from CO2 Science: The authors write that “satellite altimetry measurements since 1993 have provided unique information about changes in global and regional mean sea levels,” suggesting a mean rate of rise of 3.2 mm/yr for global sea level over the period 1993-2012 (Boening et al., 2012; Cazenave et al., 2012), which “notably exceeds the estimate of 1.8 mm/yr sea level rise for the 20th century (Bindoff et al., 2007).”
So which rate is closest to the truth?
What was done
In a study designed to answer this question, Jevrejeva et al. (2014) say they “renew the global sea level [GSL] reconstruction by Jevrejeva et al. (2006), using monthly mean sea level data collected by the Permanent Service for Mean Sea Level (PSMSL) covering the observations from 1807 to 2010,” thereby improving the GSL reconstruction by increasing data coverage “by using many more stations, particularly in the polar regions, and recently processed historic data series from isolated island stations,” as well as by extending the end of the reconstruction from 2002 to 2009.
What was learned
Quoting the five researchers, “the new reconstruction suggests a linear trend of 1.9 ± 0.3 mm/yr [7.5 inches per century] during the 20th century” and “1.8 ± 0.5 mm/yr [7 inches per century] for the period 1970-2008.”
Global sea level reconstruction since 1807, blue shadow represents 5 and 95% confidence interval
What it means
Although some regions have recently experienced much greater rates of sea level rise, such as the Arctic (3.6 mm/yr) and Antarctic (4.1 mm/yr), with the mid-1980s even exhibiting a rate of 5.3 mm/yr (Holgate, 2007), this newest analysis of the most comprehensive data set available suggests that there has been no dramatic increase – or any increase, for that matter – in the mean rate of global sea level rise due to the historical increase in the atmosphere’s CO2 concentration.[Therefore, there is no evidence of any human influence on sea levels]
The paper:
Trends and acceleration in global and regional sea levels since 1807. Global and Planetary Change 113: 11-22. Jevrejeva, S., Moore, J.C., Grinsted, A., Matthews, A.P. and Spada, G. 2014.
We use 1277 tide gauge records since 1807 to provide an improved global sea level reconstruction and analyse the evolution of sea level trend and acceleration. In particular we use new data from the polar regions and remote islands to improve data coverage and extend the reconstruction to 2009. 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 new reconstruction suggests a linear trend of 1.9 ± 0.3 mm·yr− 1 during the 20th century, with 1.8 ± 0.5 mm·yr− 1 since 1970. Regional linear trends for 14 ocean basins since 1970 show the fastest sea level rise for the Antarctica (4.1 ± 0.8 mm·yr− 1) and Arctic (3.6 ± 0.3 mm·yr− 1). Choice of GIA correction is critical in the trends for the local and regional sea levels, introducing up to 8 mm·yr− 1 uncertainties for individual tide gauge records, up to 2 mm·yr− 1 for regional curves and up to 0.3–0.6 mm·yr− 1 in global sea level reconstruction. We calculate an acceleration of 0.02 ± 0.01 mm·yr− 2 in global sea level (1807–2009). In comparison the steric component of sea level shows an acceleration of 0.006 mm·yr− 2 and mass loss of glaciers accelerates at 0.003 mm·yr− 2 over 200 year long time series.
Full paper with figures is available here: http://www.sciencedirect.com/science/article/pii/S0921818113002750#f0015
Stark Dickflüssig says: May 20, 2014 at 6:45 pm
That is, unless the Earth itself is changing size.
…………….
In 2011 I emailed Xiaoiong Wu from JPL about this hypothesis and what had become known recently. The main exchange is below.
There are features beyond satellite measurement range, such as the precise size and shape of ocean floors, that are not yet known well enough to enter into the complete solution of the sea level rise equations. There are features like the East Pacific Bulge whose size is enough to change surface sea levels with little movement of its own, but I’m not sure that there are any estimates of how fast it is changing – if it is.
There are other known unknowns like the heat input from hydrothermal vents, again poorly characterised. In summary, so little is known abut the deeper 50% of the oceans and their floors that it is dangerous science to state very much at all about mechanisms affecting sea level change. That’s even without the unknown unknowns that can pop up when study gets more intensive.
However, Prof Lu’s response was about surface measurements. Sorry for the (condensed) length.
………………………
From: Wu, Xiaoping
Sent: Tuesday, September 27, 2011 10:16 AM
To: Geoff Sherrington
Subject: Re: Radius of the Earth
Hi, Dear Mr. Sherrington:
I know of nobody that has produced or performed an independent study like what we did. Previous attempts have been blurred by the presence of several geophysical processes that are known to exist, such as GIA and the fact that the geodetic network is not evenly or densely distributed.
On the question of G, you are right that we have not analyzed it. But several papers from Lunar laser ranging and Mars tracking data have clearly shown that G is a constant to the relative precision of 1X10^(-13)/year. This number is too small to be significant when compared with measurement precisions. So, G is really a constant. And these measurements are much less affected by any possible expansion of the solid Earth. Also, if you look at the scale difference between VLBI (very long baseline interferometry, which is not subject to the influence of the GM) and satellite laser ranging, there is no evidence of variability of G at the level of 0.16 mm/yr level.
I agree that the geological processes are very hard to quantify. That is why we approached the problem with a neutral point of view. But again, in the satellite analyses, GM has been considered constant. It is very hard to believe that the Earth’s mass is changing.
From: Geoff Sherrington
Date: Mon, 26 Sep 2011 16:41:17 -0700
To: Wu, Xiaoping
Subject: Re: Radius of the Earth
Dear Professor Wu,
Thank you for the paper and your reply. As noted, I have no firm position on whether the Earth is, or has been, expanding. However, I have had the experience of long personal discussions with the most advanced thinking available on the subject at the time, in the 1970- 1990s. (Prof Carey passed away in 2002).
(cuts)
The single question that I have is: Has anyone close to you performed a clean-sheet analysis of satellite positioning with a prime aim of looking for evidence? It is possible that your impressive refinement of orbital numbers has proceeded with no direct thought that G or g might be variable because you have not examined it as a prime possibility, but as an incidental effect. I doubt that this would happen at your level, but the circular logic problem can be devilish.
Geoff Sherrington.
From: Wu, Xiaoping
Sent: Tuesday, September 27, 2011 4:51 AM
To: Geoff Sherrington
Cc: Buis, Alan D.
Subject: Radius of the Earth
Dear Mr. Sherrington:
Thank you for your interest in our published research. For your information, I am attaching a pdf version of our paper. While I cannot speak for all JPL scientists, so far I have not heard any objections from them on this paper. But in science, it always takes time for people to scrutinize previous research and build consensus gradually.
We don’t have much assumptions in this particular paper on geology. However, most of the geodetic (satellite) data have been processed by several centers assuming the gravitational constant G is constant. That assumption is supported by overwhelming evidence from Mars tracking and lunar laser ranging. Currently, the estimated dG/dt is around 1X10^(-13) G per year. This number is smaller than the measurement uncertainties and not significantly different from 0.
As a scientist, I would not call our result in stone. It is the most recent confirmation that the solid Earth is not expanding beyond our measurement accuracy using a rather comprehensive method.
…………….
GEOPHYSICAL RESEARCH LETTERS, VOL. 38, L13304, doi:10.1029/2011GL047450, 2011
Accuracy of the International Terrestrial Reference Frame origin and Earth expansion
X. Wu,1 X. Collilieux,2 Z. Altamimi,2 B. L. A. Vermeersen,3 R. S. Gross,1 and I. Fukumori1
Sorry, typo, should be Xiaoping not Xiaoiong.
NASA’s web site still presents a Climategate worthy deletion of tide gauge data in the ehole satellite era:
http://postimg.org/image/uszt3eei5/
I’ve read the paper. They don’t find there is no acceleration; as said in the abstract
” We calculate an acceleration of 0.02 ± 0.01 mm·yr- 2 in global sea level (1807–2009).”
Furthermore
“3.1 ± 0.6 mm·yr- 1 from tide gauge based reconstruction for the overlapping time period (1993–2009)”
What they do find is that acceleration varies over time. It was negative from about 1950 to 1975, and positive from about 1980 to 1995 (Fig 15). Since then it is patchy, but of course the periods available to fit a quadratic are smaller, with noisy results.
One can see from fig 3 why 1850 is such a convenient date to begin climate science, for the warmists.
oh, c’mon! Everyone knows that sea level rise is wildly out of control….. only cranks would deny it!
p.s. Did you know that the whole UNFCCC => IPCC process was launched, via activist scientists at WMO and UNEP workshops, claiming that SLR should now be somewhere between 5.5 cm and 24 cm per DECADE?? (closer to 24 cm based upon humanity’s rather tepid response to demands to slash emissions etc.).
yup, that is what they were fear mongering about when lobbying to create the IPCC:
http://judithcurry.com/2014/05/20/climate-scientists-joining-advocacy-groups/#comment-562577
Is this another example of the observations say this and the models say that, so the observations are wrong?
I am obviously speaking from the alarmist point of view.
oh, the report from which that figure with 1987 projections of SLR is linked here:
http://judithcurry.com/2014/05/20/climate-scientists-joining-advocacy-groups/#comment-562125
based upon humanity’s failure to do much under the instruction of our betters, we ought to be approaching the higher rate of 24 cm per decade of SLR anytime now….. that is what the IPCC was created to forestall !!
btw, speaking of activist scientists, Peter Gleick is listed as one of the 1987 workshop participants!
(Appendix I, p.44)
no wonder he goes nuts over this stuff, it really is his life’s work and he takes all dissent or opposition quite …. personally …. and seriously.
Steve Case says:
Try this link:
http://www.psmsl.org/train_and_info/geo_signals/gia/peltier/
I would not recommend using the Peltier GIA. The ICE-5G model is known to be grossly inaccurate, particularly in Antarctica.
“Regional linear trends for 14 ocean basins since 1970 show the fastest sea level rise for the Antarctica (4.1 ± 0.8 mm·yr− 1) and Arctic (3.6 ± 0.3 mm·yr− 1).”
And this by the way is pretty conclusive proof that there has been no major decrease in the amount of ice on Greenland or Antarctica. When an ice-cap is losing mass sea level will go down in the vicinity, both because land will be raising because of the decreased load of ice, and because the gravitational attraction of the ice-mass pulls up the sea-level around the icecap. The latter effect is surprisingly strong and means e. g. that even a complete melting of the Greenland ice-cap would have little effect on the relative sea-level in northern Europe.
“Nick Stokes says:
May 20, 2014 at 10:53 pm
I’ve read the paper. They don’t find there is no acceleration; as said in the abstract
” We calculate an acceleration of 0.02 ± 0.01 mm·yr- 2 in global sea level (1807–2009).”
As I understand this, on average sea levels have accelerated 0.02+/- 0.01mm year over 202 years or 4.04mm in total added to global sea levels. I for one is not losing any sleep over that. Bearing in mind the uncertainty over measurements even today this figure is probably no better than a guess. Like in all other measurements underpinning CAGW there is no dangerous acceleration to be found anywhere.
John Peter says: May 21, 2014 at 12:05 am
“As I understand this, on average sea levels have accelerated 0.02+/- 0.01mm year over 202 years or 4.04mm in total added to global sea levels.”
No, it is .02 mm/yr/yr, A rise of 4.0 mm/yr in the rate.
Nick Stokes says:
May 20, 2014 at 10:53 pm
I’ve read the paper. They don’t find there is no acceleration; as said in the abstract
” We calculate an acceleration of 0.02 ± 0.01 mm·yr- 2 in global sea level (1807–2009).”
—
Yes, but 1807 is not a very interesting date. There is no acceleration (by “eye-meter”) since 1860.
joshua says:
@Steve Case I noticed once that the rate seemed to increase between datasets, too. You can play with the URLs and go back at least 3 years, ex:
http://sealevel.colorado.edu/files/2014_rel3/sl_ns_global.txt
http://sealevel.colorado.edu/files/2011_rel1/sl_ns_global.txt
===
Good man! Any idea if we can access with/without inv. barometer frig as well?
daveburton says:
Here’s the full text of the paper: http://nora.nerc.ac.uk/504181/
Nice work Dave. I had a quick hunt and did not find it. I should have looked here first. WUWT is more use than Google!
Anthony, how about getting this link added to the article? http://nora.nerc.ac.uk/504181/
Nick Stokes says:
May 21, 2014 at 12:37 am
No, it is .02 mm/yr/yr, A rise of 4.0 mm/yr in the rate.
Nick, how can that match up with the paper’s figure of a current rate of rise of 1.9 mm/yr?
Almost uniform sea level rise since 1850 with recent slight deceleration – as RGB recently put it, “comes dangerously close to falsifying the whole CAGW hypothesis”.
They can’t claim accelerating ice loss and missing heat hiding in the sea with ZERO signal from sea level rise.
sibeen says: May 21, 2014 at 1:29 am
“Nick, how can that match up with the paper’s figure of a current rate of rise of 1.9 mm/yr?”
No the paper doesn’t say that. It says the rise 1993-2009 is 3.1 mm/yr.
They get acceleration by fitting a quadratic. There are examples in their Fig 16. The initial slope is negative, and the final slope exceeds 3.1 mm/yr.
Jevrejava is by no means a GW sceptic to read some of her comments, but I do think that she is a serious scientist. I have been waiting years for her to update here 2006 paper which had a data cut-off in 2002.
This is a very detailed paper and will take some time to digest.
One thing I do find rather questionable is the “acceleration” findings. Looking at their figure 16 where they fit quadratics to data from two other papers, it is clear that the data has some periodic content and that the quadratic is fitted over a peak-tough-peak section
this will give a positive “acceleration” that is probably not representative of what is really happening.
It’s just another version of the warming cosine fallacy:
http://climategrog.wordpress.com/?attachment_id=209
That is rather disappointing.
The regional breakdown is very interesting and requires more inspection. NE Pacific and NE Atlantic are nearly flat and NW or each ocean are amount the steepest gains.
Is this really steric components leading to sea levels of less dense water piling up on one side of each basin or a problem with the GAIA [sic] adjustments
Also lesser increase in southern Atlantic and Pacific. Large water mass , less warming?
Certainly plenty to chew on here. Looks like the most thorough and detailed study of sea levels to date. Though surely not with some faults, it looks very informative.
See fig 11 showing that some of the “acceleration” is due to GAIA adjustments. ( In theory glacial rebound can not be accelerating. This means there is a problem somewhere).
It’s flat before 1850, goes to an increase of about 0.5 mm/yr during 1850-2000.
That’s a fairly sharp acceleration around 1880. Seems fairly const rate of change since 1900. Perhaps someone ought to fit a quadratic to that too.
If I take the midpoint if each period 1825 and 1925 that’s 0.5mm/yr/century, or 0.005 mm/yr^2
Compare that to the figures they derive from fig 16 : 0.006 and 0.003 mm/yr^2
It should be remembered that GAIA adjusted sea rise may help calculations but are irrelevant to what matters to populations in coastal areas which most of the scare-mongering and wild claims are based on. No-one gets flooded out by an “corrected” sea level , it’s wet kind of sea level that matters.
” Fitting a second order polynomial to the GSL12 for the period
1880–2009 gives an acceleration of 0.001 mm·yr^2 , which is much
smaller than the 0.009 mm·yr−2 reported by Church and White”
“Using 10,000 Monte Carlo simulations we estimate a 5–95% confidence interval of 0.01–
0.04 mm·yr^2 for the 0.02 mm·yr^2 acceleration.”
I think that’s what is often referred to as not “statistically significant”. They don’t give any error estimation for the 1880-2009 “acceleration” of 0.001 mm·yr^2 but it is clearly it is not significant.
They seem to make a bit too much of this “finding” but at least they are thorough and above board. The data is presented with all the warts for anyone who wants to see how they got there.
Greg,
“In theory glacial rebound can not be accelerating. This means there is a problem somewher”
In theory it isn’t. The left side of Fig 10 shows that. The right side shows how that is affected by data gaps (I’m not sure why). I think Fig 11 reflects that.
To put this another way 0.001 mm·yr^2 = 10 mm/century/century
ie in 100 years time sea level (may be) rising 10 mm / century faster than it is now.
I don’t think even Bangladesh need to worry about the “acceleration”.
Indeed if we look at their figure 7 the tide gauge record shows NO change in sea level since about 2003. This seems to reflect the temperature “hiatus”. This is in contrast to the politically correct satellite record.