On late-summer mornings for about two weeks every year — after sunrise but before it gets too hot to do much of anything — corn stalks all over Nebraska mate with themselves.

The tassels sprout anthers, which release pollen, which fall onto the sticky silks below, sometimes on the same plant. Two months later, give or take, and, voilà, a fully-grown corn cob is ready for harvest.

The process supports some 23,000 Nebraska farmers and provides about $7 billion annually to the state.

But, scientists say, climate change could take a big bite out of Nebraska’s corn business, threatening an economic engine for the state and an important food source for an ever-hungrier world.

“Corn pollination almost all takes place between 8 o’clock and 10 o’clock in the morning,” said Tom Hoegemeyer, a former University of Nebraska-Lincoln agronomy professor who has studied climate change’s effects on corn. “If it’s hot early in the day, that’s really negative.”

For Hoegemeyer, who is also a member of the Elders Climate Action group of former UNL scientists, “negative” means a drop-off in corn production of at least 20% when climate change really starts to pinch around mid-century.

Nebraska’s temperature rose by about 1 degree over the past century. Climate models predict a temperature increase of 4 to 9 degrees by 2100, depending on how well the world can control greenhouse gases.

According to the Fourth National Climate Assessment, a collaboration of 13 federal agencies, agricultural productivity in central and eastern Nebraska may fall by 50% toward the end of the century, although it would increase in the higher and cooler western half of the state.

Upsetting the pollination sequence is just one potential threat to Nebraska’s Cornhusker moniker.

Higher overnight lows in July’s critical growth weeks may also mean a less-robust crop. Longer and more frequent droughts would deplete moisture levels in the soil. Irrigation can help mitigate the damage, but surface and groundwater sources may not be quite so plentiful in a hotter, drier climate.

Heavier spring rainfall in the Midwest could lead to more soil erosion, another threat to yields. For example, in 2019, flooding took 421,958 acres out of production. By contrast, in 2018, only 25,048 acres were lost during a normal rainfall, according to a 2020 UNL agriculture report.

Corn was particularly hard-hit. The 2019 spring floods prevented 344,407 acres of cropland from being planted compared with a loss of only 18,956 acres in 2018.

If there is one group that can adapt to change, it’s farmers, who have a long history of managing all manner of threats: weather, pests, market shifts brought on by trade wars.

Billions of research dollars have led to insect-resistant plants, techniques for healthier soils and new crop rotation practices. According to the U.S. Department of Agriculture, farmers in the U.S. cultivated 330 million acres in 1910, supplying food and fiber for a population of slightly more than 92 million people.

By 2006, farmers plowed the same number of acres but produced enough crops for nearly 300 million. Nebraska farmers produced 26 bushels per acre in 1900. Today, they produce more than 180 bushels per acre.

Suat Irmak, a UNL engineering professor who has studied how climate changes affect agricultural productivity, said heat can have a “huge impact on crop growth and development.” For the last decade and a half, he said Nebraska has seen more extreme temperatures and precipitation events.

But he sees ways to mitigate the worst effects. A small amount of irrigation — an extra ¼ inch — can lower field temperatures by 7 to 10 degrees. No-till farming can also help keep soil cool. And genetics can create corn varieties that better withstand drought and high heat, Irmak said.

Corn itself is already remarkably adaptable. Hoegemeyer said there are tens of thousands of varieties. Corn has been grown on the outskirts of the Arctic Circle, from sea level to mountainous regions.

But a warming planet may bring tests of a different order.

“Climate change presents an unprecedented challenge to the adaptive capacity of U.S. agriculture,” a 2013 USDA report said.

Before he retired as head of the USDA’s National Laboratory for Agriculture and the Environment, Jerry Hatfield studied just what the effects could be.

Temperatures above 90 degrees can make pollen sterile, resulting in corn cobs that look like they badly lost a fight, only with missing kernels instead of missing teeth.

Hot, dry winds carry the same risk.

But it’s higher overnight lows that worry Hatfield the most. During the day, corn uses photosynthesis to create sugars. At night, the sugars spur cell growth. When nighttime temperatures are too high — above 50 degrees — the process is much less efficient. The stored energy gets wasted, and the plants don’t grow as well.

The UNL climate study reported that the number of high-degree temperature stress days — days over 90 degrees — will increase substantially by 2041-70.

“We think we have the capacity within adaptation to basically handle climate change scenarios until about 2050,” Hatfield said. “But then, as you look at the projections going forward, we may have to have some really innovative adaptation strategies to be able to cope without tremendous impacts on productivity.”

Tyler Williams, a UNL extension educator who focuses on climate issues, worries about how climate change will affect precipitation.

“In the No. 1 irrigated state for acres, we’re heavily dependent on groundwater and it’s not an infinite resource,” he said. “If we see a decrease in summer precipitation, or even the same precipitation with increased temperatures, we will put a strain on our groundwater and surface water resources.”

As snowpack levels decrease in the Rockies, another consequence of climate change, Nebraska rivers and streams that farmers also draw water from will drop as well.

For Andrea Basche, a UNL agronomy professor who specializes in climate adaptation, the concern is the variability of the rainfall. Heavier spring rains could keep farmers from getting in their fields. Because there aren’t crops to help hold the soil in place, spring rains lead to more erosion, stripping away the earth’s productive capacity.

Climate models and recent history both “point to more water in the winter, spring and fall and less in the summer, which is very bad for the crops we grow,” Basche said.

Another concern is an increase in the number of crop-destroying bugs. Climate change impacts the survival rate, geographical distribution, population size and other factors related to pests and diseases.

“If our winters get warmer, some pests who typically die in our cold winter may be able to survive,” Williams said.

They may also be hungrier. As temperatures warm, the metabolism of pests such as aphids and corn borers speeds up.

For Nebraska, an inability to adapt will lead to a severe economic hit. Nearly 46,000 farms and ranches contributed more than $21 billion to Nebraska’s economy in 2018. According to the Nebraska Department of Agriculture, 1 in 4 jobs in the state is related to agriculture.

The effects of bad crop years in the Midwest will likely ripple across the globe. The world’s population is expected to grow from 7 billion people in 2010 to nearly 9.8 billion in 2050.

According to a World Resources Institute report, food demand will increase 50% by mid-century. To meet demand, farmers will have to increase yields at a greater rate than historic trends, the report found. A disruption in any part of the world may be enough to raise prices, adding new stress for the food insecure.

Hoegemeyer retired from the university four years ago. But he often thinks of a student from Egypt who was studying at UNL in 2011.

The student said his father back home was constantly struggling to balance the family’s little money for fuel to get to work, to feed his family and for books so his children could attend school.

“When you increase food prices in lots of the vulnerable societies across the world, it’s going to force some really ugly decisions,” Hoegemeyer said. “We have a real responsibility to deal with climate change.”

One year ago: Photos, videos from catastrophic flooding in Nebraska