EXPERTS ADVISORY

The confluence of heavy rains and a heat wave flooded much of the Midwest this week. Thousands of properties were damaged and residents were advised to leave their homes, a century-old dam nearly failed, and a railroad bridge collapsed. Three million people have been affected, and two have died.

Experts from the University of Michigan weigh in on how climate change is driving severe flooding, the associated public health risks and how cities can adapt.

Ricky Rood is a professor emeritus of climate and space sciences and engineering at the College of Engineering and an expert in climate change modeling. He can comment on how the flooding is linked to the recent heat wave and how the risk of extreme flooding is likely to increase with continued climate change.

“The summer of 2024 continues the story of recent summers with increasing temperature, heat waves, flood and drought. This sets a confusing scene,” Rood said. “When water is available, the likelihood of extreme precipitation and flooding is enhanced. We are seeing this in the upper Midwest, as a cold front displaces the stubborn heat wave.

“Along the edge of the heat dome, the precipitation is overwhelming flood-control infrastructure. Where moisture is not available, the heat increases the possibility of rapid onset of drought. East of the Rocky Mountains in summer, water vapor from the Gulf of Mexico often contributes to flooding. With the water and air both warming, we expect flooding to be more common.”

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Mohammed Ombadi is an assistant professor of climate and space sciences and engineering at the College of Engineering and an expert in modeling flooding risks in a changing climate. He is also the principal investigator of a project that aims to reduce flooding damage to Detroit by restoring green spaces both in the city and the upstream areas.

“The implementation of urban greening and reforestation plays a pivotal role in mitigating the impacts of flooding,” Ombadi said. “Increased vegetation cover significantly reduces the severity of floods by enhancing water retention within plants. This natural water management strategy not only benefits human settlements downstream, but also restores ecosystems. Emphasizing these nature-based solutions is essential for building climate-resilient communities and safeguarding urban areas against the escalating challenges of extreme weather events.”

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Carina Gronlund is a research assistant professor of epidemiology at the School of Public Health and Institute for Social Research. She is partnering with Mohammed Ombadi to quantify the benefits of flood reduction on human health in Detroit, one of 860 cities across the U.S. with a combined sewer system, meaning that storm water and sewage flow through the same pipes. During heavy rainfall, the sewage system can overflow, putting untreated sewage in rivers, basements, streets and sidewalks, and minority communities are at higher risk.

“There are quite a few risks to human health—physical and mental health—from flooding. These include drowning, electrocution and infections from contact with the flood waters,” Gronlund said. “Also, long-term mold growth in flooded areas of the home can exacerbate respiratory problems like asthma and allergies. Dealing with home damage, and potentially also relocation, is stressful and expensive, which can have short- and long-term mental health consequences. It’s important not to minimize or underestimate the long-term health consequences of these extreme events.”

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Derek Van Berkel is an assistant professor of geospatial data sciences, conservation and restoration at the School for the Environment and Sustainability and a principal investigator of the GLISA project, which explores climate adaptation solutions in the Great Lakes region.

“Those floods, they’re unprecedented,” Van Berkel said. “We didn’t know it was going to be that extreme, and it’s heartbreaking to see people suffering like that. We need to start planning now because it’s only going to get more severe and frequent with climate change. By integrating floodplain maps with maps of socioeconomic demographics, we can identify the most vulnerable areas in the city—both to flooding itself but also those who will have the most difficulty responding to the initial emergency and recovering once the waters recede. This information can help cities adapt to future floods.

“Bigger cities can incorporate climate adaptation into their planning offices, but many smaller and medium-sized cities have challenges just getting the roads fixed. This is why we and our counterparts in other regions provide planning tools for emergency preparedness and response as well as how to design climate adaptive infrastructure.”

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