Stratospheric Climate Anomalies and Ozone Loss Caused by the Hunga Tonga‐Hunga Ha'apai Volcanic Eruption

The Hunga Tonga‐Hunga Ha'apai (HTHH) volcanic eruption in January 2022 injected unprecedented amounts of water vapor (H2O) and a moderate amount of the aerosol precursor sulfur dioxide (SO2) into the Southern Hemisphere (SH) tropical stratosphere. The H2O and aerosol perturbations have persisted during 2022 and early 2023 and dispersed throughout the atmosphere. Observations show large‐scale SH stratospheric cooling, equatorward shift of the Antarctic polar vortex and slowing of the Brewer‐Dobson circulation. Satellite observations show substantial ozone reductions over SH winter midlatitudes that coincide with the largest circulation anomalies. Chemistry‐climate model simulations forced by realistic HTHH inputs of H2O and SO2 qualitatively reproduce the observed evolution of the H2O and aerosol plumes over the first year, and the model exhibits stratospheric cooling, circulation changes and ozone effects similar to observed behavior. The agreement demonstrates that the observed stratospheric changes are caused by the HTHH volcanic influences. Plain Language Summary The Hunga Tonga‐Hunga Ha'apai (HTHH) submarine volcano (21°S, 175°W) eruption in January 2022 injected unprecedented amounts of water vapor (H2O) as well as moderate amounts of aerosol precursor sulfur dioxide (SO2) into the stratosphere. The H2O and aerosol perturbations persisted throughout 2022 and were accompanied by large changes in stratospheric climate and ozone chemistry. We use a chemistry‐climate model forced by realistic HTHH inputs of H2O and SO2 to simulate these stratospheric changes. The model exhibits temperature, circulation, and ozone anomalies in response to these forcings that are similar to those observed. The agreement demonstrates that the observed anomalies impacts are caused by HTHH volcanic influences. Key Points Large‐scale stratospheric cooling and circulation changes are observed following the Hunga Tonga‐Hunga Ha'apai eruption Observations show ozone reduction in the Southern Hemisphere wintertime midlatitudes and large springtime Antarctic ozone losses in 2022 A chemistry‐climate model can track the plumes and capture observed responses to the volcanic eruption