Potential impacts of stratospheric aerosol injection on crop yields and related economic outcomes in Africa

Abstract Climate change poses a significant threat to crop production and food security in Africa, primarily by increasing dry areas across many regions. Stratospheric aerosol injection (SAI) could emerge as a potential cost-effective strategy to mitigate temperature-related impacts globally, but its implications for African agriculture remain underexplored. This study evaluates the effects of climate change and SAI on crop yields and economic outcomes across Africa. We assessed potential changes in maize, sorghum, and millet yields in future climate under the SSP2-4.5 scenario, without and with SAI intervention aimed at limiting global warming to 1.5 °C above the pre-industrial value. A process-based crop modelling system, Decision Support System for Agrotechnology Transfer (DSSAT), was forced with bias-corrected climate simulation datasets to perform a series of crop yield simulations over Africa for the study. SAI effectively and uniformly reduces warming over Africa, but it alters precipitation patterns in uneven ways. During the growing season, it offsets the climate change induced rainfall deficits in some parts of West Africa while enhancing them in Southern, East, and Central Africa. Under SSP2-4.5, maize and millet yields are projected to decline across most regions relative to the present-day levels. Sorghum shows mixed responses, with gains in parts of West and East Africa and losses elsewhere, particularly in the Sahel, Botswana, and South Africa. Compared with SSP2-4.5, SAI reduced these yield losses for maize and millet. For sorghum, it reduces the yield losses where the loss is greater than 10%. Despite reducing rainfall, SAI generally improves crop performance across the African regions, with the lowest improvement occurring in Southern Africa. Economically, all regions are projected to incur losses from declining yields under SSP2-4.5, but implementation of SAI offers partial relief, especially in West Africa, where losses are offset by approximately 73 million USD. At the national level, the greatest economical relief occurs in Nigeria, Mali, Benin, Niger, and Ghana. These findings underscore the potential of SAI to reduce climate-induced agricultural and economic risks in Africa, while highlighting regional disparities in its effectiveness. However, SAI is not a substitute for reduction of emissions or investments in adaptive capacity.