changbaishan, occurred in late 946 CE. This event is known as the Millennium Eruption or Tianchi eruption. It is one of the most powerful volcanic eruptions in recorded history; classified at least a VEI 6.
The Late Antique Little Ice Age (LALIA) was a long-lasting Northern Hemispheric cooling period in the 6th and 7th centuries AD, during the period known as Late Antiquity. The period coincides with three large volcanic eruptions in 535/536, 539/540 and 547. The volcanic winter of 536 was the early phenomenon of the century-long global temperature decline. One study suggested a global cooling of 2 °C (3.6 °F). The period contributed to the decline of the Roman Empire and influenced the second wave migration period, primarily of the early Slavs.
In 1257, a catastrophic eruption occurred at Samalas, a volcano on the Indonesian island of Lombok. The event had a probable Volcanic Explosivity Index of 7, making it one of the largest volcanic eruptions during the Holocene epoch. It left behind a large caldera that contains Lake Segara Anak. Later volcanic activity created more volcanic centres in the caldera, including the Barujari cone, which remains active.
There are two large sulfate spikes caused by mystery volcanic eruptions in the mid-1400s: the 1452/1453 mystery eruption and 1458 mystery eruption. Before 2012, the date of 1458 sulfate spike was incorrectly assigned to be 1452 because previous ice core work had poor time resolution. The exact location of this eruption is uncertain, but possible candidates include the submerged caldera of Kuwae in the Coral Sea, Mount Reclus and Tofua caldera. The eruption is believed to have been VEI-7.
Mount Rittmann is a volcano in Antarctica. Discovered in 1988–1989 by an Italian expedition, it was named after the volcanologist Alfred Rittmann (1893–1980). It features a 2 kilometres (1.2 mi) or 8 by 5 kilometres wide caldera which crops out from underneath the Aviator Glacier. The volcano was active during the Pliocene and into the Holocene, including large explosive eruptions; a major eruption occurred in 1254 CE and deposited tephra over much of Antarctica. Currently, the volcano is classified as dormant.
The Tierra Blanca Joven eruption of Lake Ilopango was the largest volcanic eruption in El Salvador during historic times, and one of the largest volcanic events on Earth in the past 7,000 years, registering at 6 on the Volcanic explosivity index (VEI), and dating back to the mid 5th century A.D. The eruption produced between 37–82 km3 (8.9–19.7 cu mi) of ejecta. The date of the eruption has been constrained within 429–433 CE by identifying its signature volcanic ash in precision-dated ice cores sampled from Greenland, thus eliminating it as the cause of extreme weather events of 535–536.
Vatnaöldur is the name of a series of craters in the Suðurland region of Iceland. They are located in the Highlands of Iceland, north–west of the Veiðivötn and north–east of Landmannalaugar, within the municipality of Rangárþing ytra. It is part of the Eastern volcanic zone (EVZ).
The 1452/1453 mystery eruption is an unidentified volcanic event that triggered the first large sulfate spike in the 1450s, succeeded by another spike in 1458 caused by another mysterious eruption. The eruption caused a severe volcanic winter leading to one of strongest cooling events in the Northern Hemisphere. This date also coincides with a substantial intensification of the Little Ice Age.
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