CEDAR RAPIDS — While the topic of climate change continues to be debated across the nation, scientists at an Iowa Ideas panel Thursday discussed how the global issue is affecting Iowans, especially farmers.
In the last 50 or 60 years, state climatologist Harry Hillaker said, Iowa has had about a 25 percent increase in precipitation, meaning an increase of about 5 or 6 inches of rainfall a year. That increase comes in early spring and summer, Hillaker said.
And while Hillaker’s charts show the state’s average temperature rising only about 1 degree Fahrenheit since 1895, the big change is that nighttime lows are warmer than they used to be. That also affects humidity levels, Hillaker said. Increased humidity creates more clouds, suppressing daytime temperatures. But those clouds act like a blanket at night, Hillaker said.
Also, the growing season for Iowa farmers is about two weeks longer, starting earlier in the spring. Another change is the decline in the early- and late-season snowfall, Hillaker said.
And that isn’t always a good thing.
“Snow reflects a lot of sunlight and insulates the air from warmer soil beneath,” Hillaker said.
For now, a longer growing season and increased rainfall for thirsty corn and soybean seedlings may seem like a plus for farmers, said Gene Takle, director of the Climate Science program at Iowa State University.
But rain also can delay crop planting. Additionally, when plants haven’t rooted to their full depths to “trap” the soil, early season rains increase erosion, Takle said.
And while Iowa farmers are working to embrace the earlier growing season and buy drainage tubes to cope with too much rain, that, too, leads to more erosion and future negative impacts, he said.
“Farmers rightly take advantage of the positive things,” Takle said. “The worrisome thing is that it trends toward things that are negative. When we look at the projection of heat waves, by midcentury in the Midwest, the one in 10 average heat wave is projected to go up by 13 degrees Fahrenheit. Corn pollen is sensitive to high temperatures. If that five-day period (of heat waves) should overlap with the pollination period in late July, that could decimate the pollination.”
Also, increased runoff leads to an larger dead zone in the Gulf of Mexico, where scientists believe chemicals used in agriculture have polluted the water to the point marine animals die, said ecologist Connie Mutel, senior science writer of the University of Iowa’s IIHR Hydroscience and Engineering.
Also, she said, because temperatures have increased in early spring, Iowa-native wildflowers are blooming three weeks earlier.
“We don’t know (they’re_ going to bloom at the same time the insects (that) feed on them or pollinate them” are there, Mutel said. “If you have a resilient, self-sustaining ecosystem, all of those interdependencies have been precisely timed. It’s devastating to species. The same is happening for birds nesting earlier. It takes hundreds of insects to feed a baby bird. If birds breed earlier and caterpillars don’t, you have another ‘disarticulation.’”
Other effects of global warming in Iowa are winters not cold enough to kill tick populations, which carry Lyme disease. That could mean a proportionate increase in environmental and health problems, Mutel said.
The problem comes down to the fact that humans have never gone through such drastic climate change, Mutel said.
“I think that climate change is one of those problems where you have to look simultaneously at the small scale and the very large scale,” she said. “When you change the climate of the globe, you’re taking apart the earth’s operating instructions.
“We know that people have been here in Iowa for 10,000 to 20,000 years,” Mutel said. “After the disappearance of the last glaciers, across the globe we’ve had a fairly stable climate. That’s allowed people to develop civilization, develop culture under stable operating conditions. Now this one degree Centigrade temperature increase — that is a global average outside of the norm of what’s happened.
“We need to know that Iowa is changing like the rest of the world is changing ... so we know how we can adapt to it ourselves,” she said.
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