Can Wisconsin’s corn take the heat? Study warns rising temperatures could be devastating

Anna Groves
Milwaukee Journal Sentinel

A warming climate could be disastrous for America's Dairyland, thanks to the effect of temperatures on a single plant: corn.

More than half of Wisconsin's top commodities depend on corn, which feeds chickens, dairy cattle, beef cattle and, yes, even humans. But researchers just announced that without new technologies, rising temperatures could put these commodities at risk.

Climate experts predict rising temperatures will affect corn yields if preventative actions aren't taken.

Climate experts project global temperatures will increase 2 to 4 degrees Celsius (that’s 3.6 to 7.2 degrees Fahrenheit) by the mid-21st century. The new study crunched the numbers to see how this would affect corn yields in the U.S. and worldwide. They found that U.S. corn yields would decrease at least 18% after this kind of warmup in mean temperature.

The team of researchers, led by Michelle Tigchelaar at the University of Washington, used a global data set of weather patterns and subsequent corn yields to predict what to expect. In addition to decreased yields, the researchers warned of increased volatility — or less consistency in yields — as global temperatures increase.

The odds that all four of the world's major corn producers (United States, China, Brazil and Argentina) would face major production losses simultaneously is virtually zero. But those odds creep up as temperatures increase — from a 7% chance on the low end to an 86% chance at the 4 degrees Celsius mark.

"Personally, I was quite surprised at the scale of the changes," Tigchelaar said. "These numbers are quite dramatic, and if they hold up, they would pose tremendous challenges to global food security."

What might this look like for Wisconsin farmers? Imagine a farmer who expects to harvest about 175 bushels of corn per acre. With projections for reductions in yield —18% for 2 degrees of Celsius warming — the farmer would start to bring in only 144 bushels on average. Add increasing volatility on top of that, and he might hit 144 in one year, get lucky the next with 158, and take a hit the following year with 130.

That's not just bad for a farmer trying to maintain a steady income. Worldwide changes in crop availability would influence food prices, too. Odds are, most consumers wouldn't see it too much in corn-on-the-cob, but price fluctuations would hit meat, dairy and the increasingly wide range of products sweetened with corn syrup — everything from soda and cereal to brats and beer.

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I think the biggest misconception about climate change is that it is a fringe problem that will affect only people in the future, and far away from our personal lives," Tigchelaar said. "Our study gives an example of the global interconnectedness of the problem: Even if the climate in Wisconsin itself remains manageable, we are all consumers in a global food market."

No one is expecting orange groves near Green Bay — or cranberry bogs in Tampa, for that matter. And, in fact, some additional heat can lengthen the growing season. But if it  gets too hot, corn stops growing and kernels no longer fill.

Many growers, scientists and economists seem to expect that developments in biotechnology and farm management will allow corn to keep growing despite any changes in climate.

Steve Moose, professor of plant breeding and genetics at the Illinois Maize Breeding and Genetics Laboratory, said breeding new varieties of corn to withstand higher temperatures is more complicated than things we’ve bred in the past, like pest or herbicide resistance.

Still, he's optimistic.

“Some will say climate change is going to happen faster than breeders can keep up. That might be a fair statement if you look at how breeding has been done in the past,” said Moose, adding that we shouldn’t underestimate the ability of the plants to adapt on their own. “The plants will respond faster than even non-plant scientists might give them credit for. It’s presented like it’s a disaster in waiting, but I’m much more optimistic. I think the combination of new tools in breeding and (farm) management will be able to keep up.”  

Paul Mitchell, professor of agricultural and applied economics, extension state specialist and director of the Renk AgriBusiness Institute at the University of Wisconsin-Madison, agreed. This research "doesn’t talk about the social adjustments at all. Farmers don’t care about variability of yields, they care about the variability of income. Crop insurance is already heavily subsidized, and there are mechanisms in place to mitigate the financial impacts. If yields go down, fine, we’ll plant more corn.”

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In the end, Tigchelaar hopes to send the message that these predictions are a worst-case scenario but still worth addressing.

"Pathways to decarbonization are often framed as ones of personal sacrifice and austerity (can't drive my car, can't eat meat, can't go on vacation)," she said. "But we can also think of them as pathways to cleaner air, lower energy bills and independence."