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

Abstract

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 CO2 induced 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%).