Panelists Address Changing Climate
Published: Friday, March 13, 2020
Indiana's climate is becoming warmer and wetter, and Elkhart County farmers are responding correctly by planting more cover crops and reducing tillage. But they may need to do other things—such as using new tractors that are better suited for wet conditions—to keep up with changes.
That's according to a Purdue University climate expert who spoke at a soil health workshop last Wednesday in Goshen.
Jeffrey Dukes, director of the Purdue Climate Change Research Center, outlined future weather trends and patterns at the Elkhart County Soil and Water Conservation District event. Later, he and several other weather experts participated in a panel discussion on climate change.
Using weather data from the past 120 years, Dukes pointed out that Indiana's average annual temperature has increased 1.3 degrees. This impacts plant growth, especially when nighttime temperatures are higher.
"Plants, just like us, are respiring all the time," Dukes said. "That is, they are losing carbon dioxide in the atmosphere—just through the metabolic process."
During the daytime, plants convert carbon dioxide into sugars through a process known as photosynthesis. But if nighttime temperatures are too warm, plants can release too much carbon into the air. Studies have shown a 3.1 bushel per acre reduction in corn yield due to excessive summer heat.
"It's sort of an exponential relationship, basically," Dukes said. "So, if you have warmer nights when the photosynthesis is not happening, you are losing carbon to the atmosphere faster and that's impacting your yield right in the heart of the growing season. That's one reason that warmer temperatures in this region have led to reduced yield."
The state is also receiving an additional 6.5 inches in precipitation compared to 1895. Dukes added that five of the seven wettest years on record have come in the past 17 years, proof that the changes are accelerating. He said that climate is changing due to a growing amount of greenhouse gases in the atmosphere.
In recent years, the rainfall, especially in winter and spring, has been more intense.
"The heaviest rainfall events are getting even heavi-er," he said. "And obviously that's not good if you want to keep the soil in your field."
While all of Indiana is seeing more precipitation, the increases are more dramatic in southern Indiana.
The Purdue climatologist said he expects this warmer-and-wetter trend to continue. By mid-century, Indiana should see warming in all four seasons and longer growing seasons, but with more frequent and intense periods of extreme heat during the summers.
The average annual temperature should climb by an additional 4 degrees in the next 30 years, he said.
By 2050, Indiana residents will see longer heat waves, with up to 20 days with temperatures above 90 degrees. The hottest days will reach 105 degrees, and even hit 111 degrees by 2080.
Winter and spring seasons will be wetter, with more precipitation falling as rain, not snow. This prediction means farmers are likely to see planting seasons similar to 2019, although the panelists agreed that last year was an extreme case.
Some in the audience expressed skepticism about these predictions and were concerned that Dukes' views were radical. Mark Jordan of Goshen, for example, questioned the climate center's forecast of a 4-degree jump in average annual temperature by 2050 when all of the previous 125 years had produced just a 1.3-degree increase.
"These are the best estimates based on the best science that we have available," Dukes responded.
But if they hold up, by 2050, Indiana would experience winters that compare to New Jersey or Delaware, while Indiana summers would resemble the type of climate seen in western Tennessee or Arkansas.
"These changes are pretty much locked in at this point, based on emissions that have already been released," he said, referring to carbon emissions. "What happens by late in this century depends a lot on what we're doing today and what we do in the next few decades."
Keith Miller, a New Paris farmer, said the Purdue expert appeared to have a "doomsday" outlook with respect to climate change. However, he agrees with some aspects of his presentation regarding how farmers can adapt to the weather. For example, Dukes said that improving soil health and planting cover crops in the fall can help with managing additional spring rainfall. To that end, he said farmers in this area are making great strides.
While a warmer climate will decrease corn yields, Dukes said these changes may create opportunities for farmers to grow different crops, such as sorghum, or even consider double cropping. Also, new tractors will be needed to handle the wet soil conditions.
While some expressed doubts about climate change in general, one panelist, Michael Lewis, a meteorologist with the National Weather Service, said there is confidence in the general prediction that water will be flowing more rapidly off farm fields and into ditches and streams. That means farmers will need to have good drainage systems.
While there will be excess water in the winter and spring, the growing season will have more extreme heat and less rainfall, according to Dukes. That will create stressful conditions for livestock, reducing their feed intake and decrease their productivity and fertility. Farmers will need to respond by having improved ventilation systems.
But as good as farmers are at adapting, Lewis said agriculture can't possibly keep pace with the rate of change.
Purdue University agronomist Eileen Kladivko emphasized the value of cover crops as a way to build soil health and prevent erosion during times of intense rainfall. She also pointed out that excess water in the spring can be stored and irrigated on crops during times of intense summer heat.
She noted that healthy soil has a greater water holding capacity, due to higher organic matter, better soil aeration and less compaction. She and other speakers drove home the point that cover crops build soil structure, making the soil less likely to break down during intense rainfall.
Last year, Elkhart County farmers grew cover crops on almost 8,000 acres, thanks to cost-share programs provided by the local Soil and Water Conservation District, according to James Hess, district manager.
Dukes, the Purdue climate specialist, applauded local farmers for embracing cover crops. He pointed out that those plants do a good job of sequestering carbon, but they can't absorb the amount of greenhouse gases that are annually released into the atmosphere.
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