Moon wobble to bring surge in coastal flooding in 2030s, NASA study predicts | Hacker News Reader

Moon wobble to bring surge in coastal flooding in 2030s, NASA study predicts

edition.cnn.com

126 pointsjeffwass43 comments

https://scholar.google.com/citations?view_op=view_citation&h...

This appears to be the article being discussed. Figure two and reference 30 give numbers for the magnitude of the 18 year variation due to moon wobble. In St Petersburg, Florida, it's a 4.7 cm variation. Other parts of the world can experience up to a 30 cm variation of high tide variation.

So basically it's definitely something to account for with the linear rise of sea level due to climate change, with some years being worse relatively to others.

Thank you for posting the original paper. Figure 2 has a great depiction of the effect. That 4.7 cm variation, because it cycles every 18 years, can increase or decrease the effects of inherent sea level rise: at a minimum of the cycle, an expected sea level increase of 8.9 cm instead ends up only being 4.1 cm; but by the next decade, an expected increase of 9.4 cm surges to a peak high tide of 14.1 cm higher than before.

One main takeaway is this effect occurs at different times around the world–within the US, different states will experience flooding in different decades. Federal mitigation efforts can be focused on regions that would be impacted first. However, by the 2030s, most seacoasts will be flooding at least on occasion due to extreme high tides.

The other effect predicted is, per year, the extreme high tide days will cluster together within a month or so in each region. They mention this because policy or planning for these types of extreme events usually think about it in terms of single isolated events, but this model predicts short “seasons” of extreme tides. Future mitigations should take that into account.

No problem, this article is being shared on other news sites now. And it's genuinely confusing to me why the original nature article isn't linked, or why Figure 2 isn't shown in any of them. The figure speaks for itself and even looks very nice. I don't understand reporting on scientific news.

EDIT: Actually axios linked to the original article, so good for them https://www.axios.com/nasa-moon-wobble-coastal-flooding-c462...

That CNN article is a crappy rewrite of this NASA press release: https://sealevel.nasa.gov/news/222/study-projects-a-surge-in...

Which itself does not have any specific data on how much peak high tides will rise.

At least it gives the period of the lunar cycle -18.6 years, and we're at the peak right now.

If I understand correctly it's mainly the effect of the moon's nodal precession [0] in combination with climate-change induced rising sea levels.

I am curious about its effects on non-US coastal cities as well (also personally, as I happen to live in one). Hopefully it will be repeated/extended in the future.

[0] https://en.m.wikipedia.org/wiki/Lunar_precession#Nodal_prece...

> If I understand correctly it's mainly the effect of the moon's nodal precession [0] in combination with climate-change induced rising sea levels.

Sea level rise since 1995 has averaged 3.4 mm per year[1].

Is there an expectation that this will accelerate significantly? or is a change in 30mm expected to contribute significantly to flooding?

[1]: https://climate.nasa.gov/vital-signs/sea-level/

As the average temperature increases, it seems reasonable to expect the rate of melting, thus sea level rise, increase. Add to that highly nonlinear effects like the "clathrate gun", and a continuing linear increase in sea level seems highly non-obvious

Warm temps push more water to the atmosphere so its not linear in terms of sea level rise. You'd expect more ice to melt but you might also see more snow, glaciers growing.

Nope, I'd expect the current trend of glaciers and icecaps melting to continue or accelerate. And for rainy seasons to get more severe. As they have been.

But this is talking about 2030, not 2100. I guess the question is, if sea level rise stopped completely today, would there be no problem in 2030?

Why is that the question? Is there any evidence to suggest that the sea level will completely stop rising today?

> Why is that the question?

Because the article is about 2030 and unless the rate of sea level rise accelerates significantly in 9 years that means sea level will be about 36 mm higher in 9 years. And it is hard for me to see how 36 mm higher sea level will flood much of anything, so it seems that the moon wobble will do most of the heavy lifting if we compare the situation today to the predicted situation in 2030.

> Is there any evidence to suggest that the sea level will completely stop rising today?

No.

Consider the mass of 36mm integrated over the area of our oceans. That mass has been converted from solid to liquid. What was once rigid is now a veritable loose canon. The effect of tidal forces is to concentrate that mass towards the moon -- so the amplitude of flooding caused by a lunar wobble should be expected to be greater with more liquid water available to participate. I wouldn't be so quick to dismiss the impact of that rise.

It seems like a lot?

Just first google result 2* C warming would be ~10cm and reading the effects of that sounds pretty bad.

https://www.vox.com/energy-and-environment/2018/1/19/1690840...

The article misses out a very important detail...

What is the scale of this effect? If I normally have a 7 meter tidal range, will I be getting a 9 meter range? Or just a 7.01 meter range?

Still trying to figure out how fracking, eating meat, and SUVs can possibly affect the Moon's wobble....

So what will coastal cities (eg Bay Area) do?

Does Bay Area have that problem even theoretically? They are quite high up. It's the flat near sea level areas like Florida that are in danger.

https://www.adaptingtorisingtides.org/

Aren't places like the pier area pretty low?

Probably look at places that already have flooding on king tides. San Diego, Newport Beach, seal beach, motto bay, etc. I think a lot of the stuff on sf bay is built on piers high above the highest tides.

Where is the flooding in San Diego? Honestly wondering, because the only places I might expect are Mission Beach and maybe Imperial Beach.

Yeah San Diego is a weird example - most of our coastal property is relatively high up.

A quick Google of "king tides flooding San Diego" shows a couple news articles mentioning National City and Imperial Beach, so your suspicions are probably correct - it's the flatter places down south that everyone forgets exist.

You might be able to answer this yourself based on the tides now. Just ask what a more exaggerated tide would do.

If current tides are putting you within 30cm of danger, then you're already flooding frequently from sea storms. Tides aren't the danger when living on the coast, wind that pushes water is.

The Dutch might have a new industry, exporting their skill at reclaiming land from the sea.

And how to keep inland areas below sea level, pumped dry reliably.

Sadly the Dutch have their own problems now and probably need to focus all of their efforts on their own coastline like the rest of us, unless you think they can export "an integrated approach, in which all stakeholders are involved in finding solutions for climate change issues" to other countries like the U.S. that are "more individualistic." https://www.pbs.org/wnet/peril-and-promise/2019/07/dutch-bar...

That's rather the opposite of this XKCD What-If on draining the oceans:

https://what-if.xkcd.com/53/

> And after 2000 years of trying to hold back the sea, the Netherlands are finally high and dry. No longer living with the constant threat of a cataclysmic flood, they're free to turn their energies toward outward expansion. They immediately spread out and claim the newly-exposed land.

Interesting to note that in the past, sea levels were 100+ meters lower. There are ancient stories that tell of now underwater landmarks.

https://en.wikipedia.org/wiki/Early_Holocene_sea_level_rise

https://theconversation.com/ancient-aboriginal-stories-prese...

Low Countries have this problem since centuries back, yes? Dikes, pumping, other options have mitigated issues. It is the developing country needing to worry, those with out money for these.

Off topic, but how are these OneTrust cookie settings GDPR compliant? I though there had to be a way to opt out of these?

Link different devices Always Active Different devices can be determined as belonging to you or your household in support of one or more of purposes.

Deleted comment

The second sentence of the article makes it clear that the moon's natural cycle combined with climate change will create an unprecedented flood risk.

No one should write articles for unbelievers. They are not unbelievers because they don't have access to enough facts. They're unbelievers for reasons of emotion, identity, contrarianism, stupidity, etc.

Is it only the United States?

No, its the moon too.

Reply on news.ycombinator.com