In the summer of 1783, the largest volcanic eruption of the past1,000 years killed 9,000 Icelanders, dumped three cubic miles of lava into the surrounding region, and spewed out more than 100 million tons of gases.
As if that weren’t bad enough, Rutgers University climatologist Luke Oman says, the eruption of the Laki volcano created a climatic disaster that rippled all across the Northern Hemisphere and caused a famine that cut the population of the Nile River valley by a sixth.
Using a NASA computer model, Oman tracked the worldwide effects of the sulfate aerosol cloud that formed following the Laki eruption. The results show that the cloud blocked enough sunlight to cool large portions of Asia and North America. Tree ring data support the model’s conclusion, showing that in some areas, the summer of 1783 was the coldest in more than 500 years. That chilling, in turn, disrupted the delivery of seasonal rains to Africa and India. Because monsoons result from the temperature differences between land and sea, the yearly monsoon was so weakened that northern Africa and India experienced a devastating drought.