21 june 2013

Scientists say drought, floods signal what's to come

By Josh O’Leary, Iowa City Press-Citizen, June 21, 2013 |

Given the choice between a drought or flooding, Johnson County farmer Russ Meade would take his chances with swampy fields any year.

“Psychologically, a drought affects you a lot worse because you’re seeing things slowly die,” said Meade, who helps run his family’s 720-acre corn, soybean and cattle farm near Tiffin.

The past two growing seasons, though, Meade has faced both extremes. Last summer, his crops wilted during the fifth-driest summer on record in Iowa. That was followed by the wettest spring in the state’s history and, locally, flooding along the Iowa River and Clear Creek, putting one of Meade’s creek-side fields under water for two days.

Scientists, politicians and officials warn that because of Iowa’s changing climate, this extreme weather is here to stay. In November, 138 scientists and researchers signed a statement telling Iowans to brace for more events such as the 2012 drought because of the ill effects of greenhouse gases. And this spring’s flooding in the Iowa City area — coming just five years after the historic 2008 disaster and 20 years after the widespread 1993 floods — has renewed the conversation about an increased frequency in extreme weather.

“You take what your weather system was, back when I was a kid in the ’70s, and put it on steroids,” said Iowa City native Rob Hogg, an Iowa state senator from Cedar Rapids whose new book is titled “America’s Climate Century.”

“That’s what we’re doing, and we’re continuing to pump more steroids into the weather system, so we’re going to get a lot more extreme floods, we’re going to get more droughts, and we’re going to have to deal with it,” Hogg said. “I think what we need to be doing is looking at what the extremes were historically, magnify them and get ready for them.”

Iowa has experienced a long-term upward trend in both precipitation and temperature over the past century, according to a 2011 report compiled for the state legislature by the Iowa Climate Change Impacts Committee, which included a number of University of Iowa researchers.

Since 1873, Iowa has had an 8 percent increase in average annual precipitation, and Eastern Iowa has experienced a greater upward trend in precipitation than the western portion of the state, according to the report. Iowa’s humidity also has increased substantially, particularly during the summer — atmospheric moisture has increased by 13 percent in the last 35 years — which can fuel thunderstorms and lead to greater rainfall.

State Climatologist Harry Hillaker said Iowa had an average 17.67 inches of precipitation this spring, which was 73 percent more than the state’s long-term spring average of 10.22 inches, and is the most of any year since record-keeping began in 1873. It topped the previous record of 15.36 inches, set in 1892.

Though a warmer climate can lead to more evaporation and thus greater precipitation, scientists are reluctant to tie specific weather events such as flooding to global warming.

No one is ready to blame flooding along Clear Creek to someone driving a big truck, jokes Witold Krajewski, director of the UI-based Iowa Flood Center.

“I don’t think the state of the science is at the point where we can attribute specific events to the global climate change that is taking place,” Krajewski said. “I wouldn’t go that far. On the other hand, the seemingly increased frequency of these weather events that everybody takes notice of is consistent with what the climate researchers have been telling us for quite a while.”

It’s not just the changing climate that has led to Iowa’s flooding woes in recent years, experts say. Humans have contributed by altering the hydrological cycle through urbanization and changing agricultural practices.

Johnson County Emergency Management Coordinator Dave Wilson said increased use of farm tiling, which rapidly drains soil beneath fields, coupled with residential and commercial development using impervious surfaces, have played large roles in flooding.

“People who think the floods are going away, they’re living under a rock,” Wilson said. “The floods are here to stay, and it’s always going to happen until we change the way we do business.”

Wilson said he expects Johnson County to be dealing with its next flood “sooner rather than later because we just think that naturally this stuff is going to take care of itself and we don’t want to own up to it. But we own a piece of the problem, and we need to fix that.”

Janelle Rettig, chairwoman of the Johnson County Board of Supervisors and a recent member of the state’s Natural Resource Commission, said extreme weather is becoming a more pressing topic at the local and state level. Particularly worrisome, Rettig said, is the increased frequency of downpour rain events the state is experiencing, which drop several inches at a time.

The Iowa Climate Change Impacts Committee’s report highlighted a significant increase over the last century of the number of days in a given year with rainfall exceeding 1.25 inches, which is the average amount of water Iowa soil can absorb in a day before runoff begins.

“Years and years ago, we didn’t have 5-inch rainfalls; that would be a rare occurrence,” Rettig said. “But if you look across Iowa on a given spring, we’re now finding major rainfalls in various locations around the state. And 8 inches isn’t unusual — that’s happened multiple times over the last few years. Nothing about our system is designed to handle that. Our storm water system isn’t; our drainage system isn’t. Huge concentrations of water just runs off instead of percolating through our system more gradually.

“Across the board, whether it’s droughts or temperatures or tornadoes or snow events, we’re seeing the extremes.”

The Iowa Climate Change Impacts Committee said growing evidence points to stronger storm systems in the Midwest, and “it is plausible that this rise in the ingredients needed for severe weather will increase the likelihood of these extreme events,” including hail storms and tornadoes.

And Iowa City is as familiar with tornadoes as it is floods: In 2006, an F-2 twister cut through downtown Iowa City, leveling dozens of buildings and sending 30 people to the hospital with injuries.

Iowa City Public Works Director Rick Fosse said that unlike a tornado, which is seen largely as “a random act of nature,” more human elements come into play during flooding disasters, which can lead to frustration among those who are affected.

“They’re viewed as the result of any number of contributing factors, from poor development practices to poor engineering to poor planning,” Fosse said. “It’s not so much a random act of nature, and that’s where some of the frustrations come from for those who have been flooded.”

While Iowa has become a wetter place over the last 50 or so years, the 138 scientists who signed what was called the Iowa Climate Statement last fall cautioned that the state can expect dry periods to be more frequent as soon as the 2020s. Iowa also will see higher temperatures in years of dry weather patterns, the scientists said.

Krajewski, who signed the Iowa Climate Statement, said that just as the Iowa Flood Center has helped the state’s flood preparedness through its initiatives, which include developing new sensors and flood models, Iowa would benefit from a larger information network encompassing other elements of the water cycle.

Krajewski said early discussions have been held with the Iowa DNR and legislators about establishing such a network that would monitor not only rivers and streams but also atmospheric moisture and subsurface soil moisture and wells.

“No matter what causes all these extremes, they are happening, so let’s get prepared,” said Krajewski, who has led the Iowa Flood Center since it was established by the Legislature in 2009.

Out on his farm near Tiffin, Meade said the flooding on the small portion of his family’s land along the creek likely will result in lower yields from that field. Still, Meade said today’s farmers are better equipped than past generations to meet whatever weather blows through in the future.

“With the genetics we have in corn and soybeans today, it makes dealing with the weather extremes a lot less risky,” he said.

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