Sensitivity of tropical monsoon precipitation to the latitude of stratospheric aerosol injections

Climate intervention through deliberate injection of sulfate aerosols into the stratosphere is one of the proposed solar radiation modification options to counteract some of the adverse effects of climate change. Although this approach can offset global mean temperature change, several studies have shown that there will be large residual and overcompensating regional changes. In this study, we estimate the impact of varying the latitudinal position of aerosol injection on the global monsoon precipitation in the RCP8.5 scenario by analyzing single point injection simulations from CESM1 where 12 teragram (Tg) of sulfur dioxide (SO 2 ) are injected each year into the stratosphere at latitudes 30° S, 15° S, equator, 15° N, and 30° N. During the period 2043–2049, relative to RCP8.5, the hemispheric mean summer monsoon precipitation decreases in the hemisphere where aerosols are injected but increases in the opposite hemisphere. The hemispheric mean monsoon precipitation changes by up to ± 10% depending on the injection location. The changes in precipitation are linked to the changes in interhemispheric temperature difference and shifts in the intertropical convergence zone. The summer monsoon precipitation over India decreases by about 21% for 15° N and 29% for 30° N injections. Thus, adverse effects are likely for regions such as India when aerosols are injected at 15° N, though injection at 15° N has been shown to be more efficient in cooling the global climate in a recent study. Our study highlights the likelihood of climate interventions leading to large regional disruptions while attempting to keep the global mean climate within a safe limit.