The January 2022 eruption of the submarine volcano Hunga Tonga–Hunga Ha’apai produced one of the most violent recent eruptions and injected a large plume into the stratosphere. Using advanced satellite measurements, researchers found the plume unexpectedly promoted chemical removal of methane emitted by the eruption. Satellites recorded unusually high formaldehyde — a short-lived product of methane oxidation — and tracked the cloud for 10 days as it moved to South America. Because formaldehyde normally lasts only a few hours, its persistence provided visible evidence that methane was being broken down continuously inside the plume, says Maarten van Herpen, first author of the study.
The team connects this result to earlier 2023 work showing that mineral dust mixed with sea salt can form iron-containing aerosols that, under sunlight, produce chlorine atoms able to react with methane. In the volcanic case, large amounts of seawater and ash were thrown into the stratosphere and sunlight acting on salt and ash likely produced highly reactive chlorine, says Professor Matthew Johnson of the University of Copenhagen. That chlorine would accelerate methane breakdown even at the higher altitudes reached by the plume.
The finding matters because methane contributes about one third of global warming and is roughly 80 times more potent than CO2 over a 20-year period, though it usually breaks down in around 10 years. Cutting methane emissions now could therefore have a noticeable climate effect within a decade, while reducing CO2 remains essential for long-term temperature stability.
The study used the TROPOMI instrument aboard ESA’s Sentinel-5P and required careful corrections for signal altitude and high sulfur dioxide. The paper appears in Nature Communications and lists researchers from Acacia Impact Innovation BV, CSIC in Spain and Utrecht University in the Netherlands. The work was supported by Spark Climate Solutions and reported by the University of Copenhagen. The team notes a key challenge is proving how much methane the plume removed, but says the results could guide efforts to speed up methane removal artificially.
Difficult words
- plume — A rising cloud of gas and particles
- stratosphere — The atmospheric layer above the troposphere
- formaldehyde — A short-lived chemical from methane breakdown
- oxidation — A chemical process where a substance loses electrons
- aerosol — Tiny particles or droplets suspended in airaerosols
- chlorine — A reactive chemical element that can break gases
- methane — A potent greenhouse gas emitted by human activity
- sulfur dioxide — A volcanic gas that affects satellite measurements
Tip: hover, focus or tap highlighted words in the article to see quick definitions while you read or listen.
Discussion questions
- What are the possible benefits and risks of trying to speed up methane removal artificially, as the team suggests?
- How could cutting methane emissions now produce noticeable climate effects within a decade, compared with reducing CO2?
- What additional evidence would you want to see to confirm how much methane the volcanic plume actually removed?
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