The Solar radiation management and evaporative heat flux over West Africa

Abstract

This study investigates how Solar Radiation Management (SRM), particularly through Stratospheric Aerosol Injection (SAI), influences evaporative heat flux—also referred to as latent heat flux (LE)—across West Africa. The region is highly sensitive to climate change due to its dependence on rain-fed agriculture, limited water resources, and frequent heat stress events. Understanding how geoengineering could affect surface energy and moisture exchange is therefore essential for future climate planning. We use a combination of datasets and climate modeling frameworks, including ERA5 reanalysis, CMIP6 simulations under two Shared Socioeconomic Pathways (SSP245 and SSP585), and results from the ARISE-SAI geoengineering experiments. The analysis covers four time periods: pre-industrial baseline, present conditions, near-future projections, and far-future projections. Across all datasets, a distinct latitudinal gradient in LE emerges: higher latent heat flux values occur in coastal, vegetation-rich areas, while significantly lower values characterize the drier Sahel. This pattern highlights the central role of surface moisture availability and land cover in determining evaporative heat flux. Under the high-emission SSP585 scenario, regional warming alters energy partitioning at the land surface, intensifying evaporative stress and increasing the likelihood of drought and agricultural losses. In contrast, SAI reduces warming, decreases extreme evaporative losses, and shifts LE values closer to those of the pre-industrial period. Cooling effects are strongest in humid coastal zones, where enhanced moisture availability supports a more pronounced response. Overall, the study suggests that SRM—if carefully managed and supported by emission reductions—could help reduce climate-related water and food insecurity in West Africa by stabilizing evaporative processes and moderating extreme heat conditions.