Six inches of sea-level rise since 1970 off the Carolinas resulted in storm surge flooding of 11,000 additional homes, according to data from scientists with the nonprofit First Street Foundation, based in New York City.
The storm surge pushed water over 25 percent or more of more than 51,000 homes, the group said in a recent press release. It estimated that, had all current homes been there in 1970, 40,000 would have flooded, and 23,000 homes would have actually flooded in 1970, given the smaller number of housing units built then.
First Street recently calculated that New Jersey has lost $4.5 billion in appreciation of home values since 2005 because of flooding related to sea-level rise.
Changes in housing development patterns also played a significant role.
Since the 1970s, development has concentrated in former wetlands, farms and conserved areas, First Street reported. Many of the homes built in those areas flooded.
“With sea levels and coastal development on the rise, the impacts of hurricane storm surge will only get worse,” said Matthew Eby, executive director of the First Street Foundation. “The time to rethink America’s sea-level rise and adaptation strategy is now.”
First Street said it used geospatial analysis to model the storm surge at the sea levels observed in 1970 and found that about 11,000 impacted properties would not have been affected then.
The study also found that 102,000 properties would be affected by Hurricane Florence's storm surge at the U.S. Army Corps of Engineers' 2050 projected sea level, which is about 15 inches above current levels.
“Even though the impact of Hurricane Florence continues to be felt, we already know that sea-level rise has made the damage significantly worse, as observed with other recent storms,” said First Street Head of Data Science Steven McAlpine. Higher sea levels cause greater storm surge, as there is more water available for hurricanes
Sea-level rise doesn't just push more water onto land. The additional water removes friction that would otherwise slow the surge, First Street said. The conservative models used in the research show increases in sea-level rise result in an additional 23 percent relative increase in storm surge, the researchers reported.
First Street Foundation is a 501c3 tech nonprofit that educates policymakers and the public about the risks, causes and solutions to sea-level rise.