Summary
The study uses the ARISE‑SAI‑1.5 dataset to assess how stratospheric aerosol injection (SAI) would affect precipitation extremes across Africa under SSP2‑4.5. SAI reduces extreme rainfall intensity and frequency—especially in East, Central and Southern Africa—while moderately increasing rainfall in parts of West Africa. Heavy‑rain indices (RX1D, RX5D, R95p, N95) weaken, and dry spells lengthen in some southern regions, indicating mixed benefits and risks. Overall, SAI redistributes, rather than uniformly reduces, hydroclimatic extremes.
Abstract
Stratospheric aerosol injection (SAI) is a proposed climate intervention method aimed at mitigating some of the impacts of anthropogenic global warming by enhancing the atmosphere’s reflectivity, thus reducing solar radiation reaching the Earth’s surface. While SAI’s extreme temperature-reducing effects are well-established, its impact on precipitation extremes remains uncertain, especially in Africa, a region highly vulnerable to climate change. Understanding SAI’s potential effects on precipitation extremes is crucial, as it could increase or decrease variability in precipitation patterns, thereby affecting food security and ecosystems. Our findings indicate that areas projected under SSP2-4.5 to experience intense precipitation, such as parts of West and Central Africa, are projected to experience a reduction in both the frequency and intensity of precipitation, whereas drier areas are expected to receive increased precipitation under the SSP2-4.5 scenario with SAI. Also, the response to this SAI scenario varies considerably across different regions, displaying a high degree of heterogeneity across multiple precipitation extreme indices. These findings underscore the need to explore other scenarios of SAI and for further regional studies to understand SAI’s implications better and to inform climate-policy decisions.
