New climate projections for Iowa are sobering

Gene Takle and Jerry Schnoor | Iowa View contributors

Show Caption Hide Caption Governor Reynolds tours flood devastation in Polk County Governor Kim Reynolds talks about what she's seen while touring areas impacted by flooding in Polk County.

In 1991, climate scientists believed that climate change in the Midwest would lead to a warmer, wetter climate, including warmer winters and more rain in spring and early summer. They were right.

Now, new climate projections are available for Iowa from the Climate Science Special Report (CSSR), prepared for the fourth National Climate Assessment report. The results may make you sweat — and build a dam around your home.

By mid-century, projections show five-day heat-wave temperatures in Iowa increasing by about 7 degrees for the average year and by 13 degrees once per decade compared to heat waves in the late 20th century. Currently, the Iowa average annual five-day maximum temperature during a heat wave is in the range of 90-95 degrees — coolest in the northeast and warmest in southwest Iowa. These new projections for 2050 would make the hottest day in a five-day heat wave in the range of 97-102 degrees. Further, 10 percent of the years (once per decade), we can expect a heat wave with maximum temperatures of 103-108 degrees.

These are really scary numbers that would have negative consequences for the elderly, the economy, for corn and soybeans, as well as beef, hogs and poultry even under sheltered confinement. These latest estimates quantify the local risk we face by not curtailing the global burning of fossil fuels and emission of greenhouse gases.

Climate change is already here. Witness the weird weather we are experiencing: A flood on the Shell Rock River and Evansdale in late September 2016 (normally the dry season in Iowa) when 10 inches of rain fell in a couple of days. Not to mention the exceptional storm on June 30 this year in Polk County. Johnston and Ankeny recorded more than eight inches of rain in a 24-hour period. Fourmile Creek in east Des Moines broke its banks, flooded homes, swept away cars, and peaked more than one foot higher than ever before recorded. Such storms were non-existent 100 years ago when a 4-inch rainfall was truly rare in Iowa.

Rainfall rates are changing with greater uncertainty than temperature, but the CSSR indicates precipitation will become more intense. A study conducted jointly by Iowa State University and the University of Iowa for the Iowa Department of Transportation reported that the decadal maximum daily widespread precipitation events covering areas as large as one-third of Iowa (specifically, the Cedar River Basin north of Highway 30) are projected to double in intensity (daily total rainfall) by mid-century, with most of this change coming before 2025. Historically, that means a once-per-decade regional storm covering a good portion of Iowa could change from an average of 3.0 inches to 4.5 inches in the near future. Sobering statistics to be sure. We may be seeing that transition already.

What can we do as communities, cities, states, businesses and global citizens to prevent and adapt to this threatening future? First, we can act individually to save energy, preserve the environment and avoid fossil fuel emissions. Next we can join a groundswell responding to climate change at the local level — cities, businesses, and organizations. Finally, we can vote and elect representatives who take these challenges seriously. Responding to climate change does not need to be painful or costly. Rather, widespread adoption of energy efficiency, renewable energy, and low carbon alternatives is the economic engine for creating jobs, opportunity, and prosperity in the future.

Gene Takle is emeritus professor of agronomy at Iowa State University.

Jerry Schnoor is a professor in civil and environmental engineering and co-director of the Center for Global and Regional Environmental Research at the University of Iowa.