Scenes from the Houston area looked like the aftermath of a hurricane in early May after a series of powerful storms flooded highways and neighborhoods and sent rivers over their banks north of the city.

More than 400 people had to be rescued from homes, rooftops and cars, according to The Associated Press. Huntsville registered nearly 20 inches of rain from April 29 to May 4, 2024.

Floods are complex events, and they are about more than just heavy rain. Each community has its own unique geography and climate that can exacerbate flooding. On top of those risks, extreme downpours are becoming more common as global temperatures rise.

I work with a center at the University of Michigan that helps communities turn climate knowledge into projects that can reduce the harm of future climate disasters. Flooding events like the Houston area experienced provide case studies that can help cities everywhere manage the increasing risk.

The first thing recent floods tell us is that the climate is changing.

In the past, it might have made sense to consider a flood a rare and random event – communities could just build back. But the statistical distribution of weather events and natural disasters is shifting.

What might have been a 1-in-500-years event may become a 1-in-100-years event, on the way to becoming a 1-in-50-years event. When Hurricane Harvey hit Texas in 2017, it delivered Houston’s third 500-year flood in the span of three years.

Basic physics points to the rising risks: Global greenhouse gas emissions are increasing global average temperatures. Warming leads to increasing precipitation and more intense downpours, and increased flood potential, particularly when storms hit on already saturated ground.

Recent floods are also revealing vulnerabilities in how communities are designed and managed.

Pavement is a major contributor to urban flooding, because water cannot be absorbed and it runs off quickly. The Houston area’s frequent flooding illustrates the risks. Its impervious surfaces expanded by 386 square miles between 1997 and 2017, according to data collected by Rice University. More streets, parking lots and buildings meant more standing water with fewer places for rainwater to sink in.

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