1 Meter of Sea Level Rise Now “Inevitable”… Eventually

Guest yawn by David Middleton

When I first read this, I was all set to ridicule it mercilessly… until I noticed the timeline…

It keeps going: 1 meter sea-level rise by 2300 is now inevitable
Analyzing a longer timeline, even if we ceased emissions in 2030.

SCOTT K. JOHNSON – 11/7/2019

Climate change is often discussed in reference to where things will be in 2100, but the story obviously doesn’t end that year. Sea-level rise in particular has an impressive amount of inertia, and a very long time will pass before it has played out fully. What will our emissions have set in motion on longer time scales?

Projecting sea-level rise in the year 2100 is difficult enough, partly because the behavior of the world’s ice sheets and glaciers is varied and complex, and partly because it depends in a big way on how much greenhouse gasses we continue emitting. Take future emissions off the table, though, and it’s possible to think about what happens out to 2300.

The future is real

That’s what a team led by Alexander Nauels did in an analysis based on a combination of our past emissions and the current Paris Agreement pledges for emissions through 2030. Nauels and his colleagues used a simple mathematical model calibrated against the results published in the most recent IPCC report. Rather than running a massive global simulation on a supercomputer, they calculated the relationship between emissions and sea-level rise in previous simulations—which projected out to the year 2300. This also allowed them to quickly process multiple variations of their question.

Considering only emissions through 2030 creates a hypothetical scenario in which warming peaks around 1.5 °C above preindustrial temperatures and starts dropping before the end of this century. This results in about 43cm (17 inches) of sea level rise by 2100, and 105cm (41 inches) by 2300. That’s what greenhouse gas emissions through 2030 commit us to, even if we emitted nothing after that.


Scott is an educator and recovering hydrogeologist who has been covering the geosciences for Ars since 2011.

ARS Technica

Could sea level rise by about 1 meter by 2300? Sure. At the current rate of about 3.2 mm/yr, it’s rising 320 mm per century… 960 mm from 2001-2300 is almost 1 meter. Sea level has been more than 1 meter higher than today for most of the past 3,000 years.

Figure 1. Global last 7,000 years, error bars omitted (Brock et al., 2008).

That said, forecasts of sea level rise that far out in the future are pointless. According to the “analysis” of the “team led by Alexander Nauels,” even if we halt all emissions by 2030, sea level will rise 43 cm (17 inches) by 2100. In their paper, Mengel et al. assert a 43 cm sea level rise (SLR) by 2100 under RCP2.6. That’s 4.3 mm/yr. We’re already nearly 20 years into this time span and SLR is stuck on 3.0 mm/yr over the entire satellite record.

Figure 2. Sea Level – NASA Goddard Space Flight Center. The y-axis is sea level variation (mm), “with respect to 20-year TOPEX/Jason collinear mean reference”. I do not include the GIA adjustment because it is fake science. In the data download, NASA includes the standard deviation. I had no idea it was that large.

I broke out the past five years because the World Meteorological Organization recently asserted that it had accelerated to 5 mm/yr over the past 5 years, a claim that is utter horst schist.

For sea level to rise by 43 cm (430 mm) over the 21st century, it would have to average 4.6 mm/yr over the next 80 years. If it started accelerating now, it would have to accelerate to 4 mm/yr by 2034, 5 mm/yr by 2065 and 6 mm/yr by 2096… But it would actually have to start accelerating. No… Neither Church & White’s, nor Nerem’s recent claims of SLR acceleration alter what the satellite data clearly demonstrate: The R² of the linear trend over the entire satellite record is 0.95… About as close to unity as nature can get.


Brock, J.C.,  M. Palaseanu-Lovejoy, C.W. Wright, & A. Nayegandhi. (2008). “Patch-reef morphology as a proxy for Holocene sea-level variability, Northern Florida Keys, USA”. Coral Reefs. 27. 555-568. 10.1007/s00338-008-0370-y. 

Mengel, M., Nauels, A., Rogelj, J. et al. Committed sea-level rise under the Paris Agreement and the legacy of delayed mitigation action. Nat Commun 9, 601 (2018) doi:10.1038/s41467-018-02985-8

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November 12, 2019 2:10 am

Questions for readers: Does anyone recall seeing an estimate of how far global temperatures have to cool to stop sea levels from rising–that is, to have a reversal in thermal expansion outweigh the mass contribution from glaciers and ice sheets? Even better, has anyone seen an estimate of how far global temperatures have to drop before ice starts to accumulate on land again?


John Tillman
Reply to  Bob Tisdale
November 12, 2019 2:44 am

Ice was accumulating on land during the Little Ice Age. In some places, it still is.

James francisco
Reply to  John Tillman
November 12, 2019 1:55 pm

Ice has accumulated on my driveway, yard and much of the USA today Nov 12 2019. I wonder if the sea level has lowered a little.

Bill Powers
Reply to  James francisco
November 13, 2019 4:18 am


Reply to  David Middleton
November 12, 2019 4:07 am

There is ice on both Polar areas and on many many mountains worldwide.

Leaving the current situation as a balance.
Cools slightly, ice advances.
Warms slightly, ice retreats.

People painting the polar areas as the source of SLR tend to ignore that those areas tend to be cold enough annually to accrete ice.
Yes, some melting occurs for a few months. The rest of the year the ice is either in stasis or accreting.

Which leaves the mountaintop ice fields as primary SLR’s source.
Warming during the brief summers melts all ice below certain altitudes. No matter how much snow fell the previous winter.
Higher altitudes lose a significant portion of their ice under summer’s longer hours of warm sunlight; but each nightfall reduces the melting or it refreezes.

e.g. Mount Washington’s summit can get winter weather during any month though Mt. Washington is at a paltry 6,288 feet (1917 meters) along latitude 44 degrees 16 minutes North.

Yet, all of the snow melts every summer. When summers shorten sufficiently for snow to remain through the summer, than we should worry.
As one moves further North in latitude, this melt period gets more and more critical.

e.g. Even in the hottest summers, one can see ice capped mountains from Las Vegas. Lose just a few days of melt period and ice accretes at lower altitudes.
Up ten degrees latitude, the mountains hold snow year round at lower altitudes.

It’s a delicate balance.
Where official meteorological agencies report 100 years of anomaly in tenths and hundredths of a degree °C.
One should be concerned that the current warming is not strong enough. Especially since glaciers were advancing at global temperatures slightly lower than today.

Reply to  ATheoK
November 12, 2019 5:24 am

Well Greenland has for most of the last 40 years definitely been losing ice mass (in 2017 and 2018 additional precipitation in the form of snow probably kept gain/loss in balance, but that’s an exception)

On the outer Barcoo
Reply to  griff
November 12, 2019 8:49 am

From “Popular Mechanics”: On July 15, 1942, six P-38 Lightning fighter aircraft and two B-17 Flying Fortress bombers encountered a blizzard while supporting the Allied war effort in the British Isles. The aircraft were forced to conduct an emergency landing on the glaciers of Greenland, and though all the crew members were rescued nine days later, the aircraft were left behind.

Over the decades, the ever-shifting ice sheets of Greenland buried the aircraft, known as the Lost Squadron, under between 250 and 300 feet of ice. Fifty years later, in 1992, one of the P-38s was extracted from the ice and restored to flying condition: the infamous Glacier Girl.

Reply to  griff
November 12, 2019 8:50 am

Griff wasn’t there a bomber from WW2 that crashed in Greenland and was subsequently buried in 250+ feet of snow before they recovered it?

Are you saying it should have been buried in 300+ of snow but due to global warming it was only 250+?

Reply to  griff
November 12, 2019 8:58 am

And Antarctica?

Loren Wilson
Reply to  griff
November 12, 2019 5:04 pm

And Greenland has definitely gained ice since the Vikings lived there, as proven by the retreating ice revealing their farms. You have to explain that cycle without evil CO2 before you can blame this cycle on CO2. It’s called the scientific method.

Reply to  griff
November 12, 2019 5:11 pm

Those planes sank into the ice, the ice didn’t get 250 feet higher.

Reply to  griff
November 12, 2019 5:13 pm

Griff, it’s warmer than it was at the bottom of the Little Ice Age.
So what?

Jeff Alberts
Reply to  griff
November 12, 2019 5:27 pm

“Those planes sank into the ice, the ice didn’t get 250 feet higher.”

It was probably both. Snow and ice piling up on top of them, and ice melting from pressure way below.

Reply to  griff
November 13, 2019 4:53 am

“…in 2017 and 2018 additional precipitation in the form of snow probably kept gain/loss in balance, but that’s an exception….”

A inquisitive person, possibly a real scientist, would ask WHY? 2017 and 2018 were not predicted to do so, yet they did? Do we know why? If we do, is the cause likely to happen again, i.e. is it again being predicted.

I suspect Michael Mann is on the case, working furiously to understand greenland ice between his lawsuit back-pedalling and nobel prize collection runs. However, he better work faster as current estimates put greenland down to zero ice by AD 3350.

Ron Long
Reply to  ATheoK
November 12, 2019 7:13 am

ATheoK, I think your comments are pretty close to reality. There is still a large area of continental glaciers left over from the last Glacial Phase of our current Ice Age, in southern Argentina and Chile. The remnant has been generally in slow retreat, but here’s the kicker: it is common to observe preserved vegetation as the ice recedes, ie, we are not at the ice minimum of normal global climate cycles. Put that in your climate models.

Reply to  Ron Long
November 12, 2019 7:57 am

There are actually very few glaciers dating back to the last Glacial Phase anywhere. Nearly all melted in the Early Holocene. All glaciers in Iceland and Scandinavia melted completely for example.

The only ones I am aware of outside Greenland and Antarctica is the Devon Island Icecap, The Barnes Icecap on Baffin’s Land and the Guliya glacier in the Himalaya. It is possible that parts of the Patagonian Icecap did survive the Holocene optimum. but there is no evidence for it as far as I know.

Reply to  David Middleton
November 12, 2019 6:41 am

” it had accelerated to 5 mm/yr over the past 5 years”…

what blatant cherry picking horse crap…..

…and anyone can go back and cherry pick 5 years showing sea level falling at an even faster rate

Brian Valentine
Reply to  Latitude
November 12, 2019 1:43 pm

The units presented here are not “acceleration”

Reply to  Brian Valentine
November 12, 2019 4:55 pm

accelerated to…….5mm…..

…and you can cherry pick any 5 yr period to show “decelerated to” or “accelerated to”

NASA says it didn’t at all > https://climate.nasa.gov/vital-signs/sea-level/

Reply to  Latitude
November 12, 2019 6:08 pm

I looked at the NOAA sea level site. If you cherry pick from the end of 2005 to 2015 you do get 5mm/year. But…. If you look at the three years since end of 2015 to end of 2018 sea level rise has ended. No more crisis.

Roger Knights
Reply to  Lowell
November 13, 2019 7:39 pm

How is 2019 shaping up?

Bob boder
Reply to  David Middleton
November 13, 2019 5:00 am

1 meter? How many cinder blocks is that? I’ll start working now pretty sure I’ll finish in less then 300 years. If they give me $50 trillion I’ll finish even quicker.

Reply to  Bob Tisdale
November 12, 2019 7:47 am

how far global temperatures have to cool to stop sea levels from rising

There is the implicit assumption that the temperature increase is behind the sea rise. However that is not necessarily true, and we sort of know that sea level has been increasing even during the periods when global average surface temperature was decreasing during the 20th century or late 19th century.

Sea level rise has two contributions, one is steric volume change associated to water temperature and the other one is ice melting. But ice melting depends not only on temperature increase, but importantly on the increase in light absorbing particles that are the product not only of fossil fuel combustion, but also of industrialization and biomass burning, and it is generally associated to population increase. This is an important contributor to sea level rise that is seldom mentioned.

It is unlikely that we will see an scenario of sea level decrease even under the cooling experienced during certain periods of the 20th century. If we clean our pollution and reduce biomass burning, we might see a more effective reduction in sea level rise than if we stop producing CO2 or if we undergo a moderate temperature reduction.

Farmer Ch E retired
Reply to  Javier
November 12, 2019 9:07 am


Has any research been conducted to estimate the effect of sedimentation on sea level rise? Rivers and dust storms add sediment to the ocean floor as does dead biomass. Many rivers have dropped hundreds of feet of sediment near their outlets since the last glacial maximum.

Reply to  Farmer Ch E retired
November 13, 2019 4:37 am

To my knowledge the effect would be negligible on a global scale over time spans of less than a million years. Locally it can be very important though.

Reply to  Javier
November 12, 2019 12:32 pm


“If we clean our pollution and reduce biomass burning, we might see a more effective reduction in sea level rise than if we stop producing CO2 or if we undergo a moderate temperature reduction.”

You might have a good point here. But I nevertheless ask you:

What is in your mind the effect of civil aviation and its combined CO2 and H2O production at tropopause altitudes? Is it so harmless as often described?

Reply to  Bindidon
November 13, 2019 4:44 am

To give a meaningful answer to that one would have to be very knowledgeable on atmospheric chemistry, which is not my case. There is a very interesting research on stratospheric humidity that shows that changes at high altitudes might be more important than usually thought.

Solomon, Susan, et al. “Contributions of stratospheric water vapor to decadal changes in the rate of global warming.” Science 327.5970 (2010): 1219-1223.

Reply to  Javier
November 13, 2019 10:04 am


Many thanks.

Reply to  Bob Tisdale
November 12, 2019 7:51 am

Sea level sank until about 1860, so temperatures at about the LIA level is apparently needed.

James Schrumpf
Reply to  Bob Tisdale
November 12, 2019 11:35 am


What meaning does a “global temperature” have, when there are ~4000 or more stations in the NOAA GHCN Monthly data set which have negative or flat annual temperature trends, mixed right in with stations that have positive trends?

Reply to  James Schrumpf
November 12, 2019 1:02 pm

James Schrumpf

No idea which GHCN record you mean. But if you mean the GHCN V3 data set with its 7280 stations, here are the current numbers for the ‘unadjusted’ variant for the 5803 stations having shown a lifetime of at least 30 years:

– below 0°C / decade: 1502
– above 0 °C / decade: 4289.

This is extracted out of a trend sequence based on the lifetime of the stations. If you calculate, for all stations having sufficient data for the period 1981-2010, the trends within this period, the situation becomes a tiny bit different.

James A. Schrumpf
Reply to  Bindidon
November 12, 2019 1:52 pm

Sorry, I was using V4.

Reply to  James A. Schrumpf
November 13, 2019 10:08 am

James A. Schrumpf

“… mixed right in with stations that have positive trends”

Oh how interesting! You tell us about 4000 GHCN V4 stations reporting negative or flat trends, but not how many didn’t…

GHCN V4 has a bit over 27000, isn’t it?


Jeff Alberts
Reply to  Bindidon
November 12, 2019 5:31 pm

So global warming isn’t.

Reply to  Bob Tisdale
November 12, 2019 1:13 pm

Finland and other parts of the world, that ware under the massive ice sheet in last ice age, are still rising. And the rate is greater than sea level rise. Meaning that the land area is growing, pushing sea aside. This should also increase the rate of sea level rise for countries that are not rising?

Reply to  Bob Tisdale
November 13, 2019 3:30 am

Many thanks to all who have replied to my questions. Since no studies were cited, I will assume there are none.

The warmists claim that sea level rise will displace millions of people, but apparently there are no studies that specifically address what needs to be done to stop it, which would be tough since sea levels have been rising since the end of the last ice age.


November 12, 2019 2:14 am

Hardly a Tsunami, whatever the outcome.

St. Ferdinand III
Reply to  HotScot
November 12, 2019 4:50 am

If sea levels are rising why are former ports such as Rye and Ephesus 2-5 miles inland?
Wasn’t Venice forecast to be drowning by 1995?

Reply to  St. Ferdinand III
November 12, 2019 5:01 am

Venice is built on muck. Subsidence there is amazing.

Reply to  St. Ferdinand III
November 12, 2019 6:26 am

They aren’t, to answer your question. This is a hoax. But if it weren’t, so what? I personally could care less about how life will be 300 years from now. Do you think that people 300 years ago did? If they did, we would probably all be absolutely miserable right now since our lives are tremendously better off than theirs were 300 years ago and the same will be true about people 300 years from now. All because of decisions that people 300 years ago made, that were entirely about improving, bettering and enriching their own lives, who could have cared less about how life would be 300 years later. People 300 years from now, and in between, will make due just like we have and will live better lives than we will. I have no idea where this weird reverse survivors guilt comes from. Is it actually envy for everything that they will have that we won’t?

Reply to  Luke
November 12, 2019 8:44 am

Maybe they’ll live much longer when they find a cure for cancers. Let’s say the average becomes 150 years. That means you have to work at least 100 years.

Reply to  Robertvd
November 12, 2019 12:54 pm

All of the oldest people on Earth live until about 115. I’m told that is the human lifespan maxima. The average of people in life who escape cancer, Alzheimer’s, stroke, heart attack, etc. is far less than that, so.

Jeff Alberts
Reply to  Luke
November 12, 2019 5:34 pm

“could have cared less”

I don’t think this means what you think it means.

Jeff Alberts
Reply to  Luke
November 12, 2019 5:40 pm

“They aren’t, to answer your question. This is a hoax.”

What is a hoax, exactly. Ephesus is actually 6 miles inland. If you estimate a 4 meter higher sea level in that area, it’s back where it should be.

November 12, 2019 2:41 am

“1 meter sea-level rise by 2300 is now inevitable even if we ceased emissions in 2030”

Do emissions have something to do with sea level rise?

Peter in Oregon:
yes of course.
The correlation is clear to see in the data.

Chaamjamal in Thailand
Did Peter get the statistics right?


Reply to  David Middleton
November 12, 2019 3:44 am

Thank you, David.
Great post as usual

Reply to  Chaamjamal
November 12, 2019 3:21 pm

Since this interglacial began, sea level rose about 400 feet before even the first automobile was produced.

Reply to  Chaamjamal
November 12, 2019 5:55 pm

At the end of the Johnson article, he seems to qualify the projections by saying it could only be 20 cm, or 8 inches by the year 2300?
Based on the geological history of the world, if we believe geological scientists, in the year 2300 we could be boiling in molten rock, completely dry, or under 1000 feet of water because all the land would collapse, with 97% of all life on earth extinct, or maybe the earth could be just completely blown up by some random heavenly body crashing into us and then waiting for another 5 billion years to agglomerate by gravity. Again, for the umpteenth time.
My favorite cartoon from years back, it may have been in the New Yorker when they were an interesting read, was the old sage in a white robe with a long white beard standing on a street corner with a tin cup for donations holding a sign that stated: “World ends Tomorrow”.
I didn’t get for quite a while that that was his lifelong career.

November 12, 2019 2:46 am

I wonder what technology will be available in 2300. We will never know.

Flight Level
Reply to  Phillip Bratby
November 12, 2019 4:15 am

Flying boats.

Clyde Spencer
Reply to  Flight Level
November 12, 2019 9:40 am

Floating cities.

Reply to  Flight Level
November 12, 2019 5:17 pm
Jeff Alberts
Reply to  Flight Level
November 12, 2019 5:41 pm

Flying monkeys.

Reply to  Phillip Bratby
November 12, 2019 5:46 am

It might not matter because there will be far fewer people in 2300 than today. Global TFR is 2.3, barely above replacement, and continuing to fall. Global population will likely peak below 11 billion, perhaps below 10 billion, before the end of this century.

In the 22nd century (2100-2199), the population will be reduced by around 75%, give or take, as global TFR’s fall well below 2. No one really knows what happens next, but my guess for 2300 is a population in the 1 to 2 billion range. It’s unlikely to be a happy time for humanity, since the global economy really depends upon population growth.

Reply to  Adam
November 12, 2019 8:36 am

Population numbers go down because people become richer. If for 2300 you predict an unhappy time for humanity there should be a rise in population.

Reply to  Adam
November 12, 2019 3:24 pm

Perhaps Naomi Oreskes is cloned and the population goes to zero.

Jeff Alberts
Reply to  Scissor
November 12, 2019 5:42 pm

That’s pretty low class. Attack her lies and policies, that’s fair game. But attacking how someone looks is immature.

Reply to  Jeff Alberts
November 12, 2019 8:49 pm

This is not a fair game.

Tom Higley
Reply to  Phillip Bratby
November 12, 2019 7:00 am

My guess is that dikes will be invented by then. Hopefully that little kid with his finger to stop leaks is still around. Sorry, couldn’t resist.

Clyde Spencer
Reply to  Tom Higley
November 12, 2019 9:42 am

Are you recommending that children give dikes the finger?

Michael S. Kelly LS, BSA Ret.
Reply to  Phillip Bratby
November 12, 2019 10:11 am

I think by then we will have installed a drain in the bottom of the sea (and, perhaps, written a song about it).

J.D Wilkes
November 12, 2019 2:48 am

According to this graph sea level was about 5 meters higher in the year 1000. Really?

Reply to  J.D Wilkes
November 12, 2019 5:28 am

See Harlech castle sea gate.

November 12, 2019 3:05 am

“Considering only emissions through 2030 creates a hypothetical scenario in which warming peaks around 1.5 °C above preindustrial temperatures and starts dropping before the end of this century.”

pre Industrial equals pre 1750 and some of the worst periods of the intermittent Little Ice age. Why would we want to get back to that bone chilling time? Why is that considered “normal” It was surely abnormal?

Anyone here like to give us a decade they consider to be the ‘normal’ one before man was supposed to have interfered?


Joe Campbell
Reply to  David Middleton
November 12, 2019 9:39 am

What’s this? Strange chart?…

Reply to  tonyb
November 12, 2019 4:53 am

Ther are those who consider that the Canary Islands currently have the best climate on the planet ..https://www.hellocanaryislands.com/best-climate-world/

But probably not so good if you like your hockey on ice or enjoy cross country skiing or curling.

So as to a best and “normal” climate decade…your choice

Reply to  GregK
November 12, 2019 6:39 am
November 12, 2019 3:17 am

Some simple questions regarding sea levels.
Very Simple Question 1. Why do we know sea level are accelerating?
Answer 1. Because the graphs seem to turn up.
Simple Question 2. Why is the acceleration assumed to be constant?
Answer 2. Because we apply a quadratic curve fit.
Question 3. Why do we apply a quadratic curve?
Answer 3. Because it is easy to do.
Harder Question 4. Why not try something different?
Answer 4. Look at this comparison between Quadratic and Sinusoidal curves for Tidal Gauge Readings.
The two curves on this plot are first the well documented quadratic fit to the Tidal Gauge readings.
Where y is the sea level and x is time based on 1800 being assigned 0.
And a sinusoidal curve (in EXCEL Format)
At a glance the 2 curves are very similar the differences between them being much less than the scatter of readings.
It is interesting to compare velocities and accelerations over the range of results.
The velocities for the quadratic vary from 0.8 mm/year in 1880 to 2.5mm/year in 2013.
Accelerations are constant at 0.0126 mm/year2.
The velocities for the sinusoidal vary from 0.7mm/year in 1880 to 2.3 mm/year in 2013.
Accelerations vary from 0.016mm/year2 in 1880 reducing to 0.0075mm/year2 in 2013.
The sinusoidal curve was based on a period of 1000 years this being considered a possible period between peaks based on history of warm periods. This resulted in an amplitude of 415mm. The 250mm is to allow for the fact that points of contraflexure do not coincide with zero sea level and the 1420 year value is a phase shift.
Other differences are that whereas the quadratic curve cannot be extended much further backwards in time, being parabolic, it has been readily extended forward with alarmist consequences. Extended backwards it reaches zero in about 1802.
On the other hand, the sinusoidal predicts a minimum level of -165mm in 1840 and a maximum of 665mm in 2340 when maximum acceleration and deacceleration will occur. The time of zero acceleration is in about 2090 when the velocity will have reached 2.6mm/year.
As both curves are similar, to a few mm, over the range 1800 to 2013 previous finding obtained using the quadratic curve are also applicable to the sinusoidal curve. The main one is that studying the residuals between the actual results and the fitted curve resulted in a sinusoidal variation over an approximate 57-year period with an amplitude of 6mm, this being probably due to the combined decadal ocean oscillations in the range of 50 to 60 years.
The above is put forward as an alternative approach that may help to add some more understanding on this complex subject. As a retired Civil Engineer, I admit it is not my field and I may be right off track, but nothing ventured nothing gained. I am at present looking at the Brest results which go back further.
Similar studies for the NASA satellite readings are difficult to justify due to the very short (26 years) period involved but that doesn’t seem to stop alarmist predictions being made. How dare they!!.

Reply to  David Middleton
November 12, 2019 3:53 am

Thanks for reply but any chance of expanding on which “It” and which work of Jevrejeva you are referring to. This will help me clear my thoughts on this complex subject.

Reply to  alankwelch
November 12, 2019 6:58 am

I have looked up Jevrejeva et al 2014 and whilst at it also Hansen et al 2016.
Jevrejeva split the post 1930 into a series of constant velocity slopes of 3.0681, 1.1526 and 3.1547 mm/year (as you show above) where as Hansen uses 3 increasing slopes of 0.6, 1.4 and 3.3 mm/year. I think Nature will act in a smoother fashion and the file
shows a combined curve made up of the best fit quadratic (my sinusoidal best fit would have sufficed just as well over this period) plus a sinusoidal addition of +/-6mm/year over a 57-year period. It’s not perfect but does indicate a fairly good trend. This figure is Appendix 2 from my paper
In the second of Jevrejeva figs shown by you the plots prior to 1860 are based on very limited data and as indicated have a much higher uncertainty . Before 1840 my sinusoidal curve is already turning upwards indicating that levels had been dropping prior to 1840. If the second of Jevrejeva curve is correct what caused the large drop in levels around 1860 which amounts to about 100mm in about 2 to 3 years – that’s one hell of a rate of drop.

Reply to  alankwelch
November 12, 2019 8:12 am

There was a huge outbreak of icebergs in the Southern Ocean 1852-59, presumably some large antarctic shelf-ice area broke up then:


Could the cooling effect on the Southern Ocean have affected sea-level? Or did the sudden sea-level change cause the shelf-ice to break up?

November 12, 2019 3:54 am

Scott K Johnson should go back to school.
ARS Technica. Weren’t they outed for hiring a known kiddyphile.Lots of smokescreen.Be interesting to see if CEO was involved in the hiring

Mark H
Reply to  DLee
November 12, 2019 2:03 pm

Yeah, ARS Technica employed Peter Bright (aka Dr Pizza), who was an avid supporter of the legalization of pedophilia and was arrested this year on charges of attempting to entice a minor to engage in illegal sexual activity (two children aged 7 and 9). Sounds like a thoroughly horrible person to me.

November 12, 2019 3:55 am

Sea level rise????

How about inland water levels rising? Isn’t that more important? Confounded rivers were full to overflowing around here in September, when they should be lower at the end of summer. Lake Michi Gamu is restlessly pound surf onto the shores, and splashing high volumes onto the dune areas where I go with my camera in the Warm Times. How am I supposed to get pictures of birds, bugs and blossoms if they’re all eaten up by the river rising and Michi Gamu throwing a temper tantrum????

Dams everywhere are badly in need of repair and/or replacement. Ole Man River is getting a bellyful of runoff from everywhere. Wait until Spring comes and the ice dams break up on the Kankakee, Missouri, Des Plaines, Rock River, Wisconsin River and the Wabash. That will be awesome!!!! The Mississippi froze in January of 1976. I was in London then, and it showed up on the news. And in 1997, it floods so badly that levees and dikes were overwhelmed and bottom land floods the way it normally would . Lots of flooding everywhere, IIRC. I expect to see it again.

And these bozos are would about sea level rising? (Snrrrttt!!!!) Amateurs!!!!!!!!! The REAL answer is right under their feet. It’s a pity they ignore it, but then, they’re probably the type that come to a flooded spot in the road, drive into it and get stuck and then have to wade out of the giant puddle and stand there looking helplessly at the news helicopter overhead. 🙂

Reply to  Sara
November 12, 2019 5:14 am

Eeewww! ” would” should be “worried”. Not enough caffeine….

John Endicott
Reply to  Sara
November 12, 2019 8:00 am

at least you typed it as “would” and not “wood”. That really would have been an “ewww”

Reply to  Sara
November 12, 2019 8:47 am

Thank, Johm Endicott! Some typos are energizinglyl comical!

Ben Vorlich
November 12, 2019 4:14 am

. Any years ago I remember watching a documentary on BBC, so long ago tha it was before Richard Black. This said that one of the reasons for the Anglo-Saxon invasion of Southern Britain at the end of the 4tb and beginningoof the 5th century AD was rising sea levels and migration pressure from the east. The graph in the artoclev

November 12, 2019 4:15 am

This is the Deification of Man.

The forces controlling sea level dwarf Man’s alleged influence.

Right-Handed Shark
November 12, 2019 4:17 am

“Nauels and his colleagues used a simple mathematical model calibrated against the results published in the most recent IPCC report.”

A work of fiction, then.

November 12, 2019 4:30 am

Latitude didn’t you post a tidal gauge here where the Sea rise from the 1800s (I think) is a slow steady rise?

Would you post again?

November 12, 2019 4:37 am

How much does thermal expansion/contraction affect the level of the oceans?
When I heat my coffee in the microwave the level goes up noticeably, but that’s about a 100 degree (f) increase.

Carl Friis-Hansen
Reply to  Dave
November 12, 2019 6:46 am

I cannot answer you question, but just give you a hing:
The above gives you the coefficient, but it is a hell more complicated than that, with different temperatures and column heights all over the oceans.
I am sure there IPCC must have some caculations there.

Don K
Reply to  Dave
November 12, 2019 8:56 am

Dave — I’m going from memory, but I think the IPCC attributes roughly half of Sea Level Rise to thermal expansion of the oceans and the other half to a combination of ice melt and ground water extraction minus new ice formation plus filling of new artificial reservoirs.

Reply to  Dave
November 12, 2019 2:40 pm

Average depth of the ocean is ~3600m so a 0.1% expansion would be 3.6m.
According to NASA:
“The estimated rate of thermal expansion, or thermosteric sea level rise, from 1971 to 2010 is 0.4 to 0.8 millimeters per year; the estimate carries a confidence level of 90 to 100 percent [Rhein et al., 2013]. This corresponds to a warming rate of 0.015 degrees Celsius per decade in the upper 700 meters of the global ocean between 1971 and 2010”.

Reply to  Phil.
November 12, 2019 7:43 pm

Note that almost all of the ocean is 5 degrees C or less. So only the very top of the ocean can have expanded. And hot water rises.
Ocean expansion is mostly a scam.

Ed Zuiderwijk
November 12, 2019 5:14 am

Sealevel in the North Sea was substantially higher in the 13th and 14th centuries than today. It fell during the Little Ice Age and after about 1840 started rising again. By 1.9mm/yr throughout. Before the notorius St Elizabeth Flood of November 1421 much of the coast was formed by sand dunes, basically from the south near Calais (now in France) to the German Bight in the north, except of course at the deltas formed by the big rivers flowing into the sea (Scheldt, Rhine/Meuse, Ems, Weser, Elbe). After the flood the dunes had been breached in many places, creating an inland sea and a chain of islands in the north.

Amos E. Stone
November 12, 2019 5:37 am

‘Scott is an educator and recovering hydrogeologist’

Do people suffer from hydrogeology? Glad he’s on the mend…

Ed Zuiderwijk
Reply to  Amos E. Stone
November 12, 2019 6:16 am

He’s recovering from his Ology. Very painful.

Clyde Spencer
Reply to  Amos E. Stone
November 12, 2019 9:52 am

Being a recovered cryologist means that he has overcome his depression through aquapuncture.

Komrade Kuma
November 12, 2019 5:51 am

It seems obvious to me that somewhere there is a secret breeding program for unicorns capable of much, much greater flatulence than anyone previously thought possible and that is what is driving CAGW and SLR.

I think we need to match the green blob’s fixation on CO2 by mentioning unicorn farts as often as possible when some extreme weather event occurs in order to create the same propaganda effect. We need to get XR to shift their focus to self indulgent obstructive protests about CO2 levels and focus on useful work in hunting down this evil unicorn program.

Folks, you know it makes sense. Well as much sense as climate science statistics.

Carl Friis-Hansen
November 12, 2019 5:58 am

Looking at Figure 1. in the article
I came to think – yes, there is a first time for everything – that we have found burials of Vikings on Greenland from 1000 years ago, at places covered with ice today. That has made the assumption that is most have been a lot warmer on Greenland at Erik The Red’s time.
Could it be a combination of higher temperature and sea level back then?
The coastal line will be further inland and moderate the local temperature at the burial places at the time.

Reply to  Carl Friis-Hansen
November 12, 2019 10:20 am

Carl: I recommend that you get hold of a copy of Else Ostergard’s “Woven into the Earth” a book about the discovery of textiles from Norse Greenland burials. Because of the shortage of wood bodies were wrapped in clothing for burial. The most famous site for that is Herjolfsnes in the southern tip of Greenland. Burials began at the end of the 10th century , but because of the mild climate at that time little of the bodies and textiles survived. Later as the ground became frozen for longer periods the textiles survived for centuries and the Greenland finds apparently constitute the best collection of North European medieval textiles so far discovered.
Norlund’s classic from 1924 : “Buried Norsemen at Herjolfsnes” is a rich source of excavation photos, showing how low lying and close to the shore was the settlement, and in fact much of the settlement and part of the churchyard has been lost to the sea since it was first recognised as a Norse site in about 1830. The coastal line has encroached since the 10th century and I read that the Danish and Greenland archaeologists are eager for volunteers to help rescue sites threatened by climate change (destroying the permafrost) and coastal erosion.
There are photos around of the site at Brattahlid (Erik the Red ‘s presumed farm) filmed from the air in late 40s or 50s, and if you compare with present day Google Earth view, the shore line has not changed at all in about 60 or 70 years. (tidal influence being low because most Norse farms in the East Settlement were at the head of fiords to take advantage of the summer warmth and more continental climate for growing hay the closer they were to the ice cap )

Reply to  mikewaite
November 12, 2019 2:20 pm

Imagine what treasures lie at 300 ft!

Man’s coastal settlements 12,000 years ago are now under 300 feet of water. Amazing discoveries await!

Reply to  mikewaite
November 12, 2019 2:48 pm

Average depth of the ocean is ~3600m so a 0.1% expansion would be 3.6m.
According to NASA:
“The estimated rate of thermal expansion, or thermosteric sea level rise, from 1971 to 2010 is 0.4 to 0.8 millimeters per year; the estimate carries a confidence level of 90 to 100 percent [Rhein et al., 2013]. This corresponds to a warming rate of 0.015 degrees Celsius per decade in the upper 700 meters of the global ocean between 1971 and 2010”.

Jeff Alberts
Reply to  mikewaite
November 12, 2019 5:51 pm

“Because of the shortage of wood bodies”

Do we still have a shortage of wood bodies?

Reply to  Jeff Alberts
November 13, 2019 12:37 am

Jeff , we still have a few, about 10 cm long, depictions of the Norse settlers carved by Inuits from drift wood and found in Greenland and Baffin Island: see Ch 17 of” Vikings , the North Atlantic Saga” ed Fitzhugh and Ward, Smithsonian , (2000)

Reply to  Carl Friis-Hansen
November 12, 2019 2:54 pm

According to GPS measurements the Greenland mainland is rising at about 3cm/year.

November 12, 2019 6:04 am

Whatever happened to the Willis Eschenbach?

Gary Mount
Reply to  Chaamjamal
November 13, 2019 2:08 am
November 12, 2019 6:42 am

3.2 mm/yr, so, you have been drinking the Satellite Altimetry Kool-Aid then? Just how were these measurements calibrated? Oh, they weren’t? I see. Very scientific.

What do the tide gauges say, again? Oh, more like 1.9 mm/yr?

The Rest of The Story…

Reply to  Michael Moon
November 12, 2019 1:57 pm

… is, Michael Moon,

that you confound, like so many others, the trend for 1880-today with the trend for 1993-today.

Here is a chart comparing, for Church & White, Jeverjeva & al and Dangendorf & al., the trends for 5-year distant consecutive periods between 1903-2009 and 1993-2009 (their common evaluation range):


It seems that while Jevrejeva shows a bias in the past, C & W shows a bias for the present. The truth will, as so often, be in between of all.

And here are the time series out of which these linear trend sequences were computed using a good old spreadsheet calculator:


For 1993-2015, NOAA’s altimetry and Dangendorf’s PMSL evaluation have nearly the same trend (2.6 vs. 2.7 mm / year). Sounds good.

Jeff Alberts
Reply to  Bindidon
November 12, 2019 5:53 pm

Why is the trend for 1993 to present more important than the overall trend?

How about the trend from 1900 to 1945 or so, where the slope was the same as your selected period?

November 12, 2019 6:44 am

And, by the way, 7 degrees F here in Chicago this morning, broke the all-time record not just for today but for the month of November, and it is only the 12th.


Reply to  Michael Moon
November 12, 2019 1:09 pm

Michael Moon

Can I console you with the news that we are here in northern Germany shortly before the third very mild winter in sequence?

Probably not…

The last winter with more than 10 cm of snow in one day is so long back that I do not remember exactly!

Jeff Alberts
Reply to  Bindidon
November 12, 2019 5:55 pm

“The last winter with more than 10 cm of snow in one day is so long back that I do not remember exactly!”

You’re probably breathing too much. You should cut back.

Reply to  Jeff Alberts
November 13, 2019 11:00 am

Jeff Alberts

Why do you remind me my neighbour’s dog?
Is it because it never leaves a tree ‘unvisited’ ?

Mike McHenry
November 12, 2019 7:27 am

As recently as this past year I have read that the principal cause of glacial melt is the direct absorption of solar radiation. The melt rate is altered by clouds and glacial snow cover. Air has a puny heat capacity so I would expect it to be a lesser factor. I have often observed this after a light snow over night on my lawn where morning air temperatures are above freezing ad the sun is shining. Snow in the shade under trees is the last to melt. Given the above I don’t see how you can compute melt rate based on air temperatures alone. Am I missing something?

Reply to  Mike McHenry
November 12, 2019 9:03 am

No, you’re not. Any meteorologist/weatherman can tell you that shade from the sun creates a microclimate that can be cool enough to keep snow from melting and leave nice snow shadows of trees on your lawn. I have a lot of photos of this kind of thing.

If the air in the sun is 34F and the air in the shade is 32F or even 31.5F, the snow will stick around until it warms up a little more.

Steve Z
Reply to  Mike McHenry
November 12, 2019 9:09 am

Mike McHenry makes an excellent point. In Salt Lake City, we had about an inch of snow in late October, which accumulated on the grass, but melted on contact on roads. After two sunny days with highs in the 40’s, all the snow was gone except on the north side of our house, with the edge of the snow coinciding with the shadow of the house at noon. It took another four sunny days with highs in the 50’s to melt the snow in the shadow of the house.

Move this scenario to Greenland, and there can be significant melting during periods of relatively strong insolation from about April through August, but little or no melting the rest of the year, when temperatures are below freezing, and the ice receives little or no sunshine. Since the Greenland ice cap is over 2,000 meters thick in most areas, the air in winter over the ice is well below freezing, but the ocean along Greenland’s east coast remains open water most of the autumn and winter due to the Gulf Stream, and storms form along the coast, pulling moisture from the ocean and dumping heavy snow on the ice cap (similar to nor’easters along the New England coast). The global-warming activists see the melting from ships just offshore in the summer sunshine, but don’t see the heavy snow in winter, since tourism in dark snowstorms doesn’t attract many people.

If most of the melting is due to direct solar radiation in spring and summer, a temperature rise of 1.5 C due to increased CO2 will not prevent snow and ice from accumulating on Greenland in autumn and winter, when there is no sunshine on Greenland, and temperatures remain well below freezing.

How much would a temperature increase of 1.5 C increase summer melting? It takes about 310 calories to raise the temperature of 1 m3 of air (at 0 C and sea-level pressure) by 1 C, but about 72 million calories to melt 1 m3 of ice. A column of air covering 1 m2 (accounting for variations on pressure) is equivalent to about 9,000 m at sea level, so that if the entire atmosphere was warmed by 1.5 C, about 310 * 1.5 * 9000 = 4.2 million calories of heat would be required per m2 of surface. This heat could melt about 0.058 m3 of ice, or a depth of 5.8 cm, or 2.3 inches.

The area of the Greenland ice sheet is about 1.71 million km2, but that of the oceans is 361 million km2, so that melting a 5.8 cm depth of ice in Greenland would raise sea level by 0.058 * 1.71 / 361 = 0.000275 m = 0.275 millimeters. Even if this occurred every year, it would only increase the current sea level rise rate (3.02 mm/year according to Figure 2) by about 9%, to about 3.3 mm/year. At that rate, the sea level would rise by about 267 mm by the year 2100, or 927 mm by the year 2300, but there would not be a major acceleration in sea level rise rate.

It is conceivable that sea level could rise by 1 meter by the year 2300, but technology (including earth-moving equipment) could make major advances by then, so that our (great-times-12)-grandchildren will have plenty of time to build seawalls around coastal cities if necessary.

Reply to  Steve Z
November 12, 2019 1:14 pm

I rarely see mention of the Danish aerial survey of 1938. That showed the that the glaciers were in recession then as now.

Michael Jankowski
Reply to  Mike McHenry
November 12, 2019 9:40 am

Also black carbon…

HD Hoese
November 12, 2019 7:29 am

“….the behavior of the world’s ice sheets and glaciers is varied and complex,.. ” In marine science (no doubt others) that translates as we don’t understand it very well. Always have to read the “fine print,” not smaller, but often buried.

November 12, 2019 7:38 am

Remember Meltwater Pulse 1B? Those were some wild times.

November 12, 2019 7:48 am

The future is real

I love that phrase. It is wrong in so many ways.

Gary Pearse
Reply to  Javier
November 12, 2019 1:49 pm

Javier: Philosophers they are not! Even academe’s philosophy department philosophers these days are not.

steve case
November 12, 2019 7:52 am

alankwelch November 12, 2019 at 3:17 am
Other differences are that whereas the quadratic curve cannot be extended much further backwards in time, being parabolic, it has been readily extended forward with alarmist consequences.

Here’s a chart from Skeptical Science attributed to Dr. Nerem.

Here’s a graph from 2011 that makes the point that extrapolation isn’t a good idea. At that time the acceleration was negative -0.06mm/year² LINK (pdf) (scroll to bottom)

Reply to  steve case
November 12, 2019 9:28 am

The fig below shows the velocity and accelerations calculated using the NASA raw data. It shows the values derived using the first 9 years of results up to using 26 years of results. As you pointed out around 2012 the acceleration went negative. This illustrates the danger of using polynomial curve fitting. Once out side the range of data the extrapolated results are solely governed by the highest term, in this case the square term.

Reply to  steve case
November 12, 2019 2:49 pm

steve case

“… extrapolation isn’t a good idea.”

You may be right.

But now we are in 2019, I had a quick look at my little sea level ods file, and so do look the monthly consecutive altimetry trends for 1993-2003 till 1993-2019:


Do you see the drop from 2005 till 2011 in the NASA trend series? (It is a bit less pronounced in the NOAA data.)

The spreadsheet calculator gives for that NASA period -0.19 ± 0.02 mm/year²; for 2012-2019, +0.22 ± 0.02 mm/year².

Do you think the data was, after the drop, subsequently adjusted to show something quite different?


Reply to  Bindidon
November 12, 2019 3:12 pm

Apos for a typo: the trends of trends should be -0.019 ± 0.002 resp. +0.022 ± 0.002 mm/year².

Jeff Alberts
Reply to  Bindidon
November 12, 2019 6:00 pm

The measurements aren’t that accurate.

steve case
Reply to  Bindidon
November 13, 2019 7:00 am

Bindidon November 12, 2019 at 2:49 pm

If you’re asking do the keepers of sea level data via satellites rewrite historical data? The answer is yes they do. Here’s a graph that visualizes those changes:

comment image

It’s coming up on two years ago that Colorado University’s Sea Level Research Group completely re-wrote the satellite record, time line and data. They bumped up the data from 1992 to 1998 which resulted in an acceleration of 0.08mm/year² that they then extrapolated out to 2100 projecting a 0.65 meter increase.

Yes there was a drop in sea level 2005-2011. The water went somewhere. Polar ice caps? The flooding in Australia? Where ever it was, it was released and the subsequent rate of sea level rise 2012-2019 reflected that release, and not an artifact of adjustments. Do you think that uptick in the rate is going to continue for the next 80 years as CU claims? I don’t know, but if I had to put money on it, I’d say it wouldn’t continue.

Reply to  steve case
November 13, 2019 10:16 am

steve case

Thanks for the info, I have Colorado SL on the HD but don’t use it.
What you see on my graphs is NASA and NOAA data.

Now, what concerns

“Do you think that uptick in the rate is going to continue for the next 80 years as CU claims?”

No idea. As I only observe, I have nothing to do with predictions. For that you at least must be able to interpret what you observe. I am not.

November 12, 2019 7:53 am

Look behind the article to the comments, which are most scary is all the mini-Greta children-of-the-corn wingeing about it! And we have the Warminista authors’ linear projecting a trend 300 years into the future. By 2300 we may be well heading into the next ice age…

On the outer Barcoo
Reply to  lgp
November 12, 2019 9:13 am

The Earth has experienced five major Ice Ages: the first in the Upper Archaean, the second in the Lower Proterozoic (300 my from 2.4 to 2.1 Ga), the third in the Upper Proterozoic (72 my, from 715 to 643 my) and the fourth in the Permo-Carboniferous (100 my. from 360 to 260 my.) The fifth Ice Age is the current Quaternary Period starting some 2.6 million years ago.

The current Ice Age is characterized by lengthy periods of glaciation punctuated by much shorter, warm inter-glacial periods such as the one that Earth is currently experiencing. The last four glaciations have each lasted roughly 100,000 years and the last four interglacials have each lasted approximately 10,000 years. The current interglacial started some 10,000 years ago.

Jeff Alberts
Reply to  On the outer Barcoo
November 12, 2019 6:02 pm

“The Earth has experienced five major Ice Ages glaciations.”


November 12, 2019 8:04 am

Yes, I agree, anything about sea-level rise is a massive yawn. Even more so than sea-ice.

steve case
Reply to  beng135
November 12, 2019 11:52 am

beng135 – at 8:04 am
Yes, I agree, anything about sea-level rise is a massive yawn. Even more so than sea-ice.

Sea level rise is probably the biggest scare they have.

Marcus Allen
November 12, 2019 8:26 am

The end of the world “inevitable” – Eventually…

Hokey Schtick
November 12, 2019 9:14 am

yep we are all going to die.

November 12, 2019 10:07 am

… they calculated the relationship between emissions and sea-level rise in previous simulations …

Seems a bit limited and presumptuous.

November 12, 2019 10:16 am

Satellite altimetry measurements of sea-level are less reliable than coastal tide gauge measurements, and satellite altimetry can only measure sea-level far from shore. It cannot measure sea-level near the coast, where it matters. Only tide gauges can do that.

Tide gauges are measuring even less sea-level rise than most of the satellite altimeters. According to tide gauge measurements, sea-level rise averages only about 1.5 mm/year, with no detectable, sustained acceleration in over nine decades.

Here’re a few locations with very long, high quality measurement records, and little distortion from vertical land motion:

1. Honolulu, Oahu, Hawaii:
comment image

Oahu is an old, tectonically-stable island, which experiences near-zero vertical land motion. The volcanoes on Oahu are believed to have been inactive for well over a million years. Like all the Hawaiian islands, it is moving horizontally, to the NW, about three inches per year. But not vertically.

Peltier’s ICE-6G(VM5a) estimate is that Honolulu is experiencing just 0.10 mm/yr uplift. Ref:

SONEL’s analysis indicates that Honolulu is subsiding (rather than rising), but just 0.23 ±0.18 mm/yr:
comment image

The CORS plot is flat as a pancake:
Also saved here:
comment image

All those numbers are tiny: +0.1 and -0.23 are opposite sign but not far apart. In other words, the models and measurements agree that Oahu is experiences little or no vertical land motion.

Oahu also gets only small tides, and its mid-Pacific location is near the pivot point of the east-west Pacific “teeter-totter,” so it is little affected by ENSO “slosh.”

The only thing atypical about Honolulu’s sea-level measurement record is its very high quality. The trend there (about +1½ mm/year = 6 inches/century) is perfectly typical.

2. Maassluis, Netherlands.

The Dutch are very diligent at measuring sea-level. Maassluis has a 171 year continuous measurement record, without a single missing month!

Like Honolulu, Maassluis has little vertical land motion. (Peltier’s estimate is that it experiences 0.13 mm/yr subsidence.) Its 2.0 mm/yr sea-level trend is onlt about 2 inches/century faster than Honolulu:

comment image

3. Cuxhaven, Germany.

Peltier estimates that Cuxhaven gets 0.72 mm/year uplift, but SONEL isn’t measuring any. The sea-level trend there is just 1.9 mm/year:


1 to 2 mm/year sea-level rise is truly negligible. It is only about four to eight inches per century. It is so slow that in many places it is dwarfed by common coastal processes, like erosion, sedimentation, and vertical land motion.

Greta Thunberg’s hometown of Stockholm is one such place. They would benefit from an increase in the minuscule global sea-level trend, because it would reduce their dredging expenses. Unfortunately for them, the sea-level trend is not accelerating:
comment image

Reply to  David Middleton
November 14, 2019 11:59 am

You’d think so, wouldn’t you? And yet the Aviso folks add 0.3 mm/yr isostatic adjustment to all their reported sea-level trends, from satellite altimetry. That’s the estimate they use for the amount by which sea-level would be falling due to ongoing sinking & broadening of ocean basins, due to meltwater load from the last deglaciation, were there no other factors affecting sea-level.

“it… means their “mean sea level” is now floating, phantom like, above the waves.”Greg Goodman

AVISO used to make adding the isostatic adjustment optional in their graphs, but they removed that feature. I wrote to them and asked them to restore the feature. They politely refused.

Date: Nov. 08, 2017
From: David Burton


In the old version it was possible to show sea-level trends with or without Peltier’s 0.3 mm/yr GIA adjustment (like this), but in the new version this does not seem to be possible. Could you please restore this capability?

When the GIA adjustment is added, the result is not the actual sea-level trend. Rather, it is an estimate of what the sea-level trend would have been were it not for the fact that the ocean floor is still slowly sinking under the weight of the meltwater from the last major deglaciation, circa 7K years ago. I would like to be able to produce graphs of the actual sea-level trend.

Thank you,

Date: Nov 17, 2017
To: David Burton

Dear Dave,

indeed on the site we have decided to distribute to the users the “oceanic climate indicator” which is the mean sea level corrected for the GIA. This decision in order to be consistent with what we do usually: it’s for example similar to compute the altimeter sea surface height taking into account the tides , or all other oceanic or atmospheric signal and the SSH is thus also not the “true” sea level. So I’m afraid you will have to decrorrect yourself the GIA correction:

The value we take into account for the computaion of GIA is -0.3 mm/year, so the value of the trend will be: MSL_trend=MSL_trend_from_file – 0.3

best regards

Françoise Mertz
Aviso User Services

Date: Nov. 17, 2017
From: Dave Burton

Thank you for your reply, Françoise.

Please, at least correct the labels on your graphs. Contrary to their labels, those graphs are not “Mean Sea Level from Altimetry,” and should not be labeled as such. They should be labeled what they are: “Mean Sea Level from Altimetry plus GIA.”

People who look at graphs of sea-level expect them to be useful for projecting actual sea-level rise (or fall, in some places). When you add a “fudge factor” like Prof. Peltier’s estimate of PGR effects, you are attempting to produce a graph which includes just some of the components of the sea-level trend, and omits others. That is useful for some purposes, but it is is not in any sense “mean sea level.”

It is not in any sense “measured,” either! Professor Peltier’s 0.3 mm/yr GIA estimate is purely model-derived. It is unmeasurable, and unverifiable.

Prof. Peltier’s GIA estimate doesn’t include any uncertainty estimate, either, so when it is added to any other quantity it is impossible to correctly deduce error margins for the sum.

I suggest that you produce graphs of actual, measured sea-level trend, which include all components of that trend, and so have not been adjusted upward by 0.3 mm/yr GIA estimate.

If you wish to also produce graphs which break that trend down into best estimates of its various components, that could also be useful for some users of your products. Such components would include major factors like steric change, grounded ice mass balance change, and PGR, and perhaps also minor factors like groundwater extraction, and dam/lake/river impoundment. (But I strongly recommend that you include error/uncertainty margins for those components, as well, and reference sources for the various estimates!)

It is deceptive to decompose the sea-level trend into estimates of its components, and then graph just some of those components (the ones which contribute to a positive trend), and omit the main negative component, which reduces actual sea-level, and mislabel the result “mean sea level.” Doing so invites criticism that you’ve put a thumb on the scale, to exaggerate sea-level rise — which is, indeed, the effect, if not the intent, of what Aviso is now doing.

Warmest regards,

Date: Dec. 29, 2017
To: David Burton

Dear David,

you will find herafter an answer of our experts:

Though we understand your remark concerning the definition of Mean Sea Level, this is not the definition of the ocean surface topography science community. The objective of the AVISO indicator (and many other processing groups such as Colorado University) is to provide the mean sea level variations in order to understand the evolutions of oceanic volume change. Thus, we correct for PGR, polar tide, earth tide, load tide… because the movements of the terrestrial crust are not the focus of this indicator. These corrections are all listed with corresponding references. We do include the corresponding uncertainties in our total uncertainty assessment of 0.5 mm/yr (PGR participates by 0.05mm/yr at 90% CL). However, we will make it clearer on the website (though not in this label) that the PGR correction is applied and how to remove it.

Best wishes for the new year

Aviso User Services

Note: As you can see (above), Aviso told me, “We do include the corresponding uncertainties in our total uncertainty assessment of 0.5 mm/yr (PGR participates by 0.05mm/yr at 90% CL).”

But to the best of my knowledge Prof. Peltier and his colleagues have not published uncertainty estimates for their 0.3 mm/yr ocean basin GIA estimate, nor for any of their other GIA / PGR figures. Tamisiea, 2011 gives a much broader range: 0.15 to 0.5 mm/year.

I wonder whether Aviso just assumed they could approximate Peltier’s uncertainty by using half of his last (only!) significant digit?

November 12, 2019 11:08 am

The year-on-year margin of error for total snowfall in Antarctica exceeds the yearly ice loss everywhere else non-arctic.

Robert B
November 12, 2019 11:50 am

“About as close to unity as nature can get.”

Maybe nature but did you see the 95% confidence intervals? Stinks of the trend being the result of method rather than coming from the data.

Reply to  David Middleton
November 13, 2019 9:07 am

The graph shows +/- 2 standard deviations of the dataset, the standard error in the current value is about 4% (95+/-4 mm).

Robert B
Reply to  David Middleton
November 13, 2019 3:28 pm

Its not the error of absolute sea level but change in sea level. There is something amiss.

November 12, 2019 3:06 pm

From what I have read it takes up to 800 years for the cold water at the
Poles to sinks and finally remerges as a up welling in the far future.

The likes of the UN’s IPCC and its Green followers are saying that if we
start to use less fossil fuel it will “”Save the Planet”” , but they are about 800
years too late.

Anyway while not being prepared to do anything about the likes of India and
China plus South East Asia, using the feeble excuse that these poor Third
World Countries must be allowed to catch up to the Western style countries
is utter nonsense.

If indeed its the death of all life on this Planet that the Greens are carrying
on about, it has to apply to the whole Worlds countries, not just the once
rich Western style countries.

This whole Green thing is clearly just a big and so far very successful
smokescreen, to cloak the long term agenda of a Socialist come
Communist type World Government, run by them of course.


Patrick MJD
November 12, 2019 5:13 pm

“Nauels and his colleagues used a simple mathematical model calibrated against the results published in the most recent IPCC report.”

A simple mathematical model? Pffft…

And the reports at that link are 5 years old or more…hardly recent.

November 12, 2019 5:20 pm

Not that “CO2 sticks around for hundreds of years” nonsense again.

Mike McHenry
November 13, 2019 7:02 am

Sea level rise is remarkably linear. This contrasts with virtual all other climate data. It’s as though sea level is buffered.

Reply to  Mike McHenry
November 13, 2019 10:56 am

Mike McHenry

“Sea level rise is remarkably linear. ”

No it isn’t. Even the PMSL evaluation with the least trend of all – Dangendorf & al. – reports about an acceleration since the Sixties.


You see from their data that the linear estimate doesn’t fit at all.

The paper:

old white guy
November 13, 2019 1:44 pm

I wonder where the water is going to come from.

Roger Knights
November 13, 2019 11:24 pm

Regarding “Figure 1. Global last 7,000 years, error bars omitted (Brock et al., 2008)”: It shows global sea level much higher (by 5 meters) 900 years ago and 2800 years ago. Isn’t that an indication of GLOBAL warming at those points in time (and hence disprove the Hockey Stick)?

November 14, 2019 9:07 am

Having made some contributions above I would like to pull my thoughts together.
You pointed out the 2 figures from Jevrejeva et al’s paper of 2014. Turning to the second one I decided to analyse the Brest Tidal Readings (1807 to 2018) in the same way as my analyse of the Full Tidal Data (1880 to 2013). I have created a comparison plot showing the quadratic best fit and a sinusoidal fit based on a 1000-year period. They appear in the links below although one has been presented already.
Full data:-
The Brest acceleration using a quadratic fit is 0.0128mm/year2 compared with 0.0126mm/year2 for full data
The sinusoidal amplitude is 450mm compared with 415mm
And the phase shift is 1400 years compared with 1420 years
These differences are negligible but the main point in the Brest results is that the results prior to 1850 do not show a rapid change as in Jevrejeva 2014 but follow a gradual change reaching a minimum in about 1850. Reading Jevrejeva 2014 it seems that the pre 1850 trend is based on only a couple of areas, namely the Baltic and the Neatlantic, as his reference to Jevrejeva 2006 revels. The Baltic readings are the set that dominate this pre 1850 trend and I would have thought that the Baltic would not be the most representative sea to use.
Referring to the first of Jevrejeva’s figures you showed he indicates over the period 1930 to 2010 three linear phases with slopes of 3.0681, 1.1536 and 3.1547 mm/year respectively. I have extracted from my paper an annotated fig 9
which shows a more curved behaviour. Over the period 1930 to 2010 the min and max slopes (velocities) are 2.261, 1,284 and 2.982 mm/year. The added sinusoidal term was a 6mm amplitude, 57-year period eye balled in and could have easily be judged as a =/-8mm/year curve which improve comparisons. Refence to Chambers et al 2012 could easily accommodate a combined average amplitude of 8mm. Nature, I think, works in a smoother manner than a series of linear portions although having said that the linear values help in judging trends.
A question I would like to ask is how long does sea level rises lag behind temperature fluctuations?
Finally, one observation that is not commonly stated has a bearing on the satellite readings as analysed by Nerem et al. The figure below is taken from my paper and shows a quadratic fit to a sinusoidal curve. That curve was derived as a good fit to the residuals resulting from the differences between the satellite readings and a straight line. When applying a quadratic fit to a set of data derived from the sinusoidal curve an acceleration almost the same as that quoted by Nerem et al is obtained showing the high accelerations quoted are due to the method used and not inherent in the data.
And finally finally its been very stimulating, and keeping the grey matter going, to participate in these discussions. As a retired (26 years and counting) Chief Design Engineer in Civil Engineering it has reawaken the thrill of analysis.

November 14, 2019 12:43 pm

It is easy to get the tide times and tide charts for the city of Venice. The tide at Venice normally varies by 1 meter. On 12th November 2019 the spring high tide was meant to be 0.99 metres. The next spring high tide will be on 25th November 2019 and is meant to be 1.04 metres. It would be interesting to dig up the tide charts of 1966 when there was even higher flood level in Venice. In any case are both the maximum and minimum tide levels of 2019 about 15 cm higher than of 50 odd years ago, to correspond with 3 mm increase per year ? Wouldn’t you expect a 15 cm higher record this year= 2.09 ? The remarkable thing is that the record wasn’t broken even with generally higher sea level.

It looks like several factors could have contributed to the 1.87 m flood level this Nov 12th 2019, which is still lower than the 1.94 m flood level of 1966. I read an article in which the author claimed that dredging to deepen the main canal for huge cruise ships to dock at Venice has aided the floods. How would anyone go about testing that claim ? Does it sound plausible ? See article , “GOOD OR BAD? THE TRUTH ABOUT THE CRUISE SHIPS IN VENICE, ITALY” on veneziaautentica

The River Sile in the north and the River Brenta to the south have long been diverted to bypass the Venetian Lagoon but can the water coming out into the Adriatic back up and flow into the lagoon under high spring tide conditions with SE winds and low pressure centered above ? What about water coming directly into the lagoon from towns on the mainland shore north of Venice ? What about amount of rain falling directly into the lagoon ? Can anyone find if the wind over the Adriatic sea on the 12th November was wholly from the south. My spot checks seem to give conflicting results.

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