Corn May Be More Vulnerable to Warming, Stanford Study Shows

Corn, the world’s second-most- widely grown grain, may be more vulnerable to global warming than previously thought, based on a study led by Stanford University that examined data from field trials.

The study found that a gain of 1 degree Celsius (1.8 degrees Fahrenheit) in temperatures would lower yields for 65 percent of Africa’s corn fields assuming optimal rainfall, Stanford said in an online statement. The same warming under drought conditions would cut corn yields for all of Africa, with declines of 20 percent or more in 75 percent of growing areas, the study showed.

“The pronounced effect of heat on maize was surprising because we assumed maize to be among the more heat-tolerant crops,” Marianne Banziger, co-author of the study and deputy head of research at the International Maize and Wheat Improvement Center, or Cimmyt, said in a statement.

Global food output will have to rise 70 percent between 2010 and 2050 as the world population swells to 9 billion people and rising incomes boost meat and dairy consumption, the United Nations estimates. Crop failures are likely to become more common this century as climate change causes more extreme weather, a study led by the U.K.’s University of Leeds has shown.

David Lobell, an assistant professor of environmental earth-system science at Stanford who led the study, linked the results of 20,000 field trials of corn in sub-Saharan Africa with weather data from across the region. The field data was gathered by El Batan, Mexico-based Cimmyt between 1999 and 2007 as part of corn-improvement trials.

Length of Exposure

The study, to be published in the journal Nature Climate Change, found that the longer corn is exposed to temperatures above 30 degrees Celsius (86 degrees Fahrenheit), the more yields decline, according to Banziger.

“The effect is even larger if drought and heat come together, which is expected to happen more frequently with climate change in Africa, Asia or Central America,” she said. That poses an “added challenge” to meeting growing demand for staple crops, Banziger said.

Wheat is the world’s most widely grown grain, followed by corn and rice, according to data from the U.S. Department of Agriculture.