The eruption of the Laki volcano in Iceland released enormous amounts of sulfur dioxide, resulting in the death of much of the island's livestock and a catastrophic famine which killed a quarter of the Icelandic population. It has been estimated that 23,000 British people died from the poisoning. Northern hemisphere temperatures dropped by about 1 °C in the year following the Laki eruption. The winter of 1783-1784 was very severe, and estimated to have caused 8,000 additional deaths in the UK. The meteorological impact of Laki continued, contributing significantly to several years of extreme weather in Europe. In France, the sequence of extreme weather events contributed significantly to an increase in poverty and famine that may have contributed to the French Revolution in 1789. Laki was only one factor in a decade of climatic disruption, as Grímsvötn was erupting from 1783 to 1785, and there may have been an unusually strong El Niño effect from 1789 to 1793. A paper written by Benjamin Franklin in 1783 blamed the unusually cool summer of 1783 in North America on volcanic dust coming from this eruption, though Franklin's proposal has been questioned.