Boston could see up to 18 days of high tide flooding next year, NOAA says

The increase in flooding at high tide is primarily the result of sea level rise, which has risen about a foot over the past century. As rising temperatures resulting from climate change warm oceans and melt glaciers around the world, sea levels are expected to rise at an accelerating rate over the next few years.

Seas now rise on average about an inch every eight years, and the number of days that coastal areas are likely to experience flooding at high tide is expected to rise sharply in coming years. NOAA predicts that sea levels could rise between 2 feet and 7 feet by 2100 and reach 12 feet by 2150.

The report projects that Boston could have 50 to 70 days of high tide flooding each year in 2050, down from the 95 days of such flooding NOAA projected for 2050 in the report. ‘last year.

“The updated numbers for 2050 are based on updated science,” said William Sweet, NOAA oceanographer and one of the report’s authors.

The city’s record for such flooding was set in 2017, when high tides inundated parts of Boston for 22 days, more than any other East Coast community.

In addition to sea level rise, flooding at high tide can be affected by changes in prevailing winds, changes in ocean currents, and the phase of the moon.

Over the next few years, high tides in Boston could be lower than the highest projections because the region is at the bottom of an 18.6-year tidal cycle, Sweet said. In the mid-2030s, when the moon’s orbit changes slightly and the tidal cycle peaks, flooding at high tide will be that much greater.

Flooding can also be mitigated by the impact of a complex weather phenomenon known as La Niña, which occurs when strong winds blow warm water away from South America and across the ocean. Peaceful. The phenomenon can affect the weather across the planet.

Last year, NOAA predicted Boston would have up to 18 days of flooding at high tide; the city had only seven days of such flooding.

Still, the pace of flooding in Boston has accelerated. Between 2010 and 2020, Boston experienced 152 days of high-tide flooding — more than in the previous 45 years — and more than triple the national average, according to NOAA data. During the same period, NOAA tide gauges across the country recorded an average of 49 days of high tide flooding.

Boston has actually recorded more high tide flooding than any other city in the country, with a total of 371 days since NOAA began keeping records in 1920.

Yet flooding at high tide is a growing problem affecting coastal communities everywhere.

Last year, three coastal communities across the United States experienced record flooding at high tide, the report said. NOAA officials said they expect more records in the coming years.

Reedy Point, Del., had six days of flooding at high tide, while Kwajalein Island in the Marshall Islands had four days and Springmaid Pier, SC, near Myrtle Beach, tied its 2021 record with 11 flood days at high tide.

The report predicts that flooding at high tide between May 2022 and April 2023 will occur on average between three and seven days, similar to the previous year. This is an increase from the two to six days expected between 2019 and 2020.

By 2050, high tide flooding is expected to occur on average between 45 and 70 days a year in coastal communities across the country, according to the report.

NOAA officials said coastal flood warnings for “potential significant risk to life and property” will become more common.

“The East and Gulf Coasts are already experiencing twice as many high tide flood days compared to 2000, flooding shorelines, streets and basements and damaging critical infrastructure,” said Nicole LeBoeuf. , director of NOAA’s National Ocean Service.

David Abel can be contacted at [email protected] Follow him on Twitter @davabel.

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