Volcanic ash accelerates methane breakdown

Satellite observations and chemical analysis of the 2022 Hunga Tonga eruption show high formaldehyde concentrations in the plume, implying reactive chlorine created by seawater–ash chemistry broke down methane on timescales of days rather than years. A mechanism resembling Saharan dust–sea interactions appears to operate in stratospheric volcanic plumes, trading a temporary methane sink for short‑term ozone erosion. — This alters estimates of methane lifetime and forcing, with implications for climate policy prioritization, methane mitigation strategies, and concerns about unintended ozone damage from aerosol‑driven chemistry.