Causes of accelerated High-Tide Flooding in the U.S. since 1950

Qiang Sun; Sönke Dangendorf; Thomas Wahl; Philip R Thompson

doi:10.1038/s41612-023-00538-5

Causes of accelerated High-Tide Flooding in the U.S. since 1950

NPJ Clim Atmos Sci. 2023;6(1):210. doi: 10.1038/s41612-023-00538-5. Epub 2023 Dec 15.

Authors

Qiang Sun¹, Sönke Dangendorf¹, Thomas Wahl², Philip R Thompson³

Affiliations

¹ Department of River-Coastal Science and Engineering, Tulane University, 627 Lindy Claiborne Boggs Center, 6823 St. Charles Avenue, New Orleans, LA 70118 USA.
² Department of Civil, Environmental and Construction Engineering and National Center for Integrated Coastal Research, University of Central Florida, Orlando, FL USA.
³ Department of Oceanography, University of Hawai'i, Honolulu, HI USA.

Abstract

The U.S. coastlines have experienced rapid increases in occurrences of High Tide Flooding (HTF) during recent decades. While it is generally accepted that relative mean sea level (RMSL) rise is the dominant cause for this, an attribution to individual components is still lacking. Here, we use local sea-level budgets to attribute past changes in HTF days to RMSL and its individual contributions. We find that while RMSL rise generally explains > 84% of long-term increases in HTF days locally, spatial patterns in HTF changes also depend on differences in flooding thresholds and water level characteristics. Vertical land motion dominates long-term increases in HTF, particularly in the northeast, while sterodynamic sea level (SDSL) is most important elsewhere and on shorter temporal scales. We also show that the recent SDSL acceleration in the Gulf of Mexico has led to an increase of 220% in the frequency of HTF events over the last decade.

Keywords: Climate-change impacts; Environmental impact.