Projected Impact of Stratospheric Aerosol Injection on Rainfall dynamics over West Africa using ARISE Dataset.

Agricultural production is highly dependent on rainfall dynamics (onset, cessation, length of rainy season) in the West African region, whose livelihood and economy are highly dependent on rainfed agriculture. The impact of global warming has been shown to lead to reduction and variability in rainfall over the region. However, Stratospheric Aerosol Injection has been proposed as one of the potential strategies to cool down and limit future global warming to 1.5ºC by injecting aerosol into the stratosphere. Nevertheless, how this strategy may affect rainfall onset and cessation and drought response to SAI, notably across the agroecological zone of West Africa, remains unclear. The present study examines the impact of global warming and Stratospheric Aerosol Injection (SAI) rainfall onset, cessation and drought regimes over West Africa. In the study we examined the potential impact of climate change and SAI on the onset and cessation of rainfall and drought regimes over West Africa using TAMSAT observation dataset and ARISE dataset for SSP2-45 with and without aerosol injection. Our result showed that climate intervention may lead to an early onset and cessation over the coastal area of West Africa compared to TAMSAT but delayed (early) onset (cessation) in the savannah and Sahel zones. The results implied a shift in the rainfall duration may be expected over the coastal area, while a decrease in rainfall duration may be expected over the Savannah and Sahel zones. For the drought regime, our result revealed an increase in extremely wet periods may be expected relative to the observation across the three zones. On the other hand, a decrease in extremely dry periods may be expected over the coastal and savannah zones but an increase in the Sahel zone. This study will enhance our understanding of the impact of climate geoengineering on rainfall dynamics in West Africa and its effect on agricultural production and food security in the region.