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New Data Released On Flood Risk Of Every Home In U.S. Due To Climate Change Impacts; 370,200 More Properties In PA At Substantial Risk

On June 29, First Street Foundation publicly released flood risk data for more than 142 million homes and properties across the country through a new FloodFactor.com website.

The data, based on decades of peer-reviewed research, assigns every property in the contiguous United States a "Flood Factor™," or score from 1 to 10, based on its cumulative risk of flooding over a thirty-year mortgage.

People can look up a property's Flood Factor and learn more about its past, present, and future flood risk at FloodFactor.com, the Foundation's new online visualization tool.

While FEMA classifies 8.7 million properties as having substantial risk, or within Special Flood Hazard Areas (SFHAs), the First Street Foundation Flood Model identifies nearly 70 percent more, or 14.6 million properties with the same level of risk.

This means nearly 6 million households and property owners have underestimated or been unaware of their current risk. This discrepancy exists because the Foundation uses current climate data, maps precipitation as a stand-alone risk, and includes areas that FEMA has not mapped.

When adjusting for future environmental factors like changing sea levels, warming sea surface and atmospheric temperatures, and changing precipitation patterns, the Foundation's model finds the number of properties with substantial risk grows to 16.2 million by the year 2050.

Pennsylvania Flood Risks

A report highlighting significant national, state, and city findings of the First Street Foundation Model, titled "The First Annual National Flood Risk Assessment: Defining America's Growing Risk" is also available.

The report shows flood risk is increasing in the state of Pennsylvania. 564,600 properties currently have a substantial risk of flooding.

The First Street Foundation Flood Model calculates the number of properties facing any risk of flooding. When looking at this broader level of risk, the data identifies 743,600 properties in Pennsylvania as at risk over the next 30 years.

Of these properties, 202,700 were categorized as facing almost certain risk, with a 99 percent chance of flooding at least once over the next 30 years.

Over the next 30 years, the number of properties with this risk will increase by another 4 percent, bringing the total number of properties with substantial risk to 587,400.

To understand personal flood risk, Americans leverage the Federal Emergency Management Agency (FEMA) Flood Insurance Rate Maps (FIRM). These maps identify 194,400 properties as having substantial risk in the state of Pennsylvania.

In comparison, the First Street Foundation Flood Model identifies 2.9 times the number of properties as facing this same level of risk. This discrepancy exists because the Foundation uses the current climate data, maps precipitation as a stand-alone risk, and includes areas that FEMA has not mapped.

These new methods uncover an additional 370,200 properties currently not identified by FEMA as having substantial risk in Pennsylvania.

When adjusting for future environmental changes, the FEMA gap further widens to 393,000 by the year 2050.

The report also identifies the communities with the greatest number of properties at risk: Philadelphia, Pittsburgh, Harrisburg, Wilkes-Barre, Williamsport, Kingston, Johnstown, Scranton Erie and Altoona.

Click Here for more information in Pennsylvania.

Additional Background

"In environmental engineering, there is a concept called stationarity, which assumes that today is going to be like yesterday, and tomorrow is going to be like yesterday," said Dr. Ed Kearns, First Street Foundation's chief data officer. "This concept used to work, but with a changing environment it's a poor assumption and no longer does. FEMA's method assumes stationarity, First Street's does not."

The model was developed by more than 80 of the world's leading hydrologists, researchers and data scientists from First Street Foundation; Columbia University; Fathom; George Mason University; Massachusetts Institute of Technology; Rhodium Group; Rutgers University; The University of California, Berkeley; and the University of Bristol.

Building upon their decades of peer-reviewed research and model outputs, as well as data from FEMA, the USGS, NOAA, and other government agencies, the collaborators were able to create the country's first publicly available comprehensive flood risk model.

"Sophisticated investors have privately purchased flood risk information from for-profit firms for years," said Matthew Eby, executive director of First Street Foundation. "First Street Foundation has not only taken this kind of data to the next level, using peer-reviewed science, but is correcting an asymmetry of information by providing free access to everyday Americans."

The model identifies the likelihood of previous flooding by recreating 55 past hurricanes, tropical storms, nor'easters and major inland flooding events. A lack of disclosure laws in many states makes this information difficult or impossible to find.

The model also calculates the current probability of tidal, storm surge, pluvial (rainfall) and fluvial (riverine) flooding for individual homes and properties.

In addition to current risk, future risk is calculated by incorporating anticipated environmental changes like sea-level rise, changing precipitation patterns, and warming sea surface and atmospheric temperatures. The technical documentation pertaining to the model development can be found online.

The First Street Foundation Flood Model and data have been shared with roughly 100 researchers from 20 of the world's top academic institutions, through the First Street Foundation Flood Lab.

The researchers, from MIT, Harvard University, Johns Hopkins University, The Wharton School of the University of Pennsylvania, and other top universities, will use the data to analyze flooding's impact on the U.S. housing market; its implications for lower income and minority communities; its cost to federal, state, and local taxpayers; climate gentrification; and fairness in federal flood mitigation spending among other issues.

"Through its Big Data partnerships and its growing team of data scientists, First Street is establishing itself as the leader in the emerging field of climate risk measurement," said Dr. Matthew Kahn, director of Johns Hopkins University's 21st Century Cities Initiative. "As a researcher seeking to understand the challenges and opportunities for U.S real estate investors in the face of rising climate risk, I look forward to continuing to partner with First Street."

Visit the FloodFactor.com website to learn more.

(Photo: Map showing areas properties of increased risk.)

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