Posted on 11/22/2006 8:44:38 AM PST by cogitator
An environmental drama played out on the world stage in the late 18th century when a volcano killed 9,000 Icelanders and brought a famine to Egypt that reduced the population of the Nile valley by a sixth. A study by three scientists from Rutgers, The State University of New Jersey, and a collaborator from the University of Edinburgh, Scotland, demonstrates a connection between these two widely separated events.
The investigators used a computer model developed by NASA's Goddard Institute for Space Studies to trace atmospheric changes that followed the 1783 eruption of Laki in southern Iceland back to their point of origin. The study is the first to conclusively establish the linkage between high-latitude eruptions and the water supply in North Africa.
"Our findings may help us improve predictions of climate response following the next strong high-latitude eruption, specifically concerning changes in temperature and precipitation," said Rutgers researcher Luke Oman, first author on the study. "Given the sensitivity of these arid regions to reductions in rainfall, our predictions may ultimately allow society time to plan for the consequences and save lives."
Eruptions of volcanoes in the tropics are known to produce warmer winters in the northern hemisphere; however, the new study shows that volcanic influences also can flow north to south, generating an array of repercussions, including both hot and cold weather.
The authors present "new, strong evidence, from both observations and climate model simulations" that high-latitude eruptions have altered northern hemisphere atmospheric circulation in the summer following, with impacts extending deep into the tropics.
Oman, Alan Robock and Georgiy Stenchikov of Rutgers' department of environmental sciences in New Brunswick/Piscataway, and Thorvaldur Thordarson at the University of Edinburgh, published their Sept. 30 study in Geophysical Research Letters, now featured online by NASA.
In June 1783, the Laki volcano began a series of eruptions, regarded as the largest at high-latitude in the last 1,000 years. The eruptions produced three cubic miles of lava and more than 100 million tons of sulfur dioxide and toxic gases, killing vegetation, livestock and people.
These eruptions were followed by a drought in a swath across northern Africa, producing a very low flow in the Nile. Laki's far-flung effects were chronicled by the French scholar Constantin Volney and his friend Benjamin Franklin.
"The [annual Nile] inundation of 1783 was not sufficient, great part of the lands therefore could not be sown for want of being watered, and another part was in the same predicament for want of seed. In 1784, the Nile again did not rise to the favorable height, and the dearth immediately became excessive. Soon after the end of November, the famine carried off, at Cairo, nearly as many as the plague," wrote Volney as reported by Oman and his colleagues.
In the northern hemisphere, the summer of 1783 was chilly - the coldest in at least 500 years in some locations, according to tree ring data. Sulfate aerosols in the atmosphere kept the warmth of the sun from the Earth's surface.
While the computer linked these reduced northern hemisphere temperatures to Laki, it also connected the dots to a weak monsoon - the seasonal winds that bring the annual rains to southern Asia and northern Africa. The unusual cold in the North lessened the temperature contrast between the land and the oceans, upon which the monsoon winds rely for their development and strength.
The modeling showed significant warming that occurred in the region west to east across Africa to the southern Arabian Peninsula and on to India during the summer of 1783. With little or no monsoon, there were no clouds to bring rain for the rivers or shield.
This is a picture of an eruption of Krafla, which is also on the rift zone; it gives an impression of what the Laki fissure eruption might have been like. Just add more lava and gas. Krafla is north of the Vatnajokull ice cap; the Laki fissures trend southwest from the ice cap (see map below picture).
Holiday Ping!
/sarcasm
Actually, if the Laki fissure eruption could be classified as Sub-arctic Unusual Volcanism (SUV), maybe it did...
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What's HMPF?
((Said by Al Gore... wringing his hands and licking his chops...))
The sound one makes in response to something peculiar that has just occurred or has just been said. Most often used when irritated. Most often a natural response/reaction.
Oh, okay. Should have thought of that, but since it was all caps, I thought it was an acronym. Thanks!
I capatilized it cause I was playing a whiney liberal...hehehehe.... ;)
HAHAHAHA! Cute!
Debate Erupts Anew: Did Thera's Explosion Doom Minoan Crete?
International Herald Tribune | 10-23-2003 | William J. Broad
Posted on 10/23/2003 5:47:33 PM EDT by blam
http://www.freerepublic.com/focus/f-news/1006850/posts
New Ice-Core Evidence Challenges the 1620s age for the Santorini (Minoan) Eruption
Journal of Archaeological Science, Volume 25, Issue 3, March 1998, Pages 279-289
13 July 1997 | Gregory A. Zielinski, Mark S. Germani
Posted on 07/29/2004 3:25:45 AM EDT by SunkenCiv
http://www.freerepublic.com/focus/f-chat/1180724/posts
Director posits proof of biblical Exodus
The Globe and Mail | 14 April 2006 | Michael Posner
Posted on 04/14/2006 8:58:16 AM EDT by timsbella
http://www.freerepublic.com/focus/f-news/1614957/posts
Constantinople's Volcanic Twilight (Kuwae eruption)
Huaynaputina (includes image)
"Huaynaputina was the site of a single catastrophic eruption in February 1600, which was remarkable not only for its intensity, but because it was the only major explosive eruption in historic times in the Central Andes. A colourful account of the eruption is to be found in the journals of Vasquez de Espinoza (translated from the Spanish in 1942). The eruption completely destroyed the pre-1600 edifice which was described as " a low ridge in the centre of a sierra". Ash from the eruption is widespread and still mantles much of the surrounding countryside as far as Arequipa, 80 km away. It now forms a useful regional stratigraphic marker horizon throughout Peru (e.g. in the Quelccaya ice cap (see Chapter 1, Figure 8; Thompson et al., 1986). In the Greenland ice core acidity profile, the eruption produced an acid "spike" larger in magnitude than the Krakatau 1883 eruption (Hammer et al., 1980; de Silva & Francis, 1990) and remarkable optical effects were reported from the northern hemisphere in 1601 (Lamb, 1970). Notwithstanding the magnitude of this eruption, its deposits have never been examined."
From the Global Volcanism Program (excerpt):
"This powerful fissure-fed eruption may have produced nearly 30 cu km* of dacitic tephra, including pyroclastic flows and surges that traveled 13 km to the east and SE. Lahars reached the Pacific Ocean, 120 km away. The eruption caused substantial damage to the major cities of Arequipa and Moquengua, and regional economies took 150 years to fully recover."
* Tambora is estimated to have been 80 cubic km.
The Voyage of Hanno"Sailing rapidly, we passed by a fiery region filled with vapors, from which great torrents of fire flowed down to the sea. The land could not be approached because of the heat.
Livio Catulo Stecchini
"We sailed away from there quickly, being struck with fear. Then, having sailed for four days, we sighted at night a land full of flames. And in the midst of it there was a fire higher than the rest which seemed to touch the stars. By day we discerned it to be a mountain of great height named Theon Ochema."
In describing a volcanic eruption from a high mountain towering over the sea Hanno mentions such details as sulphuric fumes and streams of lava. The only volcanic area in West Africa is represented by Mount Cameroon, which is still active today. It is located at the deepest point of the Gulf of Guinea, where it rises suddenly from the seashore, reaching a height of over 4000 meters. The peak of Mount Cameroon is at 4°13'N, 9°10'E. almost exactly 6° (equal to four days' sailing) east of the Great Island of Lagos. Those who have seen it from the sea consider it one of the most impressive sights in the world. The natives call it Mongana-Loba, "Mountain of the Gods," which well agrees with the Greek Theon Ochema, "Chariot of the Gods," of our text.
Typical shot. But shield volcanoes don't make great photographic subjects (from a distance) anyway. There are a few low-cloud images on the Web - it looks like a big hill.
Nice, thanks!
Regarding the famine in Egypt, there is an interesting modern parallel. I think it was in the late 1970s that the terrible north African drought in the Sahel caused such fatal famine. I came across a recent report that this was influenced toward severity by particulate air pollution drifting down from Europe. Since Europe has been cleaning up its air in recent decades, the droughts in north Africa have not been so severe.
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