<p>Modeling climate change impacts is vital for agricultural and water resource planning. This study assessed climate change effects on yields of irrigated potatoes and tomatoes and rainfed barley in Jordan’s Mediterranean highlands and evaluated implications for water productivity. Using ground data on soil, crop management, and downscaled climate projections, AquaCrop model simulated future yields under RCP4.5 and RCP8.5 scenarios, both indicating higher temperatures and reduced rainfall. Model validation showed relative root mean square error (RRMSE) values of 10% for tomatoes, 22% for rainfed barley, and up to 25% for potatoes; yield simulations for irrigated tomatoes and rainfed barley were highly accurate, though potato yields were underestimated. Projections revealed that future yields increased, particularly for potato and barley and more moderately for tomato. However, water requirements increased, reaching up to 46% for potatoes under RCP8.5, and rainfed barley remained highly variable with potential failure years, especially when warming exceeds ~ 2&#xa0;°C. Late tomato showed the highest water productivity and improved most under RCP4.5, whereas water productivity under RCP8.5 was consistently lower for both tomato plantings, indicating that higher evaporative demand can offset yield gains per unit water under high emissions. Potato exhibited the lowest water productivity and only modest changes over time, reinforcing a strong water penalty despite yield gains. Overall, the findings show that yield benefits under elevated CO₂ may come with increased water demand and reduced water-use efficiency under RCP8.5</p>