EPA Researchers are Providing Tools and Resources to Prepare Communities for Climate Change and Extreme Storms
Published April 19, 2021
Each season brings expected changes to the weather. But with climate change and the warming of the atmosphere, weather patterns are becoming less predictable with more heat waves, and increased severity of super- and local- storms.
EPA scientists are investigating the increased occurrence and intensity of extreme precipitation events, which are defined as days with precipitation in the top one percent of all days with precipitation, according to the U.S. Global Change Research Program. Many parts of the country have experienced these changes already with storms that bring high accumulations of rain or snow, resulting in flooding and threats to public health and property.
Scientists are observing, recording, and comparing precipitation event data taken over the past century and using models to study what might happen later this century because of climate change. They have found that heavy precipitation events in most parts of the United States have increased in both intensity and frequency since 1901 and are projected to continue to increase. 1
This research is important to help states, cities, and communities better prepare for increases in precipitation to reduce potential public health and environmental impacts. The knowledge can be used to plan and design water treatment systems to prevent overflow of untreated water into rivers, lakes, and other water bodies. The information also can enable cities and rural areas to better prepare and respond to frequent flooding from extreme precipitation to protect public health and property.
“Understanding how extreme weather might change from today’s conditions helps inform decision makers and can lead to more robust decisions,” says Andy Miller, Associate Director for Climate in EPA’s Office of Research and Development. He added, “A robust decision is one that works for a wide range of conditions and can be adapted later as we learn more. For example, we could design a system that can accommodate larger pumps than we need today and more easily install them when they’re needed.”
In one recent study, EPA researchers used modeling data to find that—in the worst-case scenario—there could be a more than double increase in local, three-day, 1,000-years rainfall events in Eastern North Carolina (e.g. Hurricane Florence in 2018), and up to a 30 percent increase in the maximum daily precipitation in a year in the Southeastern U.S. by 2100. An increased variability in the intensity and frequency of extreme precipitation is also projected. 2,3
“Potential changes in these very rare rainfall events shown in our models would have devastating consequences for the Eastern North Carolina region,” says Anna Jalowska, EPA researcher and lead author on the studies.
EPA’s extreme precipitation modeling research is expected to continue to expand studies to different locations and different possible climate change conditions.
The study was published in the March 2021 issue of the Nature Partner Journal Climate and Atmospheric Science. Jalowska and co-authors note in the paper that the dramatic future extreme rainfall intensities modeled for Eastern North Carolina are comparable to the most extreme rainfall events already observed in other parts of the U.S. during the first part of this century (e.g. Hurricane Harvey in 2017 in TX).
EPA has developed tools for states and others to respond to future changes in heavy rainfall, including the National Stormwater Calculator, which estimates the annual amount of rainwater and frequency of runoff from a specific site. Other tools include the Climate Resilience Evaluation and Awareness Tool (CREAT), a risk assessment application that helps utilities adapt to climate change impacts by providing a better understanding of current and long-term weather conditions. And the Time Series Viewer and Change Analysis Tool on EPA’s EnviroAtlas, an interactive web-based tool that allows users to view historic and future environmental variables from 1950 - 2099 in a time-enabled animated map, and compare a selected variable (e.g., precipitation) between selected time periods.
Increased precipitation amounts will be a challenge for the nation in the coming decades. EPA research is providing the information and tools to help reduce the impacts and provide solutions to support resilient communities.
1. USGCRP, 2018: Impacts, Risks, and Adaptation in the United States: Fourth National Climate Assessment, Volume II [Reidmiller, D.R., C.W. Avery, D.R. Easterling, K.E. Kunkel, K.L.M. Lewis, T.K. Maycock, and B.C. Stewart (eds.)]. U.S. Global Change Research Program, Washington, DC, USA, 1515 pp. https://doi.org/10.7930/NCA4.2018.
2. Jalowska, A.M., Spero, T.L. & Bowden, J.H. Projecting changes in extreme rainfall from three tropical cyclones using the design-rainfall approach. npj Clim Atmos Sci 4, 23 (2021). https://doi.org/10.1038/s41612-021-00176-9
3. Jalowska, A., T. Spero, D. Amatya, G. Gray, & J. Bowden. Changes in the Future Extreme Precipitation Using Dynamically Downscaled Simulations From 2025 to 2100 for three forested and three urban stations in Southeastern U.S. Watersheds. 7th ICRW, Zoom, NC, November 16 - 19, 2020.