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Extreme Heat and Floods Are Back in the Midwest. How Does Climate Change Play in?

By Kate Grumke

Warmer temperatures are leading to more extreme precipitation, dry periods and dangerously humid heat waves all at once. But in a complicated system, some things aren’t changing as expected.

Sweaty city and state officials loaded donated air conditioners onto trucks in a St. Louis warehouse, passing the heavy boxes down the line. On this day, the thermometer soared to 103, the hottest temperature ever recorded on June 25 in the city.

The 800 cooling units were headed to low-income seniors and people with disabilities through an organization called Cool Down St. Louis. Gentry W. Trotter founded the organization almost 25 years ago and said on days like this, the hottest day of the year so far in the city, it’s clear climate change is causing problems in the Midwest.

“This heatwave ain’t going away, it's going to get worse,” Trotter said. “And if people don't believe in climate change, duh. They need to realize that it's right here in our backyard each and every day.”

Extreme weather is returning to the Midwest as record-breaking flooding and heat have swept through the region, serving as a reminder that climate change is teeing up conditions that make these disasters more likely.

Heavy rainfall led to historic flooding in Iowa, South Dakota and Minnesota at the end of June. More than 30 new records were likely broken in these states, according to preliminary data from the National Weather Service.

“The devastation is severe, and it's widespread,” said Iowa Gov. Kim Reynolds at a press conference on June 23. “In almost every community impacted, the rivers crested several feet above record levels from the floods of 1993.”

Parts of northwest Iowa and southeast South Dakota reported rain totals from 10 to 20 inches. In Iowa, Reynolds said nursing homes and hospitals had to evacuate and some communities were without power and drinking water.

Flooding also impacted northeast Nebraska, where water reached about three miles outside of its typical channel in Burt County.

Before the flood, Burt County farmer Randy Olson said his crop was one of the best he’d had in years — now, it’s basically destroyed. He said crop insurance will help him and his neighbors break even, but it still hurts the local economy.

“That is of course a ripple effect for the economy, because if nobody has money, nobody can spend money,” Olson said. “So it kind of goes around a little bit.”

But is this flooding due to climate change?

“When you're asking about a specific event, you can't answer that easily or automatically,” said Dennis Todey, director of the U.S. Department of Agriculture’s Midwest Climate Hub.

To link specific events to climate change, scientists model different scenarios to compare how events might have played out with different amounts of greenhouse gases in the atmosphere. Without doing that, scientists can’t definitively answer if something happened because of climate change.

But warming temperatures are leading to new trends that Todey said are present in the Midwest right now, like increasing precipitation in late winter, spring and early summer, and overall larger precipitation events.

“You can't just automatically go, ‘this was climate change,’” Todey said. “But because of the overall changes in our climate, there are fingerprints of climate that show up in most everything that we do. Because our climate is changing overall, there's pieces of climate change no matter what happens.”

More water in the atmosphere

As humans release more greenhouse gases into the atmosphere, the gases trap heat.

Radiation from the sun is absorbed into the Earth and emitted as a different type of radiation. Some of that goes back into space, but it's natural for some of it to stick around, creating our hospitable planet. As humans burn fossil fuels and add more molecules like carbon to our atmosphere, we're dialing up the amount of molecules that make radiation act differently.

“Without the gas, the radiation will just pass through. But these molecules create this filter that says, ‘Wait, hold on, hold on radiation, you cannot just go in one direction,’” said Stefan Liess, a climate scientist at the University of Minnesota’s Climate Adaptation Partnership.

As the radiation bounces around, it is warming the atmosphere and also increasing the amount of energy, which Liess said leads to more extreme weather.

A warmer atmosphere also holds more water. That can lead to heavy rainfall, said Zack Leasor, Missouri’s state climatologist.

“You're increasing your supply of available potential rainfall with increasing temperatures, and so more extreme precipitation and those high-end events are what's expected to occur with more warming temperatures,” Leasor said.

But there’s also an effect on the other side of the wetness scale. Huge dumps of rain are often followed by dry periods.

“From the overall climate change aspect, we’re seeing actually a lot more rapid transition or rapid variability back and forth between dry conditions and wet conditions,” Todey said. “And it's even caused us to look at this from a different standpoint.”

Extremes in a ‘warming hole’

Heat trends are also surprising some scientists in the Midwest. As average temperatures climb around the world, the region is also warming, but this part of the country isn’t reaching the extreme daytime highs being recorded in other regions of the U.S. as often. That doesn’t mean summers are cool.

On the June day that broke a St. Louis record, first responders had multiple calls for heat-related illness. St. Louis Fire Chief Dennis Jenkerson said extreme temperatures put extra stress on people, but also on a city’s resources.

“It not only has a cumulative effect on the body, but it has a compounding effect on all the services within a region, from police to fire to EMS to the hospital systems,” Jenkerson said. “Everything gets strained.”

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