CO2 fertilization effects can fully offset the yield loss due to CO2 induced warming for major C3 crops

Rising atmospheric CO₂ can enhance global crop yield directly through the CO₂ fertilization effect (physiological effects, ), but can also reduce it indirectly through CO₂-induced warming (radiative effects, ). The overall consequences of the two opposing CO₂ effects have constituted large uncertainties in projecting future crop yields. Here, we first employ a site-level CO₂ elevation experiment dataset to constrain the simulated  effect in yield projections of an ensemble of global crop models for four major cereal crops (wheat, maize, rice and soybean). Under well-watered and well-fertilized conditions, the constrained estimates show that elevated CO₂ will increase yield of major C3 crops (spring/winter wheat, rice and soybean) by 16.7 ± 2.7% 100 ppm^-1, 9.4 ± 2.7% 100 ppm^-1, 11.2 ± 2.7% 100 ppm^-1, and 12.9 ± 2.4% 100 ppm^-1, respectively, while no significant yield gain was found for maize (1.6 ± 1.7% 100 ppm^-1). Then, by combining CO₂induced warming, crop yield response to warming and the interactive term of the physiological effects and radiative effects, we assess the integrated effects of increasing atmospheric CO₂ on crop yield at global scale. The results show that the same level of increase in atmospheric CO₂ tends to induce larger  than the yield loss by  for both wheat and rice. But for soybean and maize,  largely offsets , resulting in statistically not significant integrated effects of CO₂ for soybean (4.2 ± 15.8%) and maize (-3.0 ± 4.6%).