1783 eruption
On 8 June 1783, a
fissure with 130
craters opened with
phreatomagmatic explosions because of the groundwater interacting with the rising
basaltmagma. These are sometimes mistaken by non-volcanologists as being "
Plinian" but are not. Over a few days the eruptions became less explosive,
Strombolian, and later
Hawaiian in character, with high rates of lava
effusion. This event is rated as
VEI 6 on the
Volcanic Explosivity Index, but the eight month emission of sulfuric aerosols resulted in one of the most important climatic and socially repercussive events of the last millennium.
[4]
The eruption, also known as the
Skaftáreldar ("Skaftá river fires") or Síðueldur, produced an estimated 14 km3 (3.4 cu mi) of
basalt lava, and the total volume of
tephra emitted was 0.91 km3 (0.2 cu mi).
[5] Lava fountains were estimated to have reached heights of 800-1400
m (~2,600-4,600 ft). In
Great Britain, the summer of 1783 was known as the "sand-summer" due to ash fallout.
[6] The gases were carried by the convective eruption column to altitudes of about 15 kilometres (10 mi). The
aerosols built up caused a cooling effect in the
Northern Hemisphere.
The eruption continued until 7 February 1784, but most of the lava was erupted in the first five months. Grímsvötn volcano, from which the Laki fissure extends, was also erupting at the time from 1783 until 1785. The outpouring of gases, including an estimated 8 million tons of
hydrogen fluoride and estimated 120 million tons of sulfur dioxide gave rise to what has since become known as the "Laki haze" across Europe.
Consequences in Iceland
The consequences for Iceland—known as the
Mist Hardships -- were catastrophic. An estimated 20-25% of the population died in the famine and fluorine poisoning after the fissure eruptions ceased. Around 80% of sheep, 50% of cattle and 50% of horses died because of
dental and
skeletal fluorosis from the 8 million tons of hydrogen fluoride that were released.
[6][7]
The parish priest
Jón Steingrímsson grew famous because of his eldmessa ("fire sermon"). The people of the small town of
Kirkjubæjarklaustur were worshipping while the town was endangered by a lava stream, which ceased to flow, not far from town, with the townsfolk still in church..
"This past week, and the two prior to it, more poison fell from the sky than words can describe: ash, volcanic hairs, rain full of sulfur and
salt peter, all of it mixed with sand. The snouts, nostrils, and feet of livestock grazing or walking on the grass turned bright yellow and raw. All water went tepid and light blue in color and gravel slides turned gray. All the earth's plants burned, withered and turned gray, one after another, as the fire increased and neared the settlements."
[8] Consequences in Europe
An estimated 122
Tg (120 million tons) of
sulfur dioxide were emitted: approximately equivalent to three times the total annual European industrial output in 2006, and also equivalent to a
Mount Pinatubo-1991 eruption every three days.
[6] This outpouring of sulfur dioxide during unusual weather conditions caused a thick haze to spread across western Europe, resulting in many thousands of deaths throughout 1783 and the winter of 1784.
The summer of 1783 was the hottest on record and a rare high pressure zone over Iceland caused the winds to blow to the south-east. The poisonous cloud drifted to
Bergen in
Norway, then spread to
Prague in the
Province of Bohemia by 17 June,
Berlin by 18 June,
Paris by 20 June,
Le Havre by 22 June, and to
Great Britain by 23 June. The fog was so thick that boats stayed in port, unable to navigate, and the sun was described as "blood coloured".
[6]
Inhaling sulfur dioxide gas causes victims to choke as their internal soft tissue swells. The local death rate in
Chartres was up by 5% during August and September, with over 40 dead. In Great Britain, the records show that the additional deaths were outdoor workers, and perhaps 2-3 times above the normal rate in Bedfordshire, Lincolnshire and the east coast. It has been estimated that 23,000 British people died from the poisoning in August and September.
The haze also heated up causing severe thunderstorms with hailstones that were reported to have killed cattle until it dissipated in the autumn. This disruption then led to a most severe winter in 1784, where
Gilbert White at
Selborne in
Hampshire reported 28 days of continuous frost. The extreme winter is estimated to have caused 8,000 additional deaths in the UK. In the spring thaw, Germany and Central Europe then reported severe flood damage.
[6]
The meteorological impact of Laki resonated on, contributing significantly to several years of extreme weather in Europe. In France a sequence of extremes included a surplus harvest in 1785 that caused poverty for rural workers, accompanied by droughts, bad winters and summers, including a violent hailstorm in 1788 that destroyed crops. This in turn contributed significantly to the build up of poverty and famine that triggered the
French Revolution in 1789. Laki was only a factor in a decade of climatic disruption, as
Grímsvötn was erupting from 1783-1785 and a recent study of
El Niño patterns also suggests an unusually strong El-Niño effect between 1789-93.
[9]
Consequences in North America
In
North America, the winter of 1784 was the longest and one of the coldest on record. It was the longest period of below-zero temperatures in
New England, the largest accumulation of snow in
New Jersey, and the longest freezing over of
Chesapeake Bay. There was ice skating in
Charleston Harbor, a huge snowstorm hit the south, the
Mississippi River froze at
New Orleans, and there was ice in the
Gulf of Mexico.
[10][11]
Other consequences
There is also evidence that the Laki eruption had effects beyond Europe, with weakened
African and
Indianmonsoon circulations, leading to precipitation anomalies of -1 to -3 mm (-0.04 to -0.12 inch) per day over the
Sahel of Africa, resulting in, amongst other effects, low flow in the River
Nile.
[12] It may also have exacerbated the
Tenmei famine in Japan.
Contemporary reports
Gilbert White recorded his perceptions of the event at
Selborne:
The summer of the year 1783 was an amazing and portentous one, and full of horrible phaenomena; for besides the alarming meteors and tremendous thunder-storms that affrighted and distressed the different counties of this kingdom, the peculiar haze, or smokey fog, that prevailed for many weeks in this island, and in every part of Europe, and even beyond its limits, was a most extraordinary appearance, unlike anything known within the memory of man. By my journal I find that I had noticed this strange occurrence from June 23 to July 20 inclusive, during which period the wind varied to every quarter without making any alteration in the air. The sun, at noon, looked as blank as a clouded moon, and shed a rust- coloured ferruginous light on the ground, and floors of rooms; but was particularly lurid and blood-coloured at rising and setting. All the time the heat was so intense that butchers' meat could hardly be eaten on the day after it was killed; and the flies swarmed so in the lanes and hedges that they rendered the horses half frantic, and riding irksome. The country people began to look with a superstitious awe, at the red, louring aspect of the sun; [...]
[13] Benjamin Franklin recorded his observations in a 1784 lecture:
During several of the summer months of the year 1783, when the effect of the sun's rays to heat the earth in these northern regions should have been greater, there existed a constant fog over all Europe, and a great part of North America. This fog was of a permanent nature; it was dry, and the rays of the sun seemed to have little effect towards dissipating it, as they easily do a moist fog, arising from water. They were indeed rendered so faint in passing through it, that when collected in the focus of a burning glass they would scarce kindle brown paper. Of course, their summer effect in heating the Earth was exceedingly diminished. Hence the surface was early frozen. Hence the first snows remained on it unmelted, and received continual additions. Hence the air was more chilled, and the winds more severely cold. Hence perhaps the winter of 1783-4 was more severe than any that had happened for many years. The cause of this universal fog is not yet ascertained [...] or whether it was the vast quantity of smoke, long continuing, to issue during the summer from
Hecla in Iceland, and that other volcano which arose out of the sea near that island, which smoke might be spread by various winds, over the northern part of the world, is yet uncertain.
[14] (According to contemporary records,
Hekla did not erupt in 1783; its previous eruption was in 1766. The Laki fissure eruption was 45 miles (72 km)
[15] to the east and the
Grímsvötn volcano was erupting circa 75 miles (121 km)
[16] north east. Additionally
Katla, only 31 miles (50 km)
[17] south east, was still renowned after its spectacular eruption 28 years earlier in 1755.) The Reverend Sir John Cullum of
Bury St Edmunds,
Suffolk,
Great Britain recorded on the 23rd June 1783, the same date that Gilbert White noted the beginning of the unusual atmospheric phenomena, in a letter to
Sir Joseph Banks, then President of
The Royal Society
...‘about six o’clock, that morning, I observed the air very much condensed in my chamber-window; and, upon getting up, was informed by a tenant that finding himself cold in bed, about three o’clock in the morning, he looked out at his window, and to his great surprise saw the ground covered with a white frost: and I was assured that two men at Barton, about three miles (5 km) off, saw in some shallow tubs, ice of the thickness of a crown-piece.’
[18] Sir John goes on to describe the effect of this ‘frost’ on trees and crops:
‘The aristae
[19] of the barley, which was coming into ear, became brown and withered at their extremities, as did the leaves of the oats; the rye had the appearance of being mildewed; so that the farmers were alarmed for those crops…The larch, Weymouth pine, and hardy Scotch fir, had the tips of their leaves withered’.
[18] Sir John’s vegetable garden did not escape either, for he noted that they appeared ‘exactly as if a fire had been lighted near them, that had shrivelled and discoloured their leaves’.