27 September 2023

This is how climate change will alter U.S. agriculture

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Climate change is set to impact agricultural yields in the U.S. Midwest, a study by the University of Connecticut says. “Data suggest a 12 percent decrease in corn yields by around 2050 and 40 percent by the end of the century”

by Matteo Cavallito

 

The Corn Belt, the most productive agricultural region in the United States, is set to face significant shifts due to climate change. This is reported in research by the University of Connecticut‘s Center for Environmental Science and Engineering. The area, the study published in the journal Agricultural Systems points out, is home to most of the country’s corn and soybean production.

Here, in the heart of the U.S. Midwest, “If you look at the long-term trend, yield has grown continuously, except for years with extreme events such as flood or drought,” explains Guiling Wang, one of the researchers involved, in a note released by the U.S. university. “In the U.S. and elsewhere, this trend of increasing yield is because of technology, irrigation, and improved seed lines for example. The trend will be different in the future as climate changes.”

The research

The authors used a model called Decision Support System for Agrotechnology Transfer to simulate the response of different crop physiological processes to certain variables. These include the amount of sunlight, rainfall, temperature and moisture. This makes it possible to determine the yield at the end of the growing season for each crop. Simultaneously, simulations were conducted taking into account past temperatures and assuming future ones.

“The multi-model ensemble mean suggests a 12% decrease of maize yield by mid-century and 40% by late century, with a high degree of model consensus in the direction of changes,” the research states.

Moreover, “For individual models, the projected decrease of maize yield by late century ranges from <5% to over 80%, with the worst crop outcome corresponding to the most sensitive climate models. Soybean yield is projected to increase by midcentury with a high degree of model consensus, but such consensus is lost by late century as some projections shift to significant decreases.”

Heat and drought are the critical factors

Historically, Wang recalled, the Corn Belt has experienced the lowest yields in years characterized by the simultaneous presence of two phenomena: heat waves and drought. However, these factors tend to overlap and reinforce each other. Which makes it difficult to attribute crop yield loss to water stress or heat stress on the basis of statistical analysis. The model used, however, allows the factors to be disaggregated, thus helping researchers to draw more accurate conclusions.

“Crop yield in the Corn Belt is currently limited by water stress, but is projected to be increasingly limited by heat stress as well after the midcentury,” the study points out.

“The mounting heat stress will drive the most productive zone for maize to shift from central to northern part of the Corn Belt, but the projected increase in the northern states cannot fully compensate for the decrease in the south, causing the total production to decrease if agricultural practice stays the same.” Climate change, in short, will require new strategies.

New responses to climate change

Faced with a general rise in temperatures, researchers explain, it will first be necessary to select more heat-resistant crops. “As climate changes, farmers will not sit back and let this happen,” Wang said. “For climate adaptation, heat-resistant crops will certainly help. Another strategy is to plant crops earlier.”

The researchers, in particular, simulated earlier planting and found that this strategy mitigates some of the negative impacts of climate change in some southern states. The positive effects, however, do not completely offset the loss of yield. Overall, the scientists conclude, the technology will continue to support yield increases in the near future. But the latter will be significantly slower than in the past.