By 2030, residents of Washington, D.C., and Annapolis, Maryland, could be experiencing more than 150 tidal floods every year — up from an average of just 50 today — according to a recent study of sea level rise and coastal flood risk along the U.S. East Coast by the Union of Concerned Scientists.
In another 15 years, that number could jump to 400 floods annually, the study says. A home purchased in some of the more flood-prone parts of those two cities could see daily flooding before a 30-year mortgage was paid off, according to the study. The increased frequency will be driven by sea level rise, researchers say, which exacerbates the effects of so-called “nuisance flooding” linked to tidal cycles, rainfall, and storm surges.
Relatively few cities on the East and Gulf Coasts now face tidal flooding on a regular basis (left; circle size represents the number of flood events). But by 2045, sea level rise will bring more tidal floods to nearly every location. Many communities can expect a 10-fold increase in tidal flood frequency (right). (Image credit: Union of Concerned Scientists)
Other cities on the Atlantic coast will also see increased flood frequency: Miami, Florida, and Atlantic City, New Jersey, can expect an average of 240 flood days per year, while Philadelphia and Baltimore could average as many as 180 tidal floods by 2045, according to the study.
Over the next 30 years, coastal communities in the Eastern U.S. can expect to see a roughly one-foot increase in sea level — a mid-range scenario, by most estimates — the report noted.