A new study from NOAA reminds us that as sea levels rise, it no longer takes a strong storm or hurricane to lead to flooding.
So-called “nuisance flooding” — which results in public inconveniences such as frequent road closures, overwhelmed storm drains and compromised infrastructures — has increased on all three U.S. coasts by between 300 and 925 percent since the 1960s, according to NOAA.
Eight of the top 10 U.S. cities that have seen an increase in nuisance flooding are on the East Coast.
Annapolis and Baltimore, Maryland, lead the list with an increase in number of flood days of more than 920 percent since 1960.
New Jersey’s Atlantic City and Sandy Hook also made the top five with an increase in flood days of more than 600 percent, NOAA reports.
Port Isabel, Texas, along the Gulf coast, showed an increase of 547 percent, and nuisance flood days in San Francisco, California, increased by 364 percent.
Flooding now occurs with high tides in many locations due to climate-related sea level rise, land subsidence and the loss of natural barriers. The effects of rising sea levels along most of the continental U.S. coastline are only going to become more noticeable and much more severe in the coming decades, probably more so than any other climate-change related factor.”
Scientists took data from 45 NOAA water level gauges with long data records around the country and compared that to reports of number of days of nuisance floods.
The study defines nuisance flooding as a daily rise in water level above the minor flooding threshold set locally by NOAA’s National Weather Service, and focused on coastal areas at or below these levels that are especially susceptible to flooding.
NOAA concludes that any acceleration in sea level rise that is predicted to occur this century will further intensify the impact of nuisance flooding over time, and will further reduce the time between flood events.
It also warns that while event frequencies are accelerating at many U.S. East and Gulf coast gauges, many other locations will soon follow regardless of whether there is an acceleration in relative sea level rise.