Climate change and the future of winter wheat in Iran: Insights for food and water security

Ensuring food security in drylands requires a comprehensive understanding of climate change (CC) impacts on staple crops and agricultural water demands. This study assessed CC impacts on winter wheat yield and water use across Iran using the DSSAT-NWheat model executed within a continuous, spatially explicit 0.25°×0.25° gridded framework. The modeling integrated downscaled NEX-GDDP-CMIP6 climate projections, SoilGrids inputs, and the Global Irrigation Mapping Dataset refined with regional cultivation statistics. Under the SSP245 and SSP585 scenarios, mid- and late-century projections showed an overall increase in irrigated (5.1–17.7%) and rainfed (14.1–60.9%) wheat yields relative to the baseline, with decreases in irrigated consumptive water use (4.1–18.2%) and irrigation water consumption (12.9–33.1%). Yield gains are likely related to the combination of climate shifts and elevated CO₂. Irrigated wheat yields in southern Iran will decline, particularly under SSP585, as already short growing seasons are further shortened by extreme temperatures. While CC would likely decrease irrigation water use, rainfed water use will increase marginally due to higher precipitation and evapotranspiration. Water productivity would likely rise in most regions. Uncertainty analysis indicates a low GCM-driven spread for yield and water use, except under rainfed conditions in the late-century SSP585 scenario. Despite improved production, the national self-sufficiency ratio was projected to decline by 12.1–14.6% by mid-century and 2.5–8.1% by late-century under the assumptions of fixed cultivated area and constant per capita wheat demand, indicating that yield gains alone are insufficient to secure future food supplies. Therefore, integrated multi-scale adaptation strategies targeting both agricultural resilience and demand management are recommended.