Key message:
Increased CO2 concentrations: CO2 fertilization can enhance production, but only if water and nutrients are not limiting. C3 plants (soy, wheat) respond more strongly than C4 plants (corn)
Warmer temperatures: Warmer temperatures can increase productivity, however, there is an optimum temperature for reproductive growth. Higher temperatures increase plant water use and could cause water to become limited.
Greater weather variability: unpredictable events such as late spring frosts, or excessive rain events or droughts can harm crops. Intense extremes (very warm years, very cold nights, downpours, or droughts) can be more harmful to agricultural productivity than a small change in mean temperature or precipitation.
Crops more vulnerable to pests: insect abundances increase with temperature and plant pathogens are responsive to increased rain. Invasive weeds, insects, and pathogens are able to migrate farther north.
Longer growing season: Allows for more flexibility in the management of crops, reduces risk of early frost and allows the growth of longer-season varieties, or several harvests in some regions
More precipitation: Increased rainfall can be beneficial during the growing season but heavy downpours can cause damage to crops, N loss, erosion, and other fertility problems.