Guest Essay by Dr. Alan Welch FBIS FRAS
We have now entered the 4th decade of measuring sea level rise using the quartet of satellites Topex and Jason 1, 2 and 3. The first 3 decades were reported in the trio of papers (Ref 1), (Ref 2) and (Ref 3). These concluded that.
1. The perceived “accelerations” are mathematical accelerations occurring due to the methods of calculation, i.e. quadratic curve fitting, as used by Nerem et al [.pdf] (Ref 4) in their 2018 paper. Also, the start date of Jan 1993 also plays a major role in how the “accelerations” pan out.
2. The “accelerations” are now generally reducing year on year and are predicted to reach levels compatible with the long term (over 100 years) Tidal Gauge values during the next decade or two before stabilising over the next few decades.
3. A time span of 30 years is much too short a period to calculate actual accelerations with 3 or more times this period being needed.
In this paper “accelerations” is used to indicate that those values are mathematically produced using twice the quadratic coefficient. Having said that the trends in values since about 2012 have settled sufficiently to make actual judgements regarding long term variation and trends.
The data for year 2023 will now be analysed with emphasis on 2 aspects, namely the predicted sizeable El Niño and the shenanigans concerning the data for October and November when nearly every data value changed with some changes being quite significant at over 8mm compared with annual increases of 3 to 4 mm.
Data releases via the NASA Global Climate Change/Vital-Signs/Sea Level Rise web site were made during 2023 for January, February, April, June, October, November and December but although all were analysed, not all will be reported on. Since February 2018 the analysis of the data has taken place in a standard manner every time a new set of data has been released. Extra processing has been also done when deemed of interest. In January 2023 the NASA site added an extra column (column 13) to the data which was as column 12 but with the GIA not applied [see column definitions just below]. The diagrams appearing on the NASA website showing sea level rises also changed at this stage in using column 13 instead of column 12. The inclusion of GIA or not only affects the rate of change and not any “acceleration” as it is set to a constant change of about 0.24 mm/year. In all the analyses for this paper and previous papers column 12 results have been used.
The full definitions of these 2 columns are,
Column 12 smoothed (60-day Gaussian type filter) GMSL (GIA applied) variation (mm); annual and semi-annual signal removed.
Column 13 smoothed (60-day Gaussian type filter) GMSL (GIA not applied) variation (mm); annual and semi-annual signal removed.
At this stage I would like to thank Kip Hansen for his patience in reading and replying to my steady stream of emails and whose comments have helped me formulate my ideas. Kip has not agreed with all my findings and ideas, but a friendly rapport has taken place between us.
Starting with the February data the “accelerations” have been calculated for increasing periods spanning the time from January 1993 up to the time of calculation. The results are shown in Figures 1 and 2.
Figure 1 compares the “acceleration” trend with that obtained from assuming the sea levels deviate from a straight line in a sinusoidal manner with a period of 26 years, an amplitude of +/-4.2 mm and with a suitable phase shift. The resulting graph of “accelerations” is labelled “Sinusoidal” on Figure 1. This curve is not a sinusoidal curve but a portion of a “damped” sinusoidal curve the derivation of which is shown in the Appendix to paper 1 (Ref 1). Its long-term variation is shown in Figure 3 together with average Tidal Gauge value. In this the sinusoidal curve is converging on zero but in reality, there could be a small long-term value commensurate with the Tidal Gauge value.
At this stage it had been stated that there may be a significant El Niño starting. Figure 4 below shows a plot of the El Niño Index. This is a more recent plot at the end of 2023, but the February 2023 data coincide with just about when the Index was zero but increasing.
It was decided to try to simulate the effect of an El Niño by taking the February 2023 data, which was available in May 2023, and extending the linear trend by about 5 years. Over the first 2 years a strong El Niño effect was achieved by raising the increase in sea level by roughly an extra 10mm. Over the next year the sea level drops back to the linear trend line. The Simulated El Niño is shown in figure 5 together with the linear trend.
A note to the purists. Every month when a new month is analysed the slope of the linear fit varies slightly therefore any actual residual sea level (actual minus linear value) or sinusoidal variation is measured to a slightly modified linear line. As the slopes are generally in the range 3.2 to 3.5 mm/year this is considered acceptable as being within “engineering tolerance” and being a retired engineer, I can sleep at night with this situation.
The modified data were analysed, and “accelerations” determined. The results are shown in Figure 6. The effect of the El Niño is to increase the “acceleration” temporary by about .01mm/year2 over the next 12 months or so and then resume a downwards trend. Interestingly two previous El Niños in 2015/16 (strong) and 2018/19 (moderate) show up as wiggles on the blue curve. The associated reduction in “acceleration” since 2020 is also shown in Figure 7
The next set of data to be analysed is for June 2023 resulting in Figures 8 and 9 which indicate a small influence of the El Niño starting.
When the October data were analysed, it was clear that there had been a dramatic change in the data readings as shown in figure 10.
Figure 11 below shows the differences between the October 2023 data and the June 2023 data. Over the first 10 years there had been increases in the October data of up to over 8mm. For the next 13 years the values stayed roughly the same with a reduction of about 2 mm over the last 7 years. The kick up at the end is mainly due to the El Niño. The consequences of these changes were to reduce the slope by about 0.3 mm/year and increase the “acceleration” by about 0.008 mm/year2. As of now no explanation has been found as to why these changes occurred. The last time any changes had occurred was in August 2021 with those changes varying between -2.5 mm and 0.5 mm resulting in little change in slope and a reduction in “acceleration” of 0.004mm/year2.
The November and December data release were anticipated with some trepidation and then analysed. The changes from June 2023 to November 2023 were lower as shown in Figure 12 with a maximum change now being about 5mm. From June 2023 this resulted in a reduction in slope of about 0.2mm/year and a reduction in “acceleration” of about 0.003mm/year2.
At this stage it was decided to create a combined plot of the November data showing the NASA data and the curve produced by combining the linear line with the sinusoidal variation, Figure 13.
Figures 14 and 15 show the latest (December 2023) plots of “acceleration” and reduction in “acceleration” since the 2020 peak.
A final plot, Figure 16, shows a comparison of “accelerations” since Jan 2020 based on the February 2023 data with the added El Niño simulation and the December 2023 data. If the 2024 trend follows the simulation trends the “accelerations” will peak at about .085 mm/year2 in the late summer of 2024 and quickly start reducing at nearly 0.01mm/year2 until the next significant El Niño appears.
Who doesn’t like a prediction? I’ve put my head up over the wall but at 86, with no agenda, reputation, University role or job to keep it’s nice to have that freedom. Just have to keep taking the tablets to see it all come to fruition!!
One conclusion is that the “accelerations” as calculated are not the harbingers of Doom and Gloom that many Climate Scientists, the BBC and the Guardian Paper portray. These “accelerations” may just be mathematical quirks and not of any major physical significance, but it could be revealing to try to match them and predict future variation especially over the next 10 years or so.
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1. https://wattsupwiththat.com/2022/05/14/sea-level-rise-acceleration-an-alternative-hypothesis/
2. https://wattsupwiththat.com/2022/06/28/sea-level-rise-acceleration-an-alternative-hypothesis-part-2/
4. Nerem, R. S., Beckley, B. D., Fasullo, J. T., Hamlington, B. D., Masters, D., & Mitchum, G. T. (2018). Climate-change-driven accelerated sea-level rise detected in the altimeter era. (full text .pdf) Proceedings of the National Academy of Sciences of the United States of America, 115(9). First published February 12, 2018
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Comment by Kip Hansen:
I have facilitated the publication of this essay, the fourth of Dr. Welch’s contributions here. Dr. Welch and I have had a long-standing continuing conversation, over several years, about sea level rise [SLR] rates and the assertion by some, Nerem et al. and others, that sea level rise is accelerating (meaning for SLR, rising faster and faster). NASA/NOAA likewise call the change in the rate seen when the satellite-calculated SLR is tacked on to the global tide gauge record at the year 1996 ‘accelerating SLR”. As with all numerical data that can possibly be associated with Climate Change, there is and has been a lot of fiddling with the methods, calculations, and resulting numbers. Thus, with sea level data, for which the annual changes are small compared to the magnitude of the confounding factors, little if anything can be ascertained with any degree of scientific certainty.
Long-time readers will remember that I am not a fan of the SLR Acceleration topic – for reasons stated above.
Dr. Welch’s take on acceleration is as valid as any other out there.
Earth’s sea levels are rising – they will continue to rise for all the reasons they have risen for the last few hundred years. It is my opinion that they will continue to rise at the same rate – 2 or maybe even 3 mm per year – into the future. This slow steady rise can and will be a problem for highly developed low-lying areas. Building within 8 inches of the today’s sea level – mean high tide — is and was always exceptionally foolish.
My thanks to Dr. Alan Welch for his continuing efforts to keep a close eye on the topic which allows him to catch repeated alterations of the data sets being used.
Dr. Welch is a guest here, please treat him like you would a guest in your own home.
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I have posted several times on SLR. I agree that NASA’s SLR acceleration is merely a mathematical artifact.
The basic problem with NASA satalt is that its inherent accuracy is on the order of 3.5 cm, while it purports to measure something on the order of 3mm. GIGO. I covered that in old post ‘Jason 3–fit for purpose?’. Covered again in two posts on the newest ‘bird’ Sentinel-6.
The second fundamental problem is that the NASA SLR does not close. See old post ‘SLR, acceleration, and closure’ for details.
OTOH, the dGPS vertical land motion corrected long record tide gauges show about 2.2mm/yr, no acceleration, and exact closure.
Rud, with all due respect, I don’t believe that differential GPS enables determination of vertical land elevations to the degree of accuracy/repeatability that you imply . . . that is, in comparison to the accuracy/repeatability associated with satellite radar altimetry data.
This from Engineering and Design, USING DIFFERENTIAL GPS POSITIONING FOR ELEVATION DETERMINATION (free PDF download available at https://www.discountpdh.com/wp-content/themes/discountpdh/pdf-course/using-differential-gps-positioning-elevation-determination.pdf )
Under Paragraph A-5 “d. The aforementioned error values lead to an expected uncertainty in final orthometric height at the unknown station of approximately 30 mm (at the 95% confidence level) relative to the published elevation at the benchmark reference station.”
And under Paragraph A-6 b “Results of the testing indicated that GPS-based surveys could determine NAVD88 elevations to an accuracy of 30 mm when relative heights and differences
in geoid heights are applied.”
Of course, 30 mm vertical positioning accuracy is equivalent to 3 cm vertical positioning accuracy, approximately the same as the 3.5 cm accuracy you asserted to be a “basic problem” with NASA satellite altimetry.
See Reviews of Geophysics, Woeppelman (2015). Established that with a continuous ten year record, dGPS can resolve vertical land motion to about 0.5mm/year. The referenced paper explains how and why. The difference to your cite is the 10 year rather than ‘instantaneous’ time frame.
Now that residual uncertainty will by and large cancel out over ~70 such long record (>60 year) corrected tide gauges all over the world. Same basic cancelling geographic error assumption that the much larger assemblages of non-corrected tide gauges make in their publications.
So much more precise than satalt. I stand by my previous posts.
Thank you for your reply.
I’ll just comment that I was unaware that having a repeated number of measurements (i.e., those obtained over 10 years, as opposed to “instantaneously”) was a means to improve the fundamental accuracy of the measuring device.
I’ll obviously have to review Woeppelmans’ paper.
Short simple answer. Depends on what you are measuring.
If just random ‘jitter’ observation duration does not help accuracy at all, contrary to official NASA sat alt propaganda.
If a slow steady change (vertical land motion) observation duration does help cancel random observational jitter.
Read the cited paper for the stat details.
I do not understand the down votes for this post (I negated one of them). TYSo and Rud had a polite technical discussion where differing opinions were discussed. If you disagree with the opinions, please say why. Maybe we will all learn something.
ToldYou ==> See Rud’s reply. single or multiple pass-over satellite altitudes are rough.
Multi-year Continuously Operating GPS stations (CGPS) can produce very accurate, millimeteric, long-term averages.
Kip, my two replies:
1) Can you provide a reference/link to a scientific paper supporting that statement?
2) “Long term averages” to mm resolution is not the same thing as having measurement accuracy to mm resolution.
ToldYouSo ==> I’ll just toss my favorite references your way for the topic of VLM measurement utilizing CORS stations:
https://link.springer.com/article/10.1007/s10291-019-0902-7
doi:10.1029/2006JB004606
https://www.degruyter.com/document/doi/10.1515/jag-2020-0041/html
https://www.sciencedirect.com/science/article/pii/S2468013320300474?via%3Dihub
The search topic for papers on this topic is “Vertical Land Movement and CORS”
All CORS-based estimates of VLM are long-term averages — it is the averages which have mm accuracy. The reason long-term (years) averages are needed is to smooth out the wiggles.
Kip, thank you providing a list of references as I requested. Unfortunately, I find that none of them support the assertion that ““Multi-year Continuously Operating GPS stations (CGPS) can produce very accurate, millimeteric, long-term averages” based on measurements as opposed to mathematical averaging. That is, for a given two vertical height measurements separated in time, the rate of change in elevation is purely a function of the intervening time period . . . reductio ad absurdum: if I had a 3 cm measured change in elevation that occurred over 100,000 years I could mathematically argue there is a change rate of 0.00030 mm/yr. And a linear curve fit through those two data points would have an R^2 value of exactly 1.0.
First, let’s keep in mind that mathematical averages are NOT direct measurements that have some +/- error band . . . instead, they are mathematical (statistical) constructs having infinite precision, with an unquantified degree of accuracy as stand-alone values.
Second, the original topic of discussion was the accuracy/repeatability of sea-level vertical height determination against some constant reference geoid (presumable NAVD88 or equivalent) by a single satellite, independent of the number of measurements made by such satellite over a given period of time.
1) https://link.springer.com/article/10.1007/s10291-019-0902-7 refers to combining data from 31 networks involving a total of 3192 European GNSS stations “into one homogenized {Oh, no! – TYS} set of stations positions and velocities” covering the period of March 1999 to January 2017. One of the stated conclusions is that over that period of measurements “the weighted RMS average value” for the “Up component” of position was 3.5 mm. Mathematically, and realistically, this article does not support an argument that a single GPS based satellite can provide better than 3 cm measurement accuracy . . . rather it states that taking a difference in averages of multiple inter-dependent measurements over a given time period/number of measurements allows a mathematical-based derivation of a temporal change in vertical height to a claimed precision of millimeters. I don’t buy it.
2) doi:10.1029/2006JB004606 refers to:
“. . . 37 tide gauges; each located within 40 km of a geodetic station whose International Terrestrial Reference Frame of 2000 (ITRF2000) crustal velocity had been rigorously derived from continuous global positioning system (GPS) observations, spanning from 3 to 11 years. The tide gauges are located along the coasts of North America, Bermuda, Hawaii, and Kwajalein (in the Marshall Islands). We obtained the ITRF2000 crustal velocities by averaging values from six solutions; each produced by a team of investigators acting, essentially, independently of the other teams. We then applied crustal velocities to convert rates of relative sea level change to rates of absolute sea level change. In a sample containing 30 sites, we found that the mean rate of absolute sea level change equals 1.80 ± 0.18 mm/yr in the 1900–1999 period. The scatter about the mean for individual sites in this sample is characterized by a (weighted) RMS value of 0.85 mm/yr.
“. . . we assume that these crustal velocities have remained constant over the multidecadal time spans (30–144 years) of the sea level records (except for three sites in Alaska, as discussed later). Our study, moreover, is restricted to the coastline of North America and a few islands (see Figure 1 and Table 1). In addition, we shall discuss various error sources associated with our estimates of absolute sea level change.
“It has been recognized that the measurement noise associated with GPS observations is time-correlated. Possible sources of this correlation include monument motion (unrelated to the larger tectonic and/or GIA-induced motion that is of interest) [Langbein and Johnson, 1997], uncertainty in the satellite orbital parameters, and atmospheric and local environmental effects [Mao et al., 1999]. As a result, the standard error of a GPS-derived velocity will be greatly underestimated unless these correlations are considered. Hence to assign a standard error σU to the computed ITRF2000 vertical velocity of a geodetic station, we applied the equation . . .“
So, again we have a paper discussing averaging of data over time from multiple sources . . . as a matter of fact, nowhere in this paper is there mention of the vertical height measurement accuracy associated with a single GPS satellite. In addition, even the mathematical derivation of ground vertical velocity has been “adjusted” (Oh no!) via application of an assumed-to-necessary equation. The paper only refers to derivations of crustal velocities in terms of mm/yr changes, and of course GPS satellites don’t directly measure ground velocity rates, only satellite-to-ground distances.
(continued below)
(continued from above)
I certainly don’t buy the stated accuracy/uncertainty of “mean rate of absolute sea level change equals 1.80 ± 0.18 mm/yr in the 1900–1999 period” given in this cited article. Furthermore, it gives a value for average SLR during this time period that is distinctly at odds with the values presented and discussed in the above WUWT article . . . so much for “accuracy” in deriving SLR based via corrections for VLM measurement utilizing CORS stations. Good grief!
3) https://www.degruyter.com/document/doi/10.1515/jag-2020-0041/html (paywalled, only abstract available and reviewed by me) refers to:
“Daily data for GPS weeks 834 through 1933 were reprocessed leading to epoch 2010.0 coordinates and velocities of 3049 stations aligned to IGS14 . . . As a validation of the results, the derived velocity field is compared to several other solutions and to three regional geophysical and geodetic velocity models. These comparisons uncovered unstable stations which move differently than the regional kinematics around them. Once these are ignored, we estimate the horizontal and vertical stability of this updated realization to be better than ∼0.3 and ∼0.6 mm/year, respectively. We use the position residuals and estimated uncertainties from this reprocessing to derive long-term stability measures for all active stations serving longer than 3 years. These measures exposed ∼60 CORS with the poorest long-term stability, which have been consequently excluded from serving as mapping control.”
Oh no! . . . Again, an averaging a many measurements from different stations, with admitted filtering and cherry picking, to derive vertical velocities (a “vertical velocity field”, no less) as determined over a number of years. Again, no mention of the vertical height measurement accuracy for any GPS satellite.
4) https://www.sciencedirect.com/science/article/pii/S2468013320300474?via%3Dihub refers to:
“The absolute and relative rates of rise of the sea level are computed for the New York City area by coupling global positioning system records of the position of fixed domes nearby tide gauges, with the tide gauges’ records. Two tide gauges are considered . . .The relative rates of rise of the sea level are +2.851 and +4.076 mm/yr. The subsidence rates are -2.151 and -3.076 mm/yr. The absolute rates of rise of the sea level are +0.7 and +1.0 mm/yr.”
As with preceding references, this article makes no mention of GPS elevation measurement accuracy and only discusses mathematically-derived sea-level rise rates as adjusted using GPS data. And again, the statement “The absolute rates of rise of the sea level are +0.7 and +1.0 mm/yr” is quite at odds with the data presented for this parameter in the above WUWT article. Causing me to wonder: GIGO?
Wouldn’t you expect slightly slower sea level rise during a global cooling period such as 1940 to 1980 compared with a global warming period such as 1980 to 2024?
Don’t most NOAA tide gauge charts show that? (you need a magnifying glass to see it).
In the Tidal Gauge sea level data there is a roughly 60 year sinusoidal variation that could be put down to a global ocean decadal oscillaion. I refer to this in my 2nd paper.
Rud ==> Thanks for checking in and reminding us of your past efforts. That the link for the ‘SLR, acceleration, and closure’: a must read.
What I am attempting to do is to show that it might be possible to show how “accelerations” may change in the future. That is those “accelerations” resulting from quadratic curve fitting.
The Tidal Gauge accelerations for those followed over long periods are low ( order 0.01mm/year2 ). They will never exactly become zero, but the NASA data is being used to give a value of up to 0.1 mm/year2and then extrapolating for decades ahead. In 2022 Nerem stated that accelerations were leveling off and a couple of links below show how the thinking process goes.
https://sealevel.nasa.gov/news/259/nasa-uses-30-year-satellite-record-to-track-and-project-rising-seas/
https://www.sciencedirect.com/science/article/pii/S027311772030034X
Once NASA has pontificated on it the likes of the BBC, Guardian newspaper etc latch on and pictures of the statue of Liberty with sea water up to her waste appear, kids become fearful of the future and wrong political decisions are made.
If I can try to predict, long term trends and short changes due the likes of El Ninos, it could become informative and help to understand the process.
Many thanks for a sane and useful look at this issue.
Yes beaucoup kudos to Dr Welch (and Kip) for their interesting revelations about SLR.
(I’m afraid the only SLR numbers I’m familiar with are about the SLR I had to hump around in 1969 – 70.
It weighed about 10 lbs and packed 20 x 7.62 mm NATO rounds and discharged them at 2,700 ft / second. Nobody seemed to care much if that rated muzzle velocity was accurate to 0.05 ft/sec or not.)
Alan/Kip
I don’t know the answer to this so I’m just putting it out there.
As we all know, the moon affects the tides of the earth and the moon is moving away from the earth at a rate of 3.8 cm per annum.
Does this have a bearing on sea level rise? I’m sure it can’t be 0.3mm/yr, but is it even measurable?
So it was 1 moon diameter closer to Earth 100.000.000 years ago.
Amazing
You’re falling into the extrapolation trap
To answer your question, no one knows
It would be accelerating.
Maybe Mr Josh Willil at NASA would be able to tell us how much.
Redge ==> The gravitational pull of the Moon is what causes tides (along with the Earth’s spin) in the first place. No Moon, basically, No Tides.
That said, air pressure is known to affect local sea levels — low pressure raises relative sea level.
The Moon being 1.5 inches further away each year must have some effect, however small, on its gravitational pull at the surface of the Earth. Less gravitational pull means lower tides, lower tides may add up to lower average Relative Mean Sea Levels.
But as to how, and if, that affects overall sea levels, I have no idea. I am open to suggestions though.
Me neither, Kip.
Instinctively, I think it must affect the tides and sea level rise, but it must be minor.
Over several decades though, it must surely enter butterfly territory.
It’s the same as India slamming into Asia at a glacial pace, eventually, there has to be an effect on the climate as the Himalayas grow taller.
Redge,
That’s a good question as regards the periodic tide magnitudes, but given that global average sea-level value is based on averaging out the periodic tidal swings it shouldn’t have much effect on that value, even as the Moon moves further distant from Earth.
FWIW, I haven’t tried to even estimate the magnitude of its effect globally (I don’t know if it can even be approximated) but I would look to tectonic plate motion as being a very-long term forcing factor on global sea-level elevation change, and even accelerations/decelerations of such, as measured against a given reference geoid. That is, the tectonic-induced deformations in the ocean basins around the planet will directly affect the average level of the oceans . . . conservation of mass in a gravitational field says that more mountains (i.e., higher average land elevation) must be associated with lower ocean level, and vice versa.
“Adjustment™” of satellite sea level data began quite a long time ago.
Here we can see the adjustments™ made at the change from Topex/Posiden to Jason.
(Original Topex in red)
The above article is a very interesting presentation indicating that perceived “accelerations” in SLR rate might be due to some unknown variable, with shorter term “bumps” being associated with El Ninos.
Admittedly, it’s problematic to “back out” that there is a sustained 26-year sinusoidal cycle period based on having only 30 years of data available (as duly noted in the article).
Nevertheless, I am quite surprised to see absence of speculation as to what may be establishing the asserted 26-year period for the sinusoid variation that seems to best fit the trending of SLR on a global basis as determined by the Topex and Jason 1, 2 and 3 orbiting satellites.
A 26-year cycle period doesn’t seem to match any Sun, Earth and/or Moon individual physical parameter variation frequencies, nor resonances, that I’m aware of (e.g., something like the 22-year Hale solar cycle, or something like orbital resonances).
Pure speculation: might the Earth have a physical radial expansion/contraction (“breathing”) mode that is on the order of +/- 4 mm displacement with a 26 year period (note in Figure 13 of the above article)? . . . one perhaps driven by a yet-undetected thermal oscillation in or between Earth’s inner core, outer core, and/or mantle? Here I’m specifically NOT referring to the “normal” seismic vibrational modes of Earth (ref: https://seismo.berkeley.edu/wiki_cider/images/3/3a/Modes-cider-jirving.pdf ), but instead to a planet-wide thermal oscillation-induced expansion/contraction mode.
For example, a “wobble” of Earth’s inner core having a period of 8.5 years has been detected (see https://phys.org/news/2023-12-assumptions-year-rhythm-earth-core.html ), but this is due to dynamics and is not a thermal oscillation.
There are 18 and 19-year lunar periodicities that are known to effect the tides.
18.6 year lunar nodal cycle. Is why you need ~60 year records to wash it out.
I specifically referred to something “matching” the 26-year period of what is shown as the basic sinusoidal variation in Figure 13 of the above article.
A Earth-Moon resonance having a period of 18-19 years is really no closer to matching that than is the daily 12h25m sinusoidal period of tides on Earth.
Sorry for the delay in answering but paper came out 9pm UK time too late to catch comments.
I think I addressed why a 26 year period in a previous paper or comment to a paper. I think it may not be measuring an effect directly but as the satellites only cover from about 82 degrees S to 82 degrees N there is about 5 % lack of cover. Could there be some ocean decadal oscillation that is not being picked up. Likely suspects could be the Arctic Ocean and/or the North Atlantic Ocean or interactions between them. 26 years is not an unusual period when Ocean oscillations are concerned. The amplitude (4.2 mm) is quite small. This value was not obtained by any mathematical process or Excel function but “eyed in”. It does look too precis for comfort but you have to pick something and then follow what happens in the future.
Alan, thank you very much for your thoughtful and clear reply.
You postulated “Could there be some ocean decadal oscillation that is not being picked up.” Yes, I think that is a possibility although somewhat remote because I would question why land-based tide gauges, especially those located close to 82° S and close to 82° N (see https://psmsl.org/data/obtaining/ ), have not previously detected such a fundamental period, albeit its small amplitude (which, all things considered, should be detectable with modern tide gauge instrumentation).
I am in complete agreement with you that, as of now, postulating a real 26-year period “forcing” on variation in global SLR based on only ~30 years of satellite data is problematic . . . but I find that at least half the fun in science is in speculating about cause that produces effect 🙂
SLR rise calculations are so sophisticated that when comparing to gauges, they make use of isostatic rebound due to the reduced weight of the glaciers melting changing shoreline elevations….Yet we have no idea at all about how much 70% of the planet, which is the bottom of the ocean, may have moved up or down….because Jason can’t see it from out in space and we have no way to measure it, and depth soundings just aren’t accurate to the mm.. One must really question whether this potential error renders our 3 mm per year results somewhat speculative, at best, or meaningless at worst….
Agreed. In order to make any sense of SLR you need to know if or how the size of the bucket that holds the oceans water changes before you can determine if the amount of water changes.
DMac and RobK ==> The only sea level that matters to us humans is Relative Local Sea Level at some intersection of land and sea of interest to us. Like The Battery in NY City — relative sea level (and tides) measured there affects sea level where I live, north up along the Hudson River. Relative Mean Sea Level at The Battery rose about 10-12 inches in the last 100 years. The surface of the sea itself rose only 6-8 inches (the difference being negative vertical land movement of The Battery itself). I live almost exactly at the hinge point for Glacial Rebound, so see almost zero VLM, thus, here we have had only the 6-8 inches of SLR.
The questions surrounding the Conceptual Eustatic Sea Level — “the size of the bucket” and “total volume of water” — are not relevant in my context.
Where is sea level where it hits my shore? That’s what is important.
In this context, think Sydney, Australia.
With respect, Kip,
”Where is sea level where it hits my shore? That’s what is important.”
Thats obviously the first order concern, however, many try to extrapolate causal factors such as thermal expansion, glacial melt and terrestrial dehydration etc. The point I try to highlight is that there are many ways sea level can change whilst having zero impact from climate or CO2 in particular. Any acceleration or variation maybe independent of any anthropogenic factors.
cheers.
How does quadratic curve fitting have anything to do with satellite altimetry? What do these graphs portend to signify? Satellite orbits are complex, the altitude at which they orbit varies much more than sea level. I have been reading these posts for years and find this one incomprehensible.
All that the satellites can actually measure is the return-beam time between the satellite and the ground. The surface of the ground is not undulating and can be determined independently by surveying and GPS. Thus, the elevation of the satellite can be derived. However, in the case of the ocean, both the surface of the water and the altitude (and speed) of the satellite vary. Therefore, they have to use a model of the gravitational constant to determine the altitude of the satellite. I suspect that the spatial resolution of the model is far less than what surveyors can achieve. Also, if there are spatial variations in mascons over time, or water piles up because of wind, the model may not be as precise as is assumed.
https://en.wikipedia.org/wiki/Gravity_anomaly
Sorry for the delay in answering but paper came out 9pm UK time too late to catch comments and that also sorry you found it incomprehensible. It is a follow on from my previous 3 papers so doesn’t stand on its own.
It is trying to show that in the long term so called “accelerations” are outcomes of the method used by Nerem et co, the starting time and the short period covered. It attempts to show what I think will happen over the next few decades and predicts that levels will fall to match Tidal Gauge values.
OK, now I get it. 31 years of wonky data, measuring millimeters from orbit, and claiming an acceleration because an invented quadratic curve fits the wonky data slightly better than a straight line, wow, glad that is not MY job!!!
If the satellites used for these measurements are in geostationary orbit, they are about 35,800 km above the earth’s surface, or 42,200 km from its center. If the satellite is between the earth and the moon, the moon’s gravity pulls in the opposite direction as the earth’s gravity, and the satellite moves farther away from the earth. If the moon is on the opposite side of the earth from the satellite, the moon’s gravity pulls in the same direction as the earth, and the satellite moves closer to the earth.
Since the satellite follows the same point on the earth, it will follow a cycle of being between the earth and moon, and with the moon on the opposite side, in slightly longer than one earth day (about the same frequency as two successive high and low tides). But these variations in altitude can be tens of kilometers. How is a satellite in a variable-altitude orbit supposed to measure changes in sea level in fractions of millimeters, or less than one millionth of the variation in the altitude?
SteveZ56 ==> You ask a good question, maybe for obscure reasons, but good, nonetheless. Satellite measurement of SLR has always been “iffy” at best, and is currently in the realm of what I call “computational hubris” — the belief that using vast computational power and complex programming somehow guarantee true results.
Read any of the many essays here at WUWT on satellite measured SLR. I wrote quite a few, as have others.
The above WUWT article clearly states “. . . using the quartet of satellites Topex and Jason 1, 2 and 3.”
Topex was in a 7714.4 km altitude, near-circular (eccentricity = 0.000095) orbit with an inclination of 66 degrees. Note that Topex mission ended in January 2006.
Jason-1 is also in a 7714.4 km altitude, near-circular (eccentricity = 0.000095) orbit with an inclination of 66 degrees (but out of phase with Topex)
Jason-2 is also in a 7714.4 km altitude, near-circular (eccentricity = 0.000098) orbit with an inclination of 66 degrees (but out of phase with Topex and Jason-1)
For reference, “Generally speaking OSTM/Jason-2 has been specified based on the Jason-1 state of the art, including improvements in payload technology, data processing and algorithms or ancillary data (e.g: precise orbit determination and meteorological model accuracy). The sea-surface height shall be provided with a globally averaged RMS accuracy of 3.4 cm (1 sigma), or better, assuming 1 second averages.“
(ref: https://www.ncei.noaa.gov/sites/default/files/2020-04/Jason-2%20Products%20Handbook.pdf )
(my bold emphasis added)
Jason-3 is also in a 7714.4 km altitude, near-circular (eccentricity = 0.000098) orbit with an inclination of 66 degrees (but out of phase with Topex, Jason-1 and Jason-2)
For reference, “Generally speaking Jason-3 has been specified based on the Jason-2 state of the art, with no major change on ground segment but some changes in the instrumentation (mostly in GPS and DORIS). We can only mention the following differences: on-board automatic transitions between the Diode/DEM (Digital Earth Model) mode and the acquisition/tracking mode depending on the satellite’s position, information about altimeter mode in the telemetry and differences about radiometer calibrations. As for Jason-2 the sea-surface height shall be provided with a globally averaged RMS accuracy of 3.4cm (1 sigma), or better, assuming 1 second averages.“
(ref: https://www.ncei.noaa.gov/sites/default/files/2021-01/Jason-3%20Products%20Handbook.pdf )
(my bold emphasis added)
The orbital ephemeris of each of these satellites is determined to extreme accuracy using both on-board GPS receivers, ground based radar tracking of satellite passes and ground-based optical tracking of satellite passes (i.e., Ground-Based Electro-Optical Deep Space Surveillance, or GEODSS, System). This orbital determination accuracy in turn enables the above-stated RMS accuracies of sea-surface height.
Story tip
France’s Council of State decries industrial wind turbines, calling them illegal, requiring full environmental assessments
France’s Council of State decries industrial wind turbines, calling them illegal and absolutely requiring full environmental assessments: those installed, and those planned. It’s an annulment, with broad implications (download the ruling). The lobbying of Fédération Environnement Durable and 15 other agencies has given this impetus to a possible full halt to industrial wind failures in France. There is currently a “massacre” of the French countryside, according to anti wind activists.
The French press release
As they say, satellites with non-constant orbits around a pear-shaped geoid, bouncing signals off a surface that is moving vertically 10,000 millimeters every few seconds yet expecting to give a believable variation in measurement of ~ 3 mm a year, is difficult to believe.
drongo ==> nicely stated….and the pragmatic reality is (almost) that simple.
Has Dr Welch published his results in a peer reviewed scientific journal, e.g., Nature or Science?
You are obviously totally clueless what “journal” peer-review is all about.
(as you are about basically everything)
How about you try to argue the facts instead…
You want to do a peer-review… Here is your chance.
I have peer-reviewed it, and I find nothing wrong with it.
What is the point of calling people ‘totally clueless’ about ‘everything’? What are you trying to achieve?
The guy is asking a perfectly reasonable question, one any of us might ask. It might be motivated by the view that the work merits publication in one of the usual scientific journals. Or it might be simple curiosity.
Why not let the author simply answer the question? Or answer it yourself if you know the answer?
Arguing productively, means staying on topic, and keeping personalities out of it. The rest is anger management.
No, beetroot is trying to say the paper has not been journal peer-reviewed…
… therefore not science…
Beetroot is an alarmist trollette that has form using slime as a crutch for his lack of any sort of scientific understanding. !!
Don’t you think he should argue the facts… and not attempt slimy innuendos ??
As I said… here is his chance to review the paper.
… let’s see what happens.
I see. This was the first comment I had seen from him.
But still, Kip Hansen’s reply to him, below, is a lot more effective, because its so measured.
Beetroot has proven himself to be totally clueless.
He needs to face the truth about himself, or he won’t seek to understand anything.
What is the point calling people ‘totally clueless’ about ‘everything’ when it would be easier to call them a leftist?
Leftists study every subject in the universe with the goal of become experts on everything. Some think they are..
In reality, the ultimate result of all that study is that leftists know nothing aout everything
Exhibit A
Junpin Joe Bribe’em
Exhibit B
Kamala “word salad” Harris
Honorable Mentions
John “why the long face?” Kerry
Al “the climate blimp” Gore
Alexandria Occasionally Coherent
I try to insult a leftist every day under doctor’s orders to reduce my blood pressure and it has worked. He said: “Insult al leftist a day to keep the doctor away” … or something like that.
Who are these ‘leftists’? Kerry, Gore and AOC are indeed people advocating very silly policies, perhaps enough to qualify them as personally silly people in the eyes of many.
But who are the rest? Democrat voters in the US? Labour voters in the UK? Liberals in the UK? SNP voters in the UK? PvdA voters in Holland? SPD Germany? How about Die Linke in Germany?
At the moment for instance, if the UK polls are correct, Labour would get 45% of the votes in a General Election held today. That’s going to be north of 20 million people (there are about 49 million registered voters in the UK).
Its quite mistaken to call such a large category of people stereotyped names. They are neither stupid nor ignorant, they simply have their opinions, which may differ from yours. In fact, the attitude that those who disagree with you are stupid and ignorant is incompatible with effective participation in a functioning democracy, the guiding principle of which is that you engage and persuade to resolve policy disagreement, and that this produces better, or at least less bad, decisions than any other way of doing things.
Something WUWT is working at, in its own way, and making some progress.
It looks likely the UK increased vote for labour is due to the fact that the past 14 years of conservative government have been so, so bad…
Hey, bNasty, please save your best insults for me, or I may get the impressions that you don’t hate me as much as you had in the past
I don’t hate you, dearie.
You are not worth the effort.
But I will, however, continue to draw attention to your idiotic anti-science support of many of the AGW memes.
And your egotistical ranting trying to support those ill-begotten beliefs.
Sorry for the delay in answering but paper came out 9pm UK time too late to catch comments.
I did try to publish an earlier version of my 1st paper in PNAS. It reached peer review stage and was thrown out. In trying sites such as ResearchGate you need to have some contacts or position. An OAP living in a rural part of England, tending to the garden, listening to his music and writing the odd paper can’t get a look in!! Lucky we have WUWT.
“Peer review” does not mean what you might think it means . . . and hasn’t been so for at least the last four decades.
“A major criticism of peer review is that there is little evidence that the process actually works, that it is actually an effective screen for good quality scientific work, and that it actually improves the quality of scientific literature. As a 2002 study published in the Journal of the American Medical Association concluded, ‘Editorial peer review, although widely used, is largely untested and its effects are uncertain’ ”
— https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4975196/
“In the early 1980s, there was growing concern about the quality of peer review at scientific journals. So two researchers at Cornell and the University of North Dakota decided to run a little experiment to test the process . . .
“The researchers then altered the names and university affiliations on the journal manuscripts and resubmitted the papers to the same journal. In theory, these papers should have been high quality — they’d already made it into these prestigious publications. If the process worked well, the studies that were published the first time would be approved for publication again the second time around.
“What Peters and Ceci found was surprising. Nearly 90 percent of the peer reviewers who looked at the resubmitted articles recommended against publication this time. In many cases, they said the articles had ‘serious methodological flaws.’ ”
— https://www.vox.com/2015/12/7/9865086/peer-review-science-problems
The only real questions asked by a “journal” are..
“do we want to enter this paper into the discussion”… and
“does it say anything that we don’t want to allow to be seen”.
Obviously, “Nature” and “Science”, having been subsumed by the green ooze, could never allow themselves to publish actual science that counters “the story”.
Warren ==> The answer to your question is NO, though he naively made on attempt in the past. He is a well-retired engineer, with no academic affiliation at present. Thus, competing against the over 7 million papers submitted last year, his submission had zero chance to being published. That is just how the academic publishing arena functions. It is no reflection on his observational results from published data.
In truth, crowd review here is often far harsher than peer-review at a journal.
That said, his calculations are what they are — if you have alternative calculations you want to share, let’s have ’em.
If you want to post a counter-argument, write it up and send it to me at my first name at 14.net.
Back in the early 2000’s I was watching the Colorado U sea level website. Rise was consistently around 3.2 mm/yr. Then it began dropping, 3.1, 2.9, 2.8. I think it got down below 2.7 mm/yr when the site went dark. A month or two later the site came back, and the sea level rise was miraculously back to 3.2. Hmmm. So I dug deep, and found they had added this thing called GIA, which wasn’t really a rise in sea level, but had something to do with the sea getting bigger/deeper. So what they now called sea level wasn’t sea level, but what it would have been if … who knows what. It gave desired numbers even if it wasn’t real.
Sorry for the delay in answering but paper came out 9pm UK time too late to catch comments.
It was only after about 2012 that things started to settle down. The start date of 1993 was probably on a high so earlier slopes were lower. But from 2012 onwards some resemblance of a trend started. Also the periods involved were much shorter an that had a major effect.
I don’t like adjustments and corrections. If we need adjustments and corrections to arrive at our answer that is a bad thing. I suggest these people go down to the ocean and physically measure it then get back to me.
” I suggest these people go down to the ocean and physically measure it then get back to me.”
Sea levels are measured at the edge of the oceans in hundreds of places… where it actually matters.
There is no evidence of any significant long-term acceleration at basically any tide gauge.
Quite a few show a steady linear trend with a slight overlying oscillation.
Clueless trendologists sometimes attempt to use this oscillation to show acceleration.
Over the years R. S. Nerem etal. Manipulated the satellite data to such a large degree that nobody should consider it realistic.
NOAA says sea level rise is 1.7 to 1.8 mm per year.
Long term tide gauges yield zero to 0.01 mm per year per year of acceleration.
All the the rest of the verbiage is so much navel gazing.
I’m on an IPad somewhere, otherwise I’d put up some links and graphics to support the foregoing (-:
The late, great John Daly reported on the problems with satellite sea level measurements before he passed in 2004. Unfortunately not all of his old links/posts have been maintained.
Yes, he was great…a pioneer in this business. (along with Anthony!).
It is common to add a Ph.D. after a name where a Ph.D. was earned. I do that for authors recommended on my blog, which would inlcude this author / article on todays list. Doctor is traditionally reserved for medical doctors. Unless you are the First Lady!
It is of interest to know the subject of the Ph.D.
My best guess is from “FRAS”
FRAS may refer to: Fellow of the Royal Astronomical Society, post-nominal letters · Fellow of the Royal Asiatic Society of Great Britain and Ireland, …
Another subject
I was doing sea level research yesterday mainly by treading some of the excellent Kip Hansen sea level articles here. An index of links to all the Hansen sea level articles in the past decade would have been useful. The search engine produced too many James Hansen articles. All the Kip Hansen articles are good, but the sea level articles may be his best subject.
I am a retired Civil Engineer and obtained my PhD in developing a method of stress analysis in large mass structures such as Nuclear Power Station containment vessels. I did start work on Rocket Design (Blue Streak) in 1958 hence my FBIS which I have retained as I have kept in touch with astronautics all my life. The FRAS was to get more involved with astronomy/cosmology a passion since I was a lad – you could call it my night job!
Re this sea level work it is not to quantify any accelerations, per se, but to negate the false “accelerations” stemming from the mathematics used coupled with short time scales. Having said that I feel there may be some mileage in seeing how even these mathematical values of “acceleration” pan out over the next few years.
I have a blog with a daily climate and energy recommended reading list. It’s my judgement whether an author knows what he is talking about and whether the conclusions are backed by convincing data. You qualified immediately.
I don’t know if I will reach age 86, but if I do I only hope I will be able to chew gum and tie my shoes at the same time. Henry Kissinger was still smart at ae 100, so there’s no reason you could not top that. Good luck.
Do you think there is value in trying to find physical backup for these “mathematical values”, and assessing/quantifying the chances of future impacts, before they “pan out”?
FYI, whatever we think of AGW impacts, I believe that seal level is about the easiest to adapt to. It disproportionately affects the upper income/net worth folks, businesses, government entities, who can most easily gird up, and/or pick up and move
James Hansen qualifies to have “Ph.D” added after his name . . . so what?
Richard ==> I don;t really have a list of all my sea level stuff (or all my stuff on every topic) but this link will give you a pretty good idea of the major bits: https://wattsupwiththat.com/?s=%22by+Kip+Hansen%22+sea+level
Thanks
I did a search yesterday and the articles were not listed in chronological order. But they diBut they are today. Confuser gremlins
Did any article of yours have a chart where the date for different satellites were compared that showed a disconnect in the data that may have been smoothed away?
I think the article was more than a year ago — that’s all I remember. I had the jpeg is on an older computer that died.
Either you wrote the article with that chart or Willie E. did. I never found it but your old articles were good reading
Richard ==. Are you thinking of the charts that show the different satellite missions in different colors, end to end and overlapping? I believe that chart is still available at NOAA or NASA se level sites. I’ll take a look tomorrow.
Maybe this one (but it stops at 2015)?
“Doctor is traditionally reserved for medical doctors. Unless you are the First Lady!”
How totally unfair to pick on Dr Biden! All the lawyers in the Nuremberg trials referred to each other as ‘Doctor,’ including the ones they hanged. And just because Dr Biden didn’t have a separate career on her own like Melania Trump, and just because she doesn’t speak 5 languages like Melania Trump, and just because she isn’t as pretty as Melania Trump, isn’t any reason to knock her credentials. After all, she has exactly the same doctorate as Dr Bill Cosby, and you don’t hear anyone making fun of him, do you?
“It is common to add a Ph.D. after a name where a Ph.D. was earned. I do that for authors recommended on my blog, which would inlcude this author / article on todays list. Doctor is traditionally reserved for medical doctors. Unless you are the First Lady!”
Except in academia where the title Dr. is commonly used (which is the First Lady’s occupation).
What confidence is there that sea level can accurately be measured from a satellite
that absolute sea level is more important to people who own infrastructure located near sea level, rather than tide gauge relative sea level
that satellite numbers do not match tide gauge numbers even with a focus on tide gauges with the least subsidence
that a change of satellites did not cause a one time rise in sea level from a different set of measurement instruments, a data artifact completely unrelated to the actual tiny change in sea level
that satellite data should be the focus and tide gauge data ignored
and that NASA-GISS can be trusted to report raw unadjusted satellite data with no devious adjustments? … The same NASA-GISS that made almost all of the 1940 tio1975 global cooling “disappear” during the1990s with arbitrary “adjustments”.
With every sentence I type, my confidence in the accuracy of satellite sea level numbers declines and has now reached ZERO.
The large changes in data shown in my paper are a concern. If data are correct I am amazed by the consistency between satellites but still think that actual “accelerations” as calculated will fall to values in the region of 0.01mm/year2 (similar to Tidal Gauges) over the coming decades. Must gear up my grand children to take over my Excel files to carry on the fight!
When it gets to actual accelerations as low as 0.01mm/years we can be in the realm of much longer time frame changes – millennium? So no chance of advances in analysis at that stage.
My main concern is that the likes of Nerem still make comments like the accelerations have leveled off or perform long term extrapolation of quadratic curves, That practice should be banned.
My reply: What confidence is there that sea level can accurately be measured by tidal gauges? If one wants to correct land based tidal gauges for land uplift or subsidence (due to isostatic rebound from the last glacial period on Earth, or from depletion of underground reservoirs of water or oil, or from tectonic plate motion, or other causes) then that is done using GPS or differential GPS . . . both of which, guess what, rely on vertical height determination referenced to orbiting satellites!
ROTFL.
ToldYouSo ==> I think I already answered about the difference between the satellite se level measurements and the science of using Continuously Operating GPS installations to measure long-term average Vertical Land Movement.
Not the same thing nor subject to the same magnitude of uncertainty ranges.
A meaningless comment
What is most important to owners of infrastructure located near sea level is relative sea level INCLUDING land movements.
I was just responding to your March 22, 2024 5:38 am comment which asked the question “What confidence is there that sea level can accurately be measured from a satellite?”
Nowhere in that post of yours was there any mention of the importance of sea level rise (absolute or relative) to “owners of infrastructure located near sea level.”
But then again, I see that your use of “meaningless” is itself quite relative.
Regarding the 26 year oscillation. Has any investigation been conducted relative to geothermal volcanic activity and/or plate tectonics?