Guest Post by Willis Eschenbach
Various pundits and scientists keep talking about a threatened acceleration in the sea level rise. Here’s the IPCC Fourth Assessment Report:
Anthropogenic forcing is also expected to produce an accelerating rate of sea level rise (Woodworth et al., 2004).
The usual font of misinformation says:
Church and White (2006) report an acceleration of SLR since 1870. This is a revision since 2001, when the TAR stated that measurements have detected no significant acceleration in the recent rate of sea level rise.
Over at the inversely named “SkepticalScience” blog, which is inadequately skeptical, we find:
The blue line in the graph below clearly shows sea level as rising, while the upward curve suggests sea level is rising faster as time goes on. The upward curve agrees with global temperature trends and with the accelerating melting of ice in Greenland and other places.
The Guardian gets in their licks:
Sea levels are already on the rise as a result of increasing temperatures, because the oceans expand as they warm up, but until now scientists have had a poor understanding of how quickly ice sheets such as those in Greenland and Antarctica will begin to disappear.
Meanwhile, back in the world of reality we have the latest satellite data up to September of 2010:
Figure 1. Satellite-measured sea level rise. Errors shown are 95% confidence intervals. Data Source.
The smaller trend of the recent half of the record is statistically different from the larger trend of the first half. Will this reduction continue into the future? Who knows? I’m just talking about the past, and pointing out that we sure haven’t seen any sign of the threatened acceleration in the satellite record. Quite the opposite, in fact.
We now return you to your regularly scheduled warnings of global inundation from accelerating sea level rise …
w.
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Here are a few points about Church and White (2006)…
1. They unwisely fit the sea level rise of the previous century to a quadratic.
2. But they got the fit parameters wrong.
3. They updated their data in 2009 in a way that (amazingly) lowers any calculated acceleration.
onion says:
January 8, 2011 at 5:01 am
My analysis is “missing” the slower sea level rise before 1992???
It’s also missing the change in sea level during the last interglacial … but then it wasn’t about either of those subjects, was it?
It was about changes in the satellite sea level record and what they show. If you want to comment on the difference between the satellite records and the tide gauge records, fine. But don’t bust me just because my analysis doesn’t discuss what you think it should. You want it that way? Write your own analysis.
onion says:
January 8, 2011 at 5:10 am
I guess they might, but it will be a cold day in the place of eternal perdition before I send any traffic his way … I figured if they wanted to get there, even the slowest of the readers could figure out how to get there.
And hey, you proved me right!
w.
David says:
January 8, 2011 at 5:32 am
Haven’t a clue which graph that is, but if you go to the U Colorado site, their jpg of the data gives the same trend (3.0 ±0.4 mm/yr) as my graph shows.
w.
Stacey says:
January 8, 2011 at 6:21 am
And a good question it is. The data I used above is from the satellite sea level record. They measure the height of the ocean by radar from the satellites all over the planet and average it. That’s why it doesn’t change much over time, because it is a global average.
“hotrod ( Larry L ) says:
January 8, 2011 at 3:54 am
The gentle rising curve in the chart immediately suggests to me a segment of a sine wave plot just beginning to nose over toward its peak, with a period of perhaps 120 -150 years.”
When I read this, I checked page 21 of http://sciencespeak.com/MissingSignature.pdf
This graph seems to imply global temperatures follow a 60 year long sine wave. The graph in this sea level article just has the results from 1993 to 2011, however the slope is decreasing in both of these graphs for the period in question. Perhaps there will also be a 60 year cycle to sea level changes?
James Sexton says:
January 8, 2011 at 8:25 am
“Beautiful! hahahahahhaahhhahaha Thanks onion! Once again, the alarmist community is touting a graph that splices two distinct data sets into one graph.”
Try looking at it more closely, they are not spliced they are overlaid
“Onion, send John my thanks. At least he has an inset and a paragraph about it. Onion, those are apples and oranges. They don’t belong together.”
Apples and Oranges? Nope. Sea Level and Sea Level. If I measure my height one year with a tape measure and then measure it next year with a ruler I do believe it is acceptable to plot both points on the same graph.
“More, that very subtle (almost imperceptible) arc on the graph is probably indicative of the graphing technique employed.”
I can clearly see the rate of sea level rise is faster in the last few decades than it was in the earlier few decades. Ie accelerating.
Onion aka Khufy aka Bob aka Cthulu aka …
I’m wondering why you keep changing your handle around. Having an identity crisis?
Willis Eschenbach says:
January 8, 2011 at 11:21 am
onion: “I guess people might want to check the SkepticalScience article that the article quotes but does not link to:”
I guess they might, but it will be a cold day in the place of eternal perdition before I send any traffic his way ”
I guess not but another reason might be because the acceleration talked about at SkepticalScience is clearly on the multi-decadal scale (see the graph in the link) whereas you tried to pin their quote as talking about acceleration within the last 15 years of satellite record.
Grey Lensman says:
January 8, 2011 at 10:14 am
Grey Lensman of SF fame, you really should get out more. The ocean is in giant basins in which it “sloshes” back and forth, driven by wind, barometric pressure, currents, and tides.
These cycles are often long-term (years). At any instant, there often exists a foot or more of difference in height between various parts of the ocean. The idea that it is “gravitationally flat” simply has not stood up to the test of modern satellite measurement.
w.
Willis Eschenbach says:
January 8, 2011 at 11:21 am
onion says:
January 8, 2011 at 5:10 am
I guess people might want to check the SkepticalScience article that the article quotes but does not link to:
I guess they might, but it will be a cold day in the place of eternal perdition before I send any traffic his way …
======================================================
lol, Oops. Sry Willis, I just couldn’t help it. He put the tidal gauge stuff with the sat. data on a graph. He omitted key information. He made silly assertions with no documentation to back it up. He ignored information on a graph that he posted. In other words, it was typical alarmist drivel that I felt compelled to point out.
The ocean surface is also not “flat” (i.e. with a surface equidistant from the centre of earth’s mass) because of local variation in the Earth’s gravitational field at the surface, as any geophysicist will tell you – the ocean surface “height” varies by several centimetres as a result of the Earth’s gravitational field variation over its surface. As Willis points out also, there is ocean height variation generated by wind and and tides, with the latter resulting from the gravitational field variation at the earth’s surface caused principally by the moon’s orbit of Earth.
Willis Eschenbach says:
Stacey says:
January 8, 2011 at 6:21 am
My question is how, where and when do they measure the sea level.
The above graph as a range of +- 20mm I would have thought that the surfaces of the oceans are constantly changing.
Am I missing something?
And a good question it is. The data I used above is from the satellite sea level record. They measure the height of the ocean by radar from the satellites all over the planet and average it. That’s why it doesn’t change much over time, because it is a global average.
Don’t they use a sinking station in hong kong as a reference? Can anyone clarify this, that could mean that sea-level rise is overestimated?
latitude says:
January 8, 2011 at 7:20 am
mjk says:
January 8, 2011 at 4:17 am
Sea levels are headed in one direction: UP.
================================================
and there’s not one thing we can do about it…..
….does that make you wet your pants
Hopefully not adding to the sea level, too!
Enjoying reading as folks peel the layers off the “onion” here.
It might be interesting to note that the main reason we are even talking about this slow minor sea level change is because Warmists are blaming it on man – even though it started long before man did anything that the Warmists claim is causing whatever they are alarmed over. I have also noted that one of the main things that Warmists become alarmed over is when one applies logic to “un-fooled around with” data.
Can someone explain to me how this could be measured? we know some about plate movements, so what is the solid base from which we measure from? use a sattelite or tape measure you need a base, and I do not see how an object maybe in a geostationary orbit with all the gravitational pulls fro all the planets and star can get to .5mm?? a change of magnetism from the suns fluxes affect the diameter of the earth how? how about Constantinople sinking, the Egyptian city off the Israel coast, not to mention the river bed off the Fal estuary in Cornwall at 32 m deep. that I have seen for myself so the sea has risen. Recovered land after some time sinks as it dries out, I assume that would be sand and soil not bedrock, so after large fast sea level rises the earths crust must adjust, in what way? There are so many unknowns, and I am not a qualified scientist, that I doubt an educated guess could be made let alone a scientific prediction, the only equation that a sane man can glean from this is:-
predict sea level rise = more grant money.
JohnWho says:
January 8, 2011 at 12:26 pm
Well said Dr. Who. Why do people stop asking ” what caused this” as soon as they come to gullible warming? Are other causes possible? Will they fund me if I discover a different cause? Bingo.
Could you please post the entire chart, from 1850 so we may see is there is acceleration. The last 18 years shows about 2″ (50mm) rise, or slightly less than 3mm a year. What was the increase from 1850 to 1980? If it was less than 3mm a year then the rise is accelerating, if more then we are decelerating. Please post the big picture. Thanks.
The theory of gradual rising sea level may not consider earth’s dimensional and shape changes. Over eons of time the earth has shrunk. If that were occurring today the sea level would rise. Recently, several scientists had reported that the earth shrunk 5 mm is the last five years.
http://www.abc.net.au/science/news/stories/2007/1971663.htm
If the earth’s diameter decreased 5 mm could that explain a rise in sea level? The satellite or tide buoys would measure the depth changes of the water surfaces. However, a shrinking crust would cause the water level to increase. Has the data been corrected for earth shrinkage?
M Monce says:
January 8, 2011 at 8:29 am
I took some measurements off the above graph on the blue line. Transferred the data into excel, and got a poly fit. To make the arithmetic a bit easier, I called 1993, year 1, etc. The result is the sea level anomaly as a function of time (years)…..”
Thank you MMonce. Now you’re a person who understands acceleration! I was going to differentiate that curve as well ( I like to use a program called Origin) but you saved me the effort!
JohnWho says:
January 8, 2011 at 12:26 pm
Not peeled the layers off an onion since biology science classes! And if I remember correctly (it was 35yrs ago!), the skin/layers are basically a the same cell replicated many times – hmm, seems familiar….
But anyway – you know what they say about onion – best served finely chopped and with a hint of garlic!
>>Ric
>>Exactly where are these undercuts? Do you have photos? I assume
>>that’s a geologically active area, but I suspect the activity is mostly
>>strike-slip faulting (sideways) instead of thrust faulting (with a vertical
>>component). I hope I have that right.
The islands of Kos, Rhodos and at Antalya. The latter is best.
The location is not that geologically active (apart from earthquakes). The main faults around there are actually dip-slip faults out in the Med around Crete. The rocks at Antalya are sandy limestone that looks like old coral to me. These cliffs must be pretty stable, otherwise the large calcite curtains could not have formed upon them. They are fairly tough formations.
I tried to find out if land levels are supposed to be rising or falling in the region, but was unable to find any data. But there are no raised or submerged undercuts (snorkel diving to 7m or so), to indicate any land movement.
The rocks at Rhodes are alternate limestone/mudstone in distinct layers, which again are fairly tough. Again there are no raised or submerged undercuts that I could see.
.
Onion – thanks for your link to that website – have to say I didn’t spend long there but the first graph seemed to stop at 2005, so your point is?
Sam Hall says above:
“Chance for somebody with money to pick the property up cheap and hold it until the truth is out. A greenie would never do that, would they?”
Too late mate, Combet as the new Mnisister for CC is already on to the lurk.
He recently bought a sea front ppty in Newcastle NSW..right on the water
Obviously he doesnt believe all the crap being poured into his ears by his Department and Shonkademia …which on its own is a small relief
Cook uses the alarmists’ hoary trick of conflating GW, AGW and by inference CAGW (there’s little need to do anything about AGW unless it’s C), presumably to frighten the kiddies (nice work for an evangelical Christian).
http://www.skepticalscience.com/images/Sea-Level-1.gif
As already noted, the sea level has risen in concert with the emergence from the LIA.
Whatever influence human fossil fuel use has on the global mean temperature and therefore sea level, it was insignificant prior to 1945.
http://home.austarnet.com.au/yours/fossil%20fuel%20vs%20global%20temp.gif
It looks like a decelerating trend to me.
http://www.climate4you.com/images/UnivColorado%20MeanSeaLevelSince1992%20With37monthRunningAverage.gif
Willis Eschenbach says:
January 8, 2011 at 11:42 am
Nil Morner also describes salinity differences as affecting the sea level, that’s one of the things Argo measures.
Sea level anomaly is not an easy measurement, and that’s the main reason we argue about it.
Ralph says:
January 8, 2011 at 2:19 pm
>>Ric
>>Exactly where are these undercuts? Do you have photos? I assume
>>that’s a geologically active area, but I suspect the activity is mostly
>>strike-slip faulting (sideways) instead of thrust faulting (with a vertical
>>component). I hope I have that right.
> The islands of Kos, Rhodos and at Antalya. The latter is best.
Thanks. A brief search for photos yielded http://www.pictureninja.com/pages/turkey/image-antalya-coastline.htm which seems to show an impressive undercut in the cliff in the middle of the photo. (Note light reflecting off water beyond the shaded undercut area.)