‘Moon wobble,’ climate change expected to cause surge in flooding in US coastal communities, study says

‘Low-lying areas near sea level are increasingly at risk,’ a NASA administrator says

Editor’s note: Read more climate reporting on KSAT’s Forecasting Change page.

Every coastline in the U.S. will experience rapidly increasing high-tide flooding due to “moon wobble” and climate change, according to a new study.

But what is “moon wobble”? It isn’t a new phenomenon, according to NASA.

It is a cyclical shift in the moon’s orbit every 18.6 years and they’ve been recorded since 1728.

The wobble affects the moon’s gravitational pull and can either suppress or amplify ocean tides on earth. That mixed with rising sea levels could create risk for people who live in coastal communities, according to NASA.

“In half of the Moon’s 18.6-year cycle, Earth’s regular daily tides are suppressed: High tides are lower than normal, and low tides are higher than normal. In the other half of the cycle, tides are amplified: High tides get higher, and low tides get lower,” the study says.

The next cycle that is expected to amplify tides again will happen in the mid-2030s, NASA says. During that time, “a leap in flood numbers” is expected along the U.S. coastline, Hawaii and Guam.

The Gulf of Mexico’s coastlines were specifically mentioned as an area of concern because they are more vulnerable to flooding due to relatively narrow sea-level distributions.

“Low-lying areas near sea level are increasingly at risk and suffering due to the increased flooding, and it will only get worse,” said NASA Administrator Bill Nelson. “The combination of the Moon’s gravitational pull, rising sea levels, and climate change will continue to exacerbate coastal flooding on our coastlines and across the world. NASA’s Sea Level Change Team is providing crucial information so that we can plan, protect, and prevent damage to the environment and people’s livelihoods affected by flooding.”

Compared to hurricane storm surges, high tide floods only involve a small amount of water.

About the Authors:

Sarah Acosta is a weekend Good Morning San Antonio anchor and a general assignments reporter at KSAT12. She joined the news team in April 2018 as a morning reporter for GMSA and is a native South Texan.

Rebecca Salinas has worked in digital news for more than 10 years and joined KSAT in 2019. She reports on a variety of topics for KSAT 12 News.