No matter which of the widely accepted global circulation models ultimately comes closest to predicting the amount of warming caused by climate change, corn production will be reduced, according to a new study by Pennsylvania State University (Penn State) researchers. They evaluated the potential impacts of 18 warming scenarios, dictated by various atmospheric greenhouse gas concentrations, to determine the potential effects of future climate change on irrigated and rainfed corn yields from the 2020s through the 2090s. Although the research was focused on the U.S. Great Plains—in the heart of the nation’s top corn-producing region—the results are believed to have global implications.
To estimate yields, researchers employed the Aqua Crop model—a crop-growth simulation developed by the Food and Agriculture Organization of the United Nations—to assess the effect of environment and management on crop production, predicting yield response to water. The study site is representative of agricultural management practices in the region and represents the most densely irrigated area in the Central Plains, which is a subregion of the Great Plains. Corn is susceptible to environmental factors such as increased air temperature, increased radiation, vapor pressure deficit and humidity change, according to lead researcher Suat Irmak, professor and head of the Department of Agricultural and Biological Engineering in the College of Agricultural Sciences. He and his team noted that irrigated yields will be impacted much less than rainfed yields.
“In our study, depending on the atmospheric greenhouse gas concentrations and associated level warming, we saw declines in rainfed corn yields ranging from 2.2% to 21.5%,” he said. “Under those same greenhouse gas concentrations, the range of declines was lower for irrigated yields—from 3.7% to 15.6%, due to irrigation technologies providing more stable crop growth conditions under water- and temperature-stress.”
Global climate is very likely to warm by 2.16-3.42 degrees Fahrenheit from now to 2040, according to the Intergovernmental Panel on Climate Change, Irmak explained. The global mean surface temperature was 1.78 degrees F higher during the period 2001–20 than during the pre-industrial period of 1850–1900, the United Nations panel found. In findings recently published in Agricultural Water Management, the researchers reported that, based on their modelling results, rainfed yields will decline up to 40 bushels per acre, whereas irrigated yields are projected to decline only 19 bushels per acre. Additionally, rainfed corn yield will be more variable than yields from irrigated corn under most of the global circulation m