Coastal flooding is becoming more frequent, even on sunny days

Coastal flooding from high tides is becoming more common across much of the United States as climate change causes sea levels to rise.

Millions of people are affected every year by so-called sunny day flooding, according to A new report According to the National Oceanic and Atmospheric Administration (NOAA), on average, the United States experiences five additional days of high tide flooding each year compared to 2000.

“Over the last year we’ve seen record coastal flooding,” said Nicole LeBoeuf, director of NOAA’s National Oceanic Service.

Last year, St. Petersburg, Florida, Atlantic City, New Jersey, Charleston, South Carolina, and more than 30 other places tied or broke their records for high tide flooding days. Galveston, Texas, which consistently sees some of the most frequent flooding, Severe and frequent flooding due to high tides Of all the cities in the United States, last year there were 23 days of high tide flooding.

The costs of high tide flooding are enormous. Even a few inches of water can make neighborhoods inaccessible to some residents, including those who use wheelchairs or rely on strollers to transport their small children. And standing water can also make getting around difficult. Blocking emergency vehicles and causing secondary flooding if sewers overflow into buildings or overflow into natural bodies of water.

“People who live in the (Florida) Keys, Annapolis or Norfolk are facing traffic delays when they have to drop their kids off at school or get to work because water is flooding the streets,” said Karen Kavanaugh, a NOAA oceanographer. High tide flooding can also force businesses to close, and even a small amount of saltwater flooding can erode underground pipes and damage vehicles.

Sea levels They don’t rise at the same rate everywhereAnd the effects of high tide flooding are even more pronounced in places where sea levels are rising most rapidly, the report notes. Over the past 25 years or so, the number of days with high tide flooding has increased by as much as 250 percent or more in many regions, including the Gulf of Mexico and the Mid-Atlantic and Pacific islands.

“Decades of sea level rise are paying off,” says NOAA oceanographer William Sweet.

And there is no relief in sight as global temperatures continue to rise and sea levels continue to rise. The average number of high tide flooding days in the U.S. is expected to exceed 45 days by mid-century. Local governments in many coastal areas are racing to upgrade infrastructure to withstand saltwater, improve sewers and drainage, and budget for the costs of damage and disruption caused by high tide flooding.

While high-tide flood forecasts don’t account for storm-caused flooding, the same rising sea levels that are causing more sunny-day flooding are also exacerbating storm-caused coastal flooding, as residents of Florida, Georgia and South Carolina experienced after Hurricane Debby. The storm made landfall in Florida as a weak Category 1 hurricane and was quickly downgraded to a tropical storm, but storm surge and rain have caused catastrophic flooding across the Southeast, in part because rising sea levels mean the ocean is closer to the built-up shoreline.

“These areas are already under the yoke of rising sea levels, making the combination of Debby’s storm surge and rainfall potentially catastrophic,” LeBoeuf said.

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