Analysis of the Climatic Impacts of SO2 Injection into the Stratosphere on Precipitation Indices in the Sahel

Stratospheric Aerosol Injection (SAI) emerges as a geoengineering strategy to mitigate global warming by reflecting sunlight back into space. However, this approach raises significant concerns, particularly regarding its impact on rainfall characteristics in the Sahel. This study investigates the effects of injecting sulfur dioxide (SO2) into the stratosphere using the IPSL-CM5A-LR climate model, under two forcing scenarios: RCP4.5 (Representative Concentration Pathway of 4.5 W m–²) and a combination of RCP4.5 with geoengineering forcing (G3). The analysis focuses on future climate conditions in the Sahel, based on 30-year averages over two distinct periods: 2020–2050 and 2050–2080. The results highlight notable differences between the “with injection” and “without injection” scenarios. The number of consecutive wet days (CWD) increases with SO2 injection, indicating prolonged rainfall periods. Annual total precipitation on wet days (PRCPTOT) exhibits a slight upward trend with SO2 injection, potentially mitigating drought effects. Conversely, maximum daily precipitation (Rx1day) and five-day precipitation (Rx5day) are slightly higher in the absence of injection, suggesting a reduction in extreme precipitation intensity when SO2 is introduced. The Simple Daily Intensity Index (SDII) shows moderate variations between scenarios, with a slight decrease observed under SO2 injection. These findings indicate that SO2 injection could help stabilize precipitation regimes and reduce climate extremes in the Sahel. However, further research is crucial to gaining a deeper understanding of the long-term implications of this method and optimizing its application.