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Island volcanic eruptions in 1783-84 did not occur extreme heat wave

  Island volcano eruptions in 1783-84 did not occur extreme heat waves
Laki volcano in Iceland. It is not a typical mountain and its fragmentation to the right extends in the distance. Credit: Alan Robock / Rutgers University-New Brunswick

An enormous volcanic eruption in Iceland in 1

783-84 did not cause an extreme summer heat wave in Europe. But, as Benjamin Franklin speculated, the outbreak erupted an unusually cold winter, according to a Rutgers led study.

The study, in Journal of Geophysical Research: Atmospheres will help improve predictions on how the climate will react to volcanic eruptions in high latitude.

The Laki eruption of the eight-month volcano, which began in June 1783, was the largest spread at high latitude over the past 1000 years. It injected about six times as much sulfur dioxide into the upper atmosphere as 1883 Krakatau or 1991 Pinatubo eruption, according to co-author Alan Robock, a special professor of environmental science at Rutgers University-New Brunswick.

outbreaks coincided with unusual weather across Europe. The summer was exceptionally hot with July temperatures above 5 degrees Fahrenheit above the norm, which led to interruptions and failed harvests. The 1783-84 European winter was up to 5 degrees colder than average.

Franklin, the American ambassador in France, speculated on the causes of a 1784 paper, the first publication in English on the potential effects of a volcanic eruption on the climate.

To determine whether Franklin and other researchers were right, the Rutgers-led team performed 80 simulations with a state-of-the-art National Center for Atmospheric Research climate model. The computer model included weather during the outbreak and compared the subsequent climate with and without the effects of the outbreak.

"It was to our surprise that the hot summer was not caused by the outbreak," Robock said. "Instead, there was only a natural variation in the climate system, it would have been even warmer without an outbreak. The cold winter would be expected after such an outbreak."

  Island volcano eruption 1783-84 did not happen extremely warm wave
Another view of Laki volcanic fissure in Iceland. Credit: Alan Robock / Rutgers University-New Brunswick

The hot 1783 summer came from unusually high pressure across Northern Europe that caused cold polar air to bypass the region, the study says. After the outbreak, precipitation in Africa and Asia dropped significantly and caused widespread drought and starvation. The eruption also increased the chance of El Niño, with unusually hot water in the tropical Pacific, during the winter.

The outbreak gave rise to a sulfur-containing aerosol cloud – called "Laki haze" – which remained over most northern Hemisphere in 1783. Reports from all over Europe included lower visibility and the smell of sulfur or hydrogen sulfide. The air pollution was linked to reports of headaches, respiratory diseases and asthma attacks, along with acid rain on trees and crops, study studies.

More than 60 percent of Iceland's livestock died within a year and about 20 percent of the people died in a famine. Reports of increased mortality and / or respiratory disorders crossed Europe.

"Understanding the causes of these climate changes is important, not only for historical purposes, but also for understanding and predicting possible climate responses to future high latitude volcanic eruptions" Robock said. "Our work tells us that even with a large outbreak like Laki, it will be impossible to predict very local climate impact because of the chaotic nature of the atmosphere".

Researchers continue to work on the potential effects of volcanic eruptions on humans through the volcanic effects on the climate and social project. The Laki outbreak will be part of their research. Volcanic eruptions can have global climate impacts that last for several years.

The lead author of the study is Brian Zambri, a former postdoctoral fellow with a doctoral student at Rutgers and now at the Massachusetts Institute of Technology. Researchers at the National Center for Atmospheric Research and the University of Cambridge contributed to the study.

Large volcanic eruptions in the tropics can trigger El Nino events

More information:
Brian Zambri et al., Modeling 1783-1784 Laki Eruption in Iceland, Part II: Climate impact, Journal of Geophysical Research: Atmospheres (2019). DOI: 10, 1029 / 2018D029554

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Rutgers University

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Iceland volcanic eruptions in 1783-84 did not run extreme heat wave (2019, May 15)
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