ICELAND VOLCANIC ERUPTION IN 1783
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.
Other consequences
There is also evidence that the Laki eruption had effects beyond Europe, with weakened African and Indian monsoon 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. 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; 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. (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) to the east and the Grímsvötn volcano was erupting circa 75 miles (121 km) 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. Sir John goes on to describe the effect of this ‘frost’ on trees and crops:
The aristae 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’.
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’.
