Crop scientists have been pushing up corn yields for decades. But the newer strains just can't stand the heat
By Andrew Leonard
A troubling fact about corn: In the United States from 1940-1960, after the introduction of hybrid corn and in the wake of the disastrous Dust Bowl years of 1934 and 1936, corn yields and corn heat tolerance both grew. But since 1960, while yields have continued to grow as new hybrid and genetically modified varieties have been introduced, along with other agricultural innovations, heat tolerance has actually fallen.
Why is this significant? Because after a certain temperature, usually around 86 degrees Fahrenheit, corn yields drop dramatically. And even the most conservative mainstream climate scientist predictions about the effect of global warming include temperature rises that would hammer the corn-growing heartland of the United States.
These insights come from a fascinating new paper, "The Evolution of Heat Tolerance of Corn: Implications for Climate Change" by North Carolina State University's Michael J. Roberts, a professor of Agricultural and Resource Economics, and Wolfram Schlenker, an economist at Columbia University. The researchers take advantage of a 100 years of incredibly detailed information on corn yields and temperature records in Indiana, the third-largest corn-growing state in the U.S.
