Headline: The Looming Threat: Could Another Supervolcano Eruption Plunge Earth into a Climate Chaos?
In 1815, the Indonesian volcano Mount Tambora unleashed the most powerful eruption in recorded history, spewing massive amounts of tiny particles into the atmosphere that reflected sunlight and cooled the planet, heralding catastrophe. The subsequent "Year Without a Summer" saw global temperatures drop, crops fail, people starve, and a cholera pandemic sweep the globe, claiming tens of thousands of lives. Some even believe the eruption inspired Mary Shelley to write "Frankenstein" while she was huddled away in Switzerland’s unusually chilly summer of 1816.
More than 200 years later, scientists warn that a similar catastrophe could be on the horizon. But this time, it’s happening in a world that’s not only more populated but also much warmer due to the climate crisis.
Scientists now fear that the next supervolcanic eruption could trigger "climate chaos," according to geologist!–‘>Clive Oppenheimer, a volcanologist at the University of Cambridge. "Humans have no plan for this," he warns.
Volcanoes have long shaped our world, helping to create continents, building our atmosphere, and influencing climate. When they erupt, they release a cocktail of lava, ash, and gases, including greenhouse gases like carbon dioxide—though in quantities far smaller than those produced by burning fossil fuels.
But when it comes to climate change, scientists are most interested in another gas: sulfur dioxide (SO2).
A massive volcanic eruption can inject SO2 into the troposphere—the part of the atmosphere where weather occurs—and the stratosphere, a layer about 7 miles above the Earth’s surface where planes fly. There, it forms microscopic aerosol particles that scatter sunlight back into space, cooling the planet below. These particles can linger in the atmosphere for years.
Satellite data shows how much SO2 contemporary volcanoes emit. The 1991 eruption of Mount Pinatubo in the Philippines released around 15 million tons into the stratosphere, cooling the Earth by about 0.5°C for a few years. But for older eruptions, "we have very poor data," says Oppenheimer. To reconstruct these past events, scientists use information from ice cores and tree rings—like time capsules that preserve the secrets of past atmospheres. From them, they know that major eruptions over the past few thousand years have briefly cooled the Earth by about 1 to 1.5°C.
The 1815 eruption of Mount Tambora, for example, lowered average global temperatures by at least 1°C. Some evidence suggests that the enormous eruption of Samalas in Indonesia in 1257 helped trigger the "Little Ice Age," a cold period that lasted for centuries. There’s also evidence that massive eruptions can affect rainfall patterns, drying out monsoon systems in Africa and Asia by disrupting the temperature difference between land and sea.
Today’s world is dangerously different from the one those eruptions occurred in. It’s much warmer, which could make the next supervolcanic eruption even more catastrophic.
"Now the world is more unstable," says Michael Rampino, a professor at New York University who studies the links between volcanic eruptions and climate change. "The effects could be even worse than they were in 1815."
Counterintuitively, a warmer world could mean a more powerful cooling effect from massive volcanic eruptions. That’s because the way aerosol particles form and transport depends entirely on climate, explains Thomasuta¡flare**–Jones, a physical volcanologist at the University of Exeter. As the Earth warms, winds in the atmosphere circulate faster, so particles disperse more quickly and have less time to grow. Smaller particles scatter sunlight more efficiently, leading to greater cooling. Additionally, oceans could play a role. As their surface warms, a layer of lighter, warmer water sits on top and acts as a barrier to mixing with deeper, colder layers, potentially leading to disproportionate cooling of the ocean surface and the atmosphere above it, suggests Oppenheimer.
Climate change could even affect volcanic systems themselves. Melting ice could increase eruptions by reducing pressure and allowing magma to rise faster. Extreme weather—also a product of climate change—can penetrate deep into the Earth, where it can react with magma to trigger an eruption, notes Obrien.
But while the world grapples with global warming, a cooling period might sound appealing. Scientists argue that it would be exactly the opposite.
First, there’s an immediate effect. About 800 million people live within 60 miles of an active volcano. A massive eruption could wipe out entire cities. Campi Flegrei in Italy, for instance, shows signs of unrest and sits just west of Naples, home to around 1 million people.
In the long term, the effects could be cataclysmic. A 1°C drop in global temperatures might seem modest, but it could be severe in specific regions. The 43 AD eruption of Okmok in Alaska could have cooled parts of Southern Europe and North Africa by up to 7°C, for example. Colder temperatures, reduced sunlight, and volatile rainfall patterns could impact multiple global breadbaskets, including the US, China, and Russia, threatening global food security and potentially leading to political tension or even war, according to an analysis by insurers Lloyd’s.
Human and economic losses would be staggering. In an extreme scenario like Tambora, economic losses could top $3.6 trillion in the first year alone, estimates Lloyd’s.
Worse still, the cooling wouldn’t offer respite from climate change; the Earth would simply return to where it was before the eruption after a few years.
The next eruption could happen anywhere. Scientists monitor certain areas, like Indonesia, one of the planet’s most volcanically active regions, and Yellowstone in the western US, where it’s been tens of thousands of years since the last massive eruption. But who’s next and when is still impossible to predict, says Oppenheimer.
Massive volcanic eruptions can’t be stopped, but there are ways to prepare. Oppenheimer calls for experts to assess worst-case scenarios, conduct stress tests, and develop plans: everything from evacuations to aid efforts and ensuring food deliveries.
While some might say the likelihood of a supervolcanic eruption is still low, "that doesn’t mean it’s nothing," warns Oppenheimer. Right now, the world is wholly unprepared for the consequences such an event would likely bring. "We’re only just beginning to get an idea of what might happen."
