AR6 and Sea Level Rise, Part 1

By Andy May

This is the first of a three-part series on the IPCC’s discussion of sea level rise in their latest report, AR6 (IPCC, 2021). The report claims that the rate of sea level rise is accelerating. It is fair to ask why they think this, what evidence do they offer?

We find the following in the AR6 Summary for Policymakers:

“Global mean sea level increased by 0.20 [0.15 to 0.25] m between 1901 and 2018. The average rate of sea level rise was 1.3 [0.6 to 2.1] mm yr–1 between 1901 and 1971, increasing to 1.9 [0.8 to 2.9] mm yr–1 between 1971 and 2006, and further increasing to 3.7 [3.2 to 4.2] mm yr–1 between 2006 and 2018 (high confidence). Human influence was very likely the main driver of these increases since at least 1971.” [Bold added]

AR6 Summary for Policymakers, page SPM-6 (IPCC, 2021)

And the following in AR6, Chapter 9:

“Global mean sea level (GMSL) rose faster in the 20th century than in any prior century over the last three millennia (high confidence), with a 0.20 [0.15–0.25] m rise over the period 1901 to 2018 (high confidence). GMSL rise has accelerated since the late 1960s, with an average rate of 2.3 [1.6–3.1] mm yr-1 over the period 1971–2018 increasing to 3.7 [3.2–4.2] mm yr-1 over the period 2006–2018 (high confidence). New observation-based estimates published since SROCC [Special Report on the Ocean and Cryosphere in a Changing Climate, 2019] lead to an assessed sea level rise over the period 1901 to 2018 that is consistent with the sum of individual components. While ocean thermal expansion (38%) and mass loss from glaciers (41%) dominate the total change from 1901 to 2018, ice sheet mass loss has increased and accounts for about 35% of the sea level increase during the period 2006–2018 (high confidence).”

On page 9-8 (Chapter 9, page 8) of the AR6 report:

And, farther in Chapter 9:

“At the basin scale, sea levels rose fastest in the Western Pacific and slowest in the Eastern Pacific over the period 1993–2018 (medium confidence). …The anthropogenic signal in regional sea level change will emerge in most regions by 2100 (medium confidence).” [bold added]

AR6 Chapter 9, page 8.

It is a little distressing that in the Summary for Policy Makers (SPM) they conclude that human influence was “very likely” the main driver of the acceleration in sea level and in Chapter 9 they admit they do not expect to observe an anthropogenic signal in regional sea level change before 2100.

Global Mean Sea Level (GMSL) might have increased more in the 20th century than at any time in the past 3,000 years, but how would anyone know? There were no tide gauges or satellites 3,000 years ago. Neither tide gauges nor satellites are accurate at the millimeter level, and certainly historical records and geological proxies from three thousand years ago are not. The geological proxies of past sea level are explained by Willis Eschenbach here. Warning, if you have a sensitive stomach, don’t look at Willis’s plots!

Further, why should this mean anything? Glaciers advanced to their lowest Holocene elevations during the Little Ice Age from 1600 to 1850, swallowing entire villages in the process (Behringer, 2010, pp. 89-90). The Little Ice Age was the coldest period in the entire Holocene—roughly 11,700 years ago to the present day. As Little Ice Age glaciers melt, one would expect sea level to rise a little, but just how significant is this? More importantly can we be confident the rate of GMSL rise is accelerating?

We also find it strange that they conclude the rate of GMSL rise is increasing based on comparing linear least squares fits to selected portions of the sea level record. Figure 1 plots the entire NOAA GMSL record by quarter since April 1880. The x axis is the number of quarters (three-month periods), and mean sea level is given on the y axis through 2020. This record is built from the Church and White (Church & White, 2011) GMSL data to 2010 and University of Hawaii Fast Delivery data after that.

Figure 1. NOAA Mean Sea Level from 1880 to 2020 by quarter. Data collected by Philip Townsend. Most of this record was prepared by (Church & White, 2011). The record after 2010 is from the (University of Hawaii Sea Level Center, 2021). The period from 1971 to 2018, mentioned in the AR6 quotes above is shown in orange and a linear least squares fit to the period is displayed.

AR6 selects numerous specific intervals in the quotes above to justify their claim that the rate of sea level rise is accelerating. This claim is visually dubious since the data look a bit wavy, but linear. The period of apparent acceleration from 180 to 300 (1925-1952), looks suspiciously like 420 to 510 (1985-2007). The entire record, from April 1880 to the end of 2020 has a slope of 1.65 mm/year with an R2 of 0.97. We could cherry pick periods all day and not resolve anything significant regarding acceleration or the lack of it. The least squares statistics for the AR6 cherry-picked periods mentioned in the quotes above are given in Table 1 and compared to four I cherry-picked.

While AR6 claims acceleration is occurring with high confidence, the previous report states:

“The trend in GMSL observed since 1993, however, is not significantly larger than the estimate of 18-year trends in previous decades (e.g., 1920–1950).”

AR5: (IPCC, 2013, p. 290)

One wonders why AR6 has a different view only seven years later.

Table 1. Cherry-picked sea-level rise rates.

AR6 would have us believe that because a least squares linear fit to the rise in sea level is larger from 2006 to 2018 than from 1971 to 2018 it is accelerating. Yet from 2012 to 2020 the rate is nearly as low as from 1971 to 2018. The largest rate of rise in Table 1 is only 15 inches or 38 cm per century, hardly alarming when global tides, in the open ocean, average more than twice that; and coastal tides are often ten times that value daily. Climate changes on a temporal scale of centuries, as we can see comparing the Little Ice Age to the Medieval Warm Period, so an instrumental record from 1880 to 2020 is unlikely to capture the full range of sea level rates. Estimates of sea level rise gathered from historical and geological records show that sea level has risen much faster in the past, as shown in Figure 2 created by Robert Rohde.

Figure 2. A sea level change graph for the Holocene and the Last Glacial Maximum created by Robert Rohde. The rate of sea level rise was much higher than today from 14,000 years ago until about 7,000 years ago. The variations since 4,000 years ago are too small to measure.

Sea level is estimated using tide gauges mounted on coasts around the world. The very best of these gauges are only accurate to ±5 mm for a monthly average (NOAA, 2020). Satellite measurements of sea level are problematic unless meteorological conditions are perfect, and they are trying to measure the altitude of a moving surface. AR6 admits that satellite estimates of sea level rise “acceleration” are much smaller than the heavily massaged tide gauge records. This is discussed on page AR6 page 9-96, where we see that satellites find acceleration from 1993 to 2015 to 2006-2015 is from a rate of 3.16 mm/year to 3.58 mm/year, this is an acceleration of less than half a mm/year2 in roughly a decade. Other satellite estimates are similar. Satellite estimates of sea level are not accurate to one-half of a millimeter (Frederikse, et al., 2020).

Is the difference between an estimated global average rate of 3.8 mm/year and 1.8 mm/year statistically significant, considering the data used? Particularly when these measurements are made over a few decades? It seems unlikely, but let’s look at the data more closely.

The AR6 statements suggest that the rate of sea level rise is increasing due to human influence. This is presumably due to greenhouse gas (GHG) emissions causing surface warming, which then melts glaciers sitting on land. This raises two questions:

  1. Is the increase in the rate of sea level rise statistically significant?
  2. If so, could warming due to human GHG emissions have caused it?

From AR6:

“Heating of the climate system has caused global mean sea level rise through ice loss on land and thermal expansion from ocean warming. Thermal expansion explained 50% of sea level rise during 1971– 2018, while ice loss from glaciers contributed 22%, ice sheets 20%, and changes in land water storage 8%. The rate of ice sheet loss increased by a factor of four between 1992–1999 and 2010–2019. Together, ice sheet and glacier mass loss were the dominant contributors to global mean sea level rise during 2006-2018 (high confidence).”

AR6 page: SPM-14

Thus, ocean warming since the Little Ice Age, provides about half of sea level rise. Melting ice provides most of the rest.

From AR6:

“By 2100, GMSL is projected to rise by 0.28–0.55 m (likely range) under SSP1-1.9 and 0.63–1.02 m (likely range) under SSP5-8.5 relative to the 1995–2014 average (medium confidence). Under the higher CO2 emissions scenarios, there is deep uncertainty in sea level projections for 2100 and beyond associated with the ice-sheet responses to warming. In a low-likelihood, high-impact storyline and a high CO2 emissions scenario, ice-sheet processes characterized by deep uncertainty could drive GMSL rise up to about 5 m by 2150. Given the long-term commitment, uncertainty in the timing of reaching different GMSL rise levels is an important consideration for adaptation “

AR6 page TS-44

Some IPCC climate models predict up to 5 meters of sea level rise by 2150, when the current rate of sea level rise is less than 40 cm or 1.3 feet per century? Considering that the IPCC models have not predicted climate accurately after 30 years of trying (McKitrick & Christy, 2018), pardon my skepticism.

AR6:

“It is virtually certain that global mean sea level will continue to rise through 2100 …

Beyond 2100, GMSL will continue to rise for centuries due to continuing deep ocean heat uptake and mass loss of the Greenland and Antarctic Ice Sheets and will remain elevated for thousands of years (high confidence).”

AR6 Chapter 9, page 9-9.

The first statement is likely true, we are still warming as we come out of the Little Ice Age and I would doubt a change in direction of glacier retreat before 2100, the second statement is pure speculation, projecting beyond 2100 is reckless.

In summary, the AR6 statements about acceleration of sea level rise are based on simple cherry-picked and crude linear least squares fits to sea level data for the past 140 years. They also incorporate data and trends of ocean warming and land-based glacier melting. The problem is the rate of rise of sea level is so small today and so linear that their attempts to predict large rates of sea level rise are statistically inept and almost comical. In the next post we examine the complexity of measuring GMSL, and later in this series we will provide a more statistically significant projection of sea level rise that is much less than the wild predictions from AR6.

The bibliography can be downloaded here.

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Tom Halla
March 19, 2022 10:15 am

The long term line looks quite flat in trend. If they want to try to find a hockey stick there, it will take fancier math tricks than Mann’s.

geted
Reply to  Tom Halla
March 19, 2022 12:02 pm

The long term line looks quite flat in trend. If they want to try to find a hockey stick there, it will take fancier math tricks than Mann’s

2hotel9
Reply to  Tom Halla
March 19, 2022 1:16 pm

Tom? Who is this cut&paste troll, geted?

Latitude
Reply to  Tom Halla
March 20, 2022 8:51 am

every tide gauge shows the rate of sea level rise falling prior to 2010….
…they start their increase in the rate at 2010

you guys are not keeping your eyes on the ball….the question is….why are they not showing the rate decreasing prior to 2010

starting at 2010 is blatant cherry picking

Last edited 2 months ago by Latitude
Bindidon
Reply to  Latitude
March 20, 2022 4:01 pm

” every tide gauge shows the rate of sea level rise falling prior to 2010….
…they start their increase in the rate at 2010 ”

Where did you get THAT from, Latitude?

Here are the trends for 413 of over 1,500 tide gauges available in the data set of the Permanent Service for Mean Sea Level (PSMSL).

1) Trends over the lifetime

https://drive.google.com/file/d/1jIAhx1OifHrLF4Pf5YUqCwRenw26Ev3u/view

2) Trends over the period 1993-2018

https://drive.google.com/file/d/19dXIBq8Q7_ZtQm_V7tfcAPCmvEvHiY1P/view

Feel free to compare some station trends in the two files.

Average of the lifetime trends: 2 mm / year; of the trends for 1993-2018: 2.8 mm / year.

The difference is small, but… it exists and at many places, the trend is much higher than the average.

And here you see, for

  • the average of all the 413 stations
  • the average of the stations with at least 100 years activity
  • together with two other evaluations (Dangendorf, Foster)

how the global trend changes – from 1903-2015 till 1993-2015:

comment image

Last edited 2 months ago by Bindidon
Bindidon
Reply to  Latitude
March 20, 2022 4:08 pm

And here you see a double comparison

  • stations with at least 30 years of activity vs. with at least 100 years of activity
  • station data without / with correction for vertical land movement

comment image

Peter W
March 19, 2022 10:17 am

Looks like a typical bunch of IPCC fear-mongering garbage.

Greg61
Reply to  Andy May
March 19, 2022 10:40 am

More children have died in Ukraine the last few weeks, a war mainly the result of climate panickers policy, than all human deaths due to any human caused climate change since the big bang

2hotel9
Reply to  Greg61
March 19, 2022 1:18 pm

Yea! Stupid SUVs and barbeque grills causing the Universe to be created. Bastiches!

Rick C
Reply to  Andy May
March 19, 2022 3:02 pm

Andy: Always enjoy reading your posts. Recently the media has hyped the IPCC claim that we’ll have a foot of SLR by 2050. I did a simple calculation and it would take an acceleration of 8%/year to reach that level. That would double the rate of SLR in just 10 years. If that was happening the the rate should have doubled in the last 10 years. From 2.5 to 5 mm/y. That would be obvious in the tide gauge or satellite record if it were true.

I think the reason the climate hysterics are so adamant about hyping the mythical SLR acceleration is that drowning coastal cities is really the only serious consequence of predicted warming of 1.5 – 3 C that can’t be viewed as beneficial by most people who understand that they are more comfortable and safer in a warmer world. If the world could vote on either “warmer” or “colder” future weather, warmer would win in a landslide.

paul courtney
Reply to  Rick C
March 20, 2022 5:35 am

Mr. C: With Mr. Zuckerberg’s help and wide open mail in ballots, the dems in US could produce a win for “cold”, but they’d need a week for the extra counting.

Mark BLR
Reply to  Andy May
March 21, 2022 6:03 am

I’m one of the few who has read the bulk of each of the IPCC scientific reports (FAR through AR6) …

I too have mostly limited my reading to the WG1 reports.

AR6 is a wholly political volume; the science is gone.

A slight exaggeration there …

– – – – –

Section 1.5.4, “Modelling techniques, comparisons and performance assessments”, page 1-89 :
“Numerical models, however complex, cannot be a perfect representation of the real world.”

– – – – –

The final sentence of section 4.2.5, “Quantifying Various Sources of Uncertainty”, on page 4-20 :
“Still other uncertainties ⎼ such as further pandemics, nuclear holocaust, global natural disaster such as tsunami or asteroid impact, or fundamental technological change such as fusion ⎼ are not accounted for at all.”

– – – – –

Chapter 7 is titled “The Earth’s energy budget, climate feedbacks, and climate sensitivity”, which is a good sign.

Section 7.1, “Introduction, conceptual framework, and advances since AR5”, page 7-11 :
“The top-of-atmosphere (TOA) energy budget determines the net amount of energy entering or leaving the climate system.

It also provides a fundamental test of climate models and their projections.

Section 7.5.2, “Estimates of ECS and TCR based on the instrumental record”, includes several references to “Lewis and Curry (2015)” and “Lewis and Curry (2018)” (from page 7-95 onwards).

– – – – –

From the discussion of “Tropical cyclones” (section 11.7.1, pages 11-88 to 11-97) …

Sub-section 11.7.1.4, “Detection and attribution, event attribution”, page 11-92 :
“The cause of the observed slowdown in TC translation speed is not yet clear.”

Sub-section 11.7.1.5, “Projections”, page 11-94 :
“There is not an established theory for the drivers of future changes in the frequency of TCs.”

– – – – –

PS : My personal favourite extract showing “lack of attention to detail” in AR6, however, is in the “Introduction” section of the Technical Summary (TS), on page TS-4 :
The list of acronyms used in the WGI Report is in Annex VIII.

There is no “Annex VIII” (that I can see on the IPCC website, at least) for the AR6 WG1 report.

Unless I missed it there is no “list of acronyms (/ abbreviations)” hidden away within any of the PDF files constituting either AR6 WG1 or WG2

Rud Istvan
March 19, 2022 10:22 am

As posted here before, both Church and White and NASA satellites are suspect.

The Church and white methodology uses a large selection of tide gauges assuming vertical land motion cancels out. It demonstrably doesn’t.

The NASA data purports to be less than 1mm precision, when the tech spec for Jason 3 and now Sentinal-6 say a few centimeters. See post Jason 3 fit for purpose? And two on Sentinal-6 for details.

there are about 65 long record (>60 years) tide gauges close to a diffGPS to correct for vertical land motion. They say about 2.2mm/year and no acceleration. And, they all agree to within a mm by continent plus Japan, so not an artifact of ocean currents. Moreover, 2.2mm/year closes exactly with the sum of satellite estimated ice sheet loss and ARGO estimated thermosteric rise. Details in guest post ‘SLR, acceleration, and closure’. This number also proves the land motion deficiency in Church and White methodology.

Fred Hubler
March 19, 2022 10:29 am

They do mention that sea level rise includes a rise in sea level due to thermal expansion, but then they cherry pick the period ending in 2018 which includes a recent strong El Nino. They also leave out the glacial isostatic adjustment added each year since about 2010.

Rob_Dawg
March 19, 2022 10:41 am

14,000 years for the last 100 meters. At current maximum calculated rates 39,000 years for the next 100 meters. Some acceleration. (Check my math.)

Albert H Brand
March 19, 2022 10:44 am

There was a nice article a little while ago about Antarctica creating cold brine and injecting that into the southern ocean where it enters the bottom circulation stream which takes 800 years to complete. So I guess we could project a colder ocean sometime in the future. Since the Antarctic has been cooling for the past 60 years it will take a little time to show up.

Rud Istvan
Reply to  Albert H Brand
March 19, 2022 12:05 pm

The thermohaline circulation is generated by sea ice formation both in the Arctic and Antarctic winters. It is indeed a circulation cycle of about 800 years. But the downwelling high salinity water (sea ice formation exudes most salt making the local ocean briny, so heavy, so sinks) mostly stops below 700 meters where the salinity remains remarkably constant. The downwelling is offset by upwelling, for example off western South America. This causes the thermosteric rise over time to be mostly in the upper 700 meters (about the deepest anywhere the thermocline ends).

James Schrumpf
Reply to  Albert H Brand
March 19, 2022 5:09 pm

According to NOAA’s GHCN-Monthly Adjusted numbers, there are six stations with 700 out of 720 good monthly records since 1962. They are:

Station AYM00089611 trend from 1962-2021 is .03 per decade
Station AYM00088963 trend from 1962-2021 is .24 per decade
Station AYM00089642 trend from 1962-2021 is -.08 per decade
Station AYM00089592 trend from 1962-2021 is .03 per decade
Station AYM00088968 trend from 1962-2021 is .14 per decade
Station AYM00089564 trend from 1962-2021 is .02 per decade

Only one of those shows cooling over 60 years.

13 stations in Antarctica with at least 350 good monthly mean values between 1992 and 2021.

Here are the trends I got for those stations in 1992-2021:

Station AYM00089611 trend from 1992-2021 is .09 per decade
Station AYM00088963 trend from 1992-2021 is .16 per decade
Station AYM00089002 trend from 1992-2021 is -.12 per decade
Station AYM00089055 trend from 1992-2021 is .11 per decade
Station AYM00089532 trend from 1992-2021 is .02 per decade
Station AYM00089642 trend from 1992-2021 is -.04 per decade
Station AYM00089022 trend from 1992-2021 is .23 per decade
Station AYM00089571 trend from 1992-2021 is .2 per decade
Station AYM00089592 trend from 1992-2021 is .15 per decade
Station AYM00088968 trend from 1992-2021 is .03 per decade
Station AYM00089050 trend from 1992-2021 is -.06 per decade
Station AYM00089564 trend from 1992-2021 is .26 per decade
Station AYM00089864 trend from 1992-2021 is .47 per decade

Three of those show cooling. Not a whole lot, but not a lot of warming, either. Probably mostly within the error bounds.

Matt Kiro
March 19, 2022 10:54 am

While I am certain that the oceans have warmed over the past 140 years, we do not have enough coverage know to get an accurate reading of the oceans temperature now and we certainly didn’t in 1880. So to try an make an accurate guess in millimeters about how it much affects global sea level rise would need wide error bars.

“The first statement is likely true, we are still warming as we come out of the Little Ice Age and I would doubt a change in direction of glacier retreat before 2100, the second statement is pure speculation, projecting beyond 2100 is reckless.”

We already have photographic evidence and written testimonials about glaciers retreating and advancing just in the past 140 years, so I would have no confidence in saying that glaciers can not change back to advancing again.

Joe Born(@jhborn)
March 19, 2022 11:07 am

As I explained, a lot of that sea-level-acceleration stuff compares apples to oranges.

Fig 4.png
Matt Kiro
Reply to  Joe Born
March 19, 2022 12:41 pm

Those 22yr trend lines sure make the 30s through 60s look like there was a good amount of global warming going on.

Joe Born(@jhborn)
Reply to  Matt Kiro
March 19, 2022 12:59 pm

They almost make you question how tight the connection between surface temperature and sea-level rise really is.

Peter W
Reply to  Matt Kiro
March 19, 2022 4:25 pm

Matt, you should see the record of the melting of the Alaskan Glacier Bay glacier as recorded by the ancient sea farers from 1750 to around 1900, before the invention of the airplane, the mass-production of the automobile, and with population levels significantly lower than today. Of course you have to have copies of the charts from back then, suppressed today because the information on them is “politically incorrect.”

Dave Fair
Reply to  Joe Born
March 19, 2022 2:21 pm

UN IPCC and U.S. National Assessment reports are political propaganda. I hope in the not-so-distant future individuals will use them as examples of governmental lies to manipulate the populace.

Clyde Spencer
March 19, 2022 11:15 am

The rate of sea level rise was much higher than today from 14,000 years ago until about 4,000 years ago.

Andy, I think that should really say “… until about 7,000 years ago.”

JCM
March 19, 2022 11:22 am

Greenhouse factor appears to be a constant 1/3 from a LW radiation perspective.

1 – (TOA / Surface). We have approximate data to show this empirically. The ratio of TOA and surface temperature remains unchanged.

Those who get lost in reducing the question to L↑ and L↓ will never understand the nature of climate change.

Any increase to temperature results in an increase to both upwelling and downwelling IR.

Surface temperature is a consequence of net solar input warming and the net sensible and latent heat flux away from surface.

In the case of ocean, surface temperature also relates to variable internal oceanic circulations which have yet to be adequately characterized.

The efficiency of heat flux away from the surface is a function of surface heat capacity, moisture availability, surface pressure or density, turbulence, and the availability of condensation and precipitation nuclei.

Change any of those, change climate. Average up all the climates, and you get some notion of ‘global climate change’. Eventually, any average change to climate is projected to poles on global circulation.

Greenhouse factor x Surface Temperature = Greenhouse Effect.

Any change to surface temperature will appear to result in a change to Greenhouse Effect when viewed from a LW perspective.

However, the effect of the atmosphere, or greenhouse Factor, remains unchanged. This, despite an apparent change to greenhouse Effect.

0.3 x Ta = GEa
0.3 x Tb = GEb

Thus, moving forward, to understand climate we must understand surface energy budget.

Surface energy budget is composed of a variety of microclimates ranging from land deserts to rainforests, to various ocean surfaces with dynamic heat delivery mechanisms. Variable radiation input, variable heat flux.

Some argue if you completely plug up the IR window, such as on a humid day, you get an additional 5 W m-2 LW budget.

What causes an increase to humidity? Certainly not CO2. Humidity is a function of available precipitation nuclei all else being equal. Reduce precipitation nuclei, increase humidity.

Over ocean, the primary precipitation nuclei is limitless hygroscopic salt aerosol. For frontal systems it is ice. Over the continents it is microbes or hygroscopic bacteria. Reduce continental biota, say forest cover, increase humidity over land. Now, 40% of the land has been cleared. The consequence is increasing high pressure domes over the continents.

The point being, a water vapour feedback is independent of CO2. This critically important point has been misunderstood. Considering the greenhouse Factor is constant, an increase in humidity over continents eventually rains out over ocean. .

The ongoing incredulous mischaracterization of climate and gross negligence of relevant factors has led to fallacious policy choices.

Last edited 2 months ago by JCM
mkelly
Reply to  JCM
March 19, 2022 12:48 pm

Could please explain your first sentence?

JCM
Reply to  mkelly
March 19, 2022 1:12 pm

OLR vs LW budget at the surface. The apparent greenhouse enhancement factor.

JCM
Reply to  mkelly
March 19, 2022 1:45 pm

The exact magnitude of the factor is debatable based on one’s conceptualization of surface flux. Radiatively, some argue about the emissivity putting the value anywhere between 0.3-0.4, and constant during the observational period i.e. no trend.

Arfur Bryant
March 19, 2022 11:37 am

“Thermal expansion explained 50% of sea level rise during 1971– 2018..”
Thermal expansion is effectively ZERO at the coastline. There is simply not enough depth if water to make thermal expansion significant. Throwing the term ‘Thermal Expansion’ into a report is just another example of the IPCC talking scientific nonsense!
A 1 degree C temperature of the water (not the atmosphere) will give at most a 1% increase in volume (vertical, not lateral) of the top 100-200 metres of the central ocean. Coastal water depth will be measured in feet or inches and a 1% increase of less than 100mm of water temperature is less than 1 mm. So far the measured sea water temperature increase is way less than 1 degrees C, so any coastal rise is negligible, as attested by PSMSL measurements.
The IPCC reports are pure advocacy with little or no basis in science

Ben Vorlich
Reply to  Arfur Bryant
March 19, 2022 12:52 pm

Like heating a large flat pan of water means that the water doesn’t rise up the side of the pan, assuming that the volume of the water increases more than the internal volume of the pan? Or have I misunderstood your point?

Arfur Bryant
Reply to  Ben Vorlich
March 20, 2022 1:48 am

Hi Ben. My point was that the amount of warming estimated by the IPCC leads to an insignificant sea level rise at the coasts. Yes, a flat pan (or even better, a wok) would show no rise at the edge of the pan for a few degrees increase in room temperature. Even a few degrees increase in water temperature would show no rise because evaporation would also increase. Try the experiment! 🙂

Peta of Newark
Reply to  Arfur Bryant
March 19, 2022 2:10 pm

Here’s a nice explanation of ocean temps..
https://rwu.pressbooks.pub/webboceanography/chapter/6-2-temperature/

What is says there is that below maybe 200 metres depth, the water temperature is immovable.

Thus, (thermally induced) sea-level rise can only come about because of the expansion of that top 200 metre layer

Here’s the calcukulator…
https://www.engineeringtoolbox.com/volumetric-temperature-expansion-d_315.html

Did I do right – I put in an initial volume of 200 (assume metres, picture a square column) and for every 1° Celsius temp rise it says a volume increase of 0.14 which would equate for that fixed area square vertical column a rise in level of 14 centimetres

So, working the NOAA graph backwards (where they say circa 125mm of sea rise is due to thermal expansion, I get that to mean they are claiming an ocean temp rise of 9° Celsius

<sucks teeth> Seems about right, their accuracy is uncanny
😀

Last edited 2 months ago by Peta of Newark
Arfur Bryant
Reply to  Peta of Newark
March 20, 2022 1:50 am

Precisely Peta! It just shows how much the IPCC is not interested in actual science.

Chris Hanley
Reply to  Arfur Bryant
March 19, 2022 3:19 pm

Ole Humlum at Climate4you -> Oceans -> Sea-level in general explains it thus:
‘… Temperature-driven expansion of a column of seawater will not affect the total mass of water within the column considered, and will therefore not affect the potential at the top of the water column. Temperature-driven ocean water expansion will therefore not in itself lead to lateral displacement of water, but only lift the ocean surface locally. Near the coast, where people are living, the depth of water approaches zero, so no temperature-driven expansion will take place here … for that reason [thermal-driven expansion] is not important for coastal regions …’.

Arfur Bryant
Reply to  Chris Hanley
March 20, 2022 1:52 am

Yes Chris, that’s where I first realised the lie about AGW = significant SLR.

MarkW
Reply to  Arfur Bryant
March 19, 2022 6:28 pm

It doesn’t matter where the water expands, it will rise everywhere. If I were to find comet with a couple billion gallons of water, and dump that water into the middle of the Pacific Ocean, the entire ocean would increase in depth. For the same reason, if any portion of the ocean’s water expands in size, it impacts the entire ocean.

Arfur Bryant
Reply to  MarkW
March 20, 2022 2:00 am

MarkW, your comet us an example of a totally different mechanism. The comet has ADDED water to the system, so yes, volume everywhere would expand. With thermal expansion there is NO water added. The existing water is just thinner. Hence the expansion is only vertical, not lateral (because the neighbouring water columns are also trying to expand but can’t laterally so they have to expand vertically). Hence the vertical expansion is purely dependent on the depth of water at that location, which is effectively zero at a shallow beach. Try filling a wok with water from the cold tap, then increasing room temperature and see how much room temp increase you need before water spills out of the wok.

Mark Broderick
March 19, 2022 11:45 am

Andy May, wee typo….

“This is discussed on page AR6 page 9-96, where we see that satellites find acceleration from…..”

This is confusing !

where we see that satellites find acceleration from 1993 to 2015 to 2006-2015 is from a rate of 3.16 mm/year to 3.58 mm/year” ?

Great post !

 

Last edited 2 months ago by Mark Broderick
Ron Long
March 19, 2022 11:47 am

Good first report, Andy, I’m waiting for the other two. I think us geologists think sea level is a reasonable indicator of what state, especially liquid or solid, H2O is trending into. However, us geologists also think in terms of “Dynamic Earth”, wherein the oceans are not fixed water containers, but rather quite dynamic. For instance, Continental Drift/Plate Tectonics modifies the basin volume, undersea volcanism also, then those pesky rain/river/erosion gremlins try to fill up the basin (at rates from 1 meter per year near river mouths to 0.1 cm per thousand years in the open ocean where only wind-blown material settles), then the seawater expands because heat of undersea volcanism heats it up, then (see Canary Island Volcano) a land-based volcano pours lava into the basin, then those human rascals blow up an island to test a hydrogen bomb, etc, etc. Here is a clue about where to buy a house: the east coast of the Americas is going down and the west side is going up (never mind the volcanos and earthquakes).

cerescokid
March 19, 2022 11:49 am

Andy

Thank you for this fine article, especially this “The anthropogenic signal in regional sea level change will emerge in most regions by 2100 (medium confidence)”

I read Chapter 9 more than once and missed that sentence each time. It’s a critical point and something that some authors have stated in their own papers.

There are so many uncertainties about the rates of rise and acceleration amounts that they should be embarrassed by stating anything with confidence.

I have ordered new reading glasses.

Johne Morton
March 19, 2022 11:52 am

“Thus, ocean warming since the Little Ice Age, provides about half of sea level rise. Melting ice provides most of the rest.”

And, given the response time lag from warming, how much of the present day melting of ice is simply in response to us coming out of the LIA 100+ years ago…and this is your “existential threat”…

DMacKenzie
March 19, 2022 12:02 pm

If Sea Level rise wasn’t “accelerating” because of global warming, it would just be “decelerating” also due to global warming, due to having melted most of the temperate zone mountain glaciers….this is not worth discussing with warmunists. The fact that SL is increasing only means that someday it will decrease again, as records show it did at the end of the Little Ice Age before the present surface warming started. In fact, this SL reversal is why 1860-ish is generally considered to be the end of the LIA along with community records in the Alps showing glacier advances stopped.

Graphs showing late LIA decrease recently published at WUWT by David Middleton here.
https://wattsupwiththat.com/2021/08/10/eemian-sea-level-adjusted-downwards/

Last edited 2 months ago by DMacKenzie
Steve Case
March 19, 2022 12:07 pm

A few days ago I got beat up for reporting that long term PSMSL tide gauges averaged out to 0.01 mm/yr² of acceleration over the last 100 years. Well I looked at the distribution of those 73 stations, and about 28% were less than that. So I have to agree that noise, numbers and statistics says that you really can’t say that just because the mode was 32% 0.01 mm/yr² that it was significant.

Usually acceleration is expressed as units of distance per units of time squared. There was only one instance of that in the above article:

“This is discussed on page AR6 page 9-96, where we see that satellites find acceleration from 1993 to 2015 to 2006-2015 is from a rate of 3.16 mm/year to 3.58 mm/year, this is an acceleration of less than half a mm/year2 in roughly a decade.”

Maybe later I’ll look that their comparison of this and that linear rate from this and that time period to see what the good ol’ (v2-v1)/t=a formula I learned in high school says (-:

No mention of the Colorado Sea Level Research Group C-SLRG and their insane claim of 0.098 ± 0.025 mm/yr² acceleration of sea level rise since 1992. I mean, really? They couldn’t round it off to 0.1 mm/yr².

High Treason
March 19, 2022 12:44 pm

The bottom line in science is outcomes. REAL science makes accurate predictions. If this science is sound, an accurate prediction can be made. Pseudoscience sounds scientific, but it consistently fails with its predictions. The so-called “science” is deliberately confusing-lay people just give up-“whatever” and just accept “whatever” because those using the confusing language and terms “must know what they are talking about.”
Once people, knowing they are no experts in the field succumb to the “whatever” of just accepting the word of “experts” as gospel truth, the deception has been successful.
Almost everyone would be totally confused reading the actual report, so they will naturally gravitate directly to the summary for policymakers, especially politicians who would not have time to read the entire report anyway. “Whatever” is then blind acceptance of the politically motivated “conclusion” the summary tells them to believe and act upon. It trades on the perceived respectability of the report. This is the classic tactic of con men. They pump their own tyres to appear respectable, hiding their true intent (to deprive you of your money.) In the case of the parent body of the IPCC, it is deprive all of us of our money, access to reliable energy and ultimately deprive us of our freedom. They are not going to say this upfront, although admissions come out, which fly right over the heads of many. Example- Klaus Schwab , head of the WEF -“You will own nothing and you will be happy.” It is openly admitted, but this just flies over our heads.
Looks like the “conspiracy theorists” have some serious issues that must be investigated. If even ONE of the “conspiracy theories” turns out to be valid, then the “conspiracy theorists” cannot be just dismissed out of hand. Having said all that, there are some absurd conspiracy theories put out there that are clearly there to put “conspiracy theorists” in to disrepute. The classic one is flat earth theory, which is easy to disprove, but nutters (and perhaps saboteurs as well) come out with absurd excuses to cite as “evidence.” This then affects the credibility of all people who are on the scent of actual conspiracies.

2hotel9
March 19, 2022 1:22 pm

Well, since sea level is not rising catastrophically, or even perceptively, this is yet another pile of lies spewed by the usual lie spewing liars.

Last edited 2 months ago by 2hotel9
DMacKenzie
Reply to  2hotel9
March 19, 2022 1:50 pm

At my winter quarters on the beach, my “human perception” is that the average sea level rises and falls about a foot every couple of years. That’s because some winters the bottom concrete step from the sea wall to the beach is level with the sand and sometimes a foot above it. And the sand at that point is about 4 or 5 feet above high tide.
I don’t attribute the storms that cause this phenomenon to “climate change”. Anyway, my point is that 1 mm or 3 is irrelevant to most people….and having designed a few dikes and berms, a water level well above expected high-water has already been included in the engineering design of the sea wall, in the amount of a couple of hundred years worth. Expected storm surge is a much bigger factor….Tsunamis…oops…

Last edited 2 months ago by DMacKenzie
2hotel9
Reply to  DMacKenzie
March 19, 2022 3:01 pm

Ebb and flow. I saw a painting of some rocks in the Orleans area on Cape Cod, can see them today if you drive by on 28 and onto 6 going north, and got a picture of the same rocks a few years ago. Same amount of rock is above water now as in 1700. I am certain if you go out there and do some very scientific measurements you will find, drumroll, that the water has gone up and down, just as it has for millennia. 🤣 Nothing to get alarmed about at all.

Michael Elliott
Reply to  2hotel9
March 19, 2022 2:07 pm

If the peak of the Little Ice Age was about 1750, then we should expect a slow warming of the Earth to occur.

So allowing for at least a 800 year delay for a change in the seas temperature then we do not have a problem

There is a simple solution to all the talk of a climate problem.

Close down the UN’s IPCC. It’s just a part of the Greens objective to destroy Western cililation.

And while we are in the business of cleaning up messes, lets get rid of the so called United Nations too.

They are clearly anti Western civilation too.

Michael VK5ELL

Rud Istvan
March 19, 2022 2:02 pm

Andy, nice part one of three. Looking forward to the other two installments.

Your exposee of the contradictions between AR6 SPM and WH1 chapter nine is surprising to me, because SLR acceleration is one of easy IPCC basic flaws that skeptics look to.

Others include:
— Arctic summer sea ice gone by now
— Polar bears endangered
— Climate refugees
— Climate models getting better
All are easily verified as fundamentally failed predictions. Yet they double down each AR, making ridicule easier with each one.

DHR
March 19, 2022 2:18 pm

I just check The Battery sea level gauge in New York City from time to time. So far, it’s a straight non-accelerating increase and has been so since before Lincoln was President. And half of the reported rise is due to land sinking as shown by the nearby GPS elevation gauge. When it starts to accelerate, I will start believing sea level rise is accelerating.

TonyL
March 19, 2022 2:22 pm

Dead On Arrival.

“By 2100, GMSL is projected to rise by 0.28–0.55 m (likely range) under SSP1-1.9 and 0.63–1.02 m (likely range) under SSP5-8.5 relative to the 1995–2014 average (medium confidence).”

We look at the first claim, the smallest SLR given.
0.28 meters = 11.0 inches in 80 years = 13.8 inches / century.

This is *fully double* the generally accepted value of GMSLR of ~6. inches / century.
The number is a modeled result and is utterly unsupportable given the huge set of tide gauge data.

Dead, Dead, Dead.
It’s dead, Jim.
Dammit Jim, I am a Climate Scientist, not a Starfleet doctor.

Alex
March 19, 2022 2:27 pm

The graph is clearly accelerating.
Sorry for that

TonyL
Reply to  Alex
March 19, 2022 3:11 pm

Yes, but is the sea level?
That is the question, is it not?

angech
Reply to  Andy May
March 19, 2022 4:35 pm

”While ocean thermal expansion (38%) and mass loss from glaciers (41%) dominate the total change from 1901 to 2018, ice sheet mass loss has increased and accounts for about 35% of the sea level increase during the period 2006–2018 (high confidence).”

If 35% is ice sheet mass loss and 5% other, then from 2006-2018
ocean thermal expansion must have slowed down to 30% and ditto mass loss from glaciers.
Seems wrong at a time of increased warming?

leitmotif
March 19, 2022 6:03 pm

Andy, why do you discuss such BS? A report produced by the totally corrupt UN?

CODE RED?

GHE, ECS. SLR?

There is no evidence for any for them. In fact, I would put this in the realm of unicorns and angels dancing on the head of a pin.

Is this your main stream of income?

WUWT deserves better.

paul courtney
Reply to  leitmotif
March 20, 2022 9:51 am

Mr. motif: Ever heard the expression, “know thine enemy”? WUWT continues to expose the lies of those who have set themselves against us, and I am grateful, please give me another.

Dave(@daveandrews723)
March 19, 2022 6:16 pm

We were warned that the Maldives were on the verge of going under water. I just read they’re building five new airports to handle the booming tourism trade. Must be a lot of scuba divers heading there.

H. D. Hoese
March 19, 2022 6:32 pm

I have been watching sea level since before 1960 in places with tides from less than 1 to over 2 meters from Virginia to Texas, serious study and concern often in that period. There are places where relative sea level seems a little different since, but Fig. 1 is a screwy presentation. Why is it measured to two ‘significant’ decimal places? I know that’s about math excuses, but it is neither precision nor accuracy no matter what they claim about R squared. On coasts I have frequented freshwater, wind and barometric pressure mess with sea level a whole lot more than that. And of course soft and hard rock and sediment intersections with water do also move, some places more. There is now as long predicted considerable evidence that in the small tide Gulf of Mexico inundation amounts are rather critical,where critters can swim and play in much more than millimeter fractions involved.

This is still the best I ever read about sea level. “It seems to me to be evident that the position of a shoreline at any time and place is determined by an exceedingly complicated equation….” Shaler, Evidences as to change of sea level, 1895. Bulletin Geological Society of America. 6:141-166.

Jim Gorman
Reply to  H. D. Hoese
March 20, 2022 9:19 am

A lot of stuff going on to “measure” sea level rises due to temperature. Is any of this been verified against historical documents and historical sites? It would seem paintings, written records of seaport changes, and photographs should provide a very stable base to judge much of the math against.

If land is rising and “hiding” sea level rise, so what? Is it going to sink again without actual glaciers sitting on top of it? Where will the glaciers come from?

If some shore line is sinking causing sea level rise, so what? Has it been proven that man’s use of water pumping hasn’t caused it?

It seems like there is such a rush to blame temperature that good science is thrown in the trash can.

Pablo D
March 19, 2022 10:06 pm

How is the y axis scale set for all of these climate charts? If you want to scare people, you stretch it. If you don’t, just flatten it.

stinkerp
March 20, 2022 12:28 am

It is a little distressing that in the Summary for Policy Makers (SPM) they conclude that human influence was “very likely” the main driver of the acceleration in sea level and in Chapter 9 they admit they do not expect to observe an anthropogenic signal in regional sea level change before 2100.

Did you expect the SPM to have any scientific basis? It is a political document, written specifically for politicians. Its purpose is to promote global warming alarmist theology and give cover to politicians who can say that “the IPCC says” or “scientists agree” that it’s worse than we thought, even though the statements made in the SPM are often contradicted by the science chapters of the same report.

Never take the SPM seriously. Mock it incessantly for its numerous factual errors that conflict with what the actual science chapters say.

Geoff
March 20, 2022 3:21 am

The average rate of sea level rise was 1.3 [0.6 to 2.1] mm yr–1 between 1901 and 1971, increasing to 1.9 [0.8 to 2.9] mm yr–1 between 1971 and 2006, and further increasing to 3.7 [3.2 to 4.2] mm yr–1 between 2006 and 2018 (high confidence)

Another claim of watchmaker accuracy from a bricklayer measurement. The Jason -2 satellite is a marvellous machine but the Poseiden radar altimeters cannot make millimeter scale measurements because they were simply not designed to do so.

A 3 millimeter range resolution would require a bandwidth of at least 50 Ghz, yet the Ku band carrier frequency is just 13.5 Ghz. Even a 3 centimeter resolution would need a 5 Ghz bandwidth, which is feasible, but would never be licensed as it would blot our most satellite communications and broadcasting with every pass. It is difficult to see how such a short pulse could be engineered with enough power to obtain a detectable echo. Even if this were possible, it would be to no avail as the backscatter equation is includes a significant wave height term. A further consideration is that centimeter scale resolution implies the satellite’s position in space is known to a similar level of accuracy.

The Posiden-3 altimeter is allocated a bandwidth of 320 Mhz, centred on a 13.65 Ku band carrier, giving a best range resolution for perfectly flat water and ideal conditions of 0.47 metres. A typical 2 metre significant wave height reduces the resolution to just under a metre. 

This is the very best theoretical altimeter range accuracy that can be achieved. All the rest is averaging, lots of averaging and as we know, whilst averaging may increase precision, it never improves accuracy. 

Jim Gorman
Reply to  Geoff
March 20, 2022 9:25 am

I had obtained somewhat the same conclusion from examining the orbital height variation. Part of the precision obtained is from “averaging” height measurements over time. Think of averaging temperatures over time to get an “average” temp out to 1/1000th uncertainty.

If I remember correctly, the satellite people recognize that orbits can change in the 10 meter range due to several things happening. Think about that. Individual measurements that can vary by 10 meters, but by averaging, they can obtain millimeter precision?

paul courtney
March 20, 2022 5:47 am

I wonder if, at these IPCC events, they ban putting ice in the beverages for fear of flood by “cocktail level rise”?

bigoilbob
March 20, 2022 9:40 am

Any chance of directly linking to your quarterly values, per C&W and U of H? I have no reason to doubt them, and I am sure you thought they were available from your (good) biblio. But I’ve spent some time hunting, via biblio and from searching, unsuccessfully. I am sure that they are available, and that the problem is in my drill down, but would appreciate the help.

Thx in advance….

bigoilbob
Reply to  bigoilbob
March 21, 2022 11:39 am

Forgot. Also quantitative estimates of confidence intervals, by quarter, if any. As in, not “real, real, big”. Presumably, the data is evaluable. You did.

Macha
March 20, 2022 4:52 pm

Here in Australia the land is supposedly pretty flat and stable, so should be a good sea level gauge ( expansion) just by looking at tidelines.
https://kenskingdom.wordpress.com/2021/08/23/the-worlds-biggest-thermometer/

Nothing to see here, move on.

Bindidon
Reply to  Macha
March 21, 2022 4:22 am

Here are the trends for 376 of over 1,500 tide gauges available in the data set of the

Permanent Service for Mean Sea Level (PSMSL).

1) Trends over the lifetime
https://drive.google.com/file/d/1jIAhx1OifHrLF4Pf5YUqCwRenw26Ev3u/view

2) Trends over the period 1993-2018
https://drive.google.com/file/d/19dXIBq8Q7_ZtQm_V7tfcAPCmvEvHiY1P/view

I’m sure you will find some Australian gauges in the lists; maybe you compare the values displayed in (1) and (2), for example

196 1914 2020 107 SYDNEY,_FORT_DENISON_2_________________ -33.85 151.23 1.50

with

196 1914 2020 107 SYDNEY,_FORT_DENISON_2_________________ -33.85 151.23 26.50

The values in the last column are in mm / decade.

Pretty flat and stable, maybe!

But you certainly will have e.g. around Sydney a lot of subsidence, otherwise the lines below (without correction for vertical land movement) would look exactly like the lines above

196 1914 2020 107 SYDNEY,_FORT_DENISON_2_____________ -33.85 151.23 10.70

196 1914 2020 107 SYDNEY,_FORT_DENISON_2_____________ -33.85 151.23 35.70

As you can see, not every correction for vertical land movement leads to a higher sea level rate.

Bindidon
March 21, 2022 4:01 am

No acceleration in sea level rise, Andy May?

Hmmmh.

comment image

And here are, for the Dangendorf data represented above, the five year distant consecutive trends, from 1903-2015 till 1993-2015

comment image

Source

https://static-content.springer.com/esm/art%3A10.1038%2Fs41558-019-0531-8/MediaObjects/41558_2019_531_MOESM2_ESM.txt

What about you trying to scientifically and technically contradict them?

I never saw at WUWT any plausible evaluation of tide gauges, together with winds and ocean currents.

Bindidon
Reply to  Bindidon
March 21, 2022 4:03 am
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