The predicted climate change threatens food security in the coming years in Algeria. So, this study aims to assess the impact of future climate change on a key crop in Algeria which is rainfed durum wheat. We investigate the impact of climate change on rainfed durum wheat cultivar called Mexicali using AquaCrop crop model and the EURO-CORDEX climate projections downscaled with the ICHEC_KNMI model under RCP 4.5 and RCP 8.5. A delta method was applied to correct the incertitudes present in the raw climate projections of two experimental sites located in Sétif and Bordj Bou Arreridj (BBA)’s Eastern High plains of Algeria (EHPs). AquaCrop was validated with a good precision (RMSE = 0.41 tha−1) to simulate Mexicali cultivar yields. In 2035–2064, it is expected at both sites: an average wheat grain yield enhances of +49% and +105% under RCP 4.5 and RCP 8.5, respectively, compared to the average yield of the baseline period (1981–2010), estimated at 29 qha−1. In both sites, in 2035–2064, under RCP 4.5 and RCP 8.5, the CO2 concentrations elevation has a fertilizing effect on rainfed wheat yield. This effect compensates for the negative impacts induced by the temperatures increase and decline in precipitation and net solar radiation. An increase in wheat water productivity is predicted under both RCPs scenarios. That is due to the water loss drop induced by the shortening of the wheat-growing cycle length by the effect of temperatures increase. In 2035–2064, early sowing in mid-September and October will lead to wheat yields improvement, as it will allow the wheat plant to benefit from the precipitations increase through the fall season. Thus, this early sowing will ensure a well vegetative development and will allow the wheat’s flowering and grain filling before the spring warming period.

Maintaining sustainability in rainfed wheat production under changing climate is a grave concern for food security in Algeria. This study aims to assess the impact of future climate change on rainfed wheat yield in the semiarid Eastern High Plains (Setif and Bordj Bou Arreridj (BBA)) in Algeria using AquaCrop model. For this purpose, the EURO-CORDEX climate projections by 2035-2064 and 2065-2094 were downscaled using ICHEC_KNMI model under two representative concentration pathway (RCP) scenarios RCP 4.5 and RCP 8.5. The crop model predicted wheat yield increase by 82-95% and 77-118% at Setif and by 8-16% and 133-135% at BBA under the RCP 4.5 (2035-64 and 2065-94) and RCP 8.5 (2035-64 and 2065-94) scenarios, respectively, compared to the yield of the baseline period of 1981-2010. Future yield improvement is due to the fertilizing effect of the elevated carbon dioxide (CO 2 ) concentration in the atmosphere, which offsets the negative impacts of rising temperature, decreasing precipitations and the net solar radiation. The expected increase in yield is much higher under RCP 8.5 compared to RCP 4.5 because CO 2 concentration is higher under RCP 8.5. The model predicted an increase in wheat water productivity because of the expected decrease in evapotranspiration losses. To adapt rainfed wheat to future climate change in the study area, early sowing in mid-October provides better yields because it allows the wheat crop to take more benefits from increased precipitation during the vegetative development stage and to avoid the spring warming temperature.