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). [2]
The existence of a cooling period was proposed as a theory in 2015, and subsequently confirmed as the period from 536 to about 660 CE. [3] Volcanic eruptions, meteorites striking the Earth's surface, and comet fragments exploding in the upper atmosphere have been proposed for the climatic cooling in 536 and afterwards. A problem is that no impact crater for a meteorite has been found, even though the land area and sea beds have been well surveyed for evidence. A comet fragment half a kilometer in size exploding in the atmosphere could cause a plume of debris on the Earth and create conditions for atmospheric cooling. [4] Most evidence, however, points to volcanic eruptions occurring in 536, 540, and possibly 547, although the location of the volcano or volcanoes has not been determined. Locations such as Tavurvur in Papua New Guinea, Ilopango in El Salvador, and Krakatau in Indonesia have been proposed. [5]
Investigations in 2018 analyzed ice cores from glaciers in Switzerland and matched glass particles in the cores with volcanic rocks from Iceland, making the island nation a likely candidate for the source of the 536 eruption, although North America is also a possible location. [6] Evidence suggests that Ilopango in El Salvador was the source of the 539/540 eruption. Bipolar ice core investigations suggested that this eruption occurred in the tropics, and tree ring investigations near Ilopango found evidence of an eruption possibly in 540. However, a more recent study, examining other evidence, dated the eruption of Ilopango to the year 431, so the issue remains unresolved. [2] [7] The eruption, whatever its location, put more aerosols into the atmosphere than the 1815 eruption of Mount Tambora, which caused the Year Without a Summer. [8] Another eruption, location unknown, occurred in 547. [6] Additional evidence comes from a temperature reconstruction from the Euro-Med2k working group of the international PAGES (Past Global Changes) project that used new tree-ring measurements from the Altai Mountains, which closely matches the temperatures in the Alps in the last two centuries. [3] [9]
The impact of the volcanic eruptions was the phenomenon known as volcanic winter. In the volcanic winter of 536, summer temperatures fell by as much as 2.5 degrees Celsius (4.5 degrees Fahrenheit) below normal in Europe. ("Normal" is considered by scientists to be the average temperatures of the 1961–1990 period.) The lingering impact of the volcanic winter of 536 was augmented in 539–540, when the second volcanic eruption caused summer temperatures to decline as much as 2.7 degrees Celsius (4.9 degrees Fahrenheit) below normal in Europe. [10]
While the volcanic eruptions began the freeze, researchers think that increased ocean ice cover (feedback to the effects of the volcanoes), coupled with an "exceptional" minimum of solar activity in the 600s, reinforced and extended the cooling. [11] [12]
According to research by a team from the Swiss Federal Research Institute at Birmensdorf, the fall in temperatures led to the Arabian Peninsula experiencing a dramatic increase in fertility. [12] The boost of food supply contributed to the Arab expansion beyond the peninsula in the Islamic conquests. The cooling period also led to increased strain on the Eastern Roman Empire and the Sassanid Empire, which helped the Muslim conquest of the Levant, the Muslim conquest of Egypt and the Muslim conquest of Persia. [3]
According to research done by Israeli scientists, in 540, the size of the population of the city of Elusa, in the Negev Desert, and the amount of garbage that it generated started to shrink greatly. [13] Elusa housed tens of thousands of people during its height. [13] The major decline took place around the mid-6th century, about a century before the Islamic conquest. [14] One possible explanation for the crisis was the Late Antique Little Ice Age.
The cooling period coincided with the Plague of Justinian, which began in 541, though the connection between the plague and the volcanoes still remains tenuous. The cooling period contributed to the migrations of the Lombards and the Slavs into Roman territory in Italy and the Balkans. [3]
Year 540 (DXL) was a leap year starting on Sunday of the Julian calendar. In the Roman Empire, it was known as the Year of the Consulship of Iustinus without colleague. The denomination 540 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.
The Little Ice Age (LIA) was a period of regional cooling, particularly pronounced in the North Atlantic region. It was not a true ice age of global extent. The term was introduced into scientific literature by François E. Matthes in 1939. The period has been conventionally defined as extending from the 16th to the 19th centuries, but some experts prefer an alternative timespan from about 1300 to about 1850.
The year 1816 AD 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.
The Toba eruption was a supervolcano eruption that occurred around 74,000 years ago during the Late Pleistocene at the site of present-day Lake Toba in Sumatra, Indonesia. It is one of the largest known explosive eruptions in the Earth's history. The Toba catastrophe theory holds that this event caused a severe global volcanic winter of six to ten years and contributed to a 1,000-year-long cooling episode, leading to a genetic bottleneck in humans.
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. 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, the capital of the Eastern Roman Empire, although the impact of the cooler temperatures extended beyond Europe. Modern scholarship has determined that in early AD 536, 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.
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.
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 between 6 and 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.
Lake Ilopango is a crater lake which fills an 8 by 11 km volcanic caldera in central El Salvador, on the borders of the San Salvador, La Paz, and Cuscatlán departments. The caldera, which contains the second largest lake in the country and is immediately east of the capital city, San Salvador, has a scalloped 100 m (330 ft) to 500 m (1,600 ft) high rim. Any surplus drains via the Jiboa River to the Pacific Ocean. The local military airbase, Ilopango International Airport, has annual airshows where international pilots from all over the world fly over San Salvador City and Ilopango lake.
This timeline of volcanism on Earth includes a list of major volcanic eruptions of approximately at least magnitude 6 on the Volcanic explosivity index (VEI) or equivalent sulfur dioxide emission during the Quaternary period. Other volcanic eruptions are also listed.
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.
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.
Little Ice Age volcanism refers to the massive volcanic activities during the Little Ice Age. Scientists suggested a hypothesis that volcanism was the major driving force of the global cooling among the other natural factors, i.e. the sunspot activities by orbital forcing and greenhouse gas. The Past Global Change (PAGES), a registered paleo-science association for scientific research and networking on past global changes in the University of Bern, Switzerland, suggested that from 1630 to 1850, a total of 16 major eruptions and cooling events had taken place. When a volcano erupts, ashes burst out of the vent together with magma and forms a cloud in the atmosphere. The ashes act as an isolating layer that block out a proportion of solar radiation, causing global cooling. The global cooling effect impacts ocean currents, atmospheric circulation and cause social impacts such as drought and famine. Wars and rebellions were therefore triggered worldwide in the Little Ice Age. It was suggested that the crisis on Ottoman Empire and Ming-Qing Transition in China were typical examples that closely correlated with Little Ice Age.
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.
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.
The Grindelwald Fluctuation was a period of cooling that occurred from the 13th to the mid 19th century ; characterised by the expansion of glaciers in many parts of the world, including the Alps in Europe. It produced some of the lowest temperatures known to this holocene.
Gaza wine, vinum Gazentum in Latin, probably identical with Ashkelon wine, was a much-appreciated sweet wine produced mainly during the Byzantine period in southern Palestine, with major production areas in the Negev Highlands and the southern coastal area including the area around Gaza and Ashkelon.
The researchers suggest that the spate of eruptions combined with a solar minimum, and ocean and sea-ice responses to the effects of the volcanoes
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