The Wobbling Moon and Earth's Rising Tides

"What's new is how one of the wobble's effects on the moon's gravitational pull -- the main cause of Earth's tides -- will combine with rising sea levels resulting from the planet's warming."

"The Moon is in the tide-amplifying part of its cycle now. However, along most U.S. coastlines, sea levels have not risen so much that even with this lunar assist, high tides regularly top flooding thresholds. It will be a different story the next time the cycle comes around to amplify tides again, in the mid-2030s. Global sea level rise will have been at work for another decade. The higher seas, amplified by the lunar cycle, will cause a leap in flood numbers on almost all U.S. mainland coastlines, Hawaii, and Guam. Only far northern coastlines, including Alaska’s, will be spared for another decade or longer because these land areas are rising due to long-term geological processes."

National Aeronautics and Space Administration report, United States

"Low-lying areas near sea level are increasingly at risk and [are already] suffering due to increased flooding ... and it will only get worse."

"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."

Bill Nelson, head, NASA space agency

"It's the accumulated effect [of the floods] over time that will have an impact. If it floods ten or fifteen times a month a business can't keep operating with its parking lot under water."

"People lose their jobs because they can't get to work. Seeping cesspools become a public health issue."

Phil Thompson assistant professor, University of Hawaii, lead author NASA report

High-tide flooding in Honolulu.

Credits: Hawaii Sea Grant King Tides Project

We've been warned. The moon's future effect on our planet when it undergoes its regular 'wobble' period, now influenced as well by climate change is forecasted to behave like a large water-carrying vessel that tips too far when the oceans react to the tip by pouring their load onto nearby land masses. Coastal areas are set to be inundated all over the world, causing geological instability and great upheavals that communities are warned to prepare for, in hopes of mitigating the worse-case scenarios.

The moon's orbit undergoes a regular 'wobble', a phenomenon first recorded in 1728. The 'regular wobble' completes itself in 18.6 years. Daily tides on Earth are suppressed for fifty percent of that time span with high tides lower than normal and low tides even lower. But with the rise of global sea levels as a result of climate change the amplification effect will become more pronounced. In the second half of the cycle high tides become higher, low tides lower.

The next anticipated 'lunar assist' to high tides arrives in the mid-2030s and by then it is assumed that global sea level rise will be well established for at least a decade. A 'tipping point' will have passed, the result being a "leap in flood numbers on almost all U.S. mainland coastlines", according to NASA.

Planning ahead, according to Bill Nelson, head of the space agency, will be critical so that businesses and people's livelihoods will have a buffer of a level of protection. "High-tide floods" were examined for the study. These are also known as "nuisance floods", are not as devastating in their outcomes as storm surges caused by weather conditions such as hurricanes.

The United States experienced roughly 600 nuisance floods in 2018, according to the National Oceanic an Atmospheric Administration. Under this oncoming scenario, coastal areas of the United States could realize three to four times as many on an annual basis from the mid-2030s forward, according to NASA. The study and its conclusions produced by NASA's sea-level change science team at University of Hawaii.

"Why will cities on such widely separated coastlines begin to experience these higher rates of flooding at almost the same time? The main reason is a regular wobble in the Moon’s orbit that takes 18.6 years to complete. There’s nothing new or dangerous about the wobble; it was first reported in 1728. What’s new is how one of the wobble’s effects on the Moon’s gravitational pull – the main cause of Earth’s tides – will combine with rising sea levels resulting from the planet’s warming."

NASA report 

Nearly all US mainland coastal areas will see a surge in high-tide floods in the mid-2030s, when a lunar cycle will amplify rising sea levels, a NASA study found