The Laki Fissure
The 2010 Eyjafjallajökull eruption has ruined travel plans but does not rank as particularly disastrous, except financially for the air companies. A volcanic eruption in Iceland in 1783 – the Laki Fissure eruption – was catastrophic for the Icelanders (25% of the population died in the ensuing famine) and had serious consequences in Britain.
The amount of volcanic ash in the atmosphere over the UK gave rise to the “sand-summer”, as the 1783 summer became known. The amount of sulphur dioxide released by the eruption was colossal – 120 million tons:
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 – Wikipedia
The resulting smog – the Laki Haze – was deadly, killing as it spread over western Europe. It reached Great Britain by late June of 1783, and thousands died from sulphur dioxide poisoning, outdoor workers being particularly vulnerable.
The effect on the weather was no less dramatic. As the haze heated up, a serious of heavy thunderstorms were unleashed, hailstones causing livestock losses. Gilbert White described that summer in The Natural History of 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 . . . the peculiar haze, or smokey fog that prevailed for many weeks in this island . . . was a most extraordinary appearance, unlike anything known within the memory of man. . . . 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.
White also describes the choking heat and unusual quantities of flies, and the sense of dread generated by the look of the sky, which even he, an enlightened man, could understand:
The country people began to look with a superstitious awe at the red, louring aspect of the sun
As the eruption continued for 8 months, until February of 1784, the lengthy emission of sulphuric aerosols had a significant cooling effect on the Northern Hemisphere. The 1784 winter in the UK was particularly severe, killing thousands more: White recorded 28 consecutive frosts. The hardship generated by the Laki Fissure eruption is thought to have contributed to the explosion of revolution in France.