Why ice loss and sea level measurements via satellite and the new Shepherd et al paper are highly uncertain at the moment

There’s a paper (Shepherd et al) on ice loss and sea level rise that has been making the rounds in media (such as this article in Science Recorder, claiming it validates global warming) that is causing some stir, mainly because it has a powerfully written press release combined with a volume of researchers (47 scientists), plus additional never before used together satellite data, because more data and more scientists is always better, right?

Here’s the press release where they claim to have “clear evidence”. A deconstruction follows using NASA JPL’s own internal program documents showing that the “certainty” claimed in Shepherd et al really falls apart for lack of a stable reference for the data.


From the University of Leeds

Clearest evidence yet of polar ice losses

International satellite experts release definitive record of ice sheet changes

An international team of satellite experts has produced the most accurate assessment of ice losses from Antarctica and Greenland to date, ending 20-years of uncertainty.

In a landmark study, published on 30 November in the journal Science, the researchers show that melting of the Antarctic and Greenland ice sheets has contributed 11.1 millimetres to global sea levels since 1992. This amounts to one fifth of all sea level rise over the survey period.

About two thirds of the ice loss was from Greenland, and the remainder was from Antarctica.

Although the ice sheet losses fall within the range reported by the IPCC in 2007, the spread of the IPCC estimate was so broad that it was not clear whether

Antarctica was growing or shrinking. The new estimates are a vast improvement (more than twice as accurate) thanks to the inclusion of more satellite data, and confirm that both Antarctica and Greenland are losing ice.

The study also shows that the combined rate of ice sheet melting has increased over time and, altogether, Greenland and Antarctica are now losing more than three times as much ice (equivalent to 0.95 mm of sea level rise per year) as they were in the 1990s (equivalent to 0.27 mm of sea level rise per year). The Ice Sheet Mass Balance Inter-comparison Exercise (IMBIE) is a collaboration between 47 researchers from 26 laboratories, and was supported by the European Space Agency (ESA) and the National Aeronautics and Space Administration (NASA).

Led by Professor Andrew Shepherd at the University of Leeds and Dr Erik Ivins at NASA’s Jet Propulsion Laboratory, the study combines observations from 10 different satellite missions to develop the first consistent measurement of polar ice sheet changes.

The researchers were able to reconcile the differences between dozens of earlier ice sheet studies through careful use of matching time periods and survey areas, and by combining measurements collected by different types of satellites.

Professor Shepherd, who coordinated the study, said: “The success of this venture is due to the cooperation of the international scientific community, and due to the provision of precise satellite sensors by our space agencies. Without these efforts, we would not be in a position to tell people with confidence how the

Earth’s ice sheets have changed, and to end the uncertainty that has existed for many years.” The study also found differences in the pace of change at each pole.

Dr Ivins, who also coordinated the project, said: “The rate of ice loss from Greenland has increased almost five-fold since the mid-1990s. In contrast, while the regional changes in Antarctic ice over time are sometimes quite striking, the overall balance has remained fairly constant – at least within the certainty of the satellite measurements we have to hand.”

Commenting on the findings, Professor Richard Alley, a climate scientist at Penn State University who was not involved in the study, said: “This project is a spectacular achievement. The data will support essential testing of predictive models, and will lead to a better understanding of how sea-level change may depend on the human decisions that influence global temperatures.”


‘A reconciled estimate of ice sheet mass balance’ by Prof Shepherd et al is published in Science on 30 November 2012, DOI: 10.1126/science.1228102.


All well and good, and it looks like a home run for Professor Andrew Shepherd at the University of Leeds and Dr Erik Ivins at NASA’s Jet Propulsion Laboratory and the team of 45 others if you just read the press release. But, let’s look a bit deeper, the paper abstract reads:

A Reconciled Estimate of Ice-Sheet Mass Balance


We combined an ensemble of satellite altimetry, interferometry, and gravimetry data sets using common geographical regions, time intervals, and models of surface mass balance and glacial isostatic adjustment to estimate the mass balance of Earth’s polar ice sheets. We find that there is good agreement between different satellite methods—especially in Greenland and West Antarctica—and that combining satellite data sets leads to greater certainty. Between 1992 and 2011, the ice sheets of Greenland, East Antarctica, West Antarctica, and the Antarctic Peninsula changed in mass by –142 ± 49, +14 ± 43, –65 ± 26, and –20 ± 14 gigatonnes year−1, respectively. Since 1992, the polar ice sheets have contributed, on average, 0.59 ± 0.20 millimeter year−1 to the rate of global sea-level rise.

Note the key words here “satellite altimetry, interferometry, and gravimetry data sets” along with the second named author “Dr Ivins, who also coordinated the project…at NASA’s Jet Propulsion Laboratory”


Hold that thought about the key words, and now read this, excerpted from our previous report: Finally: JPL intends to get a GRASP on accurate sea level and ice measurements

New proposal from NASA JPL admits to “spurious” errors in current satellite based sea level and ice altimetry, calls for new space platform to fix the problem.

This recent internal PowerPoint presentation (obtained from an insider) from NASA JPL touts the new GRASP (Geodetic Reference Antenna in Space) satellite project. I’d say it is more than a bit of a bombshell because the whole purpose of this new mission is to “fix” other mission data that apparently never had a stable enough reference for the measurements being made. This promises to rewrite what we know about sea level rise and acceleration, ice extent and ice volume loss measured from space.

What is most interesting, is the admissions of the current state of space based sea level altimetry in the science goals page of the presentation, as shown in the “Key science goals” slide:

The difference between tide gauge data and space based data is over 100% in the left graph, 1.5 mm/yr versus 3.2mm/yr. Of course those who claim that sea level rise is accelerating accept this data without question, but obviously one of the two data sets (or possibly both) is not representative of reality, and JPL’s GRASP team aims to fix this problem they have identified:

TRF errors readily manifest as spurious sea level rise accelerations

That’s a bucket of cold water reality into the face of the current view of sea level rise. It puts this well-known and often cited graph on Sea Level Rise from the University of Colorado (and the rate of 3.1 mm/yr) into question:

What’s  a TRF error? That stands for Terrestrial Reference Frame, which is basically saying that errors in determining the benchmark are messing up the survey. In land based geodesy terms, say if somebody messed with the USGS benchmark elevation data from Mt. Diablo California on a regular basis, and the elevation of that benchmark kept changing in the data set, then all measurements referencing that benchmark would be off as well.

USGS Benchmark on Mt. Diablo – Image from geocaching.com

In the case of radio altimetry from space, such measurements are extremely dependent on errors related to how radio signals are propagated through the ionosphere. Things like Faraday rotation, refraction, and other propagation issues can skew the signal during transit, and if not properly corrected for, especially over the long-term, it can introduce a spurious signal in all sorts of data derived from it. In fact, the mission summary shows that it will affect satellite derived data for sea level, ice loss, and ice volume in GRACE gravity measurements:

That list of satellites, TOPEX, JASON 1-3, ICESAT1-2, and GRACE 1-2 pretty much represent all of the satellite data used in the new Shepard et al study released this week A Reconciled Estimate of Ice-Sheet Mass Balance.

In a nutshell, other JPL scientists (Yoaz Bar-Sever, R. Steven Nerem, and the GRASP Team) are saying we don’t have an accurate reference point for the satellites, and therefore the data from these previous satellite missions likely has TRF data uncertainties embedded. They say clearly in their PowerPoint presentation that:

The TRF underlies all Measurement of the Earth

And, most importantly, they call for a new space program, GRASP, to fix the problem.

Without that stable Terrestrial Reference Frame that puts the precision of the baseline satellite measurements well below the noise in the data, meaning all we have are broader uncertain measurements. That’s why the plan is to provide ground based points of reference, something our current satellite systems don’t have:

To help understand the items in the side panels:

GNSS = Global Navigation Satellite System – more here

SLR = Satellite Laser Ranging  – more here

DORIS = Doppler Orbitography and Radiopositioning Integrated by Satellite – more here

VLBI = Very Long Baseline Interferometry – more here

Taken together, these systems will improve the accuracy of the TRF, and thus the data. It’s rather amazing that the baseline accuracy didn’t come first, because this now puts all these other space based measurement systems into uncertainty until their TRF issues are resolved, and that’s an inconvenient truth.

We’ll never look at satellite based sea level data or GRACE ice volume data in quite the same way again until this is resolved.

See the JPL PowerPoint here: Poland 2012 – P09 Bar-Sever PR51 (PDF)


1. JPL admits that satellite measurement of the Earth has issues because a stable Terrestrial Reference Frame was never established for any of the satellite programs. It’s like setting out to do a terrestrial survey without having an accurate benchmark first. This puts all subsequent data derived with the stable benchmark (the stable TRF) into question.

2. The lack of a stable TRF affects most if not all satellite programs used in this new Shepherd et al paper ‘A reconciled estimate of ice sheet mass balance‘ including ICESAT and GRACE, upon which the paper heavily relies.

3. In searching both the full paper (which I purchased from AAAS) and from the extensive supplementary materials and information (SM-SI available here: Shepherd.SM-SI.pdf ) for Shepherd et al, I find no mention of TRF or “Terrestrial Reference Frame” anywhere. It appears that all 47 authors are unaware of the TRF stability issue, or if they were aware, it was never brought to bear in peer review to test the veracity of the paper and its conclusions from the satellite data. Section 3 of the Shepard et al SM-SI deals with uncertainty, but also makes no mention of the TRF issue.

4. The lack of a stable TRF puts all of the space based geodetic data into question, thus the conclusions of the Shepherd et al paper are essentially worthless at the moment, since there isn’t any good way to remove the TRF error from the data with post processing. If there were, the GRASP team at NASA JPL wouldn’t be calling for a new satellite platform and mission to solve the problem. Obviously, this isn’t an issue they take lightly.

In my opinion, the folks at NASA JPL really should get those two teams talking to one another to get a handle on their data before they make grand announcements saying :

An international team of satellite experts has produced the most accurate assessment of ice losses from Antarctica and Greenland to date, ending 20-years of uncertainty.

A good first step would be to get the GRASP  mission funded and then go back and redo Shepherd et al to see if it holds up. Until then, it’s just noisy uncertain data.

UPDATE: Figure 4 in the Shepherd et al paper shows clearly how uncertain the GRACE and other data is.  They used a brief bit of Laser Altimetry data, shown in green. Laser Altimetry is more accurate that the radar/microwave based data from the other satellite platforms, and is one of the keystones specified for the proposed GRASP mission to clean up the noisy radar/microwave based data.

Note that the Laser Altimetry data in green is essentially flat across the short period where it is included in all four panels, though there is a slight drop in Greenland, but the period is too short to be meaningful.


The uncertainty is quite clear in Table 1, which has error ranges larger than the data in some cases:


Table 1 – Reconciled ice-sheet mass balance estimates determined during various epochs, inclusive of all data present during the given dates. The period 1993 to 2003 was used in an earlier assessment (2).


newest oldest most voted
Notify of

The TRF should have been sorted first but perhaps 30 odd years ago the technology was not there. But hey, stable door and bolted horse comes to mind.

John Doe

Dude! It needs a fold!

View from the Solent

That’s Shepherd, not Shepard.
I was at the panel discussion where he unveiled this a number of weeks ago.
REPLY: Fixed thanks – Anthony


This is how they work!
You have to check everything they claim, and you get just as dissapointed everytime how they fudge the numbers makes cliams out of clean air or from pure data noise. They trade no significant trend eith konsensus instead. But they cant no more get a way with thier tricks becdause we have not only catsched up with them we are in front of them when it comes to facts datat and the science. They are corrupted with the “cause”.

Kevin Kinser

I’ve been waiting all weekend for your take on the Shepherd paper [note correct spelling of author’s name]. My understanding of the significance, though, is that despite the uncertainty with any individual measurement, the combination of multiple sources reveals a common pattern. Sort of like Nate Silver projection the election, we can be pretty confident that the ice is really melting even in the Antarctic. Not implying you are trying to unskew the pols, of course, but not sure if your critique is suggesting that underlying reality is suspect because of uncertainty or if you just want more certainty.

Even if the paper was completely accurate it attributes 11mm of sea level rise over the last 20 years to ice loss according to the BBC coverage. That is 55mm per century. And we know that infrared does not heat the oceans, only sunlight can penetrate deeply enough to make a significant impact on ocean temperature and cause expansion. So surely this renders sea level rise a non-threat due to climate change.

jack morrow

So what? The paper has been printed and it is official and if it is not factual does not matter one bit to the climate warming crowd. They will refer to this often and our politicians will use this sort of thing to obtain more of our hard earned money through some type of carbon scheme. It never ends because of the power and money involved- not the science.

Mike Mangan

They don’t need to get a handle on the data. The mission was to get this headline regurgitated by the MSM while Doha was still in progress. Mission accomplished. MSNBC, NBC, Washington Post, BBC, CBS, the NYT, the Professor and Mary Ann acted as one to plant this seed in the minds of all low-information voters out there.

Andy H

Saw an article about this in the loss-making Guardian. Damian Carrington was spinning like crazy.
So it’s down to shifting goal-posts, that makes sense.

Mike Bromley the Kurd

“The Ice Sheet Mass Balance Inter-comparison Exercise (IMBIE)” Oh boy! Another “Desert Storm” for the Climate Military! Sounds better than “General Relativity”, huh? More picking of fly poo out of black pepper. The mass balance comes from managing the crop of 47 scientists who had to cram their ideas into this little conflab. More ideas are better, aren’t they?
The absence of a TRF is interesting…glaringly so…if one considers that the entire climate change ball of wax relies on some arbitrary ‘normal’ sea level/temperature condition in order to define the change from that reference. Please, somebody, answer me this: Who decided that reference point? And if your data is essentially uncalibrated to any geodetic standard, how do you expect me to ‘believe’ any of this? Because that’s what it boils down to here. I am to believe that a gob of scientists wrote a paper in which NONE of the gob paused to consider simple calibration? Uh, WTF?

Mike Rossander

The full article is showing on the front page instead of the usual excerpt. Intentional?

Isn’t this U. of Leeds paper also undercut by the paper reported in the Nov. 29 WUWT thread, http://wattsupwiththat.com/2012/11/29/more-on-noisy-data-from-grace/ ?

Also, don’t these papers undermine this Leeds paper?

Bill Illis says:
November 2, 2012 at 5:09 am
They are going to fix the satellite records now because they have improved ocean mass (glacial melt) numbers and improved ocean heat steric rise numbers.
Eric Leuliette (of NOAA) and Josh Willis (managing the ARGO program) are arguing the rise should be reduced to 1.6 mm/year.
Basically, the previous models of glacial isostatic adjustment were not correct (shown by recent measurements using GPS of Antarctica and by redoing the assumptions used for GRACE) and the steric ocean heat rise was over-estimated (shown by the ARGO floats).
The old models allowed the researchers to adjust the Raw satellite data to get the results the models said should be there or something close to 3.0 mm/year. But the old models were flawed and we are back to 1.6 mm/year, the same number as most of the 20th Century.

Steve Keohane

more data and more scientists is always better, right?
I think I’ll defer to Willis’ take on a paper’s validity being inversely proportional to the numbers of authors.

michael hart

Well, at least the GRASP team is trying to get a grip…


@- “A good first step would be to get the GRASP mission funded and then go back and redo Shepard et al to see if it holds up. Until then, it’s just noisy uncertain data.”
The TRF may have uncertainties and errors but this does not translate into any data derived from it being ‘just’ noisy and uncertain. The magnitude of uncertainty matters, it is not a simple binary all or nothing situation. The error range is well defined and that enables any data that uses TRF to be accurately measured to a certain error range. That does NOT invalidate or refute any and all data from these sources, merely puts a limit on their error range. It is simplistic and egregious to use the residual small uncertainty in the TRF to try and reject all the improvements in the measurements of the exceptional increase in ice melt which are in any case measurede by methods that do not rely on TRF as well.
That provides a constraint on how far in error the TRF might be as the data that depend on it are confirmed by data that does not.

Bill Illis

In addition to Anthony’s comments.
The Supplemental to the paper says the Greenland mass balance numbers were calculated using the old Peltier ICE-5G VM2 glacial isostatic model.
The Antarctic mass balance and sea level contribution rates were calculated using the newer more accurate W12A and IJ05-R2 glacial isostatic models which make greater use of actual GPS measurements and better timelines on ice-sheet melt as the ice age was ending (in addition to resulting in lower overall glacier growth in Antarctica during the ice ages).
The newer glacial isostatic models cut Antarctica’s mass balance losses in half versus Peltier’s ICE-5G VM2 model. So when applied to Greenland, it is expected that the same trend (50% lower) would result.
This puts the sea level contributions much lower as well. The sea level budget will then be far off what is built into the satellite estimates and the assumptions will have to be lowered.


GRACE seems to be the best we have, but it was soon discovered to have flaws – hence the need for the proposed GRASP mission:
From http://ilrs.gsfc.nasa.gov/docs/GRASP_COSPAR_paper.pdf
Yoaz Bar-Sever (1), Bruce Haines (1), Willy Bertiger(1), Shailen Desai(1), Sien Wu (1)
(1) Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, U.S.A

The GRACE satellites offer at present the best available reference antenna in space, despite several shortcomings that we expect to remedy with GRASP…..
……Despite the important advances enabled by the GRACE based approach, this tandem mission has proved inadequate in removing potential biases at the mm level.
The deficiencies are due in part to the lack of a rigorous calibration of the GRACE antennas on the ground prior to launch. In particular, the antennas were not calibrated on the spacecraft. While GRACE offers a relatively clean geometry, simulation analysis show significant levels of both phase and pseudorange multipath. These effects could bias the effective antenna phase center by an unknown amount. Equally important, GRACE’s orbit is strongly impacted by the unpredictable, and difficult to model atmospheric drag. As a result the orbit determination of GRACE depends too much of the GPS measurements, and is susceptible to biases in the phase center of the antennas, which represent the calibration target.
Finally, GRACE flies too low to sample the full GNSS APV angles that are observe with the ocean altimetry platforms flying at 1300 km and, consequently, it cannot provide full calibration for these missions.

It sure sounds complex deriving that TRF:

At present the TRF is defined through the loosely coordinated networks of four independent space geodetic techniques:
1. Satellite Laser Ranging (SLR), in which ground-based lasers range to Earth satellites carrying suitable reflectors;
2. Very Long Baseline Interferometry (VLBI), in which ground-based radio telescopes make precise angle (or differential range) measurements to distant radio sources;
3. Global Positioning System (GPS) geodesy, in which groundbased (and some low orbiting) GPS receivers make precise one-way range and range rate measurements from orbiting GPS sources,
4. DORIS, in which ground-based beacons broadcast to receivers on Earth orbiting satellites
The current ITRF2005 reference frame has contributions from all four techniques [Altamimi et al., 2007].
For ITRF2005 SLR provides the most accurate determination of the origin (geocenter), while the TRF scale is determined from VLBI data. …
VLBI also determines the absolute orientation of Earth with respect to distant quasars, thus providing the important connection between the TRF and the celestial reference frame (CRF) (in which deep space spacecraft orbits are integrated).
Though GPS performs comparably in many individual TRF parameters [Heflin et al., 2002], uncertainties in the phase-center models for GPS satellites and ground tracking stations at the decimeter level, prevent this technique from significantly contributing to the TRF geocenter and scale determination. However, GPS is unchallenged in efficiently densifying the frame (spatially as well as temporally), transferring its precision to virtually any point on the globe or in near space through ubiquitous GPS receivers on the ground or on satellites. …
… Stability of the frame is critical for many global change measurements. For example, Morel and Willis [2005] looked at the errors in mean sea level arising from errors in the geocenter or scale determinations of the ITRF.
They found that a 10 mm error in the Z component of the reference frame can lead to an error of –1.2 mm in the determination of mean sea level, with a strong regional systematic error signal at the high latitudes….….

Anthony, 7th line up from the bottom, There’s an extra “really” and “tow” should be two.
REPLY: Fixed thanks – Anthony


Correct me if I am wrong, but even if in an absolute sense the reference value would be incorrect, then still the SLOPE in the period after 1990 would be the same, isn’t it? In other words, the reference value for the satellite data does not change the conclusion that the rate of sea level increase was higher in recent years.


I worked at JPL for two years when I was in college. They had some good people but like any organization, just one of of 50 people in any room really did the heavy lifting. Its annoying that a place that does really good space based sensing would make a rookie mistake like this.


And this paper made the BBC 10 o’clock news last Thursday and a write-up on the BBC website. Pure coincidence that it was aired by the BBC on the same day the govmunt announced its energy bill.

Gary Pearse

There is an explanation why this paper came into being. With 47 authors and the volume of satellite data, the Shepherd et al study had been in the works long before mention of the GRASP proposal. Remember, these guys have to buy the satellite data, too! (Having already received a grant for the work, etc. etc.). No mention of TRF also is deliberate, but just in case a reader is thinking about TRF, they protesteth too much about how carefully they matched times and places for the data points and used the whole basket of satellites in a collaboratative way.

alex the skeptic

(Not) off topic:
Why is it that while Europe, from Britain to Siberia down to Spain and Portugal and Italy have been taken over by snowstorms and near record cold we do not hear anything form the MSM?

Darren Potter

“In my opinion, the folks at NASA JPL really should …” shut the ‘H’ up about any ice loss and sea level rise claims until they have a handle on Terrestrial Reference Frame. They are showing themselves to be nothing more than political tools.

Darren Potter

“An international team of satellite experts has produced the most accurate assessment of ice losses from Antarctica and Greenland to date, ending 20-years of uncertainty.”
Something akin to Maxwell Smart’s admission of ‘Missed it by that much’.
As for ending the uncertainty, all they have done is cast doubt on their current claims, by acknowledging their previous accurate claims were in fact inaccurate.


Do any of those posters eager to reject the finding of exceptional ice melting exceeding any since the start of the Holocene care to detail what error the problems with TRF impart to the data ?
Does it cause an error of less than 1%, less than 5% or more than 10% ?
Unless you know the magnitude of the error you cannot just discard data you dislike.
REPLY: In your zeal, you clearly don’t understand what is going on here. The error won’t be known until they can compare the data in hand to the stable baseline. – Anthony


Notwithstanding the Envisat story, even before the satellite data were considered unaffected by orbital decay… the sea level rise was minimum.


Actually, the science is fairly certain with Earth’s water (oceans and seas) levels. Mostly due to soil erosion, water levels are rising. It will take megatons of data, and megayears of arguing, to know with any certainty the rate of rise. To link the rise to CO2, is where the science stops and the BS begins.


All I want to know is when is my place back from the beach going to be prime Esplanade property?
I’m trying to tell the punters it won’t be long now and to get in early but the thick-heads are in denial.
How do I get the joint listed as a Terrific Reference Frame or whaddyamacallit thingy with these whitecoats to impress them? Do they do after hours assessments or do they just use Google Earth and I don’t really need to be there to let them in?

The sealevel data graph shows tidal guages and satellite data have different rates. What happened to the tidal guage data after 1992? Why don’t we see that data continuing to present?
Is this because it bad news for both sides, that there is an increased rate after 1992 but less than the altimetry data?


So the melting of ice might have contributed a 5th of the total measured sea level rise and this amounts to just 2 inches over the next one hundred years and this might be attributable to CO2 (except for the last 16 years cause there’s been no warming for 16 years). On this basis they want me to turn off my central heating?


As Anthony pointed out in his direct reply to you, the magnitude of the errors to to TRF problems can not be known until a stable TRF is established.
If the error range is large enough that could actually mean that the real trend is the opposite sign from what the current satellite data show.
This means that none of the satellite measurements reliant on a TRF can be trusted until a stable TRF is established. Even the sign of the trend can not be trusted.


“Sheet Mass Balance Inter-comparison Exercise”
Translation: we did a ‘meta-analysis’ combining apples, oranges, pineapple chunks, corn syrup, and miniature marshmallows into a fruit salad and declared it nutritious.

Liberal Skeptic

First post.
Go Gentle please, been lurking for a while now
Another story to worry us (well, apparently)
“Northern hemisphere snow cover low record”
“faster than climate models”
I’m noticing a pattern. Regardless of whether these papers are support skeptical viewpoints or non-skeptic viewpoints it’s all happening at rates not predicted by the Models. All this tells me is that we still have no idea what is going on. So how can we possibly base any sort of policy on it? For now we just need to keep going, adapt to what ever is happening as it happens and if we ever get to the point where we can predict what is happening base policy on that.
^ Don’t think we’ll ever reach that point.
Yours a Liberal Skeptic.

Does anyone have a quick conversion factor between 100 Gt water = X mm Sea Level @ 4 deg C ?
The first chart with the red Tide Gauge and Blue Altimetry set me off. Another “Hide the Decline” in the making. We start measuring Altimetry in 1993, ok. But you expect me to believe that we STOPPED measuring Tide Gauges in 1993? No, they just stopped plotting the tide gauge data because — why? — it disagrees with the Altimetry? Hmmm?

Alan the Brit

“The lack of a stable TRF puts all of the space based geodetic data into question, thus the conclusions of the Shepherd et al paper are essentially worthless at the moment, since there isn’t any good way to remove the TRF error from the data with post processing.” You wanna bet, matey???? 🙂 They’ll find a way, that’s why they “reinterpreted” the satellite data, in an effort to “reconcile” it!
I have a real problem with people who want to “re-interpret” or “re-evaluate” something that didn’t show them what they wanted it to show, without “processing”, adjusting”, “refining”, or “smoothing” it afterwards to give them the picture they wanted to see!! Or is it just l’ill ol me? What a cynical old b’stard I have become in my seniority! They seem to have forgotton the fact that UNIPCC AR4 2007 SPM concurred that the Arctic was warmer in the 1940s than it is today, amongst many other things they “agree” with, particularly differences between satellite/radio sond temperature data & models being “largely resolved”, whatever that might mean!!! They just can’t seem to arrive at the logical conclusion without invoking the “Precautionary Pinciple”!


You guys are deluded if you imagine the TRF-uncertainty is big enough to change the current trend to an “opposite trend”. Check what the maximum size of the uncertainty is (hint: the JPL PowerPoint) and post it here please (I tried to do that when it was 1st reported but nobody on WUWT gived a damn).
Note also that the reference-frame affects altimetry- and gravimetry measurements differently and that it does not really affect the SAR/InSAR velocity measurements. SAR, altimetry and gravimetry show pretty much the same thing, as demonstrated in Shepherd et. al.
The GIA-models have a much larger uncertainty on Antarctica where one just cannot place GPS-stations where one pleases (no bedrock nearby on huge areas). On Greenland the problems are much smaller as the ice-sheet is relatively narrow and GPS-station can be places relatively nearby. Use of a different GIA-model will NOT reduce the Greenland mass-loss estimate by 50%.

Look at the short period of Laser Altimetry data in Figure 4 – essentially flat. Note that LA is one of the keystones of the GRASP mission to clean up the noisy data which in table one has quite error bars. If you are makign bold predictions, would you not want to get the best available data?
And, why would you need to hide your identity at ESA if you are so sure of your claims? – Anthony


Stephen Rasey, there are zero tide-gauges in the open ocean, where incidentally much of the largest sea-level changes have happened. Referring to the satellite time-series is a much more comprehensive measurement of global sea level. Tide-gauges and satellite-data agree where they can be compared.

kent Blaker

When I first read about the study I focused on the starting point, 1992. I then asked why they were not using data from tidal gauges. Tidal gauge data that goes back over 200 years shows us a 60 year cycle of up and down sea level. By using only 20 years when the tidal gauges were showing a rising sea level they of course end up with the results they did. It is the kind of “science” that con artists would use to convince the gullible.When dealing with cyclic events you always need to look at when the study starts and whether it includes at least one cycle. If it doesn’t, then the study is majorly suspect, unless it is noted that the study does not include a full cycle and was done in order to comply with grant requirments in which case it is again suspect.


Wow!! All we need is a new satellite!! The bid notice follows:
Notice to Bidders for NASAs GRASP
1. The work we want did is clearly showed on the attached plans and speserfacations. Our enganear, whose had plenty of college, spent one hell of a lot of time when drawed up these here plans and speserfacations. But nobody can think of everthing! Once your bid is in, that’s it, Brother! From then on, anything wanted by our enganear, or any of his friends, or anybody else (excep the contrakter) shall be cusidered as showed, speserfide, or emplide and shall be pervided by rhe contrakter without no expence to nobody, but hisself (meanin’ the contrakter).
2. If the work is did without no extry expence to the contrakter, then the work will be took down and did over again until the extry expence to the contrakter is satisfactory to our engangear.
3. Our engangear’s plans is right as drawed. If sumthin’ is drawed wrong, it shall be discuvared by the Contrakter, kerected and did right with no extry expence to us. It won’t cut no ice with us or our enganear if you point out any mistakes our enganear has drawed. If you do, it will be one hell of a long time before yu do any more work for use or him (meaning the engangear)!
4. The contrakter is not sposed to make fun of our enganear, his plans, or the kind of work we’re having did. If he do, it’s jest too bad for him (meanin’ the Contrakter).
5. Any Contrakter walkin’ around the job with a smile on his face is subject to review of his bid.
6. If the Contrakter don’t find all or our enganear’s mistakes before he bids on this job, or if the contrakter ain’t got enough sence to know that our enganear’s goin’ to think yp a bunch of new stuff that’s just too bad for him (meanin’ the contrakter)!
7. The Contrakter gotta use all good stuff on this job – none of this crap from Solyndra.


The laser altimetry is essentially flat since a) it was done on a campaign basis, not continuously and so it didn’t capture changes within years and b) the time-series is so short that the results depend on ice sheet “weather”. Shepherd et. al. nicely demonstrates the clear need for continuous long time-series to see what is really happening.
REPLY: “…to see what is really happening.” Agreed, they simply don’t know. This paper is just another guess based on noisy data, and having a stable baseline is key to that. There’s no getting around the need for a stable baseline – Anthony

Jim G

Even IF the numbers are correct, where is the proof that any ice sheet loss is due to CO2? How does this match up with the fact that there has been no warming for 15 years? So, if even the ice sheets are shrinking there must be other exogenous variables involved, ie cloud patterns, storm systems, under sea volcanic activity, etc.

Darren Potter

izen says: “Unless you know the magnitude of the error you cannot just discard data you dislike.”
Yet according to proponents of Global Warming one must accept conclusions derived from data with unknown magnitude of error. As in claim of 0.020** or 0.013** or 0.016** or 0.007** degree C rise in temperature per year based upon weather station data with an average error of +/- 1.86 degree C per daily reading.
**Pick your Global Warming Alarmist claim/prediction – which demonstrates the utter inaccuracies of Global Warming Faux-Climatologists, since they can’t even agree within 18% of each other.


According to JPL the TRF-related uncertainty is 0.45mm/year, see last slide here:

and if that were fully true, then they wouldn’t need to push for a new space platform and mission to correct the problem. Bottom line is we don’t know. All we have are estimates based on noisy data. If this were a skeptical paper, such things would be demanded, as it stands you give this paper a free pass, part of the problem with government funded group think of which you are a part. – Anthony

Billy Liar

Liberal Skeptic says:
December 3, 2012 at 8:17 am
You failed to point out that the Northern hemisphere snow cover low record was for the month of June and the record is only 45 years long. Maybe Eurasia is having a drought? They make no statement about the rate of change of annual precipitation in the relevant area – I wonder if that’s reducing too?

Darren Potter

Liberal Skeptic says: “All this tells me is that we still have no idea what is going on. So how can we possibly base any sort of policy on it?”
The scary part is not the possibility of Global Warming, but the world will enact inane policies based upon the recommendations / demands of Global Warming’s scientists (Faux climatologists), experts (self-proclaimed), and politicians (aka dictators).


“(Not) off topic:
Why is it that while Europe, from Britain to Siberia down to Spain and Portugal and Italy have been taken over by snowstorms and near record cold we do not hear anything form the MSM?”
Simple, high temperatures (the new normal) are global warming, low temperatures are just weather UNLESS they are really low, then it’s climate change. Got it?


I hope we’ve learned that if the satellites can’t be calibrated on the fly against a stable reference then launching them is a waste of money. Reminds me of the ACRIM vs PMOD debates.