This story originally appeared on Atlas Obscura and is part of the Climate Desk collaboration.

Corn farmers in Eastern Nebraska have long claimed weather patterns are changing, but in an unexpected way.

“It’s something I’ve talked about with my dad and grandad many times,” says fifth-generation corn farmer Brandon Hunnicutt. Along with his father and brother, the 45-year-old lives in the 400-person village of Giltner and grows about 2,000 acres of corn each year. From above, the area looks like a blip of homes surrounded by an expansive grid of circular fields. Though Brandon’s grandfather is retired, he takes an active interest in the business. “Contrary to what you’d think should be happening, both him and my dad swear up and down [that] droughts used to come more often and be a lot worse,” says Hunnicutt. “Considering it’s been 30 years since we had a really bad one, I’ve started kind of taking them at their word.”

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This is not the only noticeable development—University of Nebraska climatologists say the growing season has gotten 10-14 days longer since 1980. Hunnicutt now waits until the first weeks of November to pilot his 40-foot-wide, dump-truck-sized combine through the farm’s widely arching, seemingly endless rows of corn—enough to cover 800 city blocks.

Though subtle, the Hunnicutts have noticed these changes and more.

“To be successful in this business, you’ve got to pay close attention to the weather,” explains Brandon. In the past 20 years, on top of the above, he’s noted a gradual decrease in 100-degree days during the summer. “That missing digit isn’t something you overlook,” he asserts with a laugh. “High temperatures create a lot of anxiety. If they go on long enough, they’ll scorch your corn and put a hurtin’ on your bottom line!”

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.

“We studied data from the past 30 years and 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,” says former MIT researcher Ross E. Alter, now a research meteorologist with the U.S. Army Corps of Engineers. Alter was the lead author of a 2018 report published in the journal of the American Geophysical Union that demonstrated how land use has impacted the region’s climate more than greenhouse gas emissions. “What makes these findings so fascinating is that, while global temperatures have risen, areas like eastern Nebraska have actually cooled,” continues Alter, referring to yearly averages. “We think it’s likely heavy agriculture counteracted rising summer temperatures that might have otherwise resulted from increasing greenhouse gases.”

In other words, the man-made shift has been helpful. By increasing yields, farmers have unintentionally created weather patterns that seem to be protecting their crops and helping them grow more corn. (Of course, burning fossil fuels to plant, cultivate, harvest, process, and ship farm products has been shown to be a major contributor to rising levels of greenhouse gases.)

Though similar effects have to some degree been observed in the rice-growing regions of eastern China, the report marks the first time the effects of agriculture on regional climate change in the central U.S. have undergone comprehensive analysis. The findings document the most significant man-made regional climate shift in world history.