How a Massive Volcanic Eruption Accidentally Revealed a New Way to Destroy Methane

A violent volcanic eruption in the South Pacific has uncovered a surprising natural mechanism that could potentially help slow global warming. While volcanic events are typically associated with environmental disruption, the eruption of the submarine volcano Hunga Tonga–Hunga Ha’apai in January 2022 revealed a process that effectively “cleaned up” some of the methane pollution it released into the atmosphere.

This discovery provides entirely new insights into atmospheric chemistry and may inspire future engineered methods to remove potent greenhouse gases from the air.

The Discovery: Formaldehyde as a Chemical Fingerprint

Using advanced satellite measurements, researchers detected unusually high concentrations of formaldehyde within the massive volcanic plume following the eruption. In atmospheric chemistry, this is a critical finding because formaldehyde serves as a short-lived intermediate product created when methane is destroyed.

“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 Maarten van Herpen from Acacia Impact Innovation BV, the study’s first author.

While it is established that volcanoes emit methane during eruptions, this research marks the first time scientists have observed volcanic ash actively contributing to the removal of that pollution.

The Science: Ash, Salt, and Sunlight

The mechanism driving this methane destruction is a process the researchers first identified in 2023 in a different environmental context. Previously, they found that when Sahara dust blows over the Atlantic Ocean, it mixes with sea salt from spray to form iron salt aerosols. When sunlight hits these aerosols, it produces chlorine atoms, which then react with and break down methane.

Professor Matthew Johnson from the University of Copenhagen, one of the researchers behind both discoveries, notes that the same mechanism appeared to occur in the volcanic plume high in the stratosphere—an environment with entirely different physical conditions.

During the 2022 event, the eruption hurled vast amounts of volcanic ash and salty seawater into the stratosphere. The researchers theorize that sunlight hitting this specific mixture created highly reactive chlorine, which then dismantled the methane released during the eruption.

Why Methane Reduction is an “Emergency Brake”

To understand why this discovery matters, it’s essential to distinguish between the two primary drivers of climate change: carbon dioxide (CO₂) and methane.

• Potency: Over a 20-year period, methane is approximately 80 times as potent as CO₂.
• Impact: Methane is currently responsible for one-third of global warming.
• Lifespan: Unlike CO₂, which persists for centuries, methane breaks down relatively quickly, typically within about 10 years.

Because of this shorter lifespan, reducing methane emissions can have a noticeable impact on the climate within a single decade. This is why researchers describe methane reduction as an “emergency brake” on climate change—a tool that could help prevent critical climate tipping points while the world continues the essential, long-term work of stabilizing temperatures by reducing CO₂ emissions.

Verifying Atmospheric Cleanup via Satellite

One of the greatest challenges in climate engineering is verification: proving that a specific method actually removes methane from the atmosphere. This study addresses that problem by demonstrating that methane breakdown can be observed from space.

The research utilized the TROPOMI instrument aboard the European Space Agency’s Sentinel-5P satellite. Because the volcanic plume was at an unusual altitude and contained exceptionally high sulfur dioxide concentrations, the team had to carefully correct the instrument’s sensitivity to confirm the formaldehyde signals were real.

Jos de Laat from the Royal Netherlands Meteorological Institute, senior author of the study, emphasizes that this satellite method offers a viable way to monitor and verify the effectiveness of methane-removal strategies.

Looking Ahead: From Nature to Industry

The findings, published in Nature Communications, could serve as a blueprint for industrial engineers. By replicating this natural phenomenon—specifically the use of reactive chlorine triggered by sunlight—humans may be able to artificially accelerate the breakdown of atmospheric methane.

However, the researchers stress that any industrial application must be proven safe and effective before implementation. For now, the Hunga Tonga–Hunga Ha’apai eruption stands as a powerful reminder that the Earth’s natural systems can provide unexpected solutions to the most pressing environmental challenges.

Key Takeaways: Volcanic Methane Destruction

This research was supported by Spark Climate Solutions and involved collaborations between the University of Copenhagen, the Royal Netherlands Meteorological Institute, the Royal Belgian Institute for Space Aeronomy, CSIC in Spain, and Utrecht University in the Netherlands.