Climate Matters: Climate change increases the frequency of extreme rainfall
Parts of Iron and Reynolds counties in southeastern Missouri experienced catastrophic flash flooding last Friday, July 10, following a one-in-1,000-year rainfall event.
The Missouri National Guard used eight UH-60 Black Hawk helicopters to evacuate more than 200 children and counselors who were stranded by floodwaters at Camp Taum Sauk in Lesterville. Task Force 1, the state's Urban Search and Rescue team, participated in more than 100 rescues during the emergency.
The storms produced as much as 12 inches or more of rain in just hours across parts of Crawford, Iron, Madison, Reynolds, and Wayne counties. Floodwater quickly overwhelmed creeks, streams, campgrounds, and low-lying roads, creating life-threatening conditions.
This extreme rainfall event reflects a broader trend of intensifying precipitation extremes across the U.S. due to climate change.
From 1958 to 2021, the most extreme precipitation days have intensified in every major U.S. region, led by the Northeast with a 60% increase and the Midwest with a 45% increase in the amount of precipitation falling on the heaviest one percent of days.
The increase in extreme rainfall events is linked to a warming climate. For every one degree Fahrenheit of warming, the air can hold an extra four percent moisture, which increases the chances of heavier downpours and the risk of flash floods. Climate Central reports that hourly rainfall intensity has increased by 23% in St. Louis since 1970.
"While the rainfall rate has increased in every U.S. region, the largest increase is happening among cities in the Upper Midwest," says Climate Central's Shel Winkley.
This hazardous intensification of precipitation is expected to continue with future warming. "Looking ahead with continued warming, 85% of over 3,000 U.S. counties are projected to see at least a 10% increase in precipitation during their heaviest rain events," Shel says.
Heavy downpours can cause landslides, displace families, damage infrastructure, and expose people to hazardous debris and contaminants. Inland flooding in the U.S. caused $230 billion in damages from 1988 to 2021. Over a third of those damages are attributed to precipitation changes due to climate warming.
Racial minorities and people living in mobile homes are disproportionally affected by flooding, especially in rural areas and in the southern U.S. Climate change hits some harder, and is felt by all. "While local factors like topography and infrastructure shape how that risk plays out, it also comes down to climate change, raising the impacts and flood concerns for communities across the country," Shel Winkley says.
Search operations continued along the Black River in Missouri this week. Over the weekend, the Missouri State Emergency Management Agency deployed local response teams, including medical care teams, to Lesterville and other impacted areas. Officials continue to urge people to avoid flooded roads and damaged areas, warning that just six inches of moving water can knock a person off their feet.
