Climate change is hitting the United States’ corn and soybean belt on two fronts. Warming temperatures are both increasing evaporation of soil moisture in the region and causing weaker summer rainstorms that are dropping less precipitation in the Midwest during the growing season, according to new research by scientists at Columbia University’s Lamont Doherty Earth Observatory. The researchers said this trend will only get worse as global temperatures continue to rise.
The U.S. corn belt — which includes western Indiana, Illinois, Iowa, Missouri, eastern Nebraska, and eastern Kansas — accounts for more than a third of the global corn supply and is the world’s largest source of soybeans. The region typically gets most of its rainfall during summer months. But the new research, presented this month at the annual meeting of the American Geophysical Union, found that evaporation from soils and plants in the region is exceeding net rainfall during these months. In addition, summer storms — which are shaped by temperature differences between the poles and midlatitudes — are becoming weaker, leading to less precipitation.
As global temperatures increase, the atmosphere holds more moisture, explains a press release from Columbia University. This triggers a greater moisture difference between the Central Plains and the polar regions, “so the storms are trying harder to remove the moisture from the region, to smooth out the gradient,” said atmospheric scientist Mingfang Ting, who led the research. Ting and her colleagues’ work shows that this moisture is being transported away from the corn belt to higher latitudes, including northern regions of the Great Plains.
“Our results suggest that in the future, the U.S. Midwest corn belt will experience more hydrological stress,” Ting said in a statement.