Rising temperatures caused by climate change increase the odds that corn and wheat yields will slow even as global demand for the crops for food and fuel increases in the next 10 to 20 years, according to a study published in Environmental Research Letters.
There is as much as a 10 percent chance the rate of corn yields will slow and a 5 percent probability for wheat because of human-caused climate change, said David Lobell, the associate director of the Center on Food Security and the Environment at Stanford University, and Claudia Tebaldi, a scientist at the National Center for Atmospheric Research in Boulder, Colorado.
When anthropogenic climate change is removed from the equation, the chance crop yield growth will slow falls to about one in 200, according to a statement from the center in Boulder, Colorado.
"Climate change has substantially increased the prospect that crop production will fail to keep up with rising demand in the next 20 years," Tebaldi said in the statement. The grains are used as food and fuel.
In the past, improvements in yields per acre have helped the world keep pace with rising demand, the authors said in the paper. Anything that affects the rate of growth while population and demand swells could frustrate attempts to keep up with need and lead to global unrest.
Yields for both crops are expected to rise by 13 percent per decade through 2030, according to the United Nations’ Food and Agriculture Organization.
Lobell and Tebaldi set out to see if rising global temperatures could cut the rate of growth for corn and wheat by 10 percent in the next 20 years. Such a scenario would cut the U.N. growth estimate by almost 50 percent.
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A rise in global temperatures of 1 degree Celsius (1.8 degrees Fahrenheit) would slow the rate of growth for corn by 7 percent and wheat by about 6 percent. Corn is most vulnerable because the areas in which it is grown tend to be concentrated and therefore more susceptible to change.
"I am often asked whether climate change will threaten food supply, as if it’s a simple yes or no answer," Lobell said in a statement. "The truth is that over a 10- or 20-year period, it depends on how fast the Earth warms, and we can’t predict the pace of warming very precisely. So the best we can do is try to determine the odds."
Lobell and Tebaldi said they didn’t consider what would happen if cultivation of the crops shifted geographically in reaction to higher temperatures.
"Shifts in production to different regions, such as cool high-latitude locations where growing-season temperatures are lower, could moderate the chances of yield losses, although studies of such shifts indicate they are not occurring fast enough to significantly alter the global pattern of maize or wheat production," the authors wrote.
For instance, corn-growing areas of North Dakota and South Dakota have increased 50 percent since 2000, although the yield is still less than 10 percent of U.S. output.
The National Center for Atmospheric Research is funded by the U.S. government and managed by a consortium of more than 100 universities.