An ocean of stratospheric aerosols after the Hunga Tonga– Hunga Haʻapai volcanic eruption

Volcanic eruptions are key drivers of the natural variability of the Earth’s Climate system. The sulfate aerosols produced by major volcanic events can last for several years and reduce surface temperatures while warming the stratosphere1. However, this “classic” view is now challenged by the January 15th, 2022, Hunga Tonga Hunga Ha’apai submarine eruption. For the first time in the satellite era, a volcano injected material up to the mesosphere2 leading to an increase in the global stratospheric water vapor burden by 10% from seawater injected3. However, no information is available about the chemical properties of the plume. Herein, we show a detailed analysis of the chemical composition of the HTHH plume through a new balloon-based sampling technique. The ion chromatographic analysis of the sampled aerosols shows the presence of sea salts as opposed to a pure sulfate plume alone. The chemical analysis thereby revealed that the HTHH is more complex than initially thought and may explain the unexpected aerosol burden created by this eruption relative to the expected sulfate aerosol produced from the modest 0.6 Tg SO2 injected. These results challenge the current models that simulate the climate impacts of volcanoes.