Danger Ahead: NASA Warns of Unprecedented Frequent Coastal Flooding Due to Rising Tides, Wobble in Moon’s Orbit

We ain’t seen nothin’ yet.  That’s the bottom line in a new report looking ahead at the potential for cataclysmic weather along the nation’s coastline as soon as a decade from now.  Climate change has already increased the frequency and severity of hurricanes and other extreme weather events around the world. But the perfect storm of events – on Earth and on the Moon – has the potential for flooding well beyond what has been experienced to date.

The report indicates that coastal areas that now face just two or three floods a month may soon face a dozen or more.  These prolonged coastal flood seasons will cause major disruptions to lives and livelihoods if communities don't start planning for them now, the researchers cautioned.

Connecticut’s Department of Energy and Environmental Protection (DEEP) has not responded to inquiries from Connecticut by the Numbers for comment on the report and efforts to mitigate the impact in Connecticut.

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 what is described as a leap in flood numbers on almost all U.S. mainland coastlines, as well as on Hawaii and Guam, according to the new report.

Led by the members of the NASA Sea Level Change Science Team from the University of Hawaii, the new study shows that high tides will exceed known flooding thresholds around the country more often.  The floods will sometimes occur in clusters lasting a month or longer, depending on the positions of the Moon, Earth, and the Sun. When the Moon and Earth line up in specific ways with each other and the Sun, the resulting gravitational pull and the ocean’s corresponding response may leave city dwellers coping with floods every day or two, the report explains.

“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.”

“It’s the accumulated effect over time that will have an impact,” said Phil Thompson, an assistant professor at the University of Hawaii and the lead author of the new study, published recently in Nature Climate Change. Thompson pointed out that because high-tide floods involve a small amount of water compared to hurricane storm surges, there’s a tendency to view them as a less significant problem overall. “But if it floods 10 or 15 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.”

Ben Hamlington of NASA’s Jet Propulsion Laboratory in Southern California is a co-author of the paper and also the leader of NASA’s Sea Level Change Team. He notes that the findings of the new study are a vital resource for coastal urban planners, who may be focused on preparing for extreme events rather than more high-tide floods.

“From a planning perspective, it’s important to know when we’ll see an increase,” Hamlington said. “Understanding that all your events are clustered in a particular month, or you might have more severe flooding in the second half of a year than the first – that’s useful information.” A high-tide flood tool developed by Thompson already exists on the NASA team’s sea level portal, a resource for decision-makers and the general public. The flood tool will be updated in the near future with the findings from this study.

The publication Live Science recently pointed out that the moon influences the tides, but the power of the moon's pull isn't equal from year to year; the moon actually has a "wobble" in its orbit, slightly altering its position relative to Earth on a rhythmic 18.6-year cycle. For half of the cycle, the moon suppresses tides on Earth, resulting in lower high tides and higher low tides. For the other half of the cycle, tides are amplified, with higher high tides and lower low tides, according to NASA.

We are currently in the tide-amplifying part of the cycle; the next tide-amplifying cycle begins in the mid-2030s; — and, by then, global sea levels will have risen enough to make those higher-than-normal high tides particularly troublesome, the researchers found. 

In a little more than a decade, high-tide flooding will transition "from a regional issue to a national issue with a majority of U.S. coastlines being affected," the report’s authors wrote. Other elements of the climate cycle, like El Niño events, will cause these flood days to cluster in certain parts of the year, resulting in entire months of unrelenting coastal flooding.