Skip to main content

Record high tide flooding hit coastal communities last year

Record high tide flooding hit coastal communities last year


The problem is getting worse

Share this story

Washington’s Tidal Basins Sea Walls Crumble Due To Rising Sea Levels
A walkway at the Tidal Basin leads to a flooded sidewalk from the rising high tide on July 2nd, 2019, in Washington, DC. The Tidal Basin’s crumbling seawall and sidewalks are routinely under water due to the rising sea levels high tides and threatening some Cherry Blossom Trees. 
Photo by Mark Wilson / Getty Images

High tide flooding hit record levels in the US last year and is only expected to get worse, according to a new report by the National Oceanic and Atmospheric Administration (NOAA). Coastal communities experienced twice as many days with high tide flooding last year than they did 20 years ago. Records were either matched or broken in 14 places across the Southeast Atlantic and Gulf coastlines.

Nationally, coastal communities were hit with a median of four days of high tide flooding in the past year — although some places suffered through more than quadruple that number. NOAA’s outlook for the rest of the year until April 2022 rises to three to seven days of flooding. But because of sea-level rise tied to climate change, the long-term forecast is more alarming: 2030 could see seven to 15 days of flooding. And 2050 could bring on a whopping 25 to 75 days of high tide flooding. 

“For the first time in human history, the infrastructure we build must be designed and constructed with future conditions in mind”

That could harm roads, waste, and stormwater systems, NOAA warned. With high tide flooding becoming much more frequent, cities and neighborhoods will need to adapt. 

“For the first time in human history, the infrastructure we build must be designed and constructed with future conditions in mind along the coast,” said Nicole LeBoeuf, director of NOAA’s National Ocean Service, on a press call yesterday. “These data that we provide help communities plan where to put their buildings and how to keep people safe.”

High tide flooding, also called “nuisance” or “sunny-day” flooding, inundates streets and homes with water levels that reach up to two feet higher than the average high tide. While low and high tides are caused by the Moon, this nuisance flooding is driven by additional factors. As average global temperatures rise, oceans expand and push seawater even further ashore. The situation for coastal residents gets worse in places where land is subsiding or natural coastal barriers are eroding. Things will get even trickier in the mid-2030s when a regular wobble in the Moon’s orbit will combine with sea level rise to cause higher tides, a new analysis by NASA found.

Real estate valued at $1 trillion is vulnerable to coastal flooding — and we’re not just talking about summer beach homes. By 2050, the number of affordable housing units vulnerable to flooding could triple as a result of climate change, according to one study published last year.

In some places, the change has been extremely swift

Costly floods that in the past might have only posed a threat during a storm, might now be triggered by merely a change in prevailing winds or currents or even a full Moon, according to NOAA. The agency tracks 97 tide gauges across the US, and it looked at May 2020 to April 2021 for its new report. Eighty percent of the places where it collects data along the Southeast Atlantic and Gulf coasts saw an uptick in flood days. (The West Coast was spared some flooding because of a La Nina last year.)

In some places, the change has been extremely swift. People living along the western Gulf of Mexico saw 17 flood days last year — an astonishing 1,100 percent increase from what they experienced in 2000. Residents along the eastern Gulf had nine flood days, a 600 percent jump over the past two decades. The Southeast Atlantic coast got eight flood days, a 400 percent rise from 2000.

“We’re seeing a dramatic change in just two decades, and the conditions are changing not just in a few locations,” LeBoeuf said. This change isn’t confined to the US. Coastlines around the planet are at risk for more frequent and extreme flooding. The frequency of severe flooding in the tropics, for instance, could get 25 times worse by 2030, previous research has found.