Inside The Acceleration Factory

Guest Post by Willis Eschenbach

Nerem and Fasullo have a new paper called OBSERVATIONS OF THE RATE AND ACCELERATION OF GLOBAL MEAN SEA LEVEL CHANGE, available here. In it, we find the following statement:

Both tide gauge sea level reconstructions and satellite altimetry show that the current rate of global mean sea level change is about 3 mm yr–1, and both show that this rate is accelerating.

So the claim is that tide gauges show acceleration. Let’s start with a look at the Church and White (hereinafter C&W) estimate of sea level from tide gauges around the world, which is the one used in the Nerem and Fasullo paper. The C&W paper is here.

Figure 1. Church and White sea level rise estimate.

Not real scary …

However, there is an oddity. Let’s take a closer look at the C&W sea level estimate shown in Figure 1.

Figure 2. As in Figure 1, but with a different scale.

Now, when I looked at that, the curious part to me was the change in the recent trend. For the last quarter century, we’ve had satellite sea level data, which began in 1993. In the past, the trend of the satellite data (1993 – 2013, 2.8 ± .16 mm/year, or about an eighth of an inch per year) has been almost double the overall trend of the tide gauges (1.6 ± 0.14 mm/year).

But in this most recent C&W estimate, the recent tide gauge trend is much larger. How much larger? Well … a lot. In fact, the recent C&W estimate is greater than the satellite estimate for the overlap period …

Figure 3. As in Figure 2, showing trends for the 21-year periods before and during the satellite era.

Why the increase in trend? Well, since 1993 they’ve mixed satellite data in with the tide gauge data.

To combine the tide gauge and satellite datasets, … Church and White (2011) and Ray and Douglas (2011) use empirical orthogonal functions of the satellite data with principal components derived from the tide gauge records. Church and White analyze changes in sea level over time, enabling them to use many tide gauges, some with short records, without needing to relate the absolute level of different tide gauges. SOURCE

But is this approach justified? I mean, did the tide gauge data itself go up during that time, so that it would be reasonable to use satellite data to refine the results?

Now, that is a tough question to answer, because the tide gauge data is sparse spatially and temporally, and it is also affected by vertical land motion. But you know me … I’m a data guy. So I went and got the full set of 1,512 tide gauge records from the Permanent Service For Mean Sea Level. In passing let me say that I don’t think they could make it harder to collect the data. It is in 1,512 separate files. Not only that, but the so-called catalog looks like this:

Figure 4. PSMSL Catalog. It is great fun to convert this to a simple computer file … but I digress.

To highlight some of the problems with converting tide-gauge data to global sea level data, here are ten typical records in the dataset:

Figure 5. Typical tide gauge records.

I’m sure you can see the difficulties. Some places the land is steadily rising from post-glacial rebound, and it’s rising so fast that the sea levels are actually sinking relative to the land. In other places, the land is sinking due to subsidence and groundwater extraction. Many records are short and have gaps. Generally, it’s a mess.

So … here was my thought about how to get around these issues: You’ll note in Figure 3 above that the increase in trend between the 21 years before the satellite era and the 21-year overlap during the satellite era was 2.1 ± 0.5 mm per year. And while the trends in the tide gauges are all over the place … I can look at the difference in the trends for each individual dataset over the same period. This gets rid of the problem of vertical land movement, which is constant over such a geologically short time period. So here was my procedure.

First, from the 1,512 tide gauge records in the PSMSL dataset, I selected all the records that contained 90% data over the 21 year period before the satellite era and also had 90% data over the succeeding 21 year period during the satellite era. This left me with 258 tide gauge datasets with coverage over the full 42-year period.

Next, I calculated the trend for each of these datasets for the period before and during the satellite era.

Then, for each tide station, I subtracted the pre-satellite trend from the satellite trend. And finally, I got the median and the uncertainty of those 258 trend differences. Figure 6 shows a graphic of those results.

Figure 6. Comparison between the values and the errors of the difference between the 21-year trend before the 1993 start of the satellite record, and the succeeding 21-year trend from 1993 to the end of the Church and White records. The C&W trends are shown in Figure 3 above.

Since the error bars (orange and red) do not overlap, we can say that the C&W estimate does NOT agree with the tide gauge data. And that, of course, means that it has been artificially increased by cross-pollution with satellite data.

Let me close by saying that I think that it is very bad scientific practice to splice together a terrestrial and a satellite record unless they agree well during the period of overlap. In this case, they disagree greatly over the period of record. For the detrended values over the period of overlap (1993-2013), the R^2 value is 0.01 and the P-value is 0.37 … in other words, there is absolutely no significant correlation between the satellite data and the C&W estimate.

And this makes it very likely that Church and White are manufacturing sea level acceleration where none exists … bad scientists, no cookies.

Finally, at the end of my research into this, I find that I’m not the only one to notice the discrepancy …

Figure 7. Different results for the satellite era depending on whether or not the satellite data is illegitimately spliced into the tide gauge records. SOURCE

My best to everyone. Here I’m staying indoors on a rainy Sunday, watching American football and researching the vagaries of sea level …


As Always: I politely request that when you comment, you quote the exact words you are discussing, to avoid misunderstandings.

Data: So that others won’t have the hassles I had extracting and collating the data, I’ve put the full PSMSL dataset as a single comma-separated values (CSV) file here, and the PSMSL catalog here.

Data 2 :Commenter Bear was unable to download the files and suggested I change the end of the link. New links to PSMSL file here, and the PSMSL catalog here.

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December 17, 2018 6:09 pm

The point of it all is “climate action” that assumes that the rate of sea level rise is responsive to the rate of emissions and that therefore the rate of sea level rise can be attenuated by cutting emissions.

Also relevant

Dr. S. Jeevananda Reddy
Reply to  Chaamjamal
December 17, 2018 7:56 pm

The above article don’t support this — emission versus sea level rise. Figure 5 shows that some stations show Sea level rise and some other show the fall. Also, the data network at 1880 is different from 2013. The accuracy is affected by several factors like subsidense in land due to extraction of oil, gas, water; destruction of coastal zones against the law to meet the real estate and other ventures; sand removal, etc. etc. So, like in global warming, the word global is misnomer. So also the case with sea level rise/fall. Global averages have no meaning except fill the pages of literature. The more important issue is take the tide gauge of a location and look in to the aspects relating change in sea level. This is more useful for taking appropriate actions relating cyclonic systems impact on people living along it.

Also fitting the curve bit by bit has no meaning in such circumstances.

Dr. S. Jeevananda Reddy

old white guy
Reply to  Chaamjamal
December 18, 2018 7:38 am

I would like someone to tell me just how much sea level is affected by undersea volcanic action and other changes regarding land mass and erosions.

Reply to  old white guy
December 18, 2018 8:03 pm

… and outer space detritus accumulated over the eons adds up too.

nw sage
December 17, 2018 6:10 pm

Very useful Willis. Thank you for your lucid explanation.

Reply to  nw sage
December 17, 2018 6:58 pm

I agree with nw sage!

Reply to  nw sage
December 17, 2018 11:29 pm

Ditto…thank you Willis.
Very interesting and well done, as always.

Javert Chip
December 17, 2018 6:15 pm

Well it’s obvious to even the casual observer that we should be using tree rings.

/sarc (as if read)

December 17, 2018 6:22 pm

That is getting a bit obvious as to manufacturing results if the two methods do not overlap.

Steven Mosher
December 17, 2018 6:22 pm

“It is in 1,512 separate files. Not only that, but the so-called catalog looks like this:”

man what an ugly way of doing things

Peter D. Tillman
Reply to  Steven Mosher
December 17, 2018 7:02 pm

??? Care to unpack that? Willis E. seems to have done a reasonable and tedious job, and found Yet Another unjustified Alarmist claim.

D. J. Hawkins
Reply to  Peter D. Tillman
December 18, 2018 6:54 am

I read Steven’s comment as attaching to the clumsiness of the catalog, not about Willis’ efforts.

Reply to  D. J. Hawkins
December 18, 2018 8:14 am


Reply to  Peter D. Tillman
December 18, 2018 6:59 am

Play flagged, five yard penalty.

Perfectly reasonable and appropriate comment by Mosher there.

Reply to  Steven Mosher
December 17, 2018 8:21 pm

Sounds like a job for a database using BLOBS. (Binary Large Objects)
Then you could cook it down to one backbone DBF with 1512 records with pointers to the individual data sets. Access would be greatly enhanced and simplified. Too bad DBF tech never made it big in the scientific community.

H/T to Willis for untangling the mess and putting up the results for us.

Zig Zag Wanderer
Reply to  TonyL
December 17, 2018 11:47 pm

Too bad DBF tech never made it big in the scientific community.

I agree. It’s the same in most commercial and government organisations. As one who cut his teeth on databases, I have found this very difficult to deal with.

The underlying problem is that databases require some knowledge of a language to extract, insert and edit data, unlike a spreadsheet where the data is immediately obvious and accessible. The problem with the spreadsheet is that people add non-standard data (which you can’t do in a database without changing the structure), and you need very deep knowledge to extract specific data.

The simple fact is that databases require a language to extract data, and a language or programming to insert data, and specific skills to create the structures. That stops people using them except for large amounts of data that need structure and security.

Unfortunately, during my career as a programmer, my experience of spreadsheets caused me to break out in a cold sweat every time I was asked to turn them into databases. I ended up doubling my estimates, then quadrupling them. I still found many instances where I’d underestimated the work.

Ben Vorlich
Reply to  Zig Zag Wanderer
December 18, 2018 2:52 am

Me too, and MS Access when used in the ph” I’ve developed this Access database and we want to make it company wide”

The worst data untangling I had to tackle involved the billing data from a third party for several hundred customers each with several hundred seperate telephone lines. The file contained individual cal and data records amongst other records. The file was a single monthly output of several million lines of comma seperated fields there were about 40 different record types each with a different number of fields. There was, so they said, no documentation because no one had ever wanted to load the data into a database. After several months effort and pouring over printed output sa couple of feet high for each month I got the data into an SQL server database. The effort was worth it as the billing experts then identified errors which meant repayment of hundreds of thousands of £. Once we’d sorted it suddenly the documentation became available.

The point of this story is that it is my belief that if someone makes it difficult to get the information there is probably a good reason, even if they have spent 25 years collecting it.

Well done Willis, bien joué as they say here

A C Osborn
Reply to  Ben Vorlich
December 18, 2018 4:56 am

I have programmed in Access (and Dataease before it), Excel (Visicalc before it) and VBA for 20 years and BASIC for 30+ years.
I still help on 2 Free Forums as I retired 15 years ago.
So I know just what you guys are talking about, one of the big problems is guys creating their filing system and not accepting the need to move in to the 21 century for others to share their data.
A certain East Anglia Climate Scientist’s inabilty to effectively use Excel is legendery

Reply to  Ben Vorlich
December 18, 2018 8:34 am

Do not assume malice where incompetence is an explanation.

More often, though, ignorance of how things do NOT scale up. I learned a long time ago that when I did a quick favor for someone, to not let them take the spreadsheet or whatever. It always came back a month or so later with them asking why it was so slow now. Well, about two or three orders of magnitude more data that they’re trying to shove through it…

Reply to  Steven Mosher
December 17, 2018 9:16 pm

Thanks Willis, for all your hard work1

Reply to  Steven Mosher
December 19, 2018 12:46 pm

Thanks Steve!

bit chilly
Reply to  Steven Mosher
December 18, 2018 5:06 pm

agreed, it should be renamed the pmsl file.

Sweet Old Bob
December 17, 2018 6:26 pm

Well …. if Mannie could do it , why can’t they ?
There doesn’t seem to be any penalties for this sort of ” stuff ” …. yet .

December 17, 2018 6:30 pm

Also depends on which satellite data they are using. The data from U. Colorado are not actually measurements of sea level! They are the output of a model that combines measured sea level with a guess of how much the sea floor is being pushed down due to the increase of sea levels since the end of the last glacial (basically the opposite of glacial rebound). So the U Colorado data are really guesses about ocean VOLUME, not surface level though they attempt to portray it as such. It used to show sea level until a few years back when it stopped rising, so they had to make another “adjustment” (“glacial isostatic adjustment or GIA, they call it).

Roger Knights
Reply to  crosspatch
December 17, 2018 9:03 pm

“They are the output of a model that combines measured sea level with a guess of how much the sea floor is being pushed down due to the increase of sea levels since the end of the last glacial (basically the opposite of glacial rebound).”

According to science groupies (e.g., card-carrying “Skeptics,” science is self-correcting, so this is fake news, because it can’t happen.

BTW, suppose the ocean floor were rising; would the U. of Colo. apply a correction and say the sea level is falling?
To ask the question is to answer it.

Steve O
Reply to  Roger Knights
December 18, 2018 4:21 am

}BTW, suppose the ocean floor were rising; would the U. of Colo. apply a correction and say the sea level is falling?”
— That is a penetrating question!

A C Osborn
Reply to  Roger Knights
December 18, 2018 4:59 am

Anyone remember the first European Satellite showing Sea Level falling, it didn’t last long before being de-commissioned.

Mike McMillan
Reply to  crosspatch
December 18, 2018 2:44 am

There’s bit of history to that GIA.

I’d been watching that site since the early 2000’s. They had curves with and without barometric adjustment, and with and without seasonal adjustment.

The rate was 3.2 for a long while, then it drifted down to 3.1. Then it was 3.0 briefly, then 2.9, and 2.8. Then the web site went off the air.

How comes, everyone asked. Oh, we’re just upgrading the site and stuff.

A month or two later, the site came back up with just one curve, and golly, the rate was back to 3.2. It took a little searching to discover how they did it, because the GIA info was buried back on some other page. After we all figured it out, they finally put the info up where it might be noticed.

Don K
Reply to  crosspatch
December 18, 2018 7:13 am

Crosspatch. What you say is true, but the value Willis cites — 2.8mm/year looks possibly to have had the GIA “correction” removed and to be eustatic (apparent) sea level. Hard to tell. It’s all kind of nebulous.

old construction worker
December 17, 2018 6:36 pm

Willis, you got more patience than I do and I have a lot of patience. Good job.

December 17, 2018 6:45 pm

I have noticed several mysterious goings on with the tide gage records.
A year or two ago and prior to that, the tide gage at The Battery in lower Manhattan was shown as a continuous record back to the mid 1800s, well over 100 years.
As of the last time I looked at it, there is now a multi-year gap in the record.
Even before that, I had noticed that gaps in the data seemed to appear on various gages, and stuff I had noted years ago was no longer in evidence from the site graphs.
This makes me question pretty much all of the gap strewn records.
Some large cities in places with a long record, busy ports, and huge amounts of commercial and pleasure boat traffic, have huge gaps and short records. Why is this? Seems very suspicious.

There are some additional points worth noting: All of the graphs show data which has been processed “to remove seasonal variations”, or some such language. But I can find no mention of exactly how this is done, or when, or if the results have been refined over time.
Have they been? If so, we know what kind of shenanigans that opens the door to.

Which brings me to the last thing I want to mention right here: These tide gages and the long stretch of very smooth sea level rise going back well over a hundred years in the longest records, is not in accord with what was reported and discussed in literature and studies and textbooks back in the pre-Hansen era…IOW prior to 1988 or so we did not see such smooth trends in sea level rise…at all!
There were multidecade trends that included periods where sea level was not rising but falling.
That is all gone.
BTW…I have been saving sea level graphs from this site for many years now, although not in any systematic way but related to conversations and comments on various forums and graphs and photos (historical and recent photos of the ocean and various landmarks from a long time ago and the same places more recently…none show any discernable change in over 100 years…plenty of old photos and none can be used to demonstrate any sea level rise at all. AT ALL. Strange, eh?), and I plan to gather these from old computers and hard drives to see if suddenly appearing gaps are the only changes in recent months and years to have been made.

Reply to  Menicholas
December 17, 2018 7:19 pm

Yes, strange!

But, not surprising.

Keep us apprised.

Gary Pearse
Reply to  Menicholas
December 17, 2018 7:33 pm

Menicholas, whenever I’ve noted similarities in 20th Century raw temperature plots around the world with US raw temperature plots , ie: Canada, Greenland, Scandinavia, UK, South Africa, Paraguay, Ecuador, etc , Stokes or someone else “points out” that there was a weather station move that changed that!

Now I’m an old poker player (my father was a big time sucessful poker player) and a ‘tell’ popped out in a mind that looks for tells not only in poker, but in the game of life where bluffing goes on all the time. It occurred to me that station moves, missing data and other apparent vagaries of climate metrics, may well be, in this age of amorality, another dimension to the skulldugery that is employed by the clime syndicate (thanks to Matk Steyn for this classy term) to hide other declines or ascents as required.

Here is the Capetown raw record for example, which could be mistaken for the US one from a WUWT article of several years ago:

comment image

Tom Abbott
Reply to  Gary Pearse
December 18, 2018 5:57 am

Yes, that Capetown chart looks to be representative of a global climate trend: The 1930’s show to be as warm or warmer than subsequent years.

The TMax charts Bob Tisdale has been posting show the very same temperature profile. Bob will be posting new TMax charts in a post in the near future.

What this shows is the bogus, bastardized Hockey Stick charts of NASA and NOAA and others are a distortion of reality. Their Hockey Stick charts show temperatures steadily climbing year after year. If you believed what the Hockey Stick chart is saying, then you should be worried about the future. It *does* look scary. It makes it look like we are living in the hottest times in history. But the Hockey Stick charts are a distortion of reality.

Here’s a scary Hockey Stick “hotter and hotter” chart:

comment image

The real global temperature trend is not “hotter and hotter”. The real trend shows the 1930’s to be as warm or warmer than subsequent years. This means the Earth is NOT in unprecedented temperature territory. We are no warmer now than in the 1930’s and we are currently cooler than in the 1930’s.

The IPCC says that CO2 had no significant effect on the Earth’s temperatures during the 1930’s. Since the 1930’s was as warm or warmer than today, that means there was enough energy in the Earth’s atmosphere during the 1930’s to raise temperatures to that level without the benefit of CO2.

And if the temperature levels today are at or near the levels in the 1930’s, but no higher, then there is no reason to assume CO2 has anything to do with it as Mother Nature is perfectly capable of raising temperatures to these levels all on Her own, as was demonstrated in the past.

All these TMax charts from around the world, in both hemispheres, show basically the same temperature profile, i.,e, the 1930’s being as warm or warmer than subsequent years.

NONE of these charts resemble the bogus, bastardized Hockey Stick surface temperature charts. The Hockey Stick charts are all alone. They show a world we don’t live in.

Reply to  Gary Pearse
December 18, 2018 10:43 am

My father did not play poker, but I have been playing since I was a lad in single digits.
But he did have a saying that I overheard him using with his fellow businessmen: You cannot bullshit a bullshitter.
And growing up in the downtown of a large city, I had a heaping helping nearly daily from all angles, and knew well by the time I was done grade school that there are more flavors of it than Baskin Robbins has ice creams. And very often the people who talk the loudest and insist they are telling the truth are the worst spewers of it.
And then we have the logical fallacy crowd…
In God we trust…all others bring evidence.

Curious George
December 17, 2018 6:46 pm

Hockey stick is a nice “nature trick” by Dr. Mann – mixing data from two different sources to obtain a scary effect. Used again here. Tide gauges have their problems, but I don’t trust a satellite altimetry. If nothing else, the sea surface is not flat, there are waves from millimetre height to many metres, irregular shapes, and I don’t believe that they can extract a true average level to a millimetre accuracy.

Reply to  Curious George
December 17, 2018 6:52 pm

I expect most of us here have seen this video, but it is very instructive for anyone unaware of just how much of a counter-intuitive concept “sea level” really is.
It is short…I strongly recommend anyone interested in this issue take a couple of minutes and review it…then do a lot more reading and investigation from there:

Joe Crawford
Reply to  Menicholas
December 19, 2018 11:06 am

Thanks Menicholas, that you tube is an excellent introduction for dummies like me.

Reply to  Curious George
December 17, 2018 7:01 pm

Paraphrasing from the video: “Geodesists have constructed a detailed and accurate model of the Earth’s gravitational field to accurately model what the true sea level is for every point on Earth. It is accurate to within less than one meter.”
One meter.
Note these graphs claim an error of no more than plus or minus half a millimeter per year.
From space.
On the constantly inconstant and storm tossed ocean, where waves and wavelets are piled onto one another and in ceaseless motion. And the sloshing…OY!

Loren Wilson
Reply to  Curious George
December 17, 2018 7:38 pm

Agreed. if I understand the process, they calculate the effect of the tides and remove them mathematically. I am not sure we know the tide heights that well.

Reply to  Loren Wilson
December 18, 2018 8:55 am

I think the adjustment for tidal effects can probably be calculated down to at least micrometer accuracy.

But it does not matter – when combining data sets, you cannot end up with a set that is any more accurate than your least accurate source, at best.

Curious George
Reply to  Writing Observer
December 18, 2018 1:11 pm

In climate “science” you probably can. You have one thousand thermometers, each with a one degree accuracy. You just make an average – and you have a temperature measurement with a 0.001 degree accuracy.

bit chilly
Reply to  Writing Observer
December 18, 2018 10:18 pm

i am not so sure about calculating the tidal effects. for a start air pressure over one area effects not just that area but adjacent areas dependent upon the air pressure above them. wind direction and strength at any given time also plays a part. i have seen the tide height vary by up to a metre for a same height forecast on different days in my area of the north sea as a result of the above.

variations in current strength and direction also come into play.the various ocean basins do not hold the same amount of water over long periods of time.

given how difficult it is to measure gravity is it also not possible there are tiny changes over time that might have a small effect on sea level ?

Gary Ashe
December 17, 2018 6:47 pm

I’m shocked. not.

David L. Hagen
December 17, 2018 6:54 pm

Massive Type B Errors
Compliments Wil
lis on quantifying the individual tidal gage and satellite sea level trends and nominal uncertainties.
Your figure 6 shows NON-overlapping trends!
That indicates a very large Type B error between the tidal gage and satellite sea level trends.
Have Nerem and Fasullo never studied the international standard: BIPM’s GUM Guide to the expression of Uncertainty in Measurement?
Or NIST’s 1994 Technical Note 1297 Guidelines for Evaluating and Expressing the Uncertainty of NIST Measurement Results Barry N. Taylor and Chris E. Kuyatt

Analog Design Engineer
Reply to  David L. Hagen
December 18, 2018 8:25 am

I would also highly recommend the SAC Technical Guide 1: which gives numerous worked examples on how to apply the GUM.

Geoff Sherrington
Reply to  David L. Hagen
December 18, 2018 2:40 pm

Thank you DLH,
Please keep promoting the lack of use of BIPM procedures for errors.
We now see more commentary on climate science gross misuse of error analysis.
The momentum will grow and people will be disgusted, it will become a major topic.
Especially among scientists familiar with proper error estimation. Geoff

December 17, 2018 6:54 pm

As an old engineer who actually generated full scale ‘loft’ for aircraft we developed a bit of a calibrated eye-ball for curvature. Looking at either graph there appears to be a slight ‘cupping’ of the curve. If the data is true, it does appear as though the slope of the curve is increasing, dy/dx is acceleration.

Reply to  Rocketscientist
December 17, 2018 7:06 pm

Even us non-engineers have a perfectly serviceable Mark I eyeball.
Tide gages show no acceleration, that is the point.
The month to month and year to year variations, furthermore, are orders of magnitude larger than the measured rise over time, such that on just about all of them, one can see some months a hundred years ago during which the sea level was higher than some of the months in the past ten years.

Reply to  Rocketscientist
December 17, 2018 8:45 pm

“If the data is true”
Pretty big IF there.

Sea Level rise *IS* accelerating. This is trivially true. (At least on some tide gauges.)
Acceleration goes back to ~1975 (!)
But the acceleration is due to the Moons’ Nodal Precession, which expresses as a sine wave with a full period of 74.4 years in the tide gauge data.
(I posted the graphs which show this a couple if times here at WUWT already.)
Nothing to do with GW, AGW, CAGW, climate change, or anything else on Earth.

It is a favorite trick of the “We Are All Going To Drown” crowd to start the analysis after the upswing is underway (~1975-1980) and then extrapolate an exponential without regard to the cause or its’ sine wave nature.
Stupid Trick, old, tired and lame.

Reply to  TonyL
December 17, 2018 10:52 pm

Tony L,
Maybe I am missing something, but it seems to me that the tides push bulges of water around, and can certainly vary over time in response to changes in the orbit of the moon, but those bulges do not represent sea level rise, since they are cancelled out by corresponding low spots as water is drawn upward into a bulge.
Tide gages measure tides, but these graphs have removed the movement of the tides by averaging it out.

Reply to  Menicholas
December 18, 2018 3:22 am

Tides are daily/monthly/annual.
The Moons’ apsidal and nodal precession seems to be 74.4 years. So it is a different situation.

I have speculated that lunar SLR in the northern hemisphere is counterbalanced by a drop in the southern hemisphere. You would expect this just from simple mass balance considerations. Orbital and gravitational considerations would support the speculation. Unfortunately, widespread, long term records from the southern hemisphere seem to be too sparse and broken to support any firm conclusions.

Nonetheless: We are still confronted with long term perturbations in the SLR trends spanning decades which align with lunar orbital parameters.

Gordon Dressler
Reply to  TonyL
December 18, 2018 7:41 am

TonyL, you raise an excellent point! Is all of the SLR data referred to in the above article confined to basins/oceans in the Northern Hemisphere?

To have an unbiased review of GLOBAL SLR, one must evaluate what is happening in the Southern Hemisphere and to see if it is opposite to, or equivalent to, trends in the Northern Hemisphere. The SH has 81% of its area covered by water, as compare to 61% water coverage in the NH.

Reply to  TonyL
December 18, 2018 12:55 pm

Thank you for the reply.
I had not considered the aspect of hemispheric imbalances and a northern hemisphere bias in the tide gage locations.

A C Osborn
Reply to  Menicholas
December 18, 2018 5:49 am

That begs the question, do they use High & Low or just high tides in the calculations?

Reply to  A C Osborn
December 18, 2018 9:54 am

Here is what they say about individual tide gage graphs, and this one is Fort Myers:

“The relative sea level trend is 3.1 millimeters/year with a 95% confidence
interval of +/- 0.49 mm/yr based on monthly mean sea level data from
1965 to 2017 which is equivalent to a change of 1.02 feet in 100 years.

The plot shows the monthly mean sea level without the regular seasonal fluctuations due to coastal ocean temperatures, salinities, winds, atmospheric pressures, and ocean currents. The long-term linear trend is also shown, including its 95% confidence interval. The plotted values are relative to the most recent Mean Sea Level datum established by CO-OPS. The calculated trends for all stations are available as a table in millimeters/year and in feet/century (0.3 meters = 1 foot). If present, solid vertical lines indicate times of any major earthquakes in the vicinity of the station and dashed vertical lines bracket any periods of questionable data or datum shift. ”

Reply to  Rocketscientist
December 17, 2018 8:45 pm

It has a slight cup except for the big flat 3 year tail it now has which means some massive amount of water is going somewhere because Grace is still saying the ice is shedding

Aliens or unicorns are clearly drinking vast quantities of water without us noticing 🙂

December 17, 2018 7:06 pm

Seems to me that the only way to get a comparative reading given all the forces at play is for the conditions to be identical when measured.
Allowing for errors coming from moon position, wind effect, temperature, planetary gravitational influences
and barometric pressure makes it seem like a futile pastime.
But what do I know, I’m just an innocent bystander.

Reply to  birdynumnum
December 17, 2018 7:24 pm

You are not, IMO, wrong.
Measuring global sea level on a non-uniform ellipsoid with a highly variable gravimetric field, in addition to the variables you mention and a few others you did not, and doing so to the precision and accuracies claimed, seems to make claims of knowledge of the global temperature from over 100 years ago to within tenths of a degree look like…well…
Let’s just say both should elicit more than an eensie bit of skepticism in all but the most credulous amongst us.

Gary Pearse
Reply to  Menicholas
December 17, 2018 8:24 pm

Menicholas, at some point when the fever has abated and the current climateers have retired (But careful! on the eve of retirement zealots like Pause Buster Karl and Hottest ever Hansen tend to do big rejiggers of the climate as a farewell grift to their younger colleagues), it will be a time for attempting to repair the damage. If you have data that was disappeared, it will be valuable in the process.

I believe the raw temperature records from around the world which mostly look like the raw US temperatures, are valuable validaters of the US raw records and their own. Virtually all the warming post 1850 had occurred by 1940. The modern warming period is just a recovery from the 40 years of cooling to 1979 that had scientists warning of an imminent Ice Age. So all the warming took place with CO2 at ~280ppm and none with the added 42% addition CO2 since then. Oh the work needed woll be colossal and the records in worse formats than tide guage data.

Reply to  Gary Pearse
December 17, 2018 10:45 pm

I agree with you Gary.
An awful lot of locations have raw temperature data that look very much the same.
Very few properly sited ones show anything like the adjust temp graphs.
Besides, the alterations to the historical records of temp show a nearly perfect correlation to CO2 concentration in the atmosphere, which tells anyone paying attention what the real purpose, and hence the validity, of those alterations is.

Reply to  Menicholas
December 17, 2018 11:37 pm

Dang…need to read what I write before hitting the send button:
Very FEW properly sited…

December 17, 2018 7:08 pm

Thank you, Willis, well done.


PS: A premature Happy Holidays.

December 17, 2018 7:16 pm

Willis, IDK if this is a problem with Safari or not, but I was having problems downloading the files. When I clicked on the link it tries to load it into the browser instead of downloading the file directly. I noticed you’re using Dropbox and checked their faq. To get the files to actually download you have to change the url to have dl=1 at the end of the string instead of dl=0.

Oh, and many thanks for doing all the work to put the data in a usable form. That must have been a bear.

Ernest Bush
Reply to  Bear
December 17, 2018 9:00 pm

You can fix downloads of data and button click problems by simply opening up Chrome. Otherwise I would not use Chrome since Google uses it to track your usage.

December 17, 2018 7:31 pm

The mixing of satellite data with tide gauge data, when there is perfectly good tide gauge data available, amounts to blatant cherry-picking.

A C Osborn
Reply to  JCalvertN(UK)
December 18, 2018 5:59 am

But this consistent actions by them, adjusting Argos data to fit Buckets, Bristle cones & temps, Marcots paper etc., so nothing new, they have previous as the Police would say.

December 17, 2018 7:45 pm

Long term Sea level changes can be because the amount of water changes or the vessel that is the world’s oceans changes. To my way of thinking, unless we can know all the data regarding earth crust movement, all this type of discussion is moot. Is the vessel changing or the content, or both? Is the relative smoothness of the crust constant? I doubt that.

Reply to  RobK
December 17, 2018 8:28 pm

True dat, and a few of them are often discussed but are almost certainly impossible to accurately, or even roughly, quantify. Some others can be estimated to some degree of certainty.
One is surface water drawdowns, and some vivid examples exist, such as the drawdown of the Aral sea over the past 50 years or so.
In some places surface bodies of water have been increasing, or even added where they did not exist before, such as when new dams are constructed. Many recent and large reservoirs exist, and some older ones were still filling in decades past.
Then there are obvious things like surface snow cover, and less obvious to observe but very substantial changes in soil moisture.
Ice locked up in glaciers and ice sheets is another, and drawdown of aquifers, although some of these changes are doubtlessly very complex as they cause local ground subsidence and even perhaps large scale isostatic changes in whole continents and large islands such as Greenland. Longer term isostatic rebound from melting since the maximum of the Pleistocene glaciation is know to be causing large changes in the height of continents, rebounding up in some regions and down in adjacent areas.
Some have speculated that erosion from land areas could be adding substantially to the volume of material in and under the ocean basins, and volcanism and sea floor spreading, but also subduction and large changes from tectonic activity make this a complicated issue. The two underwater earthquakes that caused huge tsunami earlier this century near Banda Aceh and near Japan are known to have caused huge changes over a large area of the sea floor, although it may be that such shifts are a net zero change in the volume of the ocean basin as one area falls when another rises.
IOW…it aint simple.

December 17, 2018 8:11 pm

“Nerem and Fasullo have a new paper called OBSERVATIONS OF THE RATE AND ACCELERATION OF GLOBAL MEAN SEA LEVEL CHANGE, available here.”

“here” is a ref to the Nerem & Fasullo 2017 paper, which is a review I think.

However, Nerem, Beckley, Fasullo, Hamlington, Masters, and Mitchum have a newer paper, 2018, entitled “Climate-change–driven accelerated sea-level rise detected in the altimeter era” in PNAS.

Main findings (copying from abs): Satellite altimetry has shown that global mean sea level has been rising at a rate of ∼3 ± 0.4 mm/y since 1993…. this rate is accelerating at 0.084 ± 0.025 mm/y2. If sea level continues to change at this rate and acceleration, sea-level rise by 2100 (∼65 cm) will be more than double the amount if the rate was constant at 3 mm/y.

Anyway, paper here:
and a nice short read by Appell here:

December 17, 2018 8:16 pm

Question about this:

“I can look at the difference in the trends for each individual dataset over the same period. This gets rid of the problem of vertical land movement, which is constant over such a geologically short time period. ”

So, does this assume that the rate of post-glacial rebound is the same at every tide gauge, or does it allow for a different rebound rate at each tide gauge location? And if so, how?

Reply to  Observer
December 17, 2018 9:06 pm

“or does it allow for a different rebound rate at each tide gauge location?”
For every individual gauge, you compare the earlier part with the later part, then you sum all the individual results, to make the aggregate.
This method guarantees that you will see the acceleration due the the Moons’ nodal precession when using the dates C+W and Willis picked. The precession upswing for the Eastern seaboard US really gets going right around ~1993-1995. Right at the start of the satellite era(!)
Certainly, Willis does not see anything like the acceleration C+W found, and Willis shows that the statistical differences between the data sets are so large that pooling the data is statistically disallowed. {Yes, there are rules for when you can, and cannot, pool data sets.}

December 17, 2018 8:46 pm

Willis, I just wanted you to know that I am so very impressed with the complete and careful analysis you’ve done here. I also like that you clearly explained and summarized it all as well… this is important work!! It’s people like you, with arguments such as yours here, that convinced me that climate alarmism was not good science. I even made a video (titled: Climate Alarmism made me #WalkAway) about it! If you are interested, you can see it at:

steve case
Reply to  Deborah R. Castleman
December 17, 2018 10:12 pm

Deborah R. Castleman December 17, 2018 at 8:46 pm
Climate Alarmism made me #WalkAway

I just spent a half hour watching your presentation. I’m glad you finally made the switch. I look forward to seeing more of what you have to say here on WattsUpWithThat. When I scan down the comments, I’ll be reading yours.

Reply to  Deborah R. Castleman
December 17, 2018 11:03 pm

You would have us believe that you turned 18 in 1972?
I do not believe that could possibly be true.
If you said you were 50, I would say you look amazing for that age!
In any case, welcome to the light side of The Force…better late than never!
Almost everyone I know was a Democrat back in the 1970s, and we have all been on a different schedule getting that fixed.

Reply to  Deborah R. Castleman
December 18, 2018 2:13 am

That was an excellent speech Deborah. You have done well to put that together and your delivery was delightful. Bravo!

Reply to  Deborah R. Castleman
December 18, 2018 6:57 am

“These people aren’t scientists, they’re modelers”

And really that’s the whole point. They’re not scientists; they’re computer scientists who conjure virtual reality rather than delineate the flux lines of physical reality through observation-validated hypotheses as true scientists do. When they publish a study, it means that they ran computer simulations. Simulations are tools of science, not science itself; but to that profession they are science.

Reply to  icisil
December 18, 2018 1:01 pm

+ lots of plusses

Richard M
Reply to  icisil
December 18, 2018 3:14 pm

I call them computer gamers. As far as I can tell they are not even trained programmers.

steve case
December 17, 2018 8:47 pm

What it looks like over time is an oscillation of the rate of sea level rise. Rates were high in the early ’50s and by 1975 they had dropped. By 1990 they began to pick up to where they are now. So over the short term since 1990 there’s been acceleration. Over the long term since 1950, not so much. Here’s a graph
comment image
of seven tide gauges from around the world where each plotted point represents the rate of sea level rise for the previous 30 years to illustrate the point.

Clyde Spencer
December 17, 2018 9:00 pm

Following are some excerpts from a US Army Corps of Engineers paper:

“Again, a general trend toward rising sea levels is clearly apparent. All records are highly correlated with respect to some perturbations, particularly the high sea level of the late 1940’s, but not with all perturbations.” [p. 53]

‘The overall national trend is 1.5 dynamic millimeters per year with generally higher values along the mid-Atlantic coast and lower values along the Pacific coast.” [p. 57]

“Continued slow increase in sea level during the last few thousand years may be partially attributable to delayed isostatic response to the loading by higher sea levels on continental shelves.” [p. 58]

“This brief examination of the records for sea level variability in this century and over the past few thousand years demonstrates that the sea level has been changing for as long as any type of records exist. The general trend toward rising sea level at midlatitudes and falling sea level at northern latitudes has been continuing for many centuries. …, there appears little reason for believing that future predictions can be made with great confidence.” [p. 59]

D. L. Harris, 1981, Tides and tidal datums in the United States, Sp. Rpt. No. 7; U.S. Army, Corps of Engineers, Coastal Engineering Research Center, Ft. Belvoir, VA, 382 pp.

Tom Abbott
Reply to  Clyde Spencer
December 18, 2018 8:07 am

“Following are some excerpts from a US Army Corps of Engineers paper:

“Again, a general trend toward rising sea levels is clearly apparent. All records are highly correlated with respect to some perturbations, particularly the high sea level of the late 1940’s, but not with all perturbations.” [p. 53]”

It would make sense that sea levels would be higher back then following the hottest decade in recent times: The 1930’s.

It’s been almost as hot as the 1930’s in recent years, so there is a lot of melting going on now, too.

A C Osborn
Reply to  Tom Abbott
December 18, 2018 8:51 am

Except there isn’t much “melting” going on.

Reply to  A C Osborn
December 18, 2018 9:52 am

The two big dogs in the hunt are the East Antarctic ice Sheet, and the Greenland Ice Sheet.
The most recent studies show ice is accumulating on a net basis in Antarctica, and for the past two years at least, Greenland has gained mass as well, as snow fall has been far above average.

December 17, 2018 9:33 pm

Clide Speners last item sums it all up, no one really knows.

But who is advising the men holding the leaverrs of power, what are their qualifications or lack of, and what are their political leanings ?


steve case
Reply to  Michael
December 18, 2018 6:15 am

Michael … 9:33 pm …
But who is advising the men holding the leaverrs of power…?

If you do a news search on “Sea Level” you will find all sort of people and studies pushing the non-sense. John Englander, you can easily Google him, shows up quite a bit. Here’s a recent story
Maryland state law apparently requires projections of sea level rise be prepared.

If you do a daily search of Sea Level in the news you will find a daily drone of exaggeration and B.S.

Johne Morton
December 17, 2018 9:35 pm

Forgive me if this point has been brought up already. The only major land use change that corresponds approximately with the satellite era is the evaporation of the Aral Sea, which iirc was at one point something like 50 km3. I have no idea how many millimeters of sea level rise that would be, assuming it would be measurable.

Reply to  Willis Eschenbach
December 17, 2018 10:30 pm

Reckon I got the wrong answer.
I would go with what Willis calculated instead.
But I did some checking, and the Aral sea has lost a lot more than 50 km3.

Closer to 1000 km3.
It used to be 1093 km3, and is now listed as 27 km3, although some sources say it is now increasing again.
Here is one older study.
Current volume of 27 is from Wikipedia, so…

Bob boder
Reply to  Willis Eschenbach
December 18, 2018 4:22 am

“Aral Sea’s Eastern Basin Is Dry for First Time in 600 Years”
This is a post from a national geographic story, question why was it that dry 600 years ago? If the cause of the Aral drying up is Soviet era river redirecting it makes sense that it dried up now but why then?

Reply to  Johne Morton
December 17, 2018 10:07 pm

Ought to be a straightforward and simple calculation…surface area of the sea/50km3.

Surface area of the ocean is given as about 361.9 million square km (earth is ~510 million sq km x ~70.9% ocean).
So we get 361,900,000km2/50km3 = 7,238,000/km
One million millimeters per kilometer, so looks like 50 cubic kilometers of water would raise the surface of the ocean by a little over 7 millimeters… about 7.23 millimeters.
Late and tired…that may be wrong. I think I have it upside down, but 7 millimeters sounds about right.
I was good at this back when I did algebra every day.

Tom Schaefer
Reply to  Menicholas
December 18, 2018 7:11 am

OK, that is the approach I wanted to take. Start with the facts:
1) Mean sea level rise/year: 2.1 mm
2) Radius of Earth (r) : 6,378 km
3) Formula for surface area of a sphere: 4 * pi * r^2
4) Percent of Earth surface covered by ocean: 70.9
5) Volume of shell of water: Sea level Rise * 4 * pi * r2

When I calculate the volume of a shell of water 2.1mm thick on 70.9% of a sphere 6,378 km in radius I get:
~7.6 trillion cubic meters

Can the satellites confirm that that much ice is being melted off the average height of Greenland and the Antarctic every year using the average height change, which should be at least 3 to 4 times (depending on the density) the 2.1mm change in the water level? No sources and sinks!

Reply to  Tom Schaefer
December 18, 2018 10:23 am

I believe that volumetric change due to warming of the ocean water column is the reason for a good bit of the rise.
I have wondered if the oceans are still warming at the bottom layers due to the increase in global temp since the end of the Pleistocene glacial max.
Or maybe that ship has sailed and the ocean is warming due to the warmup since the LIA?
I know from field work I have done for one long time employer in years past that for even a small pond in a hot place like Florida, cold water trapped at the bottom by it’s density can stay very cold from year to year, changing only a little from the middle of summer to the middle of winter. This often leads to fish kills when this bottom water is mixed up to the top by high winds, or more commonly the first cold night in the fall or Winter.
Summer heat has a hard time reaching the bottom due to the thermocline(s), of which there may be more than one in deeper ponds and lakes.
(We manufactured equipment to prevent this from occurring, and one of my frequent tasks was doing temp and chemistry [O2, H2S, CH4, etc] profiles of the water columns)

Anywho, if a small pond in Florida still has cold water 12 to 15 feet down in August, how long does it take for an ocean to heat up that is miles deep and it is only hot over part of the surface, and cold in other places all the time…?
We have those Argo things, but how much do they tell us about how the temp has changed over hundreds or thousands of years?
Yes, we have means to determine such things from various chemicals and dead things in the ocean bottom sediments, but how comprehensive are these measurements?
If we have learned one thing, it is that confirmation bias (we all have it, but some have it EXTRA) runs strong in the Dark Side of The Force.

Johne Morton
Reply to  Johne Morton
December 17, 2018 10:30 pm

Sorry, that figure is only for the much smaller North Aral Sea remnant. Apparently the whole thing was around 1000 km3 in the 1960s.

John F. Hultquist
Reply to  Johne Morton
December 17, 2018 11:09 pm

Johne Morton wrote:
The only major land use change that corresponds approximately with the satellite era is the evaporation of the Aral Sea, …

Perhaps you are thinking of water surface only, but if so there has been much land world wide brought into irrigation, and while that doesn’t make a lake, it is still water on the land.
Beyond that concept, however, is the fact that “land use” has been changing rapidly as urban areas have grown and changed. Here is an example if one realizes that people need housing, parking, and play and work areas.
The Seattle metropolitan area had a population in 1990 of 2,559,164
In the year 2000 the population was 3,043,878.
2010 => 3,439,809.
2017 => 3,867,046

Those 1.3 M folks required a lot of land use changes.

Barry Brill
December 17, 2018 9:36 pm

It is inherently unlikely that any long-running trend in any time series would JUMP by approximately 100% at any given time, for no reason that is detectable by competent scientists. If that jump happened to coincide temporally with the advent of a competing time series, that synchronicity would be strong circumstantial evidence that the first dataset had somehow been polluted by the second.

If the jump were to coincide BOTH temporally AND spatially (ie numerically) with the arrival of the second dataset, then that would create a presumption that cross-pollution had occurred. In the absence of evidence to rebut that presumption, any reasonable person (let alone a sceptical scientist) would be satisfied that C&W’s post-1993 data fails to represent a continuation of the 1888-1893 tide gauge series.

What is the point of splicing two distinct measures, unless to “hide the decline” of correlation between the two?

David E Long
Reply to  Barry Brill
December 17, 2018 10:51 pm

Well stated Barry,
I worked for many years in industry with various types of data series, and when we graphed them we never hid their character as individual sets: they were always distinguished by using different symbols, different colors, etc. Merging them together is, like you say, hiding information. I’ve never spliced two data sets in my life. I think it is scientifically incorrect procedure. Two data sets, whether collected by different methods, or even collected by the same method but just with a gap in time, are not the same thing and cannot be correctly treated as if they are.

Don K
Reply to  Barry Brill
December 18, 2018 8:02 am

Barry — The problem is that sea level can be influenced by things like river flows, sea temperatures, and prevailing winds that can vary on decadal scales. Tide gauges — especially those with long records — are found only along coast lines (duh) and are heavily concentrated in the Northern temperate zone. Not the sampling one would like to see.

Satellite measurements OTOH, cover the world’s ice-free oceans pretty much evenly.

No one expected the two to yield exactly the same result for sea level rise. But the discrepancy between the two data sets is much larger than anyone expected or can easily explain.

Reply to  Don K
December 18, 2018 4:10 pm

I can explain it: There are so-called scientists with an agenda who have no problem fudging data and making stuff up.

December 17, 2018 9:53 pm

Over in West Australia the land has been sinking, which has not made life any easier for the boffins.

Reply to  Willis Eschenbach
December 17, 2018 11:13 pm

Hey, your not supposed to go into any details: stuff from NASA/ ESA is blindly 200% reliable Science. Leave it to the High Priests.

Reply to  Willis Eschenbach
December 18, 2018 1:34 am

How do the proponents of sea level measurement by satellite keep a straight face? Surely they must know the technique is nonsense?

Reply to  Graemethecat
December 18, 2018 12:50 pm

Can we be sure they are not sniggering up a laugh riot as they construct their narratives and spin their data?
There have been moments I have felt rather certain that we are being laughed at and played for fools.

Don K
Reply to  Willis Eschenbach
December 18, 2018 7:48 am


That means that to measure the sea level to an accuracy of ± 1 mm, you need to have an accuracy of greater than one part per billion.

It turns out that they are measuring time between a radio pulse and the mid point of the rise of the reflected pulse. Time is one thing we can measure with extreme accuracy. So much so that it probably doesn’t make much difference whether they are observing from 1300km, 130km, or 1300m. There are a lot of issues with things like uncertainties in satellite position (a couple of cm), sea surface wave shape, etc, etc, etc, so they really need to average a LOT of measurements. Which they do. It’s easy to identify problems with the measurement, but it’s not easy to explain why the problems don’t average out, or alias into seasonal affects or otherwise behave tractably.

Incidentally. It’s a fine article. Congratulations.

Gordon Dressler
Reply to  Don K
December 18, 2018 8:39 am

Ahhh . . . but the satellite altimetry data is not just as simple and measuring time. The speed of the satellite’s radio pulse is not the speed of light in vacuum . . . electromagnetic energy traveling through a medium (e.g., the Earth’s atmosphere) has a velocity of propagation that is lower than the speed of light in vacuum. To find the speed of EM waves through any other medium, its speed of light in vacuum has to be divided by refractive index of the medium. For “air” a typical refractive index is given as 1.0003, so this represents a 300 ppm reduction in EM propagation speed versus vacuum for that portion of the radio pulse propagation back and forth through the atmosphere.

However, the effective refractive index taken over the vertical column of Earth’s atmosphere at any given lat/longitude will vary with such things as total column mass (barometric surface pressure), average column temperature, and average column absolute humidity.

I don’t know the extent to which these variations are accounted for in deriving satellite altitude based on EM pulse timing, but I can easily believe that due to the highly variable nature of Earth’s atmosphere they can easily account for tens to hundreds of ppb errors that are not corrected.

Reply to  Gordon Dressler
December 18, 2018 2:23 pm

Gordon Dressler,
The increase of the optical depth due to the atmosphere is 0.0003 * 7.7 km= 2.3 m (0.0003 is the refractive index of air minus 1, the 7.7km is the thickness of the atmosphere for 1 bar).
Airpressure can vary by 10 %, so optical depth by .23 m.
A larger effect is that a 10 % higher airpressure lowers the sea surface by 1 m, this adds up to 1.23 m increase in optical depth for 10 % increase in barometric pressure.

Don K
Reply to  Gordon Dressler
December 18, 2018 5:12 pm

Ionospheric Delay is indeed an issue. For Jason, they estimate it using a dual frequency technique. As with most everything in the world of satellite Sea Level Rise, there is probably some error in their estimate of delay, but its hard to see why any errors don’t ether cancel or resolve over a very large number of measurements to a constant bias in their estimate of sea level — which shouldn’t affect the estimate of Sea Level Rise. (.. unless ionospheric delay itself is decreasing or increasing over time — which it probably isn’t … much? Hmmm … What’s the affect of the solar sunspot cycle on ionospheric delay?)

Keep in mind that the satellites are making more than 1000 measurements every second and are moving their “target point” about 8km (I think) laterally every second. A lot of stuff really will average out over time.

Gordon Dressler
Reply to  Don K
December 18, 2018 6:44 pm

“Jason-2 flies in a low-Earth orbit at an altitude of 1336 km. With global coverage between 66°N and 66°S latitude and a 10-day repeat of the ground track, Jason maps 95% of the world’s ice-free oceans every ten days. Sea surface height accuracy is currently 3.4 centimetres, with 2.5 expected in the future.” — source:

So we are faced with the C&W data giving a slope of 2.1 +/- 0.5 mm per year for the last 20 years using a large amount of data from one or more spacecraft instruments (presumably the Poseidon-3 dual frequency altimeter that is on Jason-2 or something with similar accuracy), having at best a 25 mm accuracy.

Go figure.

Tom Schaefer
Reply to  Willis Eschenbach
December 18, 2018 8:00 am

I think the accuracy has more to do with time accuracy than distance. I think you can get atomic clock accuracy on satellite emphermeris which should make such accuracy possible.

Clyde Spencer
Reply to  Tom Schaefer
December 18, 2018 8:23 am

The problem is, if the measured time decreases, how do you tell if it is the result of an increasing sea level or a decaying orbit?

Don K
Reply to  Clyde Spencer
December 18, 2018 4:37 pm

how do you tell if it is the result of an increasing sea level or a decaying orbit?

Orbit decay at 1300km should be pretty minimal and in any case, the satellite is tracked and any changes in its orbital velocity should be known quite well and reflected in the data processing.

Of course, corrections for that and a hundred other things will make the processing algorithm inordinately complex and opaque.

Reply to  Tom Schaefer
December 18, 2018 8:26 am

Maybe it has to do with what is actually meant by the term sea level, and how the level of the sea responds to the variations in the gravity field of the Earth by as much as a hundred meters in the open ocean.
All this is what I was getting at with the minute physics video.
the satellite measurements, it seems to me, have to be oriented with respect to what the ocean shape of the sea surface (IOW…what is “sea level”) is.
And the model made by geodesists is not accurate enough, and the gravimetric field is constantly varying for Lord only knows how many reasons and by how much.

Rud Istvan
Reply to  Willis Eschenbach
December 18, 2018 10:35 am

I read the Jason 2 spec manual in its entirety for essay PsuedoPrecision in ebook Blowing Smoke. Is (was?) available on line. Relevant portion is §2.3.1. The average repeatable track accuracy spec (one sigma) is RMS 3.4 cm (NOT mm) with instrument drift<= 1mm/year. I dunno how they can possibly convert that reality to the much tighter precision claimed.
There are three main uncertained that have to be accounted for in sea level satellite altimetry. 1. Signal delay caused by varying atmospheric humidity, albeit lowest over the oceans but varying for example T altitude with diurnal thunderstorm washout in the tropics.
2. Wave height, as signal from trough is bigly different than from crest. The processing ‘assumes’ average 2 meter wave height.
3. Orbital decay, as these satellites do expeience slight atmospheric drag.

December 17, 2018 10:27 pm

Bad sciencetist but good ‘climate’ sciencetist in the sense their work offers scary headlines and is the type to get into ‘reports’ and that rather than validity is what matters.

Chris Hanley
December 17, 2018 10:58 pm

Let me close by saying that I think that it is very bad scientific practice to splice together a terrestrial and a satellite record unless they agree well during the period of overlap …”.
Prof Humlum at his excellent climate4you website:
” Data from tide-gauges suggest an average global sea-level rise of 1-1.5 mm/yr, while the satellite-derived record suggest a rise of more than 3 mm/yr. The rather marked difference between the two data sets has still no broadly accepted explanation, but some of the difference is likely due to administrative changes introduced into the raw data obtained by satellites …”.
Also the data sets are measuring different things:
“… Another factor that may explain some of the difference between tide-gauge and satellite data is probably that while any temperature-driven volume expansion is recorded by the satellites, this change is not affecting tide-gauges at coastal locations, as the water depth here decreases towards zero …”.

Reply to  Chris Hanley
December 17, 2018 11:15 pm

Wait a second, on that last point: If the volume of the oceans is increasing due to thermal expansion, it should not matter what the depth is where it is measured, should it?
This would be like if I had a container that was flared out at the top, and heated it up so the water in it expanded.
It would not matter what the shape of the container is…the whole surface would rise by the same amount. That it is shallow at the edge would not mean it rose less at the edge than over the middle f the container.
Would it?
I must be missing something here.
Wonder what the guy who knows that the 50km3 goes in the numerator thinks?

Reply to  Menicholas
December 17, 2018 11:25 pm

Sorry: “…would not matter what the shape of the container is…”

Chris Hanley
Reply to  Menicholas
December 18, 2018 1:55 am

I think the answer is that the edge or “coastal locations” move out, or move inland.

A C Osborn
Reply to  Menicholas
December 18, 2018 6:16 am

The problem as the tide gauges show is that the Sea surges depending on the wind and to a smaller extent the Currents.
It has been shown that the sea sloshes not only due to spin, Moon but also wind, as they change so can the tide height.
As well as that the expansion is not equal between north, tropic and south so expansion can’t be equal due to temperature increases in the short term.

Reply to  Chris Hanley
December 18, 2018 12:54 am

“The rather marked difference between the two data sets has still no broadly accepted explanation, but some of the difference is likely due to administrative changes introduced into the raw data obtained by satellites …”

Does Prof Humlum apply this same caveat to satellite TLT data?

michael hart
Reply to  DWR54
December 18, 2018 6:59 am

A non sequitur. I don’t think the people who measure satellite TLT data mix their data with land-based thermometer measurements.

Reply to  michael hart
December 18, 2018 8:30 am

But they do calibrate using, IIRC, balloon measurements of the troposphere.

Reply to  michael hart
December 19, 2018 12:55 am

They certainly make administrative changes to the way they calibrate the raw data though, as evidenced by the fairly recent substantial, and mutually contradictory, changes to both UAH and RSS TLT.

December 18, 2018 12:50 am

Thanks for taking the trouble to download and post the tide gauge data in a single file Willis. Much appreciated.

Two quick questions:

First, was the spatial distribution of your subsection taken into account? For instance, do you know whether your surviving sets (258 from 1,512) are evenly distributed globally rather than concentrated in regions where sea level rise may be slower than the global mean? My understanding is the SLR is not evenly distributed.

Two, 21 years from start 2003 (start of satellite MSLR data) brings us to end 2013. Nerem and Fasullo appear to use tide gauge data up to end 2015 and satellite data up to end 2017. Might this also affect the difference between the trends they found and yours?


Stephen Richards
December 18, 2018 12:52 am

Let me close by saying that I think that it is very bad scientific practice to splice together a terrestrial and a satellite record

Even if they agree reasonably well. The practice of data splicing should be banned

Reply to  Stephen Richards
December 18, 2018 2:25 am

Also of note with this splicing is the terrestrial and a satellite records of data have radically different sampling rates. Can it ever be honest science to splice together such data?

December 18, 2018 12:57 am

Can not trust anyone any more-not even Church 🙂
Well done Willis E
There is long records of sea level change treated to show changes during time.
SF-CA shown here:

NASA had the same trix when they changed from gauges to satellites and stated the acceleration. I hope it was uneducated but fear something else.

Scott W Bennett
December 18, 2018 1:32 am

Good work Willis!

I would add and want to point out, the empirical oddness of the global sea level metric itself.
I stood at a particular beach at one spot on the earth and even when accounting for isostasy the data showed a rising sea level trend, and yet on that day, that month and that year, all the tide marks were equal to the those of the earliest data recorded.

This is the oddness of the metric, that it is not like filling up a bathtub that politics would have us assume. The trend is probably true but it is divorced from reality in a peculiar way because the trend could change and would then have even less meaning! The fluctuations – the ups and downs – in the signal may be larger than the total trend of course and I imagine there are good statistical explanation for this situation.

As a laymen this real world experience tends to fill one with doubt about the fears of global sea level rise!

December 18, 2018 2:29 am

Jevrejeva et al, 2014, Global Mean Sea Level Reconstruction, from PSMSL data, with GIA…

If there’s an anomaly, it’s from 1951-1992…

And, no matter how you slice it, the anomaly is insignificant…

Reply to  David Middleton
December 18, 2018 8:11 am

Some investigators have taken averages of tidal data, corrected for vertical land movement, and analyzed these in short time segments. They conclude that on decal time scales, sea rise varies over rates of almost zero to over 3 mm/yr. It is combinations of these varying global sea rise rates that give the overall trend over the past century plus.

Reply to  donb
December 18, 2018 8:38 am

And then they exaggerate the trend, assume acceleration will occur at rates not seen since meltwater pulse 1A, and project that trend to the year 2100 and claim this is what will happen and it is a function of, and only of, CO2 concentration.
California is at the point of considering condemning sea side property based on this garbage “science”. Which is really nothing more than hyped speculation and WAGuessing.

December 18, 2018 4:33 am

Interestingly in Figure 5 they used three dutch cities. Vlissingen, Hoek van Holland and Den Helder. I suspect that the readings there have nothing to do with sea level rise and everything with the sinking of the land. The soil in the Netherlands is made of peat. Because we pump out the water the soil inclines, which causes the land to drop. This is on top of the natural decline that is caused by the disappearance of the land ice on the Eifel and Vogezen that was present during the last glaciation.

I wonder if they included these considerations in their analysis.

Reply to  Koen
December 18, 2018 3:20 pm

The tectonic subsidence along the Dutch coast is ~0.5 mm/year.
The Dutch tide gauge stations measure ~1.5 mm/year sea level rise, which result in a net rise of ~1 mm/year.
For more information see:
It is in Dutch, but there is a translate button.

I assume that during the Weichsel glaciation there was no ice sheet in the Eifel and Vosges.

Tasfay Martinov
December 18, 2018 4:33 am

Meticulous and technically outstanding work.
Robust conclusion.
Devastating implications.
Well done and thanks, Willis.

Steve O
December 18, 2018 4:43 am

If the trendlines diverge where the data overlaps, then the data can’t be spliced. It’s really that simple.

But if others plan to reduce CO2 emissions by building windmills and solar panels, then I’d like to fight global sea rise by piling ice at the center of Antarctica. To study the feasibility I’ll need a large grant.

December 18, 2018 6:09 am

OK. I did not see any mention of Earth Tides in this whole thread. The planet is not a solid, it’s a viscous blob of stuff that is affected by the gravitational fields of the moon and sun that changes its shape diurnally. The water in the oceans is a whole lot less viscus than the earth under it so it’ll “seek its level” in response to the changes in the shape of the earth. The magnitude of the Earth Tide is on the order of a foot, that a whole lot more than the claimed sea level rise.
From the Encyclopedia Britannica:
Earth tides are similar to ocean tides. The Earth deforms because it has a certain degree of elasticity; were it perfectly rigid, there would be no Earth tides. Several tidal components mathematically can be shown to exist, but only four are large enough to be generally measurable; these are the lunar diurnal, the lunar semidiurnal, the solar diurnal, and the solar semidiurnal tides. Diurnal tides have a period of approximately 24 hours (1 day), and semidiurnal tides have a period of approximately 12 hours (1/2 day). The actual amplitudes of these tides in terms of vertical movement of the surface of the solid Earth are about one foot or less.

Steven Fraser
Reply to  Yooper
December 18, 2018 8:04 am

This was unfamiliar to me as an area of study. Here is a link to the Wiki page with general discussion, and links to the sources. Of particular interest to me were the implications for GPS and CERN.

Reply to  Yooper
December 18, 2018 8:51 am

The sea level is affected far more than any of these outside influences, by the gravimetric field of the Earth itself.
The area of the Indian Ocean South of India, for example, has a negative anomaly that makes sea level there 100 meters of so lower than the average height, and not too far away from there, East and Southeast of Australia, a positive anomaly piles water up 80 meters higher than the average height of sea level with respect to the center of the Earth.
These gravimetric anomalies have been carefully mapped, but how often are the measurements redone to assess the rate of change?
The overall takeaway is that an enormous numbers of factors influence the height of the sea at any given place and time, and many of these are poorly studied.
But the warmistas are running the show, and as with temperature effects, very little is taken into account and all increases are assumed to be due to global warming caused by CO2 concentration increases in the atmosphere. The satellite data for sea surface is corrected, very questionably, by the assumption that the ocean bottom is sinking and a further .3 mm per year is tacked on for good measure.
Blame it on your SUV and deniers, give dispensation for anyone who toes the warmista party line… lather, rinse, repeat…ad nauseum.

Richard Wakefield
December 18, 2018 6:15 am

I find it an amazing co-incidence that sea level rate of rise instantly doubled in 1993, the very year satellite data started. Yet not one surface station shows the doubling.

Reply to  Richard Wakefield
December 18, 2018 7:21 am

How can we possibly think that satellites and tide gauges are measuring the exact same thing?

The distance from a fixed point in earth orbit to the center of Earth is a different benchmark (than tide-gauge benchmarks) against which to make sea-level measurements, isn’t it ?

To mix the two measures seems pretty obviously wrong to me.

Or am I seeing it wrong?

Richard Wakefield
Reply to  Robert Kernodle
December 18, 2018 4:27 pm

It’s basic science to never mix data from two completely different sources with different measuring mechanisms to get a trend. The best one can do is to compare the two sets. This comparison will show very different results. To me the mixing of the two is evidence of deliberate science fraud to give a result they wanted.

Reply to  Richard Wakefield
December 18, 2018 9:23 am

Another manifestation of the incredible power of Catastrophic Anthropogenic Global Warming.
The whole meme is reminiscent of Kwai Chang Caine.
We know it is real, because they tell us so, and yet…looked for, it cannot be seen, listened for, it cannot be heard, felt for, it cannot be touched.
The Earth and the creatures on it are fragile…fragile as the wings of a butterfly, and the terrible heat of CO2 sticks to and destroys everything…clinging, like the cocoon of a silkworm.
To defeat it then, we must be able to walk upon the earth and leave all as it was before we arrived, as a Shaolin priest walks the rice paper and leave no trace, and we must run an industrial society and feed the hungry billions, powered by only the sun and the wind and a few unicorn farts (if we are fortunate enough to find any), as a Shaolin priest can walk through walls.
When we can snatch the pebble from the warmista hand, we will have learned.

December 18, 2018 6:59 am

Interesting that Willis posted his article during the same period that I have been obsessing on the sea-level-acceleration claim. So, I guess these papers, which I have been reading (attempting to ingest) are vindicated:

Curtis E. Larsen and Inga Clark (2006) A Search for Scale in Sea-Level Studies. Journal of Coastal Research: Volume 22, Issue 4: pp. 788 – 800.

There is no clear proportional exponential increase in the rate of sea-level rise.

Kolker, A.S. and Hameed, S. (2007). Meteorologically driven trends in sea level rise

These findings reduce variability in regional sea level rise estimates and indicate a meteorological driver of sea-level trends.

Houston, J.R. and Dean, R.G., (2011). Sea-level acceleration based on U.S. tide gauges and extensions of previous global-gauge analyses. Journal of Coastal Research

Our analyses do not indicate acceleration in sea level in U.S. tide gauge records during the 20th century. Instead, for each time period we consider, the records show small decelerations that are consistent with a number of earlier studies of worldwide-gauge records.

Scafetta, N., (2013), Multi-scale dynamical analysis (MSDA) of sea level records versus PDO, AMO, and NAO indexes, Climate Dynamics

On the contrary, from the decadal to the secular scales (up to 110-year intervals) the tide gauge accelerations oscillate significantly from positive to negative values mostly following the PDO, AMO and NAO oscillations. In particular, the influence of a large quasi 60–70 year natural oscillation is clearly demonstrated in these records.

Kench et al., (2015), Coral islands defy sea-level rise over the past century

Despite the magnitude of this rise, no islands have been lost, the majority have enlarged, and there has been a 7.3% increase in net island area over the past century (A.D. 1897–2013). There is no evidence of heightened erosion over the past half-century as sea-level rise accelerated. Reef islands in Funafuti continually adjust their size, shape, and position in response to variations in boundary conditions, including storms, sediment supply, as well as sea level.

December 18, 2018 7:21 am

For millions of years there are billions of km³ of fresh water (from rains, rivers & rivers) that have poured into the seas & oceans … WITHOUT WHERE THEY DO NOT UP !! ! That’s it! Quite simply because water continuously seeps into the ocean and sea floors to the magma where this poisonous soup (the fish shit in the sea!) Is heated / boiled and goes up (as in a coffee maker) to the sources (hot or cold depending on the altitude) and towards the water tables it fills.

Rud Istvan
December 18, 2018 7:29 am

Outstanding job, Willis. There is another way to show that the post 1993 trend of ~3.6mm/yr must be spurious. Wrote about it in my guest post here on sea level rise a while ago (couple of years?). It doesn’t close. To a first order approximation SLR should equal thermosteric rise plus ice sheet mass loss. Thermosteric rise can be estimated from ARGO since about 2005. Ice sheet mass loss can be estimated from GRACE with appropriate regional GIA asjustments (Antarctica modeled GIA was wrong by a factor of four until diff GPS estimates became available in 2013–Steve McIntrye had a long technical post on that), or by IceSAT (Zwally 2015). Closure is about 2.2-2.3mm/year NOT 3.6.

The closure range corresponds very nicely with the 60-70 diff GPS vertical land motion corrected long record tide gauges. Moerner says you need at least 60 years to account for the lunar nodal effect. IMO it is 75 years. So depending on the record length sample criteria, you get between about 60 and 70 stations and 2.2-2.3mm/yr. Possible issue: The resulting sample is Northern hemisphere and Atlantic ocean scewed. I didn’t bother to create a smaller unscewed sample to check, because was focused mainly on closure.

December 18, 2018 7:54 am

Most tidal gauge sea rise data are affected by vertical land movement. Several investigators, not just Church & White, use GPS satellite data to correct for that. Then, many such tidal data are averaged to obtain a global data set. Doing this indicates an increased in sea rise beginning about the time satellite altimetry data on sea level first became available. Data on ocean heat indicate increases in the 1980s, and thermal expansion comprises about 40% of overall sea rise (ice melting most of the rest). If one argues that altimetry data are wrong, then the GPS data used to correct tidal data fro vertical land motion also must be wrong. These are the same GPS data used from many other positioning determinations.
Individual tidal data may differ considerably from the global data, both because of land movement and because sea level at sea shores depends on several other characteristics, e.g. tides, winds, temperature, profiles, gravity anomalies, etc. For those living at a particular seashore, it is local se level that counts, not global sea level.

Steven Fraser
Reply to  donb
December 18, 2018 8:13 am

GPS resolution is suspect as well. ‘Commercial’ horizontal resolution is claimed at 4m, with vertical ‘worse’. Anyone have insight into what the govt (i.e., military) resolution is?

Reply to  Steven Fraser
December 18, 2018 8:48 am

The GRACE-ARGO sea level data (since about 2001) agree with the radar altimetry data. Both these and the GPS-corrected tidal data use satellite data mutually corrected for the Earth’s geode (non-spherical corrections). This may be the only commonality among the three sea level data sets.

Reply to  Steven Fraser
December 18, 2018 10:45 am

I do think that GPS data for individual stations should be shown separately. That’s just a personal prejudice – but having been to an assortment of monumented survey locations over the years that had moved over a metre horizontally between GPS surveys I feel it’s always good to see how mobile your benchmark is.

Andrew Kerber
December 18, 2018 10:50 am

I am not a statistician, just a computer nerd. But if the Confidence Interval of the study doesnt even touch the confidence interval of the tidal gauges, doesnt that imply that the calculation of the confidence interval for the study is incorrect?

Reply to  Andrew Kerber
December 18, 2018 11:14 am

For anything scientific or fact-based…yes.
But for religious affairs such as “climate change” and related matters…oh, heck no!

December 18, 2018 11:11 am

I fear that the concept of “global sea level” suffers the same shortcomings as the concept of “global temperature”.

There is no such thing as a “global sea”, whose level we can measure as such. It’s a regional concept, and, unless all regions of the world are undergoing monumental inundation by the sea simultaneously, and each region reports this, I cannot see how we ascertain any threat that the water of Earth is threatening the land of Earth any more than it always has.

I think that the ancient Greeks had a conception about a global ocean, and they named a god, Oceanus, who was the main overseer of it. Poseidon, was the Mediterranean sea God, if I understand correctly, but, as Willis would say, “I digress”.

Now for some shameless self promotion along these lines:

December 18, 2018 12:31 pm

Here is a link to a video from Tony Heller from last year.
In it, he details just a few of the more obvious instances of tampering with data, and among them are the data related to sea level rise.
He has a few very interesting graphs in this video, and among those is one from NASA from 1982, showing that there were, as of the 1982 appraisals of total global sea level changes, two distinct multi decade periods in the 20th century in which sea level was mostly static to declining from earlier peaks, before rising slightly again in subsequent years.
This graph can be seen at 3:44 in the video. The y-axis of the graph is labelled “sea level change (mm)”, which might suggest that it is a graph of changes in the rate of sea level rise, but a more careful look shows that the lines of the graph show observed sea level, not rates of change.
Superimposed on this graph are the huge alterations that have been done to the more recent versions of this graph.
Also, consider this in conjunction to what NOAA says about the individual tide gage charts and how the values for the individual months are arrived at. It is not raw data in any way, shape or form. In fact, it may be adjusted per revisions to what is now being reported as global rates of sea level rise…hard to say without more info on exactly what this sentence means:
“The plotted values are relative to the most recent Mean Sea Level datum established by CO-OPS.”

That is part of the this description of what the tide graphs are representing:
” The plot shows the monthly mean sea level without the regular seasonal fluctuations due to coastal ocean temperatures, salinities, winds, atmospheric pressures, and ocean currents. The long-term linear trend is also shown, including its 95% confidence interval. The plotted values are relative to the most recent Mean Sea Level datum established by CO-OPS. The calculated trends for all stations are available as a table in millimeters/year and in feet/century (0.3 meters = 1 foot). If present, solid vertical lines indicate times of any major earthquakes in the vicinity of the station and dashed vertical lines bracket any periods of questionable data or datum shift. ”

As with anything related to climate change and climate science, it may well be that what they say is not what is true…or at least not what they were saying about the same information before they decided to revise it to avoid any contradictions to the prevailing narrative.

At 7:17 in the video is another fascinating graph, which is a bar chart of the rates of rise for 233 tide gage stations. It clearly shows that the value of over 3.9 mm per year of sea level rise is actually only visible on about 10% of tide gage charts. Have a look at it…I would like to know what other people have to say about it.

In fact the whole video is a snapshot look at how various agencies have altered data left and right to agree with what they “expect” should be happening, given that CO2 is increasing and thus the world is warming steadily and we are now hotter than any other time in history, ice is melting at both poles and the Arctic will soon be ice free for the first time since the Earth cooled 4.3 bajillion(or is it gazillion?) years ago, and of course sea level is therefore rising at an ever increasing rate and thank the Almighty we have satellites that caught it (after they adjusted the satellite readings to correct “faulty sensors”)…

Someone up top asked for an unpacking of something that someone else said, and the question is aptly phrased for what needs to be done to even begin to unravel what the real story is with any of these measurements.
The records are recorded and kept by people who have an agenda, and telling the exact truth and detailing objective reality is not any part of that agenda…that is about the only thing that seems for certain.

December 18, 2018 1:41 pm

Academic trick No.523.

When you want to get an increasing trend when there isn’t one: splice different datasets and select which parts of one to mix with the other. Wella!

Someone should write a book on the other 522.

Jack Woodward
December 18, 2018 7:56 pm

This single thread alone demonstrates why WUWT and its commenters are such a treasure. Thanks, Willis. Thanks, Menicholas. And the rest of you. What a treat to be able to share such a calm, reasoned, rigorous, interesting discusson.

And thanks to Anthony for making it all happen.

Steve richards
December 19, 2018 12:13 am

Willis and his love of data and checking things out when they don’t feel right shows what is wrong in the climate industry.
What Willis has done should have been done hundreds times around the world by undergraduate students, as a repition experiment. Usually, most undergraduates confirm the original findings within experimental error. Very occasionally they spot an error.
The real question here is why are datatasets, papers, theories etc not being tested all the time as part of routine education?
Two possible answers- students not allowed to by their profs, or errors are not allowed to be published.

Have the original authors been approached for a comment?

December 19, 2018 6:12 am


December 19, 2018 9:29 am

It must be difficult calculating an average sea level, to the nearest milimeter, when the sea around Britain is 140m higher than the se around the Caribbean…..!!

comment image

Forrest Baker
December 19, 2018 10:52 am

I am sure this is a stupid question ( I do them often ) So would the satellite data also be measuring land change? I know it would be ‘noisy’ but could you not then use sections of the land to calibrate against sea level rise as an aggregate in order to erase potential mistakes in satellite measurements? I am sure I am REALLY stupid but to be able to use a satellite to measure a 2.8 mm change is difficult for me to do with a slew of tools that are not 36,000 kilometers away. I mean are they measuring the rate of orbital decay as well? What is the distance the satellite is decaying per year? Is the variance of an orbital path more than 2.8 mm per year?

Sorry I am sure I just need to sit down and shut up but I am curious as to the mechanisms involved because I see difficulties in the process and a number of factors that could…

Nic Lewis
December 19, 2018 1:35 pm

Many thanks for your effort carrying out this work, writing it up and making the data available in a user-friendly form.
However, after a quick read of the C&W paper I can’t see that they spliced the satellite and tide gauge data. The only use of the satellite data seems to have been to compute spatial EOF patterns. Those EOFs are used to interpolate the tide gauge data into a global field. I can’t see that the trend in the satellite sea level data affects the resulting estimate of global mean sea level rise, at least directly. Or have I missed something? I suppose it is possible that some aspect of their statistical method might cause the satellite trend to feed through to the global trend derived from the tide gauges, but I’ve not identified such an aspect.

Nic Lewis
Reply to  Willis Eschenbach
December 21, 2018 2:44 pm

I agree that the apparent sudden acceleration in the CSIRO series is odd. So is the comparative behaviour of the CSIRO and NOAA adjusted sea level time series during the 1993-2013 period of overlap assuming that the source data available at is correct. The CSIRO series haas a 1993-2013 trend of 3.67 mm/yr. The NOAA trend is rather lower: 2.81 mm/yr – still well above the 1.65 mm/yr CSIRO 1900-1993 trend. But the correlation between the detrended CSIRO and NOAA series is negligible: 0.10. Strange.

Tasfay Martinov
Reply to  Nic Lewis
December 20, 2018 12:33 pm

The real talent of on-message climate scientists is to skilfully conceal the hand that manipulates the data to suit catastrophist conclusions. It is directly analogous to what magicians or conjurers call “the prestige”. The dove must not only disappear (the turn) but it has to be brought back with a flourish (the prestige).

Thus here it is clear that satellite data has lent acceleration to sea level data, but finding exactly how – will probably require the confession of an insider.

December 20, 2018 10:45 am


I do not quite understand what you mean with

“But in this most recent C&W estimate, the recent tide gauge trend is much larger. ”

Because I just had a look at one of my Excel files, containing original CSIRO tide gauge and sat altimetry data (both downloaded in Feb 2017). But I have exactly the same estimates for the two 21 year periods as those you present here.

Maybe I misunderstand you?

Nevertheless, it is worth to underline that the trend increase you complain about did not accidentally start with the begin of the satellite measurements. Here are some linear trends for CSIRO in mm/y for successive periods:

– 1880-1920: 1.3
– 1920-1950: 1.5
– 1950-1980: 1.5
– 1980-2010: 2.4

Reply to  Bindidon
December 20, 2018 1:42 pm
December 20, 2018 9:43 pm


Call me ignorant … How can we measure millimeters and much less tenths of millimeters using centimeter systems? Sea level in relation to what?

The ITRF center is is only known within a couple of centimeters. The orbital position of a satellite such as Jason 3 is only known within a couple of centimeters after post processing orbital parameters. The geoid is a model with similar inaccuracies and the reference datum such as WGS 84 with its own inaccuracies is an overlay on the modeled geoid. Are tide gauges accurate to tenths of millimeters [even ones with nearby MORS]?. Satellite RF altitude measurement systems introduce their own errors and uncertainty especially since they are measuring an uneven constantly changing [in time and position] sea surface using RF propagation thru a constantly changing atmospheric medium.

I would agree that GPS based measurements are capable of relative averaged millimeter elevation accuracy to a surveyed terrestrial point but to transfer that measurement to an absolute frame of reference introduces all the frame of reference uncertainties.

How are we getting tenth of millimeter accuracy for sea level? What is the error budget of the entire system? Is accuracy being conflated with precision? Even if it is somehow a correct construct, isn’t it an averaged sea level plus or minus several centimeters of error?

Reply to  Bean
December 21, 2018 4:21 pm

May I propose you to read the paper?

I do not think that its authors ignore the problems you mention here.

December 22, 2018 2:49 pm

I read the paper … and I still do not understand how it is possible to measure sea level to millimeter accuracy using a measuring system accurate to centimeters.

Reply to  Bean
December 23, 2018 6:56 am

The only way for us lay(wo)men is to go into the same documents C & W had to go thru:

– TOPEX/Poseidon
– Jason-1
– Jason-2

Plus inbetween:
– Jason-3

Who wants to scientifically contradict their results must do the same job.

Albert Parker and Cliff Ollier produced a paper!

but it was heavily contradicted in

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