A statistical examination of the effects of stratospheric sulfate geoengineering on tropical storm genesis

Abstract

Abstract. The thermodynamics of the ocean and atmosphere partly determine variability in tropical cyclone (TC) number and intensity and are readily accessible from climate model output, but an accurate description of TC variability requires much higher spatial and temporal resolution than the models used in the GeoMIP (Geoengineering Model Intercomparison Project) experiments provide. The genesis potential index (GPI) and ventilation index (VI) are combinations of dynamic and thermodynamic variables that provide proxies for TC activity under different climate states. Here we use five CMIP5 models that have run the RCP4.5 experiment and the GeoMIP stratospheric aerosol injection (SAI) G4 experiment to calculate the two TC indices over the 2020 to 2069 period across the six ocean basins that generate TCs. GPI is consistently and significantly lower under G4 than RCP4.5 in five out of six ocean basins, but it increases under G4 in the South Pacific. The models project potential intensity and relative humidity to be the dominant variables affecting GPI. Changes in vertical wind shear are significant, but it is correlated with relative humidity, though with different relations across both models and ocean basins. We find that tropopause temperature is not a useful addition to sea surface temperature (SST) in projecting TC genesis, perhaps because the earth system models (ESMs) vary in their simulation of the various upper-tropospheric changes induced by the aerosol injection.

Seasonal Injection Strategies for Stratospheric Aerosol Geoengineering

“…Until recently most simulations considered equatorial injections (see, e.g., GeoMIP; e.g., Kravitz et al, ; Kravitz et al, ). This results in strong confinement of the injected aerosols in the tropics, resulting in overcooling the tropics relative to the poles [Kravitz et al, ], which also impacts meridional temperature gradients and hence storm tracks [Wang et al, ]. Furthermore, the tropical stratospheric heating due to the high tropical aerosol burden could modify the quasi‐biennial oscillation (QBO; Aquila et al, ; Richter et al, ).…”

Halving warming with idealized solar geoengineering moderates key climate hazards

“…Finally, we examined the global intensity of tropical cyclones, including hurricanes and typhoons; directly simulating tropical cyclone response to solar geoengineering in a global model for the first time 29,30 . 2xCO2 increases the sum of the power dissipation index over all tropical cyclones in HiFLOR by 17.6% compared to the control.…”

Parametric Insurance for Solar Geoengineering: Insights from the Pacific Catastrophe Risk Assessment and Financing Initiative

“…Multiple climate modeling studies show that SG would slow the rate of sea level rise (Irvine et al, 2016). Finally, and perhaps most importantly, several studies show that SG can reduce tropical cyclone intensity (Irvine et al, 2019;Wang et al, 2018).…”