Is Historic Newport, RI Threatened by Sea Level Rise?

Guest Essay by Kip Hansen

 

featured_image_NewporttThe New York Times has treated its readers to an in-depth piece in the Science section with the provocative title: ‘We Cannot Save Everything’: A Historic Neighborhood Confronts Rising Seas.  In the article, by author Cornelia Dean, the claim is made that:

 

The Claim:

“Climate change is forcing experts to reimagine the future of historic preservation here.”

“Rising seas have left preservationists wondering how, or even whether, to save some Colonial-era homes here”.

“The Point, [ in Newport, R.I.] a waterfront neighborhood here, is one of the largest, best preserved and most important Colonial-era communities in the United States. Its grid of 18th-century streets contains scores of houses built before the American Revolution, and dozens more that are almost as old.”

“Today, the neighborhood faces a new threat. The Point sits only a few feet above sea level, and because of climate change, the ocean is rising. So people have been thinking again about how to preserve the neighborhood.”

SPOILER:  Is Historic Newport, RI Threatened by Sea Level Rise?

YES and NO

Yes, the neighborhood called The Point is at risk from normal everyday, centuries-long absolute sea level rise which accounts for much of the relative sea level rise  at Newport exacerbated by the subsidence of the low-lying neighborhood as the now centuries-old fill continues to settle and to wash out from under it with each tide cycle as it has from the moment the fill was dumped into the harbor to create the land the neighborhood was built on.

No, the problems at The Point are not caused by Climate Change, unless one is referring to the change of the climate from the Little Ice Age  (16th to the 19th centuries) to the Modern Warm Period.

 For those still interested, it is a useful mental exercise to go through the steps necessary to arrive at the above conclusions.

So, let me set some of things straight concerning the claim:

a.  because of climate change, the ocean is rising.” — Sea level, worldwide, is rising and according to NOAA, “the absolute global sea level rise is believed to be 1.7 +/- 0.3 millimeters/year during the 20th century.”  2 mm a year for 100 years = 200 mm = 7.8 inches.  This long-term rate of global sea level rise is generally quoted to be 8 to 12 inches pre century — depending on the source.  The linear trend of absolute sea level rise (how much higher the sea surface is from the center of the Earth) is literally a straight line:

NOAA_SLR_Satellite

Note that NOAA makes two different statements about sea level rise:  one based on long-term historic data (as above)  — “absolute global sea level rise is believed to be 1.7 +/- 0.3 millimeters/year during the 20th century” and produces another, the graph here, of satellite measured SLR, which they state is “2.9 ± 0.4mm/year” in the satellite era.  There has, as yet, been no real definitive reconciliation between the two figures in the literature.  The long-term difference between the two, over a century, would be about 4 inches.  The satellite’s additional four inches do not appear at GPS-corrected tide gauges around the world.  The most cited reference for this is Church and White (2011) [ .pdf here ].

Church_and_White_2011_400

Our rule-of-thumb guess-timate of “8 to 12 inches” per century covers both the tide gauge and satellite calculations. There is some increase in volume of sea water as it warms, but it has not recently or radically warmed differently than since the end of the Little Ice Age, circa 1800-1850 or so.

 

The change in the climate from the Little Ice Age to the Modern Warm Period has caused, and is causing, the seas to rise at a more-or-less steady rate, for 170 years now, of about 1.5 to 3mm per year or between 5/100th  to 1/10th of an inch each year.

b.  “Climate change is forcing experts to reimagine the future of historic preservation here.” Above, we cover the “climate change” claim — it is the change from the Little Ice Age to the Modern Warm period that is the change responsible — “here” is generally Newport, Rhode Island. Let’s check the tide gauge data there:

RSLR_Newport_RI

In the last 100 years, relative sea level, at the tide gauge, has risen about 9 inches (we’ll give it the standard 8-12 if you wish). NOAA’s note at the bottom of the image gives 9.1 inches.   Remember that the tide gauge has been changed (and probably moved) several times since 1930, and it currently looks like this:

NOAA_Tide_Station_8452660

The tall white tubes on this side of the gangway are the measuring device itself, and the electronics (computers, satellite dish, etc.) are in the white waterproof steel box on the quay.  Notice that the quay is obviously constructed on fill — it not only isn’t a natural part of the land, it has been created by dumping rocks and soil into the water at the edge of the harbor, and reinforced with large blocks of concrete.  There is no way of easily determining whether or by how much the quay is settling (subsiding), thus the tide gauge, as NOAA points out, measures only Relative Sea Level and the rate of change represents 1.7mm/year plus or minus vertical land movement — in this case almost certainly subsidence.

Newport, Rhode Island does have a Continuously Operating GPS Reference Station (CORS) but it is not here at the tide gauge.  It is up on the hill, attached to bedrock:

TG_vs_CORS_Newport

NPRI_CORS_photo_600

What does that means for us?  The CORS data shows that Coasters Harbor Island, home to the US Naval War College among other things, has recently (short-term) been subsiding at a rate of about 2.6mm/year. [Important Note: the short term GPS solution for any CORS station may be different than the long-term solution.] There is a long-term solution for Vertical Land Movement (VLM) from 2006 in Snay et al. (2007) which gives the VLM as -0.01 ± 1.16/mm year, basically, zero.  This aligns with the know phenomena of geostatic hinging of the Eastern U.S. Seaboard just north of  Boston, MA, with land to the north rising and land to the south subsiding as a result of the melting miles-thick ice of the last glacial period.  With Rhode Island being just below the hinge-point, it would not be expected to be subsiding by very much.

In 2013, NOAA provided a new estimate of Relative SLR at Newport Tide Gauge of  2.58 ±  0.19/mm/yr and a VLM  Trend (as derived from tide gauge data) of -0.88 ± 0.09/mm/yr.  Notice that 2.58 mm minus 0.88 mm (negative VLM)  equals exactly (by chance?) NOAA’s long-term figure for global  absolute sea level rise of 1.7 mm/yr.

Recall, that global sea level is said to be rising at somewhere from 1.5-3.0mm year — the current subsidence of the bedrock (on a scale of months) at Newport is of an equal magnitude. So, we should see substantial change in Relative SLR at the tide gauge — it should be about Local Subsidence + Global SLR.

Is it?

The short-term subsidence doesn’t appear much in the tide gauge record — but it is very small, low single digit millimeters.    Regardless,  the tide gauge is attached to a concrete pier obviously build on fill used to create the yacht harbor we see in the satellite view, and therefore can be reasonably assumed to be subsiding at some unknown rate greater than that of the larger island, the tide gauge data shows a steady rate of Relative Sea Level Rise of 2.77mm/year — which is 0.1mm more than the measured short-term subsidence Coasters Harbor Island and in line with NOAAs most recent (2013) long-term solution for RSLR and VLM at the Newport Tide Gauge.

So to summarize, for Newport, R.I., in general, based on the tide gauge and CORS data, Relative Sea Level RISE there is running about 10 inches a century — if this has been true and steady since colonial times, we are looking at two centuries times 10 inches gives 20 inches or 0.5 meters.

It’s Worse than We Think @ The Point;:

 The Point was settled in the 17th century by Quaker refugees from Massachusetts. Then, it was little more than a spit of land sticking out into what became Newport Harbor. Soon, as its edges were filled in, a marsh became Marsh Street, and a wet area became Water Street; the path of a span that once linked The Point to the rest of Newport turned into Bridge Street.”

 The Point is one of the neighborhoods that has an association and a set of by-laws (link is a .docx).  The by-laws lay out the boundaries which I have drawn (approximately) on this map:

The_Point_Newport_RI

I’ve drawn a line pointing to Marsh Street, which runs almost the entire width of The Point. And marked a pointer to Bridge Street.   My point?  The Point used to be a little spit of and protruding into Newport Harbor — but even in colonial days they began to fill in the edges creating a vast area of new land on which colonial homes were built.  That filled area became known as The Point.  There is no longer a land feature that looks like a “point”,” narrow piece of land which sticks out into the sea” —  as one can see on the map — it is just one big flat, nearly sea-level neighborhood extending south from what is now Highway 138 down to just south of the site of the Newport Marriot Hotel, and by fiat includes Goat Island.

Being a bit leery of using NY Times bespoke photos without permission, I offer this link (opens in a new tab or window) showing why The Point has a problem — it has the same vice that much of Miami Beach has — “Miami’s vice is water, as in waterfront.  Everybody seems to want a house on the waterfront…”.  This was apparently true in colonial times as well — a whole neighborhood was built by filling a marsh and extending the land into the harbor to create more waterfront with better views for those desiring “Elaborately detailed homes [that] reveal the fortunes of those who lived there centuries ago, reeling from the incredible profits made as sea traders and an important piece of the trans-Atlantic slave trade for many years.”  [ source ].  As the Times was careful to explain “The Point sits only a few feet above sea level”. 

Built on land fill, in the days before modern harbor engineering, The Point has been subjected tidal washing of the filled areas — here’s the data in one image:

Newport_Tide_Datums

Tidal wash has been affecting The Point for 200 years….during which time Mean Relative Sea Level had probably risen about 20 inches.  Highest Recorded Tide Level at Newport was 13.31 feet (above MLLW) or ten feet above todays Mean High Water recorded on September 21, 1938.

For The Point, flooded basements and flooded first floors are not a new phenomenon, where the most of the historic houses are just a few feet above sea level.  Note that the basement floor of a home 3 feet above sea level will be below the high tide level by 5 feet or so.  If its foundation is permeable (not watertight like a swimming pool) it will need constant pumping to keep it dry.  And they do.

And the rest of the story?

 The rest of the NY Times’ piece is an interesting discussion of technical solutions for historic buildings that are endangered by the combination of slowly rising seas and slowly sinking neighborhoods.

# # # # #

Author’s Comment Policy:

This is probably my last piece on places supposedly “threatened by climate- change-caused sea level rise”.  They are boring because, when investigated closely, the problem and its cause do not change:  the absolute sea level of our oceans is rising, ever so slowly, it has been and will continue to do so until we arrive at the next cooling period.  All of the places claimed to be threatened by climate change driven SLR, which I have investigated so far,  are in fact subsiding (sinking towards the center of the earth) ever so slowly or, in some cases like Jakarta, quite rapidly.  None have exceptional (differing hugely from worldwide absolute SLR) actual rising sea levels (only rising Relative Sea Level).

I tried to save readers some time by giving a spoiler at the beginning for those in a hurry.  Any readers in Rhode Island should let us know their situation if they live on the waterfront somewhere.

Thanks for reading.

# # # # #

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Tom Halla
July 15, 2019 10:37 am

Doing fill correctly is a pain. During the Loma Prieta earthquake in 1989, the World Series quake, a neighborhood in San Francisco, the Marina district, ironically built on rubble from the 1906 earthquake, liquefied. Many of the buildings collapsed.
I can only imagine the fill technique used even earlier than 1907, and how much Newport is subsiding.

Editor
Reply to  Kip Hansen
July 15, 2019 12:16 pm

Note as well …

Capn Mike
Reply to  Kip Hansen
July 15, 2019 2:49 pm

I kinda liked the image of these do-gooders skulking out of Newport in the dead of “nite”.

Editor
Reply to  Capn Mike
July 15, 2019 6:27 pm

Capn Mike ==> Yes– a fine image. If only, they were forced to move to the frontiers of Rhode Island and Connecticut with the same sort of persecution that led the pilgrims to leave Europe.

Duane
Reply to  Tom Halla
July 15, 2019 11:37 am

It is not that properly constructed fills are “a pain”. It is that fills are like any other type of construction – they must first be engineered, and then constructed as designed. Use proper fill material, such as well sorted stable aggregates with sufficient fines (and no organic material), proper control of moisture, and proper compaction equipment and compaction effort. And of course, the probability of achieving a properly designed fill and a properly constructed fill in 17th, 18th, or 19th century land development is approximately nil. So subsidence, slope failures, and the like are to be expected.

Tom Halla
Reply to  Kip Hansen
July 15, 2019 1:07 pm

Exactly, it is something easy to do badly.

commieBob
Reply to  Duane
July 15, 2019 1:50 pm

And of course, the probability of achieving a properly designed fill and a properly constructed fill in 17th, 18th, or 19th century land development is approximately nil.

And yet the Dutch have been successfully reclaiming land for a long time.

David Chappell
Reply to  commieBob
July 15, 2019 3:04 pm

The Dutch, rather than piling rocks into the sea to create land, did it the other way round by removing the sea. OK, they had to build dykes to do so which meant using fill but that doesn’t change the basic concept.

TonyL
Reply to  commieBob
July 15, 2019 3:46 pm

commieBob comes out of nowhere, flys in at the enemy ships low, fast and hard. commieBob drops his torpedo aimed a a big fat aircraft carrier.
He gets a direct hit, opening a huge hole below the waterline.
Score one for commieBob.

MarkW
Reply to  TonyL
July 15, 2019 8:09 pm

The problem is the ship commieBob sank was one of his own.

Michael Jankowski
Reply to  commieBob
July 15, 2019 5:30 pm
andyHce
Reply to  commieBob
July 15, 2019 5:31 pm

Also Venice until lately, when preservation societies gained too much power.

Duane
Reply to  commieBob
July 16, 2019 6:06 am

Not with landfill the Dutch didn’t. Where would they get the dirt?

The Dutch used dikes and wind-powered pumps to reclaim former ocean bottom land That is a different kind of engineering, and one that the Dutch invested substantially into doing correctly. If a dike and pump system failed massive flooding and death and destruction is the result. But it was not fill, in any case.

If a landfill subsides, nobody cares. At worst someone may have to jack up the foundation a bit.

All engineering is based upon a balancing of costs and benefits. If you never care about the cost, anything will do and it needs relatively little engineering, or careful construction to meet design specs. But if the consequences of a failure are very high, then the normal thing to do is invest a lot into both the engineering design and into ensuring that the construction is done according to that design.

Landfills, at least the historic ones I was referring to, were a haphazard, unengineered, almost accidental process in most instances. In coastal areas, what happened usually was that a dredging operation, to create or deepen a shipping channel or harbor, created a source of fill that had to be disposed somewhere .. and usually the cheapest place to take that dredge spoil was to dump it along the shoreline and then you got a double benefit – new real estate to sell and develop. There was very little if any attention paid to engineering such fills.

Nicholas McGinley
Reply to  Duane
July 15, 2019 6:33 pm

As to whether it was done “correctly”, are we to suppose that houses built for a specific person and his or her family, at a particular time and place, that have now outlasted that person, and their kids, grandkids, great-grandkids, and possibly many more generations than that, are nevertheless still standing and being lived in right where they were put, somehow indicative of some sort of failure to build something properly?
I think anyone building anything, whether on fill, solid bedrock, by the ocean, on a hill, or anywhere else, probably ought to be considered to have done OK if it is still there in 200 years.
At the edge of the water on fill, lasting 200 years (and by the way not looking like they will wash away tomorrow)?
Gets the Nick Seal of Construction Approval®.

Alan the Brit
Reply to  Nicholas McGinley
July 16, 2019 12:32 am

But will Al Gore’s multi-million $ pad on the sea-front (not sure where, CA?) still be here in 2100-2019 = 81years? Mind you, he & his poverty stricken family will probably have had to sell it several times over to make ends meet (for a modest profit of course)!(Sarc off). Somebody please, please, please, explain to me why sea-front property prices aren’t plummetting due to imminent sea-level rises, sure these properties must be worthless barr scrap material value?
O/T, Reminds me of the time my late father worked at a hush-hush guvment establishment (AWRE Aldermaston), they apparently had a lab with a very powerful electro-magnet, the door sign under the official “Authorised Persons Only” sign simply said, “If you can read this sign, we’ll give a shilling for your watch!” 😉

Darrin
Reply to  Nicholas McGinley
July 16, 2019 12:34 pm

I long ago concluded our ancestors were not dumb no matter how many times people try to say they couldn’t of done “X” despite the evidence sitting in front of them. Just because they were not sitting in front of a computer with modern understanding of engineering practices doesn’t mean they couldn’t of properly engineered a fill project (no little green men needed Giorgio!). As Nicholas points out, if it lasted over 200 years they couldn’t of done to bad of a job. A poor job would be gone in a matter of years to a few decades by either sinking out of site or washed away by now.

Reply to  Tom Halla
July 15, 2019 1:37 pm

I think Newport RI is threatened by Climate Change about as much as the UN believes in rising sea levels.
Check out this on my blog.

https://thedemiseofchristchurch.wordpress.com/2016/05/06/un-headquarters-and-usd1-2-billion-upgrade-and-rising/

Cheers

Roger

Nicholas McGinley
Reply to  Tom Halla
July 15, 2019 6:49 pm

BTW…New England is no stranger to Earthquakes.
One of the largest I have found a report of, in which a magnitude is given, was the St. Anne quake of 1755, given as 6.0-6.3 with plenty of uncertainty I am sure.
Another likely bigger one was in the same region in 1727.
Rhode Island appears to be in an area with somewhat elevated risk, but much lower than the area to the north near the border of New Hampshire and Mass.

Check it out:
https://upload.wikimedia.org/wikipedia/commons/7/7d/2014_pga2pct50yrs_%28vector%29.svg

Tom Halla
Reply to  Nicholas McGinley
July 15, 2019 7:11 pm

Certainly, but as there are 300 year old masonry buildings there, it is not a major risk.

Enginer01
July 15, 2019 11:15 am

There are many other examples…New Orleans, a ship-transfer trading camp built on a sandbar on a Bangladesh-like delta sliding exorbitantly into the Gulf, islands at the mouth of the Chesapeake Bay, going the same way, even the parade grounds at the Annapolis Naval Academy, built on fill from the Severn.

curly
Reply to  Enginer01
July 15, 2019 1:08 pm

Lots of rebuilding on NY and NJ barrier islands since hurricane Sandy.
Texas as well for Gulf coast hurricanes.
If they can’t get flood and/or hurricane insurance, then blame it on global warming, “natural disaster” and guess who pays? To the tune of $120B for Katrina and Rita, and then a request of >$80B from NY, NJ and CT for Sandy. Feels like taxpayers paying for bad decisions, along with covering real estate developers’ insurance costs, including former NYC mayor Bloomberg. No wonder the little guy spews about CAGW.

Alastair Brickell
Reply to  Enginer01
July 15, 2019 2:31 pm

Enginer01
July 15, 2019 at 11:15 am

Kip, this piece is not “boring” at all…it is fascinating read and a clear explanation of what is going on. Please do not treat this as your last example. We need more of these investigative pieces to use as ammunition for the alarmists. Some non-USA examples would be very interesting too I suspect. With your help “the truth will out”!

Reply to  Alastair Brickell
July 15, 2019 3:04 pm

I would agree with Alastair. It would only get boring if you posted one every week.

As a person who has always lived a long way from water, these informative posts are very educational.

Alastair Brickell
Reply to  Kip Hansen
July 15, 2019 11:43 pm

Kip Hansen
July 15, 2019 at 6:23 pm

Wonderful!

Joel O'Bryan
July 15, 2019 11:18 am

Ah yes, a crisis if there ever were.
Action is required.
This demands immediate destruction of the western democracies’ economies.
Along with the transfer of vast amounts of middle class wealth via electricity bills to renewable energy invested hedge funds and billionaires, and energy poverty.

That should solve something. Right?

ResourceGuy
July 15, 2019 11:31 am

Just don’t ask me to pay for old northeast waterfront with other people’s money. We’re already paying for a lot of shared budget con games as it is.

Phil Salmon
July 15, 2019 11:38 am

No.
That was easy.

Phil Salmon
Reply to  Phil Salmon
July 15, 2019 5:10 pm

Kip
Thanks for the nice article.
Cities themselves slowly rise.
Look at the archaeology of Rome – the deeper you dig, the further back in time you go.
So “no” could still be in with a chance.

Reply to  Phil Salmon
July 16, 2019 3:48 pm

Kip
Exactly.
That’s about the rate of sea level rise.

Latitude
July 15, 2019 12:01 pm

my favorite tide gauge is Key West…because of all the old military..and their need for extremely accurate GPS
military says the island is not sinking, rising, or going sideways…it’s rock solid
..and so is the 100 yo tide gauge…..0.79 feet in 100 years

comment image

Reply to  Latitude
July 15, 2019 1:13 pm

Yes, Key West (and Florida) was featured in the UCS blitz on coastal flooding last summer. Here is how their models project compared to that tidal gauge.
comment image

The full report is summarized at post
https://rclutz.wordpress.com/2018/06/21/uscs-warnings-of-coastal-floodings/

Ed wolfe
July 15, 2019 12:01 pm

Yup filled land and sea level
Most cities have similar filled land
Boston big time
Sandy point
Salem ma
I could go on and on

Tom in Florida
July 15, 2019 12:12 pm

Will the Brick Alley Pub be safe?

TonyL
Reply to  Tom in Florida
July 15, 2019 3:37 pm

No problem. The Pub is on the other side of the street and a little bit up the hill which stretches all along the downtown area on that side of the street. It is several feet higher, and so should be good for another ~6 to 8 centuries.

marque2
July 15, 2019 12:30 pm

Wasn’t the whole of Rhode Island basically underwater in the 1938 New England Hurricane, and then again in 1954 under hurricane Carol? When we get the next hurricane in New England, even if it produces an inch of rain – no one will bring up that this happens every 50 years or so – instead it will be a climate change calamity!

ResourceGuy
Reply to  marque2
July 15, 2019 1:01 pm

Interesting. I’ll go look that up.

Editor
Reply to  marque2
July 15, 2019 1:45 pm

The Fox point Hurricane barrier was built in the aftermath of those storms from 1961-1966. It has been employed several times for nor’easters and other events.

https://www.nae.usace.army.mil/Missions/Civil-Works/Flood-Risk-Management/Rhode-Island/Fox-Point/ says in part:

The Fox Point Hurricane Protection Barrier in Providence is located immediately south of the Narragansett Electric Company plant, about 0.2 miles north of Fox Point and one mile south of downtown Providence.

The project provides virtually complete protection against tidal flooding from hurricanes and other coastal storms to about 280 acres of downtown Providence. The protected area includes the commercial and industrial center, transportation facilities, public utilities, and many homes. The city suffered extensive damage from the hurricane of 1938 and Hurricane Carol in 1954 when, in each instance, water depths of up to eight feet were experienced in the city’s commercial area. Damage from the 1938 hurricane amounted to $16.3 million — and damage from Hurricane Carol amounted to $25.1 million. Construction began in July 1961 and was completed in January 1966, at a cost of $15 million.

These storms made landfall between New York City and Newport. Until whatever-you-call-it Sandy, New York City hadn’t taken storm risks seriously enough to do something about it, even though there were plenty of studies that concluded mayhem would result to the subway system and basement emergency generators.

See lotsa photos at http://www.gcpvd.org/2010/02/19/fox-point-hurricane-barrier/

Robert MacLellan
Reply to  marque2
July 15, 2019 3:52 pm

Yes it was, pics are online thru the Providence Journal as they printed souvenir books for each storm. Mine are in storage or I would send you copies. The downtown of Providence was underwater each time, as I recall there is a plaque on a building there showing the flood levels also possibly an earlier storm.

tty
July 15, 2019 1:02 pm

“if this has been true and steady since colonial times, we are looking at two centuries times 10 inches gives 20 inches or 0.5 meters.”

It hasn’t. Sea level sank slowly up until c. 1860 and has been rising at a steady rate since then, so the rise over the last two centuries is probably more like 10 inches.

July 15, 2019 1:18 pm

Kip, thanks for doing your usual thorough and illustrated research on Newport. Last June, I noticed the alarms raised and produced this graph from the projections being bandied about.
comment image

John F. Hultquist
July 15, 2019 1:23 pm

Thanks Kip, well done.

Years ago we visited the other side of the island, where “The Breakers” and other large properties are located.
https://en.wikipedia.org/wiki/The_Breakers

41.469, -71.297

Lat/Long is to the Cliff Walk along that area. Looks like rip-rap has been placed there.
Water is 30 feet or so below.

Editor
July 15, 2019 1:29 pm

In a longer time frame, Newport may be under threat when sea level drops as that will mean the next glaciation is underway. It may escape – the last glaciation stopped at Cape Cod and the islands, which it made….

Nicholas McGinley
Reply to  Ric Werme
July 15, 2019 6:56 pm

Yup.
I think Long Island is basically a terminal moraine, from not one but two ice sheets.

Don K
July 15, 2019 2:03 pm

The article seems pretty near perfect to me. The only thing I’d add is that while SLR isn’t very rapid, there isn’t any reason to expect the sea level to stop rising any time soon. To paraphrase Everett Dirksen — eight inches here and eight inches there and in a few centuries you’re talking actual trouble. I’m sure our distant descendants will handle the problem — maybe lift all the antique housing up ten feet or so and put it on pilings driven down to bedrock.

TonyL
July 15, 2019 2:22 pm

and therefore can be reasonably assumed to be subsiding at some unknown rate greater than that of the larger island

*sigh*
Assume Nothing! Measure It!
You got bedrock outcrops nearby, measure from there. One of those rock outcrops might even have one of those bronze USGS survey markers. Those things show up in the strangest places, and they even seem to have an affinity for tide gauges, for some strange reason. So measure the change of an area built on fill vs. a reference point on bedrock. (I would bet a cup of coffee that it has already been done.)
******************
Allow me to digress:
Out in the Berkshires, there is an engineering marvel known as the Hoosac Tunnel. 4.75 miles of railroad tunnel built right through a ridge of mountains known as the Hoosac Mountains. Construction was 1851-1875. The engineers claim to fame is that when the east and central tunnel segments met, in the middle of the mountain, the overall survey measurement error was about 0.5 inches. (!!!!!) In 1870.

Contrary to popular opinion, a lot of them really did know what they were doing back then.
But I digress.
****************************

Not all fills are going to settle like New Orleans. Around New England, we have lots of gravels and glacial tills. Tidal currents sweeping to and fro sweep fine particles further out to the bay, leaving a fairly stable base. Use more glacial till or gravel as additional fill, and after a few decades, you are stable.
Do not guess, measure.
See the reference to the Hoosac Tunnel, above. People really did know what they were doing, back in the day. But how could this be, our technology is so much better today???

It has been suggested, that back in the day, people did not have computers, so they actually had to think about what they were doing.

TonyL
Reply to  Kip Hansen
July 15, 2019 8:05 pm

I saw that. VLM *calculated* from tide gauges. They are guessing.
You constantly bang on about subsidence, even when there is no good reason to suspect it. In fairness, if you are on the Mississippi delta, or Galveston, TX, subsidence might be foremost of your concerns. But New England is not those places.
Here we go:

Notice that the quay is obviously constructed on fill — it not only isn’t a natural part of the land, it has been created by dumping rocks and soil into the water at the edge of the harbor, and reinforced with large blocks of concrete. There is no way of easily determining whether or by how much the quay is settling (subsiding), thus the tide gauge, as NOAA points out, measures only Relative Sea Level and the rate of change represents 1.7mm/year plus or minus vertical land movement — in this case almost certainly subsidence.

Those are granite blocks, not concrete. That tide gauge site is *old*. Look at the layout, the total fill is probably not more than 8 – 12 feet thick. How much settling do you really think you are going to have in a 12 foot thick pile after 100 years?
The Point (downtown):
Yeah, sure. If there was settling over time, you would see the signs. Sections of the seawall bulging out or sagging down, pavement ripples or waves going up and down in the sidewalk and street, along with pavement cracking. I certainly have seen this stuff going on in other places, but in Newport, no, no, and no. When was that area filled anyway? 200+ years ago? And to what depth, perhaps 12 feet max? Sometimes you do not need a CORS to see what you can see.
In the absence of further data specifically on settling, I would rate the sites as stable. I certainly would not jump to subsidence as my one size fits all answer. This is not New Orleans.
Remember what I said about the Hoosac Tunnel, people did not have computers, so they had to think.

tty
Reply to  TonyL
July 16, 2019 2:31 am

“You constantly bang on about subsidence, even when there is no good reason to suspect it.”

Just about the whole eastern seabord of the US is subsiding, with the exception of part of Maine and perhaps southernmost Florida.

There are at least six reasons for this, two natural and four human-caused:

1. The ”forebulge” of the Laurentide ice-sheet is still subsiding

2. The east coast of North America is an old passive continental margin which normally tends to sink

3. Sediment compaction – always goes on in alluvial deposits, and if new sediment isn’t deposited (which it isn’t any longer e. g. in the Mississippi delta due to the levees) the ground will subside

4. Groundwater withdrawal, for use or drainage

5. Oil or natural gas extraction

6. Compaction of landfill (which can be exacerbated by 4.)

The two first have been operative for tens of thousand years which is easy to see on the map. The coast from Cape Cod all the way to the Rio Grande bears all the hallmarks of a sinking coastline with typical rias (drowned river valleys) like the Chesapeake, coastal marshlands and the most extensive system of barrier islands in the world.

TonyL
Reply to  Kip Hansen
July 16, 2019 7:24 am

Fair enough, to find out is to know.
I took a look at the site with the Google Maps satellite view. The tide gauge electronics are *just* barely visible by the last dock on the right (way down at the bottom of the island). A bit further down and to the right is a curious round piece of pavement. Surrounding this circle is a narrow ring of some sort.
This was a gun emplacement. The main part of the gun would pivot in the center circle. The rear iron wheels on the gun carriage would follow the track of the outer circle. This was how the gun was aimed. The guns could vary from large cannon to absolutely *huge* mortars. An example of such a mortar emplacement has been preserved at the fort on Castle Island in Boston Harbor. It is also informative to know when such defenses were getting outdated and were no longer getting built.
The very existence of such a structure speaks volumes about the age and purpose of the installation. Another fascinating bit of history to check out.

TonyL
Reply to  Kip Hansen
July 16, 2019 8:37 pm

@ Kip Hansen:
My guess is that it was part of what was known as the Harbor Defense of Narragansett Bay. This was run by the United States Army Coast Artillery Corps harbor defense command. Active from 1895 – 1950, starting with the Endicott program.
Checking a map, I see that this particular location affords a gun to command all of:
A) The entrance to the harbor
B) The entire waterfront area of Newport
C) Goat island
Goat island was particularly important because it was the home of the Naval Torpedo Station, the US Navy’s primary research, development, and manufacturing center for torpedoes.
This gun would have been an adjunct to Fort Wetherill and Fort Adams, the primary defenses of Newport. However, Forts Wetherill and Adams were poorly placed to defend against a sneaky evasive attack like going around Conanicut island to the west and approaching the War College and the Torpedo Station from the north. The gun emplacement would have put a stop to that nonsense.
We can also note that as the area was envisioned to carry one (or more) of those huge heavy guns, the construction of the area would have been wholly different from that of some random “fisherman’s pier” down at the waterfront.
Also worth noting is that this one gun emplacement is one that looks to have been preserved. There is no telling how many others there may have been, but were done away with due to the growth of the facility.

tty
Reply to  Kip Hansen
July 17, 2019 3:18 am

“Goat island was particularly important because it was the home of the Naval Torpedo Station, the US Navy’s primary research, development, and manufacturing center for torpedoes.”

Considering the quality of US WW2 torpedoes a german attack would have been just about the best thing that could have happened to the USN.

TonyL
Reply to  Kip Hansen
July 17, 2019 10:39 am

@ Kip Hansen

the settling of the base for the gun is apparent in Google Maps satellite view as extensive cracking of the surface and deterioration of the seaward edge.

OMG!!! Lordy, Lordy, Lordy.
The cracks are straight lines and segmented. This so obviously reflects the placement of the stone blocks which pave the area. After the stone block paving was completed, the whole was covered with a skim coat of cement. It is this skim coat which has broken up giving the surface it’s somewhat tattered look. The cement coatings were a common practice at the time. The cement coat has cracked and worn as a result of mundane weathering, nothing to do with settling.

@ tty
German torpedoes were just as bad at the start. More surprisingly, both suffered from the exact same set of multiple defects. This included faulty depth control and faulty detonators, at a minimum. The difference is that the Germans got right on the job when it became obvious that something was wrong. The Americans went full denial, blaming everybody else in sight.
Meanwhile, back in Tokyo:
A new torpedo, named the Long Lance made it’s debut. It was an unknown quantity, but American Commanders were warned to be extremely wary, as this weapon was new and state-of-the-art. In the early days of the war, a Japanese and American combat group mixed it up in classic surface battle style. (both groups were about evenly matched, consisting of a heavy cruiser, 1 or 2 light cruisers, and some destroyers, or so.) After a while, they broke apart to evaluate the situation, as both sides had given and received numerous hits from heavy guns. An opportunity presented itself as the Americans sailed steady along just outside gunnery range. The Japanese scored 2 torpedo hits at 16,000-18000 yds. Then, incredibly, they scored a third hit at a jaw-dropping 22,000 yds.
I tried to recover a link to the battle for you, but no luck.

Derg
July 15, 2019 2:27 pm

Thanks Kip

Tom Murphy
July 15, 2019 3:00 pm

In 1989/1990, I was an industrial hygiene consultant on the construction of the (then) newer Publicly-owned Treatment Works (POTW) or Waste Water Treatment Facility (WWTF) in Newport, Rhode Island. The WWTF is located at the intersection of the (then) Goat Island Connector and Washington Street. My employer was retained to monitor occupational exposures to lead and mercury in the excavated soils after the general contractor began unearthing what appeared to be an unmarked landfill.

And there was an extensive excavation because the majority of the WWTF is situated below grade. Subsequently, my employer determined that elevated lead and mercury concentrations were present throughout the whole of the excavation. Dating of the artifacts extracted from the excavation concluded the landfill was likely active during the Early Republic era (est. 1790-1820).

So, yes – a majority of The Point (less commonly known as Easton’s Point) is definitively built atop not only filled saltmarsh but an Early Republic-era landfill, as well. An historic map of Newport from 1777 reveals just how much was eventually filled (i.e., the entire cove to the north of the Draw Bridge and Long Wharf) – http://mediad.publicbroadcasting.net/p/wrni/files/201410/map_Blaskowitz.jpg .

Ian MacCulloch
July 15, 2019 4:47 pm

Well this tale has put the end to the fantasy of eustatic rises taking place along the Atlantic sea board post last ice age. I am with the ore or less universal constant with local variations. We still have quite some way to go to reach the +2.0 metre peak that was reached about 6,000 yrs BP. If sea side planners want a bench mark then that is it. And that is go guarantee as the highest peak in the last 150,000 years was at 16 metres. Take your pick planners

tty
Reply to  Ian MacCulloch
July 16, 2019 2:44 am

It’s not a fantasy. Eustatic rise is going on up north where the ice was (about 3 feet per century around Hudson Bay), but at the same time the fore-bulge outside the ice-cap is sinking back as material slowly flows back into the depression under the old ice-sheet. The zero line is somewhere in Maine.

Here is a map of the eustatic rise in northern Europe:

http://www.klimatupplysningen.se/wp-content/uploads/2014/04/Absolut.jpg

This is very precisely known since it has been studied for more than two centuries and the sea-level in the Baltic can be used as a datum. It is not nearly as well mapped in North America, where it was impossible to measure inland before GPS:

comment image

tty
Reply to  Kip Hansen
July 16, 2019 9:37 am

https://www.researchgate.net/publication/286867540_Crustal_motion_and_deformation_monitoring_of_the_Canadian_landmass

Here is another interesting paper on the same subject:

www2.unb.ca/gge/Personnel/Santos/JGeodyn2007_final.pdf

Frank
July 15, 2019 10:15 pm

Kip wrote: “because of climate change, the ocean is rising.” — Sea level, worldwide, is rising and according to NOAA, “the absolute global sea level rise is believed to be 1.7 +/- 0.3 millimeters/year during the 20th century.” … Note that NOAA makes two different statements about sea level rise: one based on long-term historic data (as above) — “absolute global sea level rise is believed to be 1.7 +/- 0.3 millimeters/year during the 20th century” and produces another, the graph here, of satellite measured SLR, which they state is “2.9 ± 0.4 mm/year” in the satellite era. There has, as yet, been no real definitive reconciliation between the two figures in the literature.”

If you add a few more words, the difference may make sense: The AVERAGE rate of SLR over the 20th-century is believed to be 1.7 +/- 0.3 millimeters/year. The AVERAGE rate of SLR during the satellite altimetry era (1993-present) era has been 2.9 ± 0.4 mm/year. Two different periods can have two different AVERAGE rates. Superficially, the rate of SLR appears to have increased, though we can not precisely say in which decade or decades the increase occurred. During the 20th century, the central estimate for average rate of rise over 30-year sub-period varied from near 0 to 3 mm/year, but during most periods the 95% confidence interval for these average rates includes 1.7 mm/yr. In other words, we are barely sure the average rate of rise changed. (Look at your data for Providence.)

Has the rate of SLR accelerated? Probably, but using tide gauge records for one period and satellite altimetry of another isn’t robust evidence for acceleration and satellite altimetry involves large correction factors and potential for systematic error. It’s been a quarter-century since the satellite altimetry era began and we probably should be able to use (or soon be able to use) tide gauges alone to confirm that that average SLR has been higher than 1.7 mm/yr since 1993. So far, AFAIK no one has made such a claim.

Frank
Reply to  Kip Hansen
July 17, 2019 10:52 am

Kip: There is no inconsistency to resolve between an average SLR of 1.7 mm/yr for the 20th century and the higher values for the satellite era. There is no doubt that warming over the last half century should be increasing the rate of SLR. ARGO and earlier technology clearly shows heat flowing into the deep ocean. That flow occurs by bulk convection and bulk convection of heat must be accelerating as surface water warms. However, when warming is only producing about 1 inch/decade of SLR and many other factors effect local sea level, it took many decades to be accurately reported (globally) against the background of noise. That rate of SLR hasn’t proven to be a major problem in the past, but we are now perhaps a foot closer to serious problems in low lying communities.

For the alarmist scenario of 1 m of SLR to occur, SLR needs to rise from the current rate (about 1 inch/decade) with an acceleration of 1 inch/decade/decade. That would be 2 inches of SLR in the 2020’s, 3 inches in the 2030’s … and 9 inches in the 2090s. Clearly SLR has NOT been accelerating at this rate in the past few decades. If you believe the latest corrections to the satellite altimetry record (which lowered the amount of rise detected by the first satellite), acceleration over the last 25 years has been 0.075 mm/yr/yr or about 0.3 inch/decade/decade. If that amount of acceleration persisted for the remaining decades, SLR would total about 20 inches, about the central estimate provided by AR5. Sea level would be rising at 4 inches/decade at the end of the century.

The uncertainty in the drift in satellite altitude is on the order of 1 cm/year and this problem was unresolved when AR3 was written. After that, scientists began calibrating the altitude of the satellite as it passed over various known sites on the surface, beginning with an abandoned oil drilling platform off Southern California. (The oil drilling platform has a tide gauge and GPS receiver to track VLM) Now (as I understand it) there is a network of calibration sites whose mutual consistency is monitored. The history of SLR has been determined from two independent sets of satellites and some additional inconsistencies were eventually resolved.

So the real problem isn’t 1.7, 2.3 or 3.2 mm/yr. The real problem is the acceleration common sense physics tells us to expect, but can’t predict OR MEASURE with any real accuracy right now. IMO, the sensible course would be to tell the alarmists to shut up until SLR reaches 2 inches/decade. And I’d remind skeptics that SLR was 20 m/degC of warming and even a small fraction of that rise is going to dramatically change our coast line someday. In both cases the question we can answer is how fast.

Frank
July 15, 2019 11:05 pm

Ian: The evidence supporting the existence of a global highstand 6,000 years ago is mixed. Dave Middleton showed you only places where there was evidence for such a highstand and didn’t eliminate those places (Hawaii, Red Sea) that are geologically unstable. There may have been such a high-stand, but the evidence on this subject is contradictory.

In any case, 20th-century SLR of roughly 2 mm/yr is 2 m/millennium. A highstand of 1 m or two a few millennia ago still implies rates of sea level change that as smaller in magnitude that we are experiencing right now. If today’s rate of rise lasted for 5 millennia, the change would be 10 m.

I find it easier to think in terms of inches/decade. Today, SLR is slightly above 1 inch/decade. Averaged over the 20th century, slight less than 1 inch/decade. To approach 1 m by 2100, one needs an acceleration of 1 inch/decade/decade. Clearly that isn’t happening now. When SLR increases to 2 inches/decade, then we can start worrying about acceleration.

tty
Reply to  Frank
July 16, 2019 10:17 am

There most certainly was a highstand in the Pacific. All low islands that have been investigated have clear evidence for it. Many islands lost their freshwater lens during the highstand.
And it shows up in other areas too. In the Baltic it is known as the Littorina transgression.

Frank
Reply to  tty
July 17, 2019 11:04 am

tty: There is evidence for the presence and absence of local highstands in sea level. Such differences could be explained by local VLM. Warm period like the MWP, RWP and Minoan WP could be responsible for the modest changes in global sea level. Can we construct a convincing GLOBAL record from this data? My amateur opinion is that when we get to global changes slower than 1 m/millennium lasting for periods less than 1 millennium, we could be dealing with noise. 1 m/millennium is about 0.4 inches/decade. That is barely detectable even today with tide gauges and look how much tide gauges vary from location to location.

4TimesAYear
July 15, 2019 11:39 pm

They’ve known about the subsidence for quite some time. Yet they want to blame it on sea level rise alone.

fhsiv
July 16, 2019 6:10 am

In addition to the effect of long term fill settlement on the measured rates of change, is the effect of compression of the underlying natural soil materials that the fills were placed upon. Many modern harbors are located where there were pre-existing natural conditions that were favorable maritime activities, such as at the mouths of rivers and in natural bays. These locations are more likely to be underlain by natural deposits susceptible to long term compression ( i.e. river delta deposits, bay muds, etc.). Not only do these deposits consolidate naturally over time, but are also subject to additional compression induced by loading from the construction of man made fills and structures. Settlement of the structures that the tidal gauges are mounted on is also aggravated by consolidation induced by dewatering and ground water pumping.
I believe that the statistics regarding sea level rise are contaminated by this bias in the siting of gauges at settlement prone locations. And for some reason, the gauges chosen to exemplify a higher rate of sea level rise are invariably located at sites susceptible to this type of long term settlement.

Steve O
July 16, 2019 6:38 am

What’s that now? We can’t save everything because the seas are rising? Where was the NYT when Democrats were subsidizing the rebuilding of New Orleans?

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