Future Wheat Yield Variabilities and Water Footprints Based on the Yield Sensitivity to Past Climate Conditions

This article analyzed the wheat yield variabilities and water footprints under projected future climate based on wheat yield sensitivity to past (1980–2017) trends of maximum temperature (Tmax), minimum temperature (Tmin), solar radiation (Rn) and rainfall (P) for the semi-arid condition of Punjab, Pakistan. The past and projected future trends of the climate variables were identical featuring prominent Tmin rise than Tmax accompanied by Rn and P declines. Based on the past influences and the projected future trends of the climate variables, Tmin was the principal driver of wheat yield decline followed by the Tmax, P and Rn. Wheat evapotranspiration and net irrigation water requirement declined due to the influence of both decrease of growing season length and Rn for the first half of 21st-century, and this trend reversed during the second half of 21st-century. These phenomena were caused by different degree of climate warming between the two-time slices. Due to future wheat yield decline and a gradual rise in green water scarcity the blue and grey water footprints rise consistently particularly during 2nd-time slices. CO2 enrichment showed limited mitigation potential of nullifying the warming-induced threats on future wheat yield and water footprints.