Projected Agroclimatic Changes and the Vulnerability of Rain-fed Cereal Systems in North-eastern Senegal

Abstract In the Sahel region, rain-fed cereal production remains heavily dependent on climatic conditions, the future evolution of which raises major challenges for food security. This study assesses projected changes in agroclimatic conditions and the vulnerability of millet and sorghum cropping systems in five departments in north-eastern Senegal by 2050. Projections from a set of two CMIP6 models (CNRM-CM6-1 and MPI-ESM1-2-HR), calibrated using the Quantile Delta Mapping (QDM) method, were utilised under the SSP2-4.5 and SSP5-8.5 scenarios and compared with the 1981–2010 reference period. Agroclimatic indicators were calculated using CHIRPS and ERA5-Land data, and then correlated with departmental yields observed over the period 1981–2022. The results show a decrease in cumulative rainfall across all departments, reaching 17% in Podor under the SSP5-8.5 scenario, associated with a later onset and a shortening of the rainy season by 12 to 21 days. The projected warming, ranging from + 1.25°C to + 1.45°C depending on the scenario, is primarily reflected in an intensification of chronic heat stress linked to the mean temperature. The sensitivity analysis reveals that cumulative rainfall significantly explains yield variability in Kanel and Ranérou, but not in Podor, Matam and Linguère. A composite vulnerability index, combining exposure and agroclimatic sensitivity, identifies Podor as the most vulnerable department. These results highlight the need for region-specific adaptation strategies, based on agroclimatic indicators rather than on annual totals alone.