A giant volcano may have accidentally uncovered a powerful new way to destroy methane in Earth’s atmosphere.
In January 2022, the underwater volcano Hunga Tonga–Hunga Ha’apai in the South Pacific unleashed one of the most powerful eruptions ever recorded in modern times. But scientists have now discovered that the eruption did something completely unexpected: it also helped remove some of the methane pollution released into the atmosphere. Researchers say the surprising effect could eventually provide clues for slowing global warming.
After analyzing satellite data from the enormous volcanic plume, scientists detected unusually large amounts of formaldehyde in the atmosphere. That finding was important because formaldehyde forms briefly when methane breaks down, making it a key sign that methane destruction was taking place high above Earth.
“When we analyzed the satellite images, we were surprised to see a cloud with a record-high concentration of formaldehyde. We were able to track the cloud for 10 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,” explains Dr. Maarten van Herpen from Acacia Impact Innovation BV, first author of the study, which has just been published in Nature Communications.
“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,” he adds.
Volcano Ash and Sunlight Triggered Methane Breakdown
Researchers believe the eruption activated a chemical process that scientists only recently identified in another part of the world.
In earlier work published in 2023, researchers found that dust blowing from the Sahara Desert across the Atlantic Ocean can combine with salt from sea spray. Together, they form tiny particles known as iron salt aerosols. When sunlight hits these particles, chlorine atoms are produced. Those chlorine atoms react with methane and help break it down in the atmosphere. The discovery changed scientists’ understanding of chemistry in the lower atmosphere.
“What is new—and completely surprising—is that the same mechanism appears to occur in a volcanic plume high up in the stratosphere, where the physical conditions are entirely different,” says Professor Matthew Johnson from the Department of Chemistry at the University of Copenhagen, one of the researchers behind both discoveries.
The Tonga eruption blasted huge amounts of salty seawater into the stratosphere along with volcanic ash. Scientists believe sunlight reacting with this mixture generated highly reactive chlorine, which then helped destroy methane released during the eruption. The high formaldehyde levels seen in satellite observations provided evidence that methane was actively breaking down.
Researchers estimate the eruption released around 300 gigagrams (Gg) of methane, roughly equal to the yearly methane emissions from more than two million cows. At the same time, the volcanic plume removed approximately 900 megagrams (Mg) of methane per day, an amount comparable to the daily methane emissions from two million cows.
Why Methane Matters for Climate Change
Methane currently accounts for roughly one-third of global warming. Over a 20-year period, methane traps about 80 times more heat than CO2. However, methane does not remain in the atmosphere nearly as long as carbon dioxide. It usually breaks down within about 10 years.
Because methane disappears relatively quickly, cutting methane pollution now could slow warming within the next decade. Some scientists describe methane reduction as an “emergency brake” on climate change—one that could help lower the risk of climate tipping points in the coming years. Researchers emphasize, however, that reducing CO2 emissions remains essential for long-term climate stability.
Discovery Could Help Future Climate Technologies
The scientists behind the study say their findings may support efforts to develop technologies that speed up methane removal from the atmosphere, similar to the natural process triggered by the volcano. Several possible approaches are already being explored, but one major obstacle has been proving how much methane is actually removed.
“How do you prove that methane has been removed from the atmosphere? How do you know your method works? It’s very difficult. But here we address that problem by showing that methane breakdown can in fact be observed using satellites,” says Dr. Jos de Laat from the Royal Netherlands Meteorological Institute, senior author of the study.
The research relied on the TROPOMI instrument aboard the European Space Agency’s Sentinel-5P satellite, which tracks greenhouse gases and air pollution around the world every day.
“Retrieving formaldehyde from TROPOMI in a stratospheric volcanic plume is far outside the instrument’s standard operating conditions — we had to carefully correct the satellite’s sensitivity for the unusual altitude of the signal and account for interference from the high sulfur dioxide concentrations. Getting these corrections right was essential to confirm that what we were seeing was real,” said Dr. Isabelle De Smedt, Royal Belgian Institute for Space Aeronomy.
The researchers say the discovery could inspire future engineering solutions designed to reduce methane pollution safely and effectively.
“It’s an obvious idea for industry to try to replicate this natural phenomenon — but only if it can be proven to be safe and effective. Our satellite method could offer a way to help figure out how humans might slow global warming,” concludes Matthew Johnson.
Scientists Say Methane Estimates May Need Updating
Researchers say the findings may require scientists to revise the global methane budget, which estimates how much methane enters and leaves Earth’s atmosphere.
“We now know that atmospheric dust—for example from a volcanic eruption—impacts the methane budget, meaning the budget of how much methane is added to the atmosphere and how much is removed. Because dust has not previously been taken into account, it is important that we correct the data on which these estimates are based,” says Matthew Johnson.
Reference: “Satellite quantification of enhanced methane oxidation applied to the stratospheric plume following Hunga Tonga-Hunga Ha’apai eruption” by Maarten M.J.W. van Herpen, Isabelle De Smedt, Daphne Meidan, Alfonso Saiz-Lopez, Matthew S. Johnson, Thomas Röckmann and Jos de Laat, 7 May 2026, Nature Communications.
DOI: 10.1038/s41467-026-72191-4
The research team included Maarten van Herpen (Acacia Impact Innovation BV, Netherlands); Isabelle De Smedt (Royal Belgian Institute for Space Aeronomy, Belgium); Daphne Meidan and Alfonso Saiz-Lopez (CSIC, Spain); Matthew Johnson (University of Copenhagen, Denmark); Thomas Röckmann (Utrecht University, Netherlands); and Jos de Laat (Royal Netherlands Meteorological Institute, Netherlands).
The research was supported by Spark Climate Solutions.
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