Hunga Assessment Report Published
The APARC assessment report on the impact of the huge 2022 Hunga eruption has just been published. The Hunga volcano in the tropical Pacific erupted in January 2022, sending a plume of vaporised seawater deep into the stratosphere in an explosion that equalled the size of Krakatoa’s in 1883.
The Hunga assessment report’s main findings include:
- The eruption increased global stratospheric water vapour by about 10 percent, much of which remains in the atmosphere in 2025 (see Zhou et al., 2026).
- Very large eruptions usually cause a stratospheric warming effect, but Hunga did the opposite, cooling the stratosphere.
- While Hunga did affect stratospheric ozone in the Southern Hemisphere, its effects on the Antarctic ozone hole (see Zhou et al., 2024) and surface climate were minor.
We contributed to the report (and co-authored Chapter 5) through calculations of the impact of the eruption on ozone, and on quantification of the processes that are slowly removing the water vapour.
Selected media links:
Contributing TOMCAT papers
Chipperfield, M.P., S.G. Heddell, S. Dhomse, W. Feng, S. Chang, G. Mann, X. Zhou and H.C. Pumphrey, Ongoing large ozone depletion in the polar lower stratospheres: The role of increased water vapour,
Faraday Discussions, 258, 216-233, doi:10.1039/D4FD00163J, 2025.
Zhou, X., S.S. Dhomse, W. Feng, G. Mann, S. Heddell, H. Pumphrey, B.J. Kerridge, B. Latter, R. Siddans, L. Ventress, R. Querel, P. Smale, E. Asher, E.G. Hall, S. Bekki and M.P. Chipperfield, Antarctic vortex dehydration in 2023 as a substantial removal pathway for Hunga Tonga-Hunga Ha'apai water vapour,
Geophys. Res. Lett., 51, e2023GL107630, doi:10.1029/2023GL107630, 2024.
Zhou, X., Q. Chen, W. Feng, S. Heddell, S.S. Dhomse, G. Mann, H.C. Pumphrey, L. Millan, M.L. Santee, M.P. Chipperfield, When will the stratospheric water vapour return to pre-Hunga level? Communications Earth and Environment, xx, xx, (submitted version), 2026.