Report: High-tide flooding to increase
Sea-level rise to cause damage more often
It doesn’t take a storm to inundate the coast with potentially ruinous floodwaters.
“Nuisance” or “sunny day” hightide flooding is becoming more commonplace in the U.S., and a federal report released Tuesday by the National Oceanic and Atmospheric Administration warns that such flooding will worsen in the decades to come as seas continue to rise.
“America’s coastal communities and their economies are suffering from the effects of high-tide flooding, and it’s only going to increase in the future,” said Nicole LeBoeuf, acting director of NOAA’s National Ocean Service. As sea-level rise continues, damaging floods that decades ago happened only during a storm now happen more regularly, according to NOAA.
Although not mentioned in the report Tuesday, seas are rising in part because of climate change: According to an online NOAA fact sheet, “The two major causes of global sea level rise are thermal expansion caused by warming of the ocean (since water expands as it warms) and increased melting of landbased ice, such as glaciers and ice sheets.”
In a call with reporters Tuesday, LeBoeuf said that “climate change and carbon emissions are a factor at play when we look at how tides are rising.” In 2019 alone, 19 locations along the east coast and Gulf coast set or tied records where rapidly increasing trends in high-tide flooding have emerged, NOAA said.
“Evidence of a rapid increase in sealevel rise related flooding started to emerge about two decades ago, and now is very clear,” the report said. “NOAA’s National Weather Service is issuing record numbers of watches (and) warnings for coastal flooding. This will become the new normal unless coastal flood mitigation strategies are implemented or enhanced.”
Last year, the Southeast saw a threefold increase in flooding days compared to 2000. For example, Charleston, S.C., had 13 days where flooding reached damaging levels, compared to the two days that were typical in 2000.
And along the western Gulf coast, percentage increases were the highest, greater than fivefold. In Texas, Sabine Pass and Corpus Christi had 21 and 18 flooding days in 2019, and in 2000 those locations would typically only experience about one and three days, respectively. “As a Chesapeake Bay resident, I see the flooding firsthand, and it is getting worse,” said William Sweet, a NOAA oceanographer with the National Ocean Service and lead author of the report.