For every degree Celsius of increase in global mean temperature, yields are expected to decrease by 7 percent for corn, 6 percent for wheat, and 3 percent for rice. It is true that farmers have had to deal with wild weather for as long as humans have been putting seeds in the ground. But this is different. This is not about freaky hailstorms and random cold snaps. As Donald Ort, a professor of plant biology at the University of Illinois Urbana-Champaign, explained to me, “The largest single global change that threatens food security is high temperature.”
