Future projections of aridity change across Africa's climatic regions

This study investigates future spatiotemporal shifts in aridity across Africa's nine climatic zones using two established metrics: the UNEP Aridity Index (UNEP-AI) and the De Martonne Index (DMI). The analysis draws on high-resolution precipitation and temperature outputs from 16 NEX-GDDP-CMIP6 models, complemented by observational data from the Climatic Research Unit (CRU). Projected changes for the period 2024–2100 were evaluated under two emissions scenarios (SSP2–4.5 and SSP5–8.5). Bias correction was conducted using the Delta method, while potential evapotranspiration (PET) was estimated via the Hargreaves approach. Results indicate a pronounced intensification of aridity across the continent, with the Mediterranean (MED), Central Africa (CAF), West Southern Africa (WSAF), East Southern Africa (ESAF), and West Africa (WAF) zones exhibiting the strongest drying tendencies. In the Sahara (SAH), a northward displacement of aridity classes is projected, where some hyper-arid zones shift toward less extreme classifications due to marginal precipitation increases. Although certain regions, including NEAF and SEAF, show indications of potential reduction in aridity, others, particularly the MED zone are projected to experience substantial worsening of dry conditions, especially under SSP5–8.5. This study advances earlier continental-scale assessments by providing refined, region-specific projections consistent with the IPCC AR6 climatic-zone framework. The findings underscore the urgent need for targeted adaptation strategies that account for regional climatic drivers and emphasize the importance of integrating socioeconomic dimensions into future aridity and vulnerability assessments.