Abstract
The January 2022 eruption of the Hunga volcano (20∘S) injected 150 Tg of water vapour into the middle atmosphere, leading to an increase in the stratospheric water burden of 10%, unprecedented in the observational record. In the first two years post eruption the stratospheric burden hardly changed, leaving the residence time of volcanically injected water vapour, a key control on its climate impact, uncertain. Here, using satellite observations, we show a substantial decline from 2024 to early 2025, the largest drop since the eruption. Comparison with 3-D numerical model simulations shows that the long-term removal of the Hunga water has now entered a new phase, with stratosphere-troposphere exchange playing an increasingly important role, exceeding Antarctic dehydration in 2024. We estimate that the additional stratospheric water vapour is now decaying steadily with an e-folding time of 3 years and will reach the observed pre-Hunga range of variability around 2030.
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Data availability
MLS satellite data, including the version 5 H2O data used in this paper49, are publicly available at https://disc.gsfc.nasa.gov. TOMCAT model outputs are available on request from the corresponding authors. All of the pre-processed model data (for example, monthly mean water vapour mass averaged globally and over Antarctica from TOMCAT and water vapour mass interpolated onto the MLS vertical coordinates) are available at Zenodo (https://doi.org/10.5281/zenodo.18193651)50.
Code availability
Code from the TOMCAT CTM is available on suitable request from Martyn Chipperfield. The code used to generate all of the figures in this analysis is available at Zenodo (https://doi.org/10.5281/zenodo.18193651)50.
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Acknowledgements
X.Z. and Q.C. acknowledge funding from the National Natural Science Foundation of China (U2442210, 42275059, 12411530093). M.P.C. and S.S.D. were supported by the NCEO TerraFIRMA, NERC LSO3 (NE/V011863/1) and ESA OREGANO (4000137112/22/I-AG) projects. G.M. received funding from the NERC MeteorStrat (NE/R011222/1) and from NCAS via the NERC ACSIS (NE/N018001/1). S.H. was supported by the Leeds-York-Hull NERC DTP Panorama (NE/S007458/1). The TOMCAT model simulations were performed on the UK Archer2 and Leeds ARC HPC systems. Work at the Jet Propulsion Laboratory, California Institute of Technology, was carried out under a contract with the National Aeronautics and Space Administration (80NM0018D0004).
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X.Z. and M.P.C. designed the study. M.P.C., X.Z., and W.F. designed and performed TOMCAT simulations. X.Z. analysed the data and produced the figures. X.Z., M.P.C., and H.C.P. drafted the initial text. S.S.D., S.H., G.M., L.M., M.L.S. and Q.C. contributed substantially to the interpretation of findings.
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Zhou, X., Chen, Q., Feng, W. et al. Residence time of Hunga stratospheric water vapour perturbation quantified at 9 years. Commun Earth Environ (2026). https://doi.org/10.1038/s43247-026-03216-5
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DOI: https://doi.org/10.1038/s43247-026-03216-5
