Effect of elevated CO₂ concentration and increased temperature on physiology and production of crops

Increasing concentration of global atmospheric CO₂ and temperature are the two most important factors in the national list of the impact of climate change on crop yield. This brief summary focused on research advances on the impact of increasing CO₂ and temperature on crop photosynthesis, respiration, transpiration, yield, quality, etc. The review shows that increasing CO₂ increases the rates of photosynthesis and transpiration, but decreases respiration rate and stomatal conductance. Though crop quality decreases with increasing yield, there is no general research consensus on this trend. C3 and C4 crops’ response to variations in CO₂ concentration is inconsistent, with short- and long-term effects on photosynthetic pathways. It is generally conceived that atmospheric temperature increase inhibits crop photosynthesis, reducing crop yield. Most of the existing reports on the response of crop yield to climate change focus on crop modeling or simulation experiment. Research also shows discrepant model/simulation results. There are also discrepant yield assessment results from different scholars. Some recent studies suggest that rising temperatures have a nonlinear effect on crop yield. Crop yield declines rapidly when temperatures exceed threshold values. As most of the simulation experiments are conducted in gas chambers (which are quite different from real-world conditions), their conclusions require further validation. The crop model results generally lack verifications by experiment.