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


90 thoughts on “Sea level rise, subsidence and hurricanes… Oh my!!!

      • Interestingly, better management of the aquifer has made a difference…

        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, nor affects from harbor dredging and “island building.”

      • Aquifers do recharge. However, if the rock or sediment matrix has collapsed, resulting in subsidence, there will be less pore space in the reservoir.

      • 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

      • I think you’re right based on the GPS data… but the HGCSD subsidence maps indicate otherwise.

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

      • 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.

      • The subsidence maps aren’t based on the tide gauge data or GPS. They are based on geodetic surveys.

    • 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.

      • 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.

    • 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.

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

    • 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.

  2. 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.

    • Great video! Galveston is one of our favorite places to visit. My wife and I were married in a historic church in Galveston… St. Joseph’s was built in 1860 and survived the 1900 hurricane.

    • … 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.

    • 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.

      • 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.

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

    • That’s because the gray area of the subsidence map is covering up most of the two orange “up” arrows. You can see the tip of one of the arrows just above Pelican Island. PowerPoint only allows me to render one color transparent. I opted for white. There is a yellow “up” arrow visible to the northeast at Sabine Pass.

  4. Alternatively
    This graph shows four apparently ‘co-related’ variables
    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.

    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.

    • 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).

      • 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.

      • 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.

      • 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.”

  5. 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.


    • 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.

  6. 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.

  7. 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.

    • 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.

    • 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.

  8. 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.

    • 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.

      • 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, I am flattered and honored by your compliments. My work has pretty well been the inverse of eclectic. All “little oil” (as opposed to Big Oil).

      I worked East Texas from 1981-1988 and then I’ve worked the Gulf of Mexico (mostly East Cameron South Addition and Garden Banks) ever since. The first offshore project and first 3d survey I ever worked was a field in East Cameron South Addition. I’ve worked that same field for 4 of the 5 companies I’ve worked for… ;)

    • 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.

  9. 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.

  10. 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.

    • I does push the weirdness envelope… It logically compares to “We have to pass the bill, so we can see what’s in it”… ;)

  11. 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.

  12. Quote: Oceans have these things called “waves.”

    Hell’s bells. The alarmists have only just discovered clouds and are yet to fully falsify the records to cope with that. These wave things will have them scratching their heads although of course storm surges are very popular.

  13. 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.

  14. 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.

  15. 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:

  16. David,

    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!

    • It started its maritime life as a North Sea train ferry. Helix is kind of like the Thunderbirds of oilfield services vessels.

  17. 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

  18. 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.

    • “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.

      • 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.

    • Inescapable fact? Really?

      It looks like everyone needs to adjust their data.

      The recent announcement of accelerated sea level rise was due to a decision to apply a downward adjustment to the data in the early 1990’s.

      They dropped the early 1990’s from about 3.4 mm/yr to 1.8 mm/yr. Present day sea level rise remains where is was prior to the proposed adjustments. They propose to slow down the past to make the present appear to be accelerating.

      • Try to follow along. I will try not to use any big words.

        When the observations don’t match the models, adjust the observations…

        Satellite snafu masked true sea-level rise for decades

        Revised tallies confirm that the rate of sea-level rise is accelerating as the Earth warms and ice sheets thaw.

        Jeff Tollefson
        17 July 2017

        The numbers didn’t add up. Even as Earth grew warmer and glaciers and ice sheets thawed, decades of satellite data seemed to show that the rate of sea-level rise was holding steady — or even declining.

        Now, after puzzling over this discrepancy for years, scientists have identified its source: a problem with the calibration of a sensor on the first of several satellites launched to measure the height of the sea surface using radar. Adjusting the data to remove that error suggests that sea levels are indeed rising at faster rates each year.

        “The rate of sea-level rise is increasing, and that increase is basically what we expected,” says Steven Nerem, a remote-sensing expert at the University of Colorado Boulder who is leading the reanalysis. He presented the as-yet-unpublished analysis on 13 July in New York City at a conference sponsored by the World Climate Research Programme and the International Oceanographic Commission, among others.

        Nerem’s team calculated that the rate of sea-level rise increased from around 1.8 millimetres per year in 1993 to roughly 3.9 millimetres per year today as a result of global warming. In addition to the satellite calibration error, his analysis also takes into account other factors that have influenced sea-level rise in the last several decades, such as the eruption of Mount Pinatubo in the Philippines in 1991 and the recent El Niño weather pattern.

        The view from above

        The results align with three recent studies that have raised questions about the earliest observations of sea-surface height, or altimetry, captured by the TOPEX/Poseidon spacecraft, a joint US–French mission that began collecting data in late 1992. Those measurements continued with the launch of three subsequent satellites.

        “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.


        “As records get longer, questions come up,” says Gavin Schmidt, a climate scientist who heads NASA’s Goddard Institute for Space Studies in New York City. But the recent spate of studies suggests that scientists have homed in on an answer, he says. “It’s all coming together.”

        If sea-level rise continues to accelerate at the current rate, Nerem says, the world’s oceans could rise by about 75 centimetres over the next century. That is in line with projections made by the Intergovernmental Panel on Climate Change in 2013.

        “All of this gives us much more confidence that we understand what is happening,” Church says, and the message to policymakers is clear enough. Humanity needs to reduce its output of greenhouse-gas emissions, he says — and quickly. ”The decisions we make now will have impacts for hundreds, and perhaps thousands, of years.”


        Nature News

        Steven Nerem leads the sea level team at the University Colorado. This is what their sea level trend looks like today:

        A nice, steady 3.4 mm/yr (+/-0.4 mm)

        The adjustment, he refers to in the Nature article will move the early 1990’s down to 1.8 mm/yr and the present up to 3.9 mm/yr.

        So… They accomplished accelerated sea level rise by slowing down the past.

        I also provided you with the current sea level trends from all of the other academic and government groups tracking satellite altimetry sea level. All of them show steady trends of about 3 mm/yr.

        None of these groups have adjusted their data yet.

        Just a few months ago, Nerem and company published a paper bemoaning the fact that they had yet to detect any acceleration…

        A little perspective…

        More perspective…

        And more perspective…

        Dr. Nerem suggests that his adjusted sea level trend could lead to 75 cm (750 mm) of sea level rise by the end of the century. This would necessitate a late 21st century rate greater than the Holocene transgression..

        When there was a helluva lot more ice to melt…

      • “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.

      • 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?

    • 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:

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