Between June 8, 1783, and February 7, 1784, the eruption of the Laki volcanic system in the south of Iceland produced 8 million tons of fluorine and 120 million tons of sulfur dioxide. The released fluorine and sulfur dioxide caused massive climate changes across the Northern Hemisphere, ranging from the United States to Japan.

The climate changes triggered one of the most important social changes in history — The French Revolution. 6 million people died of climate change caused by the Laki eruption. The 1783 Laki eruption was one of the largest eruptions in recorded history.

Naturally, Iceland suffered the most from the Laki eruption. Twenty-five percent (approximately 9,000) of Iceland’s population died either from the eruption or the famine which followed.

Eighty percent of sheep, fifty percent of cattle, and fifty percent of horses died from eating grass contaminated with fluorine.

During the years following the Laki eruption, Icelanders were so desperate, they didn’t want to dance anymore.

“The Icelanders stopped dancing and unlike the Norwegians and Faroe Islanders, we lost the old dances.”

— Professor Gunnar Karlsson

The rest of Europe, too, suffered from the direct and indirect effects of the eruption.

The fog was so thick, the boats could not navigate and were forced to stay in harbors. The sun was blood-colored.

In England, 23,000 people died in 1783 from inhaling sulfur dioxide gas. Sulfur dioxide reacts with moisture in the lungs and forms lethal sulfurous acid.

Destructive thunderstorms formed with huge hailstones killing cattle. The summer of 1783 was very hot, followed by an extremely harsh winter.

The spring resulted in massive floods since the snow thawed faster than the frozen ground beneath. The floating ice was destroying bridges and dams.

But the indirect impact was even more deadly. The eruption caused crop failure, which resulted in food shortages across Europe. People were starving.

The French population grew from 18 million in 1700 to 26 million in 1789. Paris alone had 600,000 people. One-third of them were unemployed.

Inefficient farming methods prevented farmers from growing enough food to feed the growing population. Any surplus of food was difficult to move from the countryside to the cities because of bad transportation networks.

The population growth, inefficient farming, and terrible transportation infrastructure caused the prices of food to grow by sixty-five percent.

In addition, the French king Louis XVI tried to solve the enormous state debt by a devaluation of money, which caused massive inflation.

All the above would be a good enough reason for the revolt against the ruling elite, but the final straw that brought the camel’s back was the Laki eruption.

Because of the Laki eruption, France faced extreme drought combined with summer storms in 1788, which caused crop failure. During the 1788-89 winter, low temperatures caused the rivers to freeze and prevent the delivery of grain to the cities.

On top of all that, in spring 1789, heavy floods destroyed crops. By March 1789, France ran out of grain.

The soldiers were deserting since their families were starving, the peasants all across France were protesting against the king.

Louis XVI sent Swiss mercenaries to the streets of Paris to establish order. Unfortunately, it was too late.

On July 14, 1789, the hungry Parisian mob attacked the Bastille prison, thus starting the bloody French Revolution.

Four years later, Louis XVI and his wife, Marie Antoinette, were executed by guillotine.

People revolt only if they starve. Hungry men and women have nothing to lose. The fact which held true for French Revolution in distant 1789 as well as for the Arab Spring in 2008.

France was on a trajectory to revolution, whether or not the Laki eruption would have happened. But it was the Laki eruption that significantly speed up the events.

Even in the present day, we would face huge difficulties in mitigating massive climate changes caused by the Laki eruption, let alone in the 18th century when technology was far less developed.

The Laki eruption is a strong reminder of how devastating climate changes are. As of today, we are in the middle of the biggest one in the last thousand years.

The scarry part? We are doing far too little to stop it.

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