Multi-model projections of trade-offs between irrigated and rainfed maize yields under changing climate and future emission scenarios

Abstract Eighteen global circulation models (GCMs) were evaluated to determine the potential impacts of future climate change on irrigated and rainfed maize yields using the FAO AquaCrop model on an inter-annual and decadal basis (2020 s until 2090 s). Prior to deemed fit for future simulations, AquaCrop model was subject to comprehensive calibration and validation using extensive field-measured long-term datasets. We observed declines in (decadal) rainfed maize yields, ranging from 2.2% (0.2 t/ha) to 17% (1.4 t/ha) and from 8.1% (0.6 t/ha) to 21.5% (1.7 t/ha) under Representative Concentration Pathways (RCPs) RCP 4.5 and RCP 8.5, respectively. The range of declines was lower for irrigated yields [3.7% (0.5 t/ha) to 6.7% (1.0 t/ha) and 4.3% (0.6 t/ha) to 15.6% (2.2 t/ha) under RCP 4.5 and RCP 8.5, respectively]. Near maximal yield declines were distributed uniformly across the century and almost all decades exhibited > 10% yield declines under at least one emission scenario. Both economic (grain yield) advantage associated with irrigation (difference in irrigated and rainfed yields) and yield stabilizing benefit of irrigation (difference in rainfed and irrigated yield variability) are projected to decrease significantly (p