ejected more than 1,000 cubic kilometers (240 cubic miles) of pumice and ash during a single eruption event at some point in the Earth’s past. To put this into perspective, a super-eruption contains the force of 1,000 Hiroshima nuclear bombs exploding per second¹,². Supervolcanoes on Earth include Yellowstone, Long Valley in California, Toba in Indonesia, and Taupo in New Zealand. The last supervolcano eruption on Earth happened at the Taupo volcano 27,000 years ago¹.
Global supervolcano eruption effects
During a supervolcano eruption, there would be a great deal of ash falling in the surrounding region and the formation of a giant caldera depression as the ground collapses following a the eruption due to the withdrawal of magma from within the volcano. Supervolcano eruptions can also change the global climate for years to decades, causing much colder weather. This occurs because volcanoes put sulfur gases that form aerosols made of sulfuric acid into the atmosphere which would quickly spread throughout the world³.
A full eruption of the Yellowstone volcano would put 2,000 million tons of sulfur into the atmosphere. Within 2-3 weeks, the rest of the Earth would be covered with the sulfuric acid aerosols, dropping average global temperatures by as much as 10 degrees, and in some places, such as in the Northern Hemisphere, temperatures would drop as much as 12 degrees³.
These cooler global temperatures could last as long as 6-10 years, and then temperatures would warm back up to normal temperatures. Such a disruption in global temperatures would likely cause the seasonal Monsoon to fail due to larger temperature reductions in the Southern Hemisphere, and lead to drought in the Asian countries that depend on the Monsoon rains³.
If the Yellowstone volcano were to fully erupt, ash would bury a large portion of the United States, killing millions of people. Within 1,000 cubic km of the eruption, most people would die from the inhaled ash in the air that forms a cement-like substance in the lungs³.
Most of the magma of a supervolcano would not become lava but would instead be blasted into the atmosphere, and would float around as extremely hot and sharp particles³.
Some of the ash from the Yellowstone volcano would also reach Europe and other parts of the world, but outside of the U.S., the ash would be more like a dusting, so such areas would not experience the worst effects of such an eruption from the Yellowstone volcano³.
The impacts of ash include³:
- Killing animals and humans
- A reduction in the light from the sun
- Causing rainfall that leads to mudslides
- Water supply pollution
- Decimating crops and vegetation
Such impacts to the Earth’s environment as well as a large portion of its population would lead to major disruptions in the global economy as well as our way of life.
What is the likelihood of a supervolcano eruption?
Most scientists believe that the chance of a large globally-altering eruption, such the one that could occur at the Yellowstone volcano, are very unlikely for the next several thousand years. However, scientists do believe that another super-eruption might possibly occur at some point in the distant future²,³.