An increase in atmospheric [CO2] from today's 372 to 550 μmol mol−1 would increase net leaf photosynthesis by 12–36%, while elevation to 700 μmol mol−1 would generate a stimulation of 18–63%, for a leaf temperature of 25 °C. The lower end of these ranges represents light-limited photosynthesis, while the greatest stimulation occurs under light-saturated conditions, when the amount of Rubisco is assumed to be limiting. Since crop canopies in the field gain their carbon in roughly equal quantities from light-limited and light-saturated photosynthesis, actual gains are likely to be in the middle of these ranges