Every 18.6 years, the moon completes a cycle in which the satellite’s orbit moves through various planes relative to Earth’s equator.  While an average stargazer likely doesn’t notice it, the pattern influences the tides around the world.

According to a NASA report published in the journal “Natural Climate Change,” this “wobble” of the moon will combine with worsening sea rise due to climate change conditions to cause frequent flooding due to unusually high tides, impacting coastal cities and developments as well as islands.

“We’re going to have sort of a double-whammy,” William Sweet, an oceanographer at the National Oceanic and Atmospheric Administration (NOAA) and author of the study, said Wednesday. “It means that coastal communities — unless they adapt and fortify — are likely to expect even greater flooding than they might otherwise.”

The planet is in the fading phase of one of these Moon wobbles now, and according to NOAA, some cities along the coast of the Atlantic Ocean and the Gulf of Mexico–Corpus Christi and Galveston in Texas and Bay St. Louis-Waveland, Mississippi–have reported flooding from unusually high tides in 2020 and 2021.  Those communities reported 20 days of flooding due to tides in the 12 months prior to April 2021.

By 2030, seven to 15 days of such flooding is expected nationally. Two decades later, estimates indicate that there could be an average of 25 to 75 days a year, NOAA predicts.

“You might have a situation where a business might have its parking lot flooded 10 or 15 times in a month — that’s not a nuisance any longer. That’s a significant economic impact on that person,” Phil Thompson, director of the University of Hawaii Sea Level Center, said. “It’s really the accumulated impact of many small, seemingly minor issues. But when a minor issue occurs chronically, it becomes a bigger problem.”