Climate Change and Extreme Rainfall

Last week Climate Central launched "When It Rains It Pours", a new web-based tool that shows the number of extreme precipitation events that have occurred each decade going back to before the 1950s. The results clearly show how the number of extreme precipitation events is on the rise.

Extreme precipitation events increase the risk of localized flooding. This is particularly true in cities where these events can quickly overwhelm the local storm sewer capacity, causing backups that can flood people's homes, close streets, and cause public health problems. These health problems range from mold that grows in the sodden floors and walls of flooded properties to exposure to raw sewage in communities where stormwater and sewage are collected in the same pipes.

Extreme precipitation events also increase the likelihood of regional floods as evidenced by recent flooding in Texas, Oklahoma, and Louisiana. Since Memorial Day weekend, much of the region has received more than eight inches over the normal rainfall.

Here are a few things that the U.S. should do to become safer from flooding and extreme rainfall:

  1. Implement President Obama's updated flood protection standard. The Federal Flood Risk Management Standard would ensure that federal agencies build bridges, schools, and water and wastewater treatment plants that better withstand flooding and storm surges from hurricanes. Unfortunately, members of Congress are trying to prohibit federal agencies from implementing this much needed reform, and they need to wise up to the long-term cost savings it offers.
  2. Make it easier for people to relocate to higher ground. NRDC has developed a proposal for reforming the National Flood Insurance Program that would make insurance more affordable for low and middle-income property owners, while also guaranteeing them assistance to relocate after suffering major flood damage.
  3. Increase the resilience of our drinking water, wastewater, and stormwater systems. Treatment plants are all too often built in floodplains. Stormwater systems are usually not designed with future extreme rainfall events in mind. NRDC wants to see states make better use of funding they already have to make the nation's water infrastructure better prepared for the impacts of climate change.
  4. Better assess the risks of extreme precipitation due to climate change. At NRDC's urging, FEMA recently decided to require states to include an assessment of climate risks when developing disaster preparedness plans, also known as Hazard Mitigation Plans. These plans are important sources of information about community vulnerability and are used to prioritize how best to mitigate risks from future extreme storms and flooding.
  5. Finally, USEPA and states need to move forward with the Clean Power Plan. Lowering the amount of carbon dioxide we emit is critical if we're going to limit the impacts of climate change.

About the Authors

Rob Moore

Senior Policy Analyst, Healthy People & Thriving Communities program

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