Potential effects of stratospheric aerosol injection on the mean and extreme climate of South America

Abstract This study assesses the potential climate effects of stratospheric aerosol injection (SAI) across South America using simulations from the Geoengineering Large Ensemble. We analyze and compare projected changes in mean and extreme temperature and precipitation under a high radiative forcing scenario (RCP8.5), with and without SAI, for 2021–2050 and 2051–2080. Results indicate that SAI would substantially reduce warming, particularly in extreme temperatures. Without SAI, maximum and minimum temperatures in the South American monsoon (SAM) and southeastern South America (SES) regions are projected to increase by over 4 °C by 2051–2080. However, with SAI these increases are limited to below 1 °C with some regions like SAM, SES, and parts of northern and southeastern South America potentially experiencing negative temperature changes. Precipitation responses under SAI simulations show an overall reduction in the magnitude of the projected changes in mean and extreme precipitation compared to the high-forcing scenario without SAI. The mean and wettest precipitation changes in SES may be reduced, whereas the drought duration in northeastern South America and NSA could be shortened. In addition, SAI could alleviate persistent drought conditions in southwestern South America (SWS). The compensation and eventual reversal in SWS are explained by slight increases in precipitation during the cold season March–April–May. While SAI could reduce climate extremes in South America, its uneven effects introduce uncertainties and raise the need for further research.