Multi-model assessment of future drought risk over West Africa using NASA NEX-GDDP CMIP6 simulation

Résumé

Abstract West Africa experiences significant climatic variability, with temperature and precipitation patterns strongly influencing the region’s environmental and socioeconomic systems. This study evaluates the performance of ten NASA NEX-GDDP climate models in simulating historical temperature and precipitation across West Africa and examines projected drought under moderate (SSP2-4.5) and high (SSP5-8.5) emission scenarios. Observed datasets from CHIRPS and CRU were used for model evaluation using statistical metrics such as correlation coefficient, centered root mean square error, mean bias error, and Taylor diagrams. Results indicate that the models show high spatial agreement with observed data ( r > 0.9), capturing the general spatial distribution and variability of temperature and precipitation. Simulation performance was generally better for temperature ( r = 0.95–0.97) than for precipitation ( r = 0.91–0.97), a pattern that is physically consistent with the greater spatial coherence of temperature fields relative to convective precipitation, although precipitation is slightly underestimated and temperatures are marginally overestimated. A persistent divergence between SPI and SPEI trends across all timescales indicates that rising evaporative demand has already been moderating effective moisture gains during this period. Future projections reveal a consistent north-south climatic gradient. Under SSP2-4.5, mild to moderate drought conditions are projected over the Sahel, while relatively wetter conditions persist along the Guinea Coast. Under SSP5-8.5, this contrast intensifies, with increased drought severity in the Sahel and a shift toward near-normal to moderately dry conditions in parts of the Guinea Coast when evapotranspiration effects are considered. Overall, the multi-model ensemble provides consistent indications of increasing aridity in northern West Africa and growing water stress influenced by rising temperatures, highlighting potential implications for water resources and climate adaptation planning in the region.

Citer ce document

Accès au document

Texte intégral en lecture en ligne, réservé aux abonnés SPHAERO et aux membres de l'institution. Se connecter

Auteur(s)

Statistiques

Consultations : 1

Téléchargements : 0