DES MOINES — Iowans who like to talk about the weather and the pros and cons of climate change got a double dose of information to consider Thursday.
In the near term, a team of Iowa experts in natural resources, agriculture, homeland security and the U.S. Geological Survey reported parts of the state are beginning to show signs of stress in groundwater conditions for the first time in a year.
Dry conditions continue to slowly expand, according to the state experts’ latest water summary update, raising concerns that below-normal summer rainfall is leading to drought conditions in some parts of Iowa. Statewide summer rainfall was 10.74 inches, or nearly 3 inches below normal.
"For the third month in a row, Iowa received below-normal rainfall. After such a wet start to the year, the below-normal rainfall has pushed more than half of the state into abnormally dry or moderate drought conditions," said Tim Hall, coordinator of hydrology resources for the state Department of Natural Resources (DNR). More than half of Iowa is now rated as at least abnormally dry according to the National Drought Monitor, while streamflow conditions in areas away from border rivers have moved into the normal flow range, he noted.
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Looking long term, James Boulter, a professor of chemistry in the Watershed Institute for Collaborative Environmental Studies at the University of Wisconsin at Eau Claire, issued a report Thursday indicating Iowa is becoming hotter and wetter – a trend he attributed to climate change – causing policy-makers and community leaders to face challenges as well as economic and health consequences with more-frequent flooding that he said may become more-extreme events as the climate changes. He noted that total statewide damage estimates from the 2019 flooding are staggering and likely to rise as western Iowans struggle with the effects of excess Missouri River basin runoff that led to 47 levee breaches and Iowa’s eastern border underwent 38 days in which the Mississippi River topped flood stage earlier this year.
“Science is giving us warnings,” said Boulter, whose report -- available at www.iowapolicyproject.org -- was supported by a grant from the Environmental Defense Fund in concert with the Iowa Policy Project -- a liberal-leaning nonprofit public policy research and analysis organization in Iowa City. “Even those who have not lived it have seen the pictures, of rooftops surrounded by floodwaters, breached levees, destroyed grain bins and impassable roads. Flooding is getting worse, and we have public policy options that can lessen the impact in the coming years.”
Boulter noted that average temperatures overall in Iowa have risen 0.4 degrees Fahrenheit per decade over the past four decades, adding up to nearly 5 percent in total increase, while Iowa’s rainfall from May 2018 to last April topped 50 inches – breaking a 116-year-old record by about 2.5 inches. He also said snow accumulations in Iowa, Minnesota and Wisconsin were substantially higher while rainfall in the Upper Mississippi River Basin has risen steadily and high-rainfall days have become more intense. “A range of climate models predict that by 2041 to 2050, there will be another 30 percent increase in the frequency of two-day precipitation events whose rainfall totals set a five-year record,” he added.
Boulter’s report noted that flooding in Iowa this year appears to be a repeat of other recent “100-year flood” events such as 1993, 2008 and 2011. A recent report by the Iowa State University Institute for Transportation found that “for the Cedar River Basin in Iowa, the 100-year flood ... of the 20th century is projected to be a 25-year flood in the 21st century, with associated increased frequency of flooding of agricultural land,” according to Boulter’s report. “Iowans have to wonder — is this our future in a changing climate?” he asked.
Boulter’s report compares the Intergovernmental Panel on Climate Change future scenarios in which society makes choices to mitigate its impacts on the global climate – concluding that the least-ambitious response is consistent with some of the most-alarming potential climate outcomes while. conversely, future climate impacts could be greatly reduced using a “more-robust” response that exceeds what the United State previously had committed to in the 2015 Paris Accord in emissions reductions.
“The study makes a compelling argument that a changing climate may produce more historic-level floods in the region and that the conditions that led to the 1993 floods may become a new normal,” said Boulter, who told Iowa reporters on a conference call that “in one way or another, policy responses are inevitable. The question is do we do them now in a proactive way or do we do them much later in a reactive way at which point they will be much more expensive and much more intrusive. That’s really the question that we have to ask.”