Sea level rise, subsidence and hurricanes… Oh my!!!

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Michael Palmer
July 18, 2017 8:59 am

Just out of curiosity: If Galveston were to stop pumping groundwater forthwith, would the subsidence be reversible? Are there any such precedents?

D. J. Hawkins
Reply to  David Middleton
July 18, 2017 9:37 am

Wouldn’t natural recharge lift the overburden?

Reply to  David Middleton
July 18, 2017 9:58 am

Aquifers replenish themselves eventually, on the other hand some of that replenishment can be a result of saltwater intrusion.

Bill Illis
Reply to  David Middleton
July 18, 2017 11:28 am

Galveston GPS stations have subsidence at:
– 4.59 mms/year between 1998 to 2003; and,
– 3.44 mms/year between 2006 to 2014.

Mike McMillan
Reply to  David Middleton
July 18, 2017 11:46 am

I’m right on the 2 foot line. That explains a lot.

Reply to  David Middleton
July 18, 2017 7:13 pm

Re: “All of the subsidence at Galveston Island occurred before 1978. This would lead to an acceleration in sea level rise after 1978 if there was never any subsidence…”
I think there might be a typo in that.
1. If subsidence ceased by 1978, then you’d see a deceleration in sea-level rise after 1978, as the rate of sea-level rise decreased from being the sum of GMSLR + VLM to being GMSLR alone.
2. I don’t think all of the subsidence occurred before 1978. Galveston Island is still experiencing extremely atypical local sea-level rise, more than 4x the global average, which I think has to be due to subsidence. This is the measurement record from the best tide-gauge on Galveston Island:

GMSLR = Global Mean Sea Level Rise
VLM = Vertical Land Motion

Reply to  David Middleton
July 18, 2017 11:06 pm

If the subsidence maps are correct, ecstatic sea level rise would have been diminishing from 1906-1978 and then accelerating afterwards because the isostatic component would have changed.

In my opinion, it is more probable that the Galveston Island just slowly sinks much irregarding the ground water use (and draining) that leads to collapse of the porous structure of sediments under the city. But because I lack data at the gauge – and probably that data has not been measured / collected to a good precision, I restrain from claiming it is so.
How precise yearly subsidence info there exists at the tide gauge? The GPS values are only recent and thus don’t give a good overall picture.

Reply to  Michael Palmer
July 18, 2017 6:06 pm

No. The subsidence is not reversible. As we pump out the groundwater, it allows the material in the ground to settle, losing some of the space. Pumping water in will refill the remaining spaces, but will not expand the spaces to where they were.

Paul R. Johnson
Reply to  Michael Palmer
July 18, 2017 8:38 pm

Just such a proposal was made several years ago to lift Venice out of its lagoon. See here:

Reply to  Paul R. Johnson
July 20, 2017 10:18 am

Back in the day they raised Chicago about 10′ without too much drama. Course now the EPA studies would take a decade and then the lawsuits would take decades longer so well…forget it.

Chuck in Houston
Reply to  Michael Palmer
August 2, 2017 6:22 am

Hi David and Michael – US Gulf coast subsidence is not only due to water and hydrocarbon extraction. There’s also geologic subsidence – tons and tons of material discharged from the Mississippi river over eons. The entire gulf coast is sinking and has been for a very long time. And, of course, the barrier islands and the Mississippi delta are basically mud/sand.

Tom Halla
July 18, 2017 9:01 am

The green fund-raising efforts called “news” rarely mentions subsidence, as melting glaciers are so much scarier.

Reply to  Tom Halla
July 18, 2017 9:21 am

That is for sure. I have heard nearly every major news outlet reference sea level rise when talking about the big iceberg from the last week, ignoring the basic physics involved with floating ice shelves being part of glacial advances/growth. Let alone the history of even bigger icebergs being ignored.

Reply to  Tom Halla
July 18, 2017 9:23 am

I wonder how many in the media would even understand this item from NOAA?comment image

July 18, 2017 9:09 am

Excellent article, except that I don’t think it’s groundwater withdrawal which is causing the subsidence. It’s because most of Galveston Island is built on silt which was pumped out of the harbor.

J Mac
Reply to  daveburton
July 18, 2017 10:14 am

Very interesting!

Reply to  daveburton
July 18, 2017 10:23 am

… most of Galveston Island is built on silt which was pumped out of the harbor …

It kind of reminds me of Seattle. There they filled in around the buildings to raise the street level by as much as two stories. The resulting tunnels have become a tourist attraction. link Seattle was originally built in a location that was too low but there is some subsidence where they built on sawdust fill.
Nobody is predicting a worst case sea level rise of more than a meter by 2100. link Seattle has demonstrated that cities can deal with much more than that.

Reply to  commieBob
July 20, 2017 4:28 am

In my city of Port Coquitlam, we are building new construction several meters above the original land height, at least in the areas near the Pitt River and mouth of the Coquitlam river.

Reply to  daveburton
July 18, 2017 10:23 am

Only the buildings in the city of Galveston were raised. This was in response to the 1900 hurricane whose storm surge went over the island. The tidal gauge stations are not in the city but in the harbor and should not be affected.
As a person who lived in the Houston/Galveston area from 1979 to 1997, I believe the areas south of Houston switched their water source from well-water to lake water in the early 1990s in response to the threats posed by subsidence. If well-water is a major factor in subsidence then it is not apparent on the map above. As an example, I find it interesting that the greatest subsidence is located in the most industrialized portion of Houston, the Houston ship channel. It sure looks like land use and subsidence has a far greater effect on coastal flooding than rising sea levels from global warming.

Reply to  Bill Huber
July 18, 2017 10:59 am

Water isn’t just pumped for drinking. The petrochemical facilities pumped a great deal for use in their processes, hence the correlation of subsidence with the industrialized areas along the ship channel.

Reply to  daveburton
July 18, 2017 11:09 pm

Wow. Thanks for this piece.

Clyde Spencer
July 18, 2017 10:04 am

TYPO: “About have of the DOE’s Goretastic claim…”

Clyde Spencer
July 18, 2017 10:07 am

I don’t see the colors for sea level trends on Figure 4 — and I’m not even wearing my eclipse glasses, yet.

July 18, 2017 10:12 am

This graph shows four apparently ‘co-related’ variablescomment image?zoom=2
Most of the north American continent is subject to postglacial uplift. The uplift extends to the northern portion of the North American tectonic plate, which btw. covers about 50% of the Arctic Ocean.comment image
If the Arctic Oceans floor is rising (Hudson Bay area has risen about 2m, yes two meters, in the last hundred years) then all that water has to go somewhere else. About 30% of the long term gravity anomaly in the N. Canada is a directly associated with post-glacial uplift, which in turn is reflected in the short term (on dacadal scale) of the local magnetic variability .
It could be postulated that the local magnetic change is a good metric for the uplift variability, and consequently the sea level rise.

Gary Pearse
Reply to  vukcevic
July 18, 2017 11:38 am

Up and down somewhere else!

Reply to  vukcevic
July 18, 2017 11:43 am

Actually most of the Arctic Ocean bottom is probably sinking. The areas that are rising are the ones which were glaciated. Most of the Arctic Ocean is to deep to beglaciated, so it would have been in the “forebulge” zone outside the glaciated areas during the last ice-age and is now sinking back (like most of the US).comment image

Reply to  tty
July 18, 2017 12:38 pm

I assumed that since Florida is sinking and Canada rising that the plate is (solid enough) to be tilting around some imaginary ‘midpoint’ axis. If the places as far south as Florida from the glaciation line is sinking, then at least parts of the Canadian Arctic Ocean would be rising. In that respect I would think that the above illustration from SIAM may be somewhat misleading, but then I’m not geologist.

Reply to  tty
July 18, 2017 1:09 pm

It is somewhat misleading. The forebulge is a lot wider than in the illustration. Just how wide is uncertain, but it seems clear that e. g. Bermuda is within the forebulge zone and possibly the Bahamas too. The width may be variable since it depends on the viscosity of the lithosphere which is definitely variable, but only very vaguely known.

Reply to  tty
July 18, 2017 1:42 pm

I just found this map (if correct) shows clearly up and down areas (confirming my assumptions as outlined above)
“(left) Vertical GPS site motions with respect to IGb00. Note large uplift rates around Hudson Bay, and subsidence to the south. Green line shows interpolated 0 mm/yr vertical “hinge line” separating uplift from subsidence. (right) Horizontal motion site residuals after subtracting best fit rigid plate rotation model defined by sites shown with black arrows. Red vectors represent sites primarily affected by GIA. Purple vectors represent sites that include effects of tectonics.”

Reply to  tty
July 18, 2017 1:47 pm
Reply to  vukcevic
July 18, 2017 11:54 am


J Mac
July 18, 2017 10:13 am

Texas Flood – Stevie Ray Vaughn

I Came I Saw I Left
Reply to  J Mac
July 18, 2017 10:30 am

Great loss as a musician.

I Came I Saw I Left
July 18, 2017 10:29 am

You know if your fill a bathtub halfway, mark the level on all 4 sides, add more water, mark the level on all 4 sides, drain the water, then measure the 4 level deltas you will find that they are never equal to each other.

Louis Hooffstetter
Reply to  I Came I Saw I Left
July 19, 2017 6:58 pm

Despite the sarcasm, your point is valid. Climatologist witch doctors intentionally confuse the general public by conflating subsidence with sea level rise. They are two completely separate and independent issues driven by completely separate and independent mechanisms.

July 18, 2017 10:34 am

Interestingly, it has been suggested that spent nuclear fuel (mischaracterized as “waste”) although not producing enough energy to drive the turbines of a nuclear plant any longer, still retains an enormous amount of its previous energy – roughly 95%. That means that, instead of spending money to bury the spent fuel for a long period to allow their radioactivity to return to background levels, which does nothing more than heat the enclosure that contain them, we should use our brains and place them into cask containers (currently being used) , which they will heat initially (and for a very long time afterward) to a temperature well beyond the boiling point of water – up to 350 degrees. This essentially free energy can easily be used to desalinate an enormous amount of seawater , removing the need to extract water from a city’s aquifer, perhaps eliminating most subsidience.

July 18, 2017 10:40 am

Most of the subsidence shown on that map IS in fact related to groundwater withdrawal, with some impact also from oil and gas removal as well, hence the two bullseyes around the Texas City and Baytown areas, where refineries pumped huge amounts of O&G in the past and huge volumes of GW for use in their processes. The subsidence in the Houston-Galveston area has been greatly mitigated near the coast in recent years as most of the communities and large volume users have been converted over to surface water supplies provided by the City of Houston. Not all of the petrochemical assets susceptible to storm damage are floating or moored to the bottom in the gulf. Some of the largest petrochemical complexes in the country are between Galveston and Houston and are mostly located at or below 20′ above sea level.

Reply to  TheOtherTex
July 18, 2017 10:56 am

I should correct myself to say that the “refineries” didn’t pump huge amounts of O&G…but large numbers of wells placed very near the refineries did. For an interesting view of things, go to Google Earth and search for “Tabbs Bay” near Baytown, Texas. If you look north of Hog Island on the 1978 historical image on Google Earth, you can see several dozen oil wells in Tabbs Bay. I have historical photos from that area showing an enormous cluster of wells in the bay in that areas over a period of several decades. Those wells correlate to one of the small bullseyes showing around 10′ of subsidence on David’s original map. The subsidence along the bay near Baytown was so severe that the Brownwood Subdivision was bought out by the government due to repeated flooding and is now used as a nature center.

Reply to  TheOtherTex
July 18, 2017 11:13 am

The completion of GCWA’s infrastructure mostly ended major groundwater withdrawal on municipal and industrial scale.

Reply to  TheOtherTex
July 18, 2017 11:12 am

Texas City, Kemah, LaMarque, and Galveston (most all of Galveston County) including rice irrigation in Galveston and Brazoria Counties, is supplied water by Gulf Coast Water Authority. The freshwater needs of the refineries and chemical plants are supplied by same. The source is the Brazos River. The infrastructure for the drinking water and raw water from the Brazos was essentially completed in the mid-seventies. That transition ties nicely with the end of the subsidence in the maps above.
The levee’s surrounding Texas City were built in the 50’s/60’s. They were originally 17′ AMSL…. for a Cat 3 surge….not anymore.
I worked down there from 1999-2007, the last for were with GCWA.

Gary Pearse
July 18, 2017 11:31 am

David, you are a treasure! I’m a geologist and geological engineer (BSc Eng ’61, MSc Geol 68) with an eclectic work history still practicing full time as a consultant in mining and metallurgy.
My first work – Geological Survey of Manitoba, then hydrologist along the rightofway of the Greater Winnipeg Floodway (Red River of the North) , at the time second only to the Panama Canal in terms of cubic yardage excavated, and in town water supply during which I discovered the extension of the former old Missouri River channel at depth below Lake Agassiz bottom clays in Manitoba when it flowed north to the Arctic during earlier interglacials (reversed flow during glacial damming and was captured by a river that is now the lower modern Missouri). Did Geo Survey work, mineral exploration and metallurgical in Nigeria (co-founder and lecturer at Nigerian School of Mines), other Africa, mineral economics for Canadian Feds writing chapters in the Canadian Minerals Yearbook,
I worked for the oil and gas industry for 5yrs, went on to consulting in mining, exploration and metallurgy. I keep up my interest O&G and even wrote a tech-ec report on the proppants (Frac sand- natural and manufactured) industry in North America for Roskill Information Services in UK (Roskill. com) which they sell for a small king’s ransom! And have an interest in climate and never miss one of your excellent articles. Real geologists came to the fight relatively late. I used to think the alarm was real before delving in.

Reply to  Gary Pearse
July 18, 2017 11:47 am

Geologist all around, my daughter is one, working for a well known international mining company, one of the largest. Strangely many of them, including the three world largest have headquarters in the UK, while the UK virtually has no mining of any consequence.

Reply to  vukcevic
July 18, 2017 11:37 pm

You don’t have to live in the shadow of a head frame.
And if you are the supplier of capital rather than labour you generally choose not to be near it except for the yearly photoshoot for the annual report

Gary Pearse
Reply to  Gary Pearse
July 18, 2017 2:06 pm

David, you certainly are eclectic and thorough in your wide ranging topics demolishing Big Climate. I consider the neomarxbrothers’ policies to solve a non problem to be the biggest threat that mankind has ever faced and we need application of logic, incisive analytics and a skill with words like you possess in this task. I’ve always thought of geological deduction as the pinnacle of forensics. I have a beautiful example of just this idea: The global warmth and biological productivity of the Eocene was determined by a variety of such forensic analyses. The following direct window into the Eocene was discovered in the Ekati Diamond pipe near the Arctic Circle in NWTerritories in northern Canada: redwood chunks dating at 53Mybp – real wood with crystallized sap seams and even the red color was preserved- were found my miners at the 300m level in the open pit. Did the MSM jump all over this story? Of course not. Enjoy.

July 18, 2017 11:42 am

Great article as always, David.
Harris county (Houston) is almost all exclusively surface water now. The conversion happened over many years, but (back in the day) western Harris County was covered with rice farms which were told they could no longer pump water to flood their rice patties. The farmers got the message, and eventually sold their farms to create subdivisions.
The main culprits of the sinking were the refineries. They use a lot, and the sinking surrounds their wells. But all in the multi-county area had to stop using ground water. There was resistance from small water districts who wanted to keep using ground water. After all, the surface water reservoir is in east Harris County, and the water districts in western Harris County weren’t interested in converting.
As the map shows, some areas sunk more (faster) than other areas.
When Hurricane Alicia struck, it devastated low lying areas that had sunk the most along upper Galveston Bay. It completely took out one subdivision called Brownwood in Baytown. The owners were forced to leave. This has since been turned into a nature center. The evidence of sinking/destruction of Brownwood was the last straw, and was used as the scare tactic to get/force the rest of Harris County on surface water.

July 18, 2017 11:47 am

So the big financial threat from fantasised extreme climate change is to oil rig assets that would be rendered valueless in a decarbonised economy. Rather a weird argument.

July 18, 2017 12:17 pm

It is the never ending flow of b.s. by the climate obsessed that I despise the most. The simple, closed minded anti-reality positions of the climate true believers is so predictable and so deceptive.

July 18, 2017 1:31 pm

Thank you David for another informative article.
My first visit to Baytown was in the mid 60’s and was told then by an engineer that the local subsidence and flooding at high tide was due to ground water removal. It may be more complicated but the issue has been going on for a long time.
Living along the NJ coast, I know that the barrier islands have been sustained since I was a youngster by pumping sand from the ocean back to the beaches and the streets still flood during a heavy rain.

July 18, 2017 1:48 pm

The “Adjustocene”? I’m going to have to remember that one- BRILLIANT!

July 18, 2017 3:02 pm

SUBSIDENCE: The go-to site for subsidence (or its opposite) in the USA is always the NOAA CORS project.
The data available for Galveston, TX is:
Galveston seems to be rising up a bit in the last few years, rather than subsiding. One must remember that Galveston is built on a sand bar — a barrier island — not solid ground.

July 18, 2017 4:54 pm

Climate change sea level alarmism is nonsense. At any location, the local sea level is dominated by land movements, not climate change. And worldwide, coastal land areas over the past 30 years have actually increased (e.g. from river silting and land uplift) more than they have decreased (e.g. from subsistence), as revealed from actual satellite observations:

J Mac
July 18, 2017 5:09 pm

Yet another thoroughly educational and entertaining article, refuting the ‘topping-the-snorkel’ assertions of accelerating sea level rise while leading us through so many more points of historical and geological interest! Thank You!

July 18, 2017 6:25 pm

“The Helix Producer I DP2 monohull floating production unit”
I like it!

Dr. S. Jeevananda Reddy
July 18, 2017 9:52 pm

Sea level change — raise and fall — are associated with several natural [earthquakes, volcanoes, tsunami, etc] and man made causes [destruction of coastal zones, water-oil-gas extraction, testing of atomic bombs, dumping of waste along the coast lines, etc]. For each station or region the detailed analysis on cause and effect must be studies by taking account the natural cyclic variations including associated with the Moon’s phases.
I discussed these aspects in my latest book [Climate Change and its Impacts: Ground Realities” [2016].
Dr. S. Jeevananda Reddy

Zack aa
July 18, 2017 10:24 pm
Announcing a lawsuit demanding compensation from oil companies for sea level rise.

July 19, 2017 1:31 pm

The beauty of tide gauge charts is that there are plenty of them all over the world, so they can be cherry-picked to find those where local vagaries provide meat for those who seek to mislead.
The inescapable fact of the satellite record is that the global rate of sea level rise has doubled since the late 20th century – and is accelerating.

Tom Halla
Reply to  Jack Davis
July 19, 2017 1:38 pm

“Cherry picking”? A bit of projection there, Jack? The only “acceleration” in sea level rise is almost certainly due to grafting tide-gauge records onto satellite estimates. The problems with the satellites has been covered quite extensively, and you almost certainly know that, and do not care.

Reply to  Tom Halla
July 19, 2017 7:45 pm

David Middleton – this is my third attempt to reply to you – somehow my replies don’t get through. So I won’t waste much time on this one.
1. They didn’t adjust the data to fit the model. They corrected an error in the data and then found it agreed with multiple other real world data.
2. That there was a data error had been verified by others:
““Whatever the methodology, we all come up with the same conclusions,” says Anny Cazenave, a geophysicist at the Laboratory for Studies in Space Geophysics and Oceanography (LEGOS) in Toulouse, France.
[…]” (the omitted section didn’t suit your argument?)
3. You guys spend your time besmirching what is in fact a magnificent international collaborative effort. We should all be thankful that these guys are out there and able to forewarn us.

Reply to  David Middleton
July 19, 2017 3:08 pm

No – you guys are just plain wrong:
You’d be a danger to the planet if you weren’t holed up here in your ghetto talking crap to fellow travellers who have a taste for crap.
The world is fast waking up to the climatic emergency and you guys will melt away – shamefaced.

Reply to  David Middleton
July 19, 2017 5:19 pm

“When the observations don’t match the models, adjust the observations…”
Paranoia is not such a big word either – and might apply to your claim.
They didn’t slow the past, they corrected an instrument error.
If the adjustment for satellite error is valid, your argument collapses. “It’s all coming together.” That’s what any detective says when he starts pulling all the threads of the case together and appreciating the big picture. These guys are experiencing the thrill of the chase while you guys sit back and misconstrue their data for murky personal reasons. Only a jaundiced observer would take the statement as evidence of malfeasance.
Probably time for a new more powerful and accurate satellite – in the appropriate orbit. Spacex is offering cheap rides.

Reply to  David Middleton
July 20, 2017 1:48 pm

David Middleton wrote, “When the observations don’t match the models, adjust the observations…”
Jack Davis replied, “Paranoia… might apply to your claim.”
Just because you’re paranoid that doesn’t mean they aren’t out to get you. The Climategate emails provide ample cause to suspect a thumb on the scale. Do you recall this discussion between Phil Jones and Tom Wigley about how to adjust-down the 1940s “warm blip,” to support the Hockey Stick narrative?

From: Tom Wigley
To: Phil Jones
Subject: 1940s
Date: Sun, 27 Sep 2009 23:25:38 -0600
Cc: Ben Santer
Here are some speculations on correcting SSTs to partly
explain the 1940s warming blip.
If you look at the attached plot you will see that the
land also shows the 1940s blip (as I'm sure you know).
So, if we could reduce the ocean blip by, say, 0.15 degC,
then this would be significant for the global mean -- but
we'd still have to explain the land blip.
I've chosen 0.15 here deliberately. This still leaves an
ocean blip, and i think one needs to have some form of
ocean blip to explain the land blip (via either some common
forcing, or ocean forcing land, or vice versa, or all of
these). When you look at other blips, the land blips are
1.5 to 2 times (roughly) the ocean blips -- higher sensitivity
plus thermal inertia effects. My 0.15 adjustment leaves things
consistent with this, so you can see where I am coming from.
Removing ENSO does not affect this.
It would be good to remove at least part of the 1940s blip,
but we are still left with "why the blip".

BTW, Jack, how are you coming on your quest to find even one high-quality, long-term, sea-level measurement record which exhibits significant sea-level rise acceleration? Are you ready to give up yet? Are you ready to admit that none of the high-quality, long-term, sea-level measurement records show significant, sustained acceleration in rate of sea-level rise?

Reply to  Jack Davis
July 19, 2017 7:14 pm

Jack Davis wrote, “You’d be a danger to the planet if you weren’t holed up here in your ghetto talking crap to fellow travellers who have a taste for crap.”
Mind your manners, Jack. This is not Tamino’s silly blog.
Tom Halla and David Middleton are trying to help you understand this. David, especially, has been very generous with his time. Show a little gratitude
Jack Davis wrote, “The inescapable fact of the satellite record is that the global rate of sea level rise has doubled since the late 20th century – and is accelerating.”
That is untrue. If you know how to read a graph, and if you actually read what David Middleton wrote to you, you should know that what you wrote is untrue.
Even President Obama’s former Undersecretary for Science, Dr. Steven Koonin, has noted that:

“Even though the human influence on climate was much smaller in the past, the models do not account for the fact that the rate of global sea-level rise 70 years ago was as large as what we observe today.”

Neither the satellites nor the tide gauges have measured significant, sustained sea-level rise acceleration.
In the case of the satellite altimetry, that’s pretty meaningless, because the data is very poor quality, and endlessly corrected/adjusted, and the longest single-instrument measurement records are only about a decade. The trends measured by satellite altimeters depend more on the instruments than on the actual sea-level.
But the tide gauge data is excellent. We have many long, high-quality, trustworthy, sea-level measurement records from tide gauges, including around five dozen extending back for more than a century. Those data needn’t be constantly corrected, adjusted & homogenized.
None of those high-quality, long-term, sea-level measurement records have measured significant sea-level rise acceleration since the 1920s or before. At most sites it’s been more than a century since they’ve measured significant sea-level rise acceleration.
Jack wrote, “The beauty of tide gauge charts is that there are plenty of them all over the world, so they can be cherry-picked to find those where local vagaries provide meat for those who seek to mislead.”
No, they can’t.
I challenge you to try it. See if you can find even one high-quality, long-term (>100 year) sea-level measurement record which shows significant acceleration.
You can’t do it, because there aren’t any.
That’s why “those who seek to mislead” about sea-level mostly talk about satellite altimetry, and/or tide gauges with very short measurement records. The high-quality, long-term measurement records all show the same thing: anthropogenic GHG emissions and anthropogenic global warming have not caused sea-level rise to measurably accelerate.
Measured rates of sea-level change vary from location to another, mostly due to local differences in VLM. But most of the VLM processes close to linear on century-level and shorter timescales, so they have little effect on acceleration. Consequently, all the highest-quality, long-term, sea-level measurement records show the same thing w/r/t acceleration: two-thirds of a century of soaring GHG levels and the associated global warming have caused no significant, detectable acceleration in the rate of sea level rise.
North Pacific:
South Pacific:
US East Coast:,+RI&boxcar=1&boxwidth=3
The average is just under 1½ mm/year (about 6 inches/century). Honolulu & Wismar are about average, Sydney is slightly below average, Newport, RI is quite a bit above average. But all of them show the same thing w/r/t acceleration: there’s been none since the 1920s or before.
Perhaps your problem is that you know how to recognize “acceleration” in a graph. If that is the case, this should help you:

Reply to  daveburton
July 19, 2017 7:37 pm

I hate it when my typos invert the meaning.
  “Perhaps your problem is that you know how…”
should be:
  “Perhaps your problem is that you don’t know how…”

Reply to  daveburton
July 19, 2017 8:23 pm

Dave, of course I know acceleration when I see it on a graph.
About 1900, when the Scandinavian chap whose name I forget (Arhellius?) calculated the effect that doubling atmospheric CO2 would have on planetary temperature, he was pretty much in agreement with modern science. What he didn’t foresee was that we would be up there so fast – that carbon powered industry would accelerate as fast as it has. He thought it might take a thousand years to get CO2 levels to where they are today.
That’s at the base of the problem we have in interpreting the data. The physical chemistry of carbon and its heat trapping ability has been well understood for almost 200 years. However, the radical build-up in atmospheric carbon levels has ocurred over such a short period of time geologically that it is easy to make spurious arguments and fail to realise the big picture from a very small section of time.
I’m over arguing today – it won’t be too many years now before the science will be irrefutable and you’ll be wondering why you couldn’t see it.
Either that, or you’ll still be arguing it’s not happening when the waves are breaking over Lady Liberty’s sandals.

Reply to  daveburton
July 20, 2017 2:45 am

Jack Davis wrote, “Either that, or you’ll still be arguing it’s not happening when the waves are breaking over Lady Liberty’s sandals.”
Don’t hold your breath waiting for that, Jack.
The Lady Liberty’s sandals are more than 150 feet above sea level.comment image
Since 1925, sea-level at Battery Park, NYC, has been rising at a remarkably steady 3.18 ±0.18 mm/year (and at least half of that is subsidence, rather than GMSL rise).
Despite a 33% (100 ppmv) increase in CO2 and a 83% (0.84 ppmv) increase in CH4, in all that time the rate of sea-level rise has not accelerated, at all.
Using the high end of the confidence interval (3.36 mm/yr), at the current rate 150 feet of sea-level rise would require 11,339 years.
To get 150 feet of GMSL would require melting the entire Greenland Ice Sheet, plus the entire West Antarctic Ice Sheet, plus 62% of the East Antarctic Ice Sheet.
Did you try to find “even one high-quality, long-term (>100 year) sea-level measurement record which shows significant acceleration”?
Do you acknowledge that you can’t find one, because there aren’t any, because sea-level rise hasn’t accelerated since the 1920s?

Reply to  daveburton
July 20, 2017 3:54 am

OK – it was an attempt at a colorful turn of phrase. I didn’t expect you to take it literally.
It has acceleated – the most recent determination is, as you’ve said, a doubling of rate in about twenty years. As with all good science, I expect that contention to be rigorously tested and checked from different angles in the near future.
I also expect you guys to find fault with any support for the contention – it’s human nature and it may be our downfall.

Reply to  daveburton
July 20, 2017 6:04 am

Jack Davis wrote, “the most recent determination is, as you’ve said, a doubling of rate in about twenty years.”
What is this “as you’ve said” nonsense? I don’t know who you’re addressing, but all three of us have explained to you that there’s been no acceleration. There certainly hasn’t been any “doubling of rate” in the last twenty years.
Perhaps you were confused by that silly Sallenger “hotspot” Nature Climate CHange paper, “Hotspot of accelerated sea-level rise on the Atlantic coast of North America.” It was based on data through 2009, and focused on the NYC Battery Park gauge.
Here’s what’s happened there since 2009:
Takeaway lesson: The ocean is full of water, and it sloshes.

Reply to  daveburton
July 20, 2017 6:28 am

David Middleton wrote, “Sea level was rising at about 3.5 mm/yr in the early 20th century. The rate declined to about 1 mm/yr during the mid-20th century. Since about 1985, the rate of sea level rise has returned to about 3.5 mm/yr. That is not an acceleration.”
David, that Jevrejeva graph doesn’t look anything like the individual tide gauge measurement records.
Here’s Honolulu, 1930-present, +1.29 ±0.27 mm/year:
Here’s Honolulu, 1930-1960, +1.53 ±1.31 mm/year:
Here’s Honolulu, 1960-1985, +2.13 ±1.78 mm/year:
Here’s Honolulu, 1985-present, +1.62 ±1.17 mm/year:
Here’s Wismar, Germany, 1930-present, +1.61 ±0.28 mm/year:
Here’s Wismar, 1930-1960, +1.82 ±1.29 mm/year:
Here’s Wismar, 1960-1985, +1.38 ±1.57 mm/year:
Here’s Wismar, 1985-present, +1.37 ±1.55 mm/year:

Reply to  daveburton
July 20, 2017 1:32 pm

According to Peltier, there’s very little isostatic movement at Honolulu and Wismar. (Negative is uplift, positive is subsidence; the last column is the estimated current rate.)

  53.900  11.467   54 120021 WISMAR                      0.22     0.20     0.21
  21.307 202.133  155 760031 HONOLULU                   -0.10    -0.09    -0.10

  53.900  11.467   54 120021 WISMAR                      0.01     0.00     0.01
  21.307 202.133  155 760031 HONOLULU                   -0.20    -0.19    -0.19
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