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Record-Breaking High Tide Floods Are on the Rise

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Flooding after an October 2019 storm in Florida. Expect even more of this in the near future.
Flooding after an October 2019 storm in Florida. Expect even more of this in the near future.
Photo: Joe Raedle (Getty Images)

There’s no need to wait for the watery future of our coasts. Data from 98 sites along the U.S. coast shows that high tide flood are on the rise.

Using data from May 2019 to April 2020, a new report from the National Oceanic and Atmospheric Association shows that coastal communities saw a median flood frequency of four days in 2019. That’s just shy of last year’s record-setting median of five days. Some coastal areas got hit worse than others: 19 locations on the Atlantic and Gulf of Mexico coasts broke or tied their all-time high tide flooding records, including Corpus Christi and Galveston in Texas as well as Annapolis, Maryland, and Charleston, South Carolina.


“In 2019, Charleston suffered 13 days of damaging flood levels, compared to about two days in the year 2000,” Nicole LeBoeuf, acting director of NOAA’s National Ocean Service, said on a press call. “In my home state of Texas, Sabine Pass and Corpus Christi had 21 and 18 days of flooding in 2019, where they saw only about one and three days [in 2000], respectively.”

NOAA defines a high tide flooding—also called sunny-day or nuisance flooding—as any instance where tides exceed 1.75 feet above the daily average high tide and begin teeming into streets or shooting up through storm drains. These floods can spill into people’s basements and other establishments and may cause damage that costs even more to repair than that caused by extreme storms. Instances of high-tide flooding in the U.S. has increased rapidly over the past couple of decades.


The culprit for this rapid increase in high tide flooding is sea level rise. Globally, sea levels are rising by about an inch every eight years. And the country has seen sea levels rise by 1.1 feet since 1920, the scientists found, and that trend has been accelerating over the past decade.

The rise is being caused by ocean waters that are expanding as they heat up and melting land ice in Greenland and Antarctica. The latter of which accounts for two-thirds of the rise, according to William Sweet, an oceanographer with NOAA on the call. Both are symptoms of the climate crisis, though the report doesn’t mention “global warming” or “climate change.

The scientists also includes projections of future high-tide flooding occurrences, and they expect this trend of increasing risk to continue. By 2030, their projections show that coastal communities in the U.S. will see up to 16 days of high tide flooding per year. By 2050, those areas could see up to 50 days of these sunny day floods per year. They didn’t make predictions past 2050, but as LeBoeuf said, without drastic action to draw down greenhouse gas emissions and slow climate change, “you see where this is going.”