Scientists Stunned As Volcano Removes Methane From the Air

The January 2022 eruption of the underwater Hunga Tonga–Hunga Ha’apai volcano in Tonga released massive amounts of methane but also triggered an unexpected chemical reaction that destroyed some of the gas in the atmosphere. Scientists analyzing satellite data detected unusually high levels of formaldehyde—a byproduct of methane breakdown—in the volcanic plume, which persisted for over a week as it traveled toward South America. The discovery suggests volcanic ash and saltwater ejected into the stratosphere generated chlorine atoms when exposed to sunlight, mirroring a previously identified process involving Sahara dust and sea spray. Researchers estimate the eruption emitted around 300 gigagrams of methane but simultaneously removed approximately 900 megagrams daily, comparable to the daily emissions of two million cows. Methane is a potent greenhouse gas, responsible for roughly one-third of global warming, with 80 times the heat-trapping capacity of CO2 over 20 years. While it breaks down faster than CO2, reducing methane emissions could act as an 'emergency brake' on climate change, potentially lowering risks of tipping points in the coming decade. The findings, published in *Nature Communications*, highlight a natural mechanism that could inspire future climate technologies. Lead author Dr. Maarten van Herpen noted that volcanic ash had not previously been linked to methane destruction, offering new avenues for studying atmospheric chemistry and mitigation strategies. Researchers emphasize that while methane reduction could provide short-term climate relief, long-term stability still depends on cutting CO2 emissions. The Tonga eruption’s unexpected methane-clearing effect may now guide further exploration of similar processes to combat global warming.