9. Wiping Out a Fourth of Iceland’s Population
The Laki Eruption’s deadliness was a result of its steady gas releases during its eight months of rumbling and periodic small explosions. Massive amounts of gasses, including fluorine and over 120 million tons of sundry sulfuric dioxides, were released into the air. They produced fog and haze as far away as Syria. The fluorine settled on Iceland’s grass, which gave grazing animals fluoride poisoning and killed most of the island’s livestock. The loss of livestock in turn caused a quarter of Iceland’s human population to starve to death.
But Iceland was and remains sparsely populated, so the death of a quarter of its population did not make Laki history’s deadliest eruption. The impact was beyond Iceland, where the eruption led to a decline in temperatures in the northern hemisphere. Winter temperatures in the US, for example, dropped 10 degrees Fahrenheit in 1783, and remained below normal for several years afterward. Laki’s deadliest impact was not in the US or North America, either, however.