After all these billions of years, it never fails to amaze me that, beneath the crust of the earth, there are superhot gases that could, at a moment’s notice, change all our lives. Since our country was founded, there have been two volcanic mega-events that caused widespread death, destruction, and—surprisingly—temporary global cooling.
In answer to a question from an American reader, ESA, one of the staff writers of The Iceland Review wrote the following about Laki:
The Laki eruption (aka Skaftáreldar) took place over an eight-month period between June 8, 1783, and February 7, 1784. The eruption occurred in the Lakagígar craters in fissures on either side of Laki mountain between Mýrdalsjökull and Vatnajökull in the southern highlands and the adjoining Grímsvötn volcano in Vatnajökull….
The eruption began as a fissure with 130 craters opened with phreatomagmatic explosions. This event is rated as 6 on the Volcanic Explosivity Index (VEI). The scale is open-ended with the largest volcanoes in history given magnitude 8. For comparison, the 2010 Eyjafjallajökull eruption is rated as magnitude 3 on VEI.
The Laki eruption produced an estimated 14 km3 (3.4 cubic miles) of lava, and the total volume of tephra emitted was 0.91 km3 (0.2 cubic miles). Lava fountains were estimated to have reached heights of 800 to 1,400 meters (2,600 to 4,600 feet).
The gases emitted, including an estimated 8 million tons of hydrogen fluoride and 120 million tons of sulfur dioxide (SO2), caused the death of over 50 percent of Iceland’s livestock, leading to a famine killing approximately 25 percent of the country’s inhabitants.
The Laki eruption and its aftermath caused a drop in global temperatures, as SO2 was spewed into the Northern Hemisphere. This caused crop failures in Europe and may have caused droughts in Asia. The eruption has been estimated to have killed over six million people worldwide, making it the deadliest in historical times.
Not too long after, in 1816, there was another mega volcanic event. Bill McGuire, in The New Scientist (28 March 2015), wrote:
Two hundred years ago, a simmering tropical volcano tore itself apart in spectacular fashion. Mount Tambora, on the Indonesian island of Sumbawa, erupted in a colossal blast that led to the deaths of more than 70,000 people in the region. So large was the explosion that its reach extended far beyond South-East Asia, loading the stratosphere with 200 million tonnes of sulphate particles that dimmed the sun and brought about a dramatic cooling with widespread ramifications half a world away.
The extended climate disruption saw 1816 dubbed “the year without a summer.” There was a wholesale failure of harvests in eastern North America and across Europe, contributing to what economic host John Post has called “the last great subsistence crisis in the western world.” Famine, bread riots, insurrection and disease stalked many nations, while governments sought to cope with the consequences of a distant geophysical phenomenon they didn’t understand.
It can happen again at any time somewhere along the Ring of Fire that encircles the earth. Pray that it doesn’t happen in our lifetime.