NASA warns that moon ‘wobble’ could mean severe coastal flooding, lasting a month or more, in near future

Science

SILive.com 16 July, 2021 - 09:44am 65 views

When will the moon wobble?

The moon is currently in the tide-amplifying part of its 18.6-year wobble, in 2021. But most U.S. coastlines have not yet seen enough sea-level rise to notice the flooding effects. NBC 10 PhiladelphiaMoon ‘Wobble' in 2030s Will Increase High Tide Flooding in NJ, Del. Shore Towns

Scientists say it’s less like a wobble and more like a slow, predictable cycle. And while the phenomenon will contribute to rising tides caused by climate change, it is just one of many factors.

Sometimes, the moon seems to move in mysterious ways.

It’s mostly circles and ovals, depending on your perspective. But there is also something else — a so-called wobble — animating those rotations and revolutions. According to a study published last week, the phenomenon is expected to lead to more flooding here on Earth in the middle of the next decade.

While that may sound alarming, the wobble is nothing new. It is a regular oscillation that humans have known about for centuries, and it is one of many factors that can either exacerbate rising sea levels or counteract them, alongside other variables like weather and geography.

The authors of the study, published in the peer-reviewed scientific journal Nature Climate Change, aimed to untangle all of those variables in an effort to improve predictions about the future of floods. Their results underscored a basic fact separate from the movement of the moon: Our oceans are rising because of climate change.

“They’re getting awfully close to the brim in coastal communities due to decades of sea level rise,” said William V. Sweet, an oceanographer with the National Oceanic and Atmospheric Administration and one of the paper’s authors.

Rising temperatures caused by greenhouse gas emissions are not the only cause of higher flood risks, and the report explored the interplay of many variables that push and pull at ocean levels.

“It’s really helping diagnose and disentangle the predictability of the tide and its potential impacts along the coast,” Dr. Sweet said.

But in news media reports about the study, one particular variable seemed to capture outsize attention: the moon wobble. The study warned that we should expect this wobble to heighten high tides in the middle of the 2030s, but it also showed that this prediction does not apply uniformly to every coastline everywhere.

As NASA put it in a news release last week: “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.”

So where, exactly, does this wobble come from?

First, some background: High tides on this planet are caused mostly by the pull of the moon’s gravity on a spinning Earth. On most beaches, you would see two high tides every 24 hours.

The moon also revolves around the Earth about once a month, and that orbit is a little bit tilted. To be more precise, the moon’s orbital plane around the Earth is at an approximate five-degree incline to the Earth’s orbital plane around the sun. (Here are a couple videos to illustrate this.)

Because of that, the path of the moon’s orbit seems to fluctuate over time, completing a full cycle — sometimes referred to as a nodal cycle — every 18.6 years. “It happens on such a slow scale,” said Benjamin D. Hamlington, a co-author of the paper who leads the Sea Level Change Team at NASA. “I think ‘precession’ is a more specific word than wobble.”

At certain points along the cycle, the moon’s gravitational pull comes from such an angle that it yanks one of the day’s two high tides a little bit higher, at the expense of the other. This does not mean that the moon itself is wobbling, nor that its gravity is necessarily pulling at our oceans any more or less than usual.

“The emphasis on the nodal cycle is a little bit different from the message we were trying to convey,” Dr. Hamlington said. But he added that the phenomenon was worth paying attention to.

High-tide flooding related to climate change is expected to break records with increasing frequency over the next decade, and people who want to accurately forecast that risk have to work with a lot of noisy data, including weather patterns, astronomical events and regional tidal variation.

The moon wobble is part of that noise, but it has always maintained its own slow, steady rhythm.

“It’s just acting in the background as sea levels rise,” said Brian McNoldy, a senior research associate at the University of Miami’s Rosenstiel School of Marine and Atmospheric Science.

“During its most rapid upward phase, it acts to enhance the effective sea level, and during its most rapid downward phase, like we’re in now, it acts to suppress the effective sea level,” said Mr. McNoldy, who has written about the lunar nodal cycle but was not a part of the Nature study. “It is not part of sea level rise projections, because it’s not sea level rise; it’s just an oscillation.”

Other variables aside — and speaking very generally, since every region is different — the effect of the wobble could cause high tide levels at a beach to oscillate by one or two inches over the course of its long cycle.

That may sound small. But in certain situations, it can matter quite a bit.

“It just kind of raises the baseline,” said Philip R. Thompson, the lead author of the study and the director of the Sea Level Center at the University of Hawaii. “And the more your baseline is raised, the smaller weather event you need to cause a flooding event.”

Understanding that baseline is important even when we are in the phases of the nodal cycle that would seem to counteract rising sea levels, which is what’s happening now.

“If we know what’s going on, then we shouldn’t be complacent,” Dr. Thompson said. “It’s important to realize that at the mid-2030s point, where the switch flips and the natural cycle seems to amplify the rate of sea level rise, then we are going to see a rapid change.”

Read full article at SILive.com

Sci-Simplified: What Is the Moon Wobble, and How It Could Lead to Disastrous Floods in World's Coastal Regions | The Weather Channel - Articles from The Weather Channel | weather.com

The Weather Channel 17 July, 2021 - 08:10pm

Among the enumerable and widespread repercussions of such melting, one of the scariest is the rising of the sea levels. It has the potential to inundate the coastal regions of the world, effectively impacting the lives of millions of people globally.

Coupled with the climate-change-induced rise in sea levels, the tides in Earth’s oceans—which are controlled by the Moon's gravitational pull—could also play a role in the severe flooding of worldwide coastal areas by the time the ongoing decade approaches its end.

The grim projections are detailed in a new first-of-its-kind study conducted by the US space agency NASA, which elucidates how the moon’s elliptical orbit around Earth and the moon’s wobble effect can lead to considerable changes on our planet.

The moon wobble is nothing but a regular swaying in the moon’s orbit. It was first documented way back in 1728. This wobble takes over an 18.6-year period to complete, and continues in a cyclic fashion.

The moon wobble impacts the gravitational pull of the moon, and therefore, indirectly influences the ebb and flow of tides here on the Earth. In fact, as per the NASA study, each wobble cycle has the power to amplify and suppress the tides on Earth.

One half of the 18.6-year cycle suppresses the tides, which means that the high tides get lower, while the low tides get higher than normal. Once this cycle completes, the situation flips—in the subsequent cycle, the tides are amplified, with high tides getting higher and low tides, lower!

The lunar cycle is expected to shift again by mid-2030, and in the coming phase, the tides will amplify once again.

The upcoming changes in the lunar cycle will pose a serious threat, as the amplified high tides coupled with the rising sea levels will make the risk of flooding far greater across all coastal regions of the globe.

The study predicts that the high tide-associated floods—also known as nuisance floods or sunny day floods—may occur in clusters that could last for months or even for longer periods!

This surge will be closely associated with the position of the Moon, Earth and the Sun. A NASA statement explains: “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.”

As per NOAA, episodes of such flooding are already on the rise, especially across the U.S. Atlantic and Gulf coasts. In 2019, over 600 such floods were reported from the US. With these grim projections, the flooding situation is likely to worsen, especially for people living in the low-lying regions of the globe.

The study and its findings have been published in the journal Nature Climate Change and can be accessed here.

Moon ‘wobble,’ rising sea levels to cause surge in floods in 2030s—NASA

INQUIRER.net 16 July, 2021 - 08:46pm

A natural lunar cycle paired with rising sea levels due to climate change will result in a surge in flooding in the mid-2030s, National Aeronautics and Space Administration (NASA) researchers said.

The said floods are expected to exceed known flooding thresholds at least in the United States. These floods will also sometimes occur in clusters that can last for a month or even longer, which will depend on the positions of the Earth, Moon and Sun.

“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,” he added.

Thompson said that these high-tide floods involve less water than those in storm surges, which may lead to the public seeing it as a less significant problem.

“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,” he said.

The trigger for these floodings is from the so-called “wobble” in the Moon’s orbit, which takes 18.6 years to complete. NASA noted that this wobble is nothing new, however, as it was first reported in 1728.

“The researchers uncovered these tipping points in flood numbers by studying 89 tide gauge locations in every coastal U.S. state and territory but Alaska,” NASA explained.

“They created a new statistical framework that mapped NOAA’s widely used sea level rise scenarios and flooding thresholds, the number of times those thresholds have been exceeded annually, astronomical cycles, and statistical representations of other processes, such as El Niño events, that are known to affect tides. They projected results to 2080,” it added.

Coastal urban planners, meanwhile, should take note of this study, said study’s co-author Ben Hamlington, who works at NASA’s Jet Propulsion Laboratory in Southern California.

He pointed out that planners may not be preparing for these frequent and high-tide floods and that they may focus more on extreme events.

““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,” Hamlington was quoted as saying. Ian Biong /ra

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NASA Says 'Moon Wobble’ May Cause a Problem for Earthlings | Digital Trends

Digital Trends 16 July, 2021 - 01:00am

To add to the growing number of climate issues already facing humanity, NASA said that a periodic “wobble” performed by the moon will combine with rising sea levels to cause increasingly serious high-tide flooding events along coastlines in the U.S. and beyond.

According to a recent study conducted by NASA’s Sea Level Change Team and published this month in the Nature Climate Change journal, the gravitational pull of the moon is likely to cause “dramatic increases in flood numbers” in coastal cities in the mid-2030s.

Painting a grim picture for some communities living close to the sea, NASA said, “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,” adding that such events could also happen in clusters and last for more than a month at a time.

NASA said the moon wobble is a natural, recurring event that takes place across its 18.6-year cycle. For half of the cycle, the moon’s gravitational pull suppresses daily tides, decreasing high tides and increasing low tides. But during the other half of the cycle, tides are amplified, with high tides increasing and low tides decreasing.

Right now the moon is in the tide-amplifying part of its cycle, but current sea levels mean that most coastal cities in the U.S. are still out of the danger zone. However, when the next tide-amplifying cycle hits in the 2030s, researchers say sea levels will have risen further, with NASA’s data forecasting potentially troublesome flood events for some coastal communities.

Phil Thompson, an assistant professor at the University of Hawaii and the lead author of NASA’s study, said that while high-tide floods tend to be less serious than hurricane storm surges, the former could be particularly problematic if they begin to happen multiple times a month, after all, as Thompson put it, “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.”

Commenting on the study’s findings, NASA chief Bill Nelson said: “Low-lying areas near sea level are increasingly at risk and suffering due to the increased flooding, and it will only get worse.”

However, offering a ray of hope, Nelson added that NASA’s Sea Level Change Team is working to provide crucial information to enable cities to “plan, protect, and prevent damage to the environment and people’s livelihoods affected by flooding.”

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