,,- Utrecht University, Institute for Marine and Atmospheric research, Utrecht, department of Physics, Utrecht, Netherlands (c.e.wieners@uu.nl)
Tropical cyclones can cause extreme weather (wind, rain, storm surges) but also provide beneficial precipitation. Their frequency, trajectories and intensity are expected to shift under global warming and these changes may not all be restored by Stratospheric Aerosol Injection (SAI), even if the same global mean surface temperature is achieved.
Despite their importance to climate risk, the effects of SAI on tropical cyclones has not been much studied, because resolving tropical cyclones requires a model resolution of a quarter degree or higher, whereas SAI simulations so far, including GeoMIP and ARISE, typically work with much lower resolutions.
We studied the effect of SAI on tropical cyclone trajectories and risk potential using three simulations in CESM1 at 0.1º ocean and 0.25º atmosphere resolution: one at constant year-2000 conditions (“present-day”), one in which CO2 increases strongly (“RCP8.5”), and one in which CO2 increases as in RCP8.5, but global mean surface temperature is cooled back to year-2000 conditions from 2050 onwards by means of SAI (“SAI”).
To save computation time, we use the atmosphere component CAM (rather than the several times more expensive WACCM). CAM does not model the evolution of stratospheric aerosol, hence we force the model with stratospheric aerosol fields obtained from CESM-WACCM simulations (Tilmes et al, 2018). The aerosol concentrations are scaled using a feedback procedure in order to achieve the temperature target (de Jong et al, 2025).
In agreement with the literature, we find that under RCP8.5, the number of tropical cyclones decreases, but peak winds and precipitation increase, albeit with regional differences. Sea Surface Temperature (SST) increases in all regions, which is favourable for tropical cyclone development, but vertical windshear also increases in most regions, which is unfavourable. SAI largely compensates the effect on SST, but its effect on shear varies per region. Globally, tropical cyclone counts decrease even further under SAI, while the frequency of strong (windy or wet) cyclones is roughly restored. Therefore, SAI may reduce the risk from tropical-cyclone-related extreme weather, but also decreases cyclone-related precipitation, on which some coastal regions depend.
References:
Tilmes et al., 2018: https://journals.ametsoc.org/view/journals/bams/99/11/bams-d-17-0267.1.xml
De Jong et al., 2025: https://gmd.copernicus.org/articles/18/8679/2025/
How to cite: Wieners, C., de Jong, J., and Baatsen, M.: Impact of SAI on tropical cyclones in a high-resolution simulation, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-8382, https://doi.org/10.5194/egusphere-egu26-8382, 2026.
