Tonga’s Enormous Volcanic Eruption Cleaned Up Part of Its Own Methane Emissions in 2022, Hinting at a Way to Fight Climate Change

Researchers analyzed satellite imagery of the volcanic plume and found evidence that the potent greenhouse gas had broken down. The work could inform artificial interventions aiming to mitigate global warming, scientists say

Margherita Bassi | Daily Correspondent

June 4, 2026 12:14 p.m.

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Hunga Tonga–Hunga Ha’apai’s eruption in January 2022 was among the most violent volcanic eruptions of the modern era. New research reveals that the blast, located off Tonga in the South Pacific, was also a rather polite one, as the submarine volcano’s explosion came with a chemical reaction that disposed of some of its own methane emissions.

Scientists examined satellite images of the volcanic plume and found an unexpectedly high concentration of formaldehyde, a gas that temporarily forms when methane breaks down in the atmosphere. The finding, published in May in the journal Nature Communications, suggests that a methane clean-up process was taking place in the stratosphere in the wake of the eruption. Though further research is necessary to truly understand the chemistry at play, this natural mechanism could inspire artificial global warming interventions.

“We were able to track the cloud for ten days, all the way to South America. Because formaldehyde only exists for a few hours, this showed that the cloud must have been destroying methane continuously for more than a week,” Maarten van Herpen, a co-author of the study and a researcher at the Dutch consulting firm Acacia Impact Innovation BV, says in a statement. “It is known that volcanoes emit methane during eruptions, but until now it was not known that volcanic ash is also capable of partially cleaning up this pollution.”

The chemical process driving the cleanup is not new. It seems to be the same one described in 2023 over the Atlantic Ocean, where dust from the Sahara can combine with sea salt from sea spray. This creates small particles called iron salt aerosols, and when sunlight reaches the particles, chlorine atoms form, which help destroy atmospheric methane.

That this process seems to have taken place in a volcanic plume in the stratosphere, however, is “new—and completely surprising,” Matthew Johnson, a co-author of the study and a chemist at the University of Copenhagen, tells CNN’s Laura Paddison. Johnson also participated in the 2023 research.

Hunga Tonga–Hunga Ha’apai blasted salty ocean water into the air, ultimately pumping enough water vapor into the stratosphere to fill more than 58,000 Olympic swimming pools. When sunlight hit this cloud, it could have sparked reactions that produced chlorine, and the chlorine could have broken down the methane in a process that resulted in formaldehyde.

“It is quite surprising that these formaldehyde levels were observed,” Folkert Boersma, an atmospheric scientist at Wageningen University in the Netherlands who did not participate in the study, tells Science News’ Javier Barbuzano. “That points to something that I did not know myself.”

According to the team’s calculations, the eruption released a grand total of around 300,000 metric tons of methane, and roughly 900 metric tons of the gas were broken down each day.

As human-generated emissions of greenhouse gases, including methane, continue to warm the planet, the idea is that this natural cleanup process could inspire an artificial intervention to remove even more methane. But some researchers are wary of the implications.

Pete Edwards, an atmospheric chemist at the University of York in England who was not involved in the study, tells CNN that the impact of such a strategy would be difficult to predict. The volcano’s methane-removing chemistry occurred in the stratosphere, and any intervention by humans would be in the troposphere below it.

Boersma, meanwhile, argues that the world should focus on releasing less carbon dioxide and methane before injecting anything into the atmosphere. “We all know what to do,” he tells Science News. “It’s not shooting chlorine into the stratosphere, it’s just making sure that we reduce emissions.”

Margherita Bassi | Read More

Margherita Bassi is a freelance journalist and trilingual storyteller. Her work has appeared in publications including BBC Travel, Discover magazine, Live Science, Atlas Obscura and Hidden Compass.