Claims that sea level rise is 3.3 mm/year are looking increasingly like a grand hoax. David A. Burton runs the sea level rise resource site sealevel.info posts an analysis showing sea level rise is only half of what it is claimed to be.
Sea Level Rise Only Matters At The Coasts
By David A. Burton
Many may not be aware of this, but satellite altimeters are incapable of measuring sea-level at the coasts, among other significant problems.
Coastal tide gauges, on the other hand, measure sea-level at this important location – which is where it really matters. Tide gauge measurements of sea-level are far more reliable than satellite altimetry, and of much longer duration. The longest tide-gauge records of sea-level measurements are nearly ten times as long as the combined satellite measurement record, and twenty times as long as any single satellite measurement record.
No sign of any acceleration
NOAA has done linear regression analysis on sea-level measurements (relative sea-level) from 225 long term tide gauges around the world, which have data spanning at least 50 years. (Note: the literature indicates that at least 50-60 years of data are required to determine a robust long term sea-level trend from a tide gauge record.) There’s no sign of any acceleration (increase in rate) in most of those tide-gauge records.
More than 85% of stations show less rise than 3.3 mm/year
The rate of measured sea-level rise (SLR) varies from -17.59 mm/yr at Skagway, Alaska, to +9.39 mm/yr at Kushiro, Japan. 197 of 225 stations (87.6%) have recorded less than 3.3 mm/yr sea-level rise. At 47 of 225 stations (20.9%) sea level is falling, rather than rising. Just 28 of 225 stations (12.4%) have recorded more than 3.3 mm/yr sea-level rise.
The average SLR at those 225 gauges is +0.90 mm/yr. The median is +1.41 mm/yr.
That appears to be slightly less than the true global average, because a disproportionate number of those 225 stations are northern hemisphere stations affected by post glacial rebound (i.e., the land is rising faster). On the other hand quite a few long-term tide gauges which are substantially affected by subsidence (i.e., the land is sinking), often due to extraction of water, oil, or natural gas, or due to the location having been elevated with fill dirt which is compacting (Ex.: Galveston).
I downloaded the two sea-level measurement spreadsheet files (U.S. and global) from NOAA’s page, and combined them into a single Excel spreadsheet. For ease of sorting I changed the U.S. station ID numbers by adding an “A-” prefix. I also added “average” and “median” lines at the end of the spreadsheet.
The average of all 375 NOAA-analyzed stations is 1.28 mm/yr, and the median is 1.71 mm/yr:
NOAA says that the average is 1.7-1.8 mm/yr. Some of the difference between the calculated average and NOAA’s figure for MSL rise may be due to the addition of model-derived GIA adjustments to the measured rates when calculating the average to account for post glacial rebound (PGR). My guess is that they’re using Prof. Richard Peltier’s figures. Unfortunately, those figures are only very loosely correlated with what is actually happening at the tide-gauge locations.
Prof. Peltier also estimates that melt-water load from the melting of the great ice sheets (~10k years ago) is causing the ocean floors to sink by enough to cause a 0.3 mm/yr fall in sea-level, absent other factors. That number (0.3 mm/yr) is usually added to calculated “global average” sea-level rise rates, inflating the reported average, even though the resulting sum is not truly sea-level, and is not useful for projecting sea-level for coastal planning. It’s an attempt to calculate what the rate of sea-level rise would be were it not for the hypothesized sinking of the ocean floor.
50-60 years of data needed to establish trend
Unfortunately, many of the tide station records in NOAA’s expanded list of 375 are too short to be appropriate for measuring sea-level trends. The literature indicates that at least 50-60 years of data are needed to establish a robust sea-level trend from a tide station record. But the shortest record in NOAA’s list is Apra Harbor, Guam, with just 21 years of data. The text at the top of NOAA’s page says, “Trends with the widest confidence intervals are based on only 30-40 years of data.” But that is incorrect. I suspect they wrote it before they added the gauges with very short records.
So I also made a version of this spreadsheet in which stations with records shorter than 50 years are omitted.
Considering only tide stations with records of at least 50 years, the average and median rates of MSL rise (of the 225 remaining stations) are 0.90 mm/yr and 1.41 mm/yr, respectively:
I also tried limiting it to stations with records of at least 60 years, with very similar results: average 0.77 mm/yr, and median 1.37 mm/yr.
The average (0.90 mm/yr) is probably unrealistically low, due to the disproportionate number of stations in northern Europe which see low or negative rates of measured sea-level rise due to post glacial rebound. The fact that the average is less than the median also suggests that there are a disproportionate number of low-end outliers.
I also tried another approach, in which I excluded the most extreme latitudes. I started with just the “50+ year” stations, and included only stations within a latitude range of 45 (i.e., I excluded stations above 45 north or below 45 south). The resulting average and median for 137 stations were 2.22 mm/y and 2.02 mm/yr, respectively:
That approach largely solves the problem of low-side bias introduced by stations which are affected by PGR (which lowers the calculated average), but it doesn’t solve the problem of high-side bias introduced by stations affected by subsidence (which raises the calculated average). So the average (2.22 mm/yr) is probably unrealistically high. The fact that the average is greater than the median also suggests that there are a disproportionate number of high-end outliers.
So I tried another approach, this time explicitly eliminating “outliers.” I started with just the “50+ year” stations, but excluded the 40 stations with the lowest rate of sea-level rise (including most of those experiencing falling sea-level), and the 30 stations with the highest rate of sea-level rise (including most of those experiencing severe land subsidence, like Galveston, which is built on sinking fill dirt).
The resulting average and median rates of sea-level rise (calculated from 155 stations) are both 1.48 mm/yr:
That figure, 1.48 mm/yr, is the current best estimate of globally averaged coastal sea-level rise. At first glance excluding more low outliers than high outliers might seem to bias the result to the high end. But I think it is justifiable because of the disproportionate number of northern European and North American stations at locations where the land is rising due to post glacial rebound. The fact that the median and average are equal suggests that there aren’t disproportionate numbers of either high or low outliers.
I also tried excluding the low and high 35 stations, and the result was an average MSL rise of 1.36 mm/yr, and median 1.41 mm/yr, which suggests that it includes more low outliers than high outliers.
Note that 1.48 mm/yr is less than six inches per century. Also if you add Peltier’s +0.3 mm/yr GIA to that calculated 1.48 mm/yr global average rate of MSL rise, the sum is within NOAA’s 1.7-1.8 mm/yr range.
It is not possible to torture the tide-gauge data into yielding a globally averaged rate of relative sea-level rise anywhere near 3.3 mm/yr.”
David A. Burton has a BS in Systems Science from Michigan State University, and an MA in Computer Sciences from the University of Texas at Austin.
He is a Board Member of NC-20, and one of the organization’s Science Advisors. In 2011 he wrote a comprehensive critique of the Coastal Resource Commission’s 2010 North Carolina Sea-Level Rise Assessment Report, identifying numerous serious errors in that document. He was also a member of the NC Sea Level Rise Impact Study Advisory Committee, a member of the NC Portal Project Review Committee, a U.N. IPCC AR5 WG1 Expert Reviewer, and is webmaster of the sealevel.info website.
38 responses to “Sea Level Analyst: “Not Possible To Torture Coastal Tide-Gauge Data Into Yielding A Sea-Level Rise Anywhere Near 3.3 mm/yr”!”
Calculating the rise net of GIA and possible ocean basin sinking is important for many purposes, of course.
But for the most important purpose — protecting coastal cities — isn’t the unadjusted rate of rise the key number? Guessing, GIA and ocean basin sinking have been constant during the past 50-100 years — and are likely to remain constant during the usual planning horizon of 50 years.
So we’re concerned with the past rate of change, and its 2nd derivative (acceleration). This means that the unadjusted gauge reading can be used without adjustment. As you have done here.
Am I missing something?
I agree, Editor of the Fabius Maximus website.
BTW, the short duration of the satellite altimetry record is not the sole reason, nor even the most important reason, that coastal tide gauge measurements are much more trustworthy than sea-level measurements made by satellite altimetry. Physicist Willie Soon explains the problems very well, starting at 17:37 in this very informative hour-long lecture.
Mr Editor 😉
You would need very long records to be able to extract any significant change in acceleration from the data.
All the long term gauges I’ve looked at appear to be as close to linear as you can get within the noise, with no sign of any obvious change in rate.
David’s the one with the data available (nice summary, well done sir 🙂 ), so I hope he backs up my eye-balled conclusion.
AndyG55 wrote, “All the long term gauges I’ve looked at appear to be as close to linear as you can get within the noise, with no sign of any obvious change in rate.”
I agree, Andy, for the great majority of tide gauges. However, there are some tide gauges which showed slight apparent acceleration in sea-level rise in the late 1800s or early 1900s. In each case it is ambiguous whether it was a true change in trend or a mere random fluctuation. But there are enough such gauges that averages of long-term gauges tend to show a very slight acceleration, which ceased by about 1925.
E.g., Wismar, Germany and Swinoujscie, Poland seem to have recorded a slight apparent up-tick in rate of SLR around 1860:
At Aberdeen, England, there appears to have been a slight up-tick around 1890:
At Philadelphia, PA there appears to have been a slight uptick around 1910:
At Fernandina Beach, Florida and Seattle, Washington there might have been a slight uptick around 1920:
Note that since the great majority of anthropogenic increases in CO2 happened since the 1940s, we can clearly say that anthropogenic CO2 hasn’t detectably affected the rate of sea-level rise.
Only one tide gauge record in the world resembles Jim Hansen’s predictions:
Oops! Scotland, sorry!
I am not in the habit of nitpicking, but there is a minor problem with your wording I would like to clarify.
The first derivative of change with respect to time is rate of change, and the second derivative of change with time (or first derivative of rate of change) is acceleration.
The first derivative of sea level w/r/t time is rate of change (e.g., 1.48 mm/yr). The 2nd derivative of level = the first derivative of rate of change = acceleration.
“Many may not be aware of this, but satellite altimeters are incapable of measuring sea-level at the coasts, among other significant problems.
Coastal tide gauges, on the other hand, measure sea-level at this important location ”
That is an interesting starting point for this debate. Are readers here aware, that satellites are unable to accurately measure surface temperature?
And that we have much longer time series for surface temperature than for satellite temperature?
But in the sea level data you prefer the tide gauges, while on temperature of course only satellite data matters.
Now apart from that, you need to look NOT at averages, but at some area weighted average like we do with temperature data.
and we also can counter check with satellite data and with calculations based on heat expansion and land ice loss.
Gees sob.. everyone knows the surface temperatures are concocted and massively tortured to give a warming trend, as well as being heavily affected by UHI, etc
There is mounds of evidence that this it the case..
They are totally UNRELIABLE.
They haven’t done that yet to the tide gauges.
They can’t find reasons to lower the sea level of the past like they have with the massive cooling of the past in the temperature fabrications.
Instead they have found ways to “adjust” the satellite altimetry to give a sea rate rise that is larger than reality.
And please, don’t even suggest that NOAA start tampering with sea level gauges using area weight etc.. a further invitation to fraud.
“And please, don’t even suggest that NOAA start tampering with sea level gauges using area weight”
You simply can not measure global sea level without using an area weight on the data. Any result without it will be pure nonsense!
Your post shows a major misunde3rstanding: there is no such thing as “not doing an area weight” on such data.
If you do not make such an adjustment, you also do an area weight. But it is purely random, as you give more weight to the area that has more tide gauges.
The same is true for temperature data. If you do not adjust for time of observation bias, you will also get an adjusted temperature result: the random adjustment of the time of observation changes.
by the way, why are you attacking me and not Dave? he seems to be in favour of “adjustments” for sinking/raising land. How dare he do that?!?
I understand precisely..
You want them to MANIPULATE the data to suit the agenda.
TOBS is farce…. yet another “adjustment” of raw data wide open to fabrication. !!
SG has shown using real data that it is a minimal adjustment at most, yet it is the MAIN thing that is used to CREATE a warming trend in the GISS data..
UHI on the other hand is totally ignored, because a proper adjustment for that would mean LOWERING the current urban temperatures.
Its a SCAM .. and people like you are continuing to try , against all reason, to support it..
How much do YOU make from the scam each year , s.o.b. ???
“And please, don’t even suggest that NOAA start tampering with sea level gauges using area weight etc.. a further invitation to fraud.”
…and they’ll do it vengefully and hatefully.
sod wondered why, “in the sea level data you prefer the tide gauges, while on temperature of course only satellite data matters” ?
I’m glad you asked, sod.
With sea-level, gravity works to continually balance water levels across the oceans (well, water mass, actually), so we can expect that long term trends at all tide-stations will be very similar, if adjusted for land movement. In the short term, many factors, like ocean currents, wind, air pressure, etc. can cause local differences in sea-level, but they are temporary. Over the long term, gravity brings water levels back into gravitational equilibrium. It matters little where you add meltwater to the oceans: the long term effect on sea-level is the same everywhere.
That’s the most important reason that tide gauges are a very good way to measure sea-level trends. If the global rate of sea-level rise should substantially accelerate, perhaps because of an acceleration in the melting of the Greenland ice sheet, it will be evident in the tide gauge records everywhere.
Additionally, individual tide gauge measurements are simple, reliable, precise, and immune to accidental distortions due to erroneous “adjustments.” The timing of the daily highs and lows is well understood and perfectly predictable, so even extremely simple instrumentation, from long ago, produced very reliable measurements.
Sea-level measurements from tide gauges are the highest quality climate data in existence, by far.
Unfortunately, surface temperature measurements are a whole different kettle of fish.
Most fundamentally, there’s no reason to expect that a change in temperature trend at one location will be mirrored in other locations. Gravity does not work to balance temperatures.
Consequently, the only way to detect a long term global (or even regional) trend change without using satellite data is by measuring at a LOT of surface locations, and combining the data. You really need good quality, continuous, long-term temperature measurement coverage of the entire globe.
But we simply don’t have that. Not from thermometers at the surface, anyhow. Not even close!
To begin with, only a small percentage of the Earth’s land surface has good thermometer coverage, and even in those countries with the best coverage there are terrible quality control problems with the data.
Unlike sea-level measurements, for temperature measurements there are a very large number of factors which can distort the data records. Although Six’s Registering Thermometers have been around a long time, because the timing of highs and lows is unpredictable, changes in reading schedules can introduce biases in the older data, as can many other factors. Changes in instrumentation, changes in the surrounding landscape (e.g., mowing, tree growth, paving, etc.), and even changes in the paint on the Stevenson Screens can cause major systematic measurement distortions.
Plus, consider the effect of moving a measurement station. Tide gauges are referenced via surveying techniques to stable geological reference points called “benchmarks.” So even if a tide gauge is moved, or destroyed in a storm and then replaced, the data from the new and old instruments are precisely comparable.
That’s not the case for temperature gauges. There’s no comparable process to ensure effective continuity of data from different gauges.
In the oceans, the situation is even worse. MUCH worse. Air temperature measurements at stationary points over the surface of the ocean for the most part simply do not exist. So water temperatures are commonly substituted, but they are often very different from air temperatures, and even water temperatures are poorly and sparsely sampled, by varying methods.
What’s more, temperature gauges come and go. Whole countries full of gauges come and go with shifts in political and economic conditions, so “global” temperature indexes are necessarily derived from varying collections of gauges.
When surface temperature measurements are combined to produce “global” temperature indices, there are innumerable opportunities for biases to be incorporated, either accidentally or intentionally. Temperature “corrections,” variations in station selection, weighting and “gridding” methodologies, “homogenization,” etc., all can greatly effect the result.
The surface temperature data sucks. The only temperature data with good coverage is from satellites.
I once attempted to find out what adjustments accounted for the large retrospective changes in U.S. surface station “average” warming reported by NOAA & GISS. The answer is that it is mysterious. Strangely, nobody seems to know. At least, Prof. Scott Mandia of the “Climate Science Rapid Response Team” doesn’t know and was unable to find out.
The bottom line is that tide gauge measurements of sea-level are of very high quality, and very trustworthy, and vastly superior to the satellite measurements.
W/r/t temperature measurements, the situation is approximately reversed.
Thanks for the long reply. I appreciate that you took the time.
I am rather unconvinced though (you might not be surprised by that).
To answer your question on surface temperature first, Zeke wrote a good article about the US on the Curry page.
The biggest change seems to be time of observation, but that also seems to be the reply that you got in your e-mail exchange or is it not?
You mention a lot of arguments that support your position on tide gauges being better than thermometers measurements, but you simply leave out all the arguments that go the other way. For a start, we have soi much more thermometers than gauges.
I also do not understand, why sea surface temperature is a bad proxy for surface air temperature over the sea, while satellite measurement kilometers above the sea is a good proxy for air over the sea.
“I also do not understand”
We know that !!
read up on lapse rate etc..
Learn something, if you can !!!
Sea level satellite altimetry works like a radar. Sending out a signal, measuring the time til it returns. You wanna tell me you can measure fractions of a millimeter with that? With a wavelength of 20 cm, and a satellite whose height constantly varies, and a changing gravitational field? Yeah well, another wall pretend scientists can bang their head on for a century, sure, maybe they enjoy being funded for that but I’d rather trust a material tide gauge.
Microwave measurement via satellite is trivial. You measure how much comes in. THen you perform a tomography algorithm. If you don’t trust tomography, you are anti science and you probably also don’t believe in modern medicine.
And yes, tomography is a word and has a wikipedia entry.
The ferocious winds over the Southern Ocean are a massive big deal. Don’t underestimate them. Gravity isn’t going to average that effect out.
…and tide gauge stations are of course missing exactly where they’re needed…
Paul, wind and ocean currents can certainly pile up water in one place, at the expense of someplace else. But, unless there’s a substantial CHANGE in those winds or currents, they won’t cause a long-term DIFFERENCE in local sea-level trend.
At Panama, the Pacific averages 8-9 inches higher than the Atlantic, due to the effects of persistent wind and water currents. (From hour-to-hour, as tides slosh the water around, the difference can be much greater.) But the long-term sea-level trends there are largely unaffected by those currents, so the long term sea-level trends on both sides of the Canal are the same.
Here’s the trend at the Pacific entrance of the Canal:
Here’s the trend at the Atlantic entrance of the Canal:
As you can see, the short term fluctuations at the two gauges are quite different, but the long term trends are nearly identical.
Note that “long term,” in this context, means at least 50-60 years. That’s what the literature indicates is needed to robustly measure the sea-level trend from a tide gauge record, because of long term multidecadal cycles like the AMO.
Fortunately, we have hundreds of tide gauge records which are at least that long. Many of them two or three times that long.
There are long term trends in windyness. Read, over centuries. Find the records of the East India corporation.
I’m not talking about trends Dave.
I’m talking about absolute sea level.
Not sea level anomaly.
Not sea level trend.
Not sea level acceleration.
But rather sea level — Absolute sea level.
Fixed-point sampling is aliasing from a spatiotemporal field coupled to air-sea interaction more generally (wind, evaporation, transport, precipitation) that oscillates nonuniformly.
All of the major oscillations (interannual, decadal, multidecadal, centennial) have spatiotemporal wind, evaporation, transport, & precipitation components.
It’s all coupled together as one bundle.
What I suspect is not widely- and well-understood in the online climate discussion community is that these factors account for persistent 2 meter sea surface height (SSH) heterogeneities:
Note especially the Southern Ocean and remember that Antarctica has been ringed by ferocious winds (the driver of the Antarctic Circumpolar Current) ever since Drake Passage opened up.
Bill Illis has done an excellent job eradicating dark ignorance of that key event with simple enlightenment:
It’s refreshing when such a key point can be made so concisely (a single powerfully informative image).
The ferocious winds are driven by the steep equator-pole gradient over the obstacle-free ocean ring.
web & image search term to try:
The image search alone will point to enough material to keep an industrious hunter busy all day.
Remember Joe Fletcher (rare wisdom from NOAA)?
Remember what he put in plain, simple, common sense terms?
He advised us of a key factor:
the size of the warm pool
Joe was on the bull’s eye.
His powerfully simple tip was easy to verify:
What’s labeled “SAM” in the latter image is really a proxy for one of the key components affecting the size of the warm pool.
On semantics alone there’s an extremely high risk of misinterpretation.
Some reinterpretation and relabeling of terms may be warranted.
Misunderstandings stem from failure to differentiate between high frequency (interannual) and low frequency (multi-decadal-to-centennial) components, which are oriented on orthogonal spatial axes.
There are 2 other components.
One is the familiar multidecadal term.
The place to look for the multidecadal term in wind fields is where winds blow from the Sahara out over the part of the Atlantic with spectacular surface heat, salinity, and evaporation (a spot which is unique in the global context).
The multidecadal aberrations you’ll find there are coupled to solar cycle length and it’s derivatives — illustrations here:
That leaves one (more difficult to understand) component which I will not spend time addressing here today. (I recognize that nonstationary cyclic volatility observations that can’t be done with oldschool fourier methods are pushing the community deep into discomfort territory ….maybe people need time to adapt to changing perspective at a pace they can tolerate.)
The pump action in the north has different geometry than in the south.
Note especially a stability of summer-winter southern pattern that does not exist in the north:
From an image search for
here are a few more examples with different color schemes (which affect perception):
“The only temperature data with good coverage is from satellites.”
Satellites don’t even measure temperatures.
And they must correct for satellite orbital decays, solar storms, and instrumental drift. Not easy….
Which is why they are verified countless times and locations by weather balloon direct measurements from the most accurate thermometers. They are also immune to an incorrect UHI wag and a host of other surface data problems.
From Jevrejeva et al 2014:
– There is a good agreement between the rate of sea level rise (3.2 ± 0.4 mm·yr− 1) calculated from satellite altimetry and the rate of 3.1 ± 0.6 mm·yr− 1 from tide gauge based reconstruction for the overlapping time period (1993–2009)
The plot with their data digitalized:
So, yes, you can get the same sea level rise with gauges, without torturing the data. If you accept they didn’t torture the data (I don’t think so). But only if you use data from 1993 in both cases.
From 1880 they find a very minor acceleration in sea level rise:
But the same data from 1900 gives a decleleration of about the same amount (they don’t say it).
The search for acceleration is most important.
NOAA provides a help for some stations.
“Variation of 50-Year Mean Sea Level Trends”
And for a 50 year mean, their analysis can bee made up until 1990 today.
Is it not possible to do some calculations to indicate acceleration or not from today and backwards?
There is a very good reason that satellite measures of sea level do not match tide gauges. Satellites are measuring mid-ocean sea level and specifically exclude shore line sea level.
Dave: Did you calculate the average rate of SLR at each tide gauge over the full length of each record? You report an average start year of about 1920. If so, your rate is not the rate since satellite altimetry began and can not be compared with the satellit rate. You need to use tide gauge data from only the satellite altimetry era – which being a shorter period has greater uncertainty,
You are assuming no acceleration. Statistical evidence for acceleration is weak, but absence of strong evidence is not proof that no acceleration exists.
Frank asked, “Did you calculate the average rate of SLR at each tide gauge over the full length of each record?”
NOAA did that calculation. (Simple linear regression.)
Frank also wrote, “You are assuming no acceleration. Statistical evidence for acceleration is weak, but absence of strong evidence is not proof that no acceleration exists.”
I wasn’t writing about assumptions, I wrote about measurements. What I wrote was, “There’s no sign of any acceleration (increase in rate) in most of those tide-gauge records.” Which is right.
There’s been no detectable acceleration (increase) in the rate of sea level rise in response to the large post-WWII increase in CO2 levels. Many climate activists are predicting that the rate of sea-level rise will increase by a factor of ten or more over the next 70 years, because of anthropogenic increases in CO2 levels. But that’s irrational.
The rate of sea-level rise hasn’t increased at all over the last 70+ years, despite very large anthropogenic increases in CO2 levels. If the last 100 ppmv increase in CO2 levels caused no detectable acceleration in sea-level rise, then what is the likelihood that the next 100 or 200 ppmv increase in CO2 levels will cause an enormous acceleration in sea-level rise?
Zilch. There’s no chance of it. We’ve already done the experiment.
It is not impossible that sea-level rise could accelerate slightly. But it is irrational to expect a huge acceleration in sea-level rise due to CO2 emissions, when we’ve already done the experiment, and we know that it’s caused no detectable acceleration at all.
The vast majority of human GHG emissions have been since the 1940s. Since then, we’ve driven up CO2 from about 300 ppm to 400 ppm – yet the rate of sea-level rise hasn’t increased at all. In fact, the best studies show a slight decrease in the rate of coastal sea-level rise.
The lack of acceleration in rate of sea-level rise is despite the fact that two factors unrelated to climate change should have been expected to cause some acceleration in sea-level rise over the last 50 years:
1. The rate of groundwater aquifer pumping & depletion has increased; much of that water ultimately ends up in the oceans.
2. The mid-20th century dam-building boom (think Aswan!) has ended. (Dams retain water in reservoirs which otherwise would end up in the oceans, and more dams retain more water.)
The fact that, despite those two factors, there’s been no measurable increase in the rate of sea-level rise suggests that the meltwater contribution to sea-level rise is decreasing, rather than increasing.
This fact is a huge problem for the models that IPCC alarmists (and the Pope!) rely on. Dr. Steven Koonin was undersecretary for science in the Energy Department during President Obama’s first term. After he left that position, he finally felt at liberty to tell the inconvenient truth. He said, “Even though the human influence on climate was much smaller in the past, the models do not account for the fact that the rate of global sea-level rise 70 years ago was as large as what we observe today.”
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One thing that I’ve been wanting to know… is there any data on the mean subsurface level of the bottoms of the oceans? I mean, if the level of an ocean floor raises, wouldn’t that cause the level of water against the coastline to rise also?
I ask this because I have been reading stories of how land elevations in California have been dropping due to over pumping of ground water. This got me to thinking about the mechanics of plate tectonics possibly having an effect on the height of the ocean bottoms. I hope you see my point.
Tom, I don’t think there’s anything resembling measured data for that. But it is thought that the ocean floors are, on average, sinking slightly, due to flip-side of post-glacial rebound.
When the great ice sheets melted circa 10K years ago, a LOT of water flowed from the land into the oceans. Much of the land which was deeply covered in ice sheets is still rebounding as the result of the weight of that ice having been removed. That’s why sea-level is falling at many northern locations, like this one:
The weight of that meltwater was added to the oceans, and is presumably causing the ocean floor to sink. Professor Richard Peltier has estimated the magnitude of the effect of that sinking to be the equivalent to about 0.3 mm/yr sea-level fall.
Climate alarmists often add that number (0.3 mm/yr) to calculated averages of sea-level rise rates, to inflate the supposed “global” rate of sea-level rise, even though the sum is not actually the rate of change of the level of the surface of the sea:
“2. The mid-20th century dam-building boom (think Aswan!) has ended. ”
Are you serious about this point?
This source has done the calculation for a km³ of water (less than 3 microns).
Aswan dam (132 km³) was filled over 6 years.
Have you done any kind of calculation on this subject that supports your “acceleration thesis”???