Springtime cold air outbreaks (at least two consecutive days
during which the daily average surface air temperature is below 95 % of the simulated average wintertime surface air temperature) are projected to continue to occur throughout this century.19 As a result, increased productivity of some crops due to higher temperatures, longer
growing seasons, and elevated CO2 concentrations could be offset by increased freeze damage.20
Heat waves
during pollination of field crops such as corn and soybean also reduce yields (Figure 18.3).4 Wetter springs may reduce crop yields and profits, 21 especially if growers are forced to switch to late - planted, shorter -
season varieties.