Combined and separate effects of future climate change and elevated atmospheric CO2 on maize growth and water consumption in the US Corn Belt.

BACKGROUND

The joint effects of climate change and rising atmospheric CO2 concentration ([CO2]) can alter maize phenology, yield, and water use, but the extent to which elevated [CO2] offsets climate-related impacts on C4 maize remains uncertain. This study quantified the combined and separate effects of future climate change and elevated [CO2] on irrigated maize growth and water consumption in the Southwestern Plain of the Great Lakes (SPG) - a region of the US Corn Belt. A validated Agricultural Production Systems sIMulator (APSIM) model was driven by three bias-corrected global climate models (GCMs) under Representative Concentration Pathways (RCPs) 4.5 and 8.5 for the near-future (2025-2049), mid-future (2050-2074), and far-future (2075-2099) periods. For each period, paired simulations were conducted using baseline [CO₂] (378 ppm) and period-specific elevated [CO₂] concentrations.

RESULTS

Maximum temperature increased more than minimum temperature during the growing season. Compared with RCP 4.5, RCP 8.5 resulted in a greater shortening of growing-season duration under warming (GSD-w), greater yield loss, and a greater increase in water footprint. Annual precipitation increased toward the far future under RCP 8.5, whereas growing-season precipitation showed a non-monotonic response and fell below the 1995-2014 baseline in the far future. Elevated [CO2] reduced average projected yield losses by 2.7 percentage points under RCP 4.5 and by 3.5 percentage points under RCP 8.5, while reducing water footprints by 12.1% under RCP 4.5 and by 19.3% under RCP 8.5. However, elevated [CO₂] offset GSD-w shortening by only 0.2 days under RCP 4.5 and 0.3 days under RCP 8.5.

CONCLUSION

Elevated [CO2] partially alleviated climate-related yield losses and increases in water footprint but did not offset the adverse effects of future warming, particularly under RCP 8.5. Adaptation strategies should combine region-specific water management with adjustments in sowing date and cultivar selection. © 2026 Society of Chemical Industry.