Corn field with blue sky

Growing Corn Is Changing The Climate

Excerpted from: Americans have planted so much corn that it’s changing the weather

Some corn farmers with large acreage have reported that droughts seem to come less often and be less severe. Also, there appears to be fewer days with temperatures over 100 degrees — high temperatures can create anxiety.

This is not the only noticeable development — University of Nebraska climatologists say the growing season has gotten 10-14 days longer since 1980.

Data from the past 30 years has found that the intensification of corn production has increased average summer rainfalls by about 35 percent and decreased average summer temperatures by as much as one degree Celsius.

2018 MIT Climate Report

A 2018 report issued by climate researchers at the Massachusetts Institute of Technology claims to have solved the mystery and verified farmers’ suspicions: Namely, that large-scale corn production has changed the weather.

Over the past 70 years, farmers in America’s midwestern Corn Belt have made vast leaps in production. From 1950 to 2010, annual harvests increased by more than 400 percent, jumping from 2 billion to 10 billion bushels. In addition to making the area the world’s most productive agricultural region, climate scientists at MIT say the boom has created its own weather patterns.

Data from the past 30 years has found that the intensification of corn production has increased average summer rainfalls by about 35 percent and decreased average summer temperatures by as much as one degree Celsius. What makes these findings so fascinating is that, while global temperatures have risen, areas like eastern Nebraska have actually cooled. Scientists believe that it’s likely that heavy agriculture counteracted rising summer temperatures that might have otherwise resulted from increasing greenhouse gases.

By comparing observed historical trends in the Corn Belt’s climate to those predicted by a variety of global simulations used by the World Climate Research Program (WCRP), which coordinates climate research sponsored by various international organizations, the report showed the models were inaccurate for the region (they predicted summer temperatures would rise and rainfall would increase by just four percent). Though the WCRP models accounted for greenhouse gas emissions and other human and natural factors, they did not consider agricultural intensification.

More corn means more transpiration which, in turn, produces slightly cooler temperatures and increased precipitation. The fact that corn is a non-native species boosts the effect.

Corn Sweat — Large-scale Corn Production

Corn sweat graphic On one hand, it has to do with what Hunnicutt and other farmers refer to as corn sweat. This happens when photosynthesis boosts the amount of water vapor in the air. When a plant’s pores, called stomata, open to allow carbon dioxide to enter, they simultaneously allow water to escape. Known as transpiration, the process cools the plant and surrounding air, and increases the amount of water going into the atmosphere and returning as rainfall.

Native Versus Non-Native Species

The predominant native vegetation in the mid-west. Farmers have replaced the area’s vast seas of grass with millions acres of corn, which transpires at a rate 20 percent higher than indigenous grasses. Agriculture is literally funneling moisture into the atmosphere, and all that humidity has created a kind of protective bubble against rising temperatures.

Increased In Corn Production

Growing more corn — and thus, creating more transpiration — would have been impossible without advances in farming efficiency. The introduction of high-yielding varieties, better irrigation, and soil management techniques, along with the ability to use computer sensors to closely monitor field conditions, have all contributed to soaring yields.

One of the biggest factors is the widespread use of cover crops, crop residue management, and no-till farming methods.

Together, the practices have erased the need for conventional tillage, dramatically increased organic matter in the soil, reduced evaporation and runoff, and lowered summer surface temperatures. With time, the native clay-based soil has become much healthier and better at retaining water. This has made crops more resilient to traumatic weather events and, in general, much more productive.

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