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.
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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.
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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
Abstract
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”
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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.
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)
Summary:
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:
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CostCo says: Greenland is losing mass 5 times faster than only 20 years ago.
0 x 5 = 0
Nothing to worry about.
CostCo:
Your post at December 4, 2012 at 11:09 am says in total
Ah! So you claim to know of some defences of the failure of the project reported in the paper, but you don’t say what they are.
Quad Erat Demonstrandum
Richard
CostCo says: “Sorry, what “drifts” are you talking about exactly?”
Drift as in over time equipment gets further away from calibration. Which can induce unknown quantity of error into equipment.
Ever seen an elevator stop 1/4″ to 2″ above or below the floor it is stopping on? That would be one such example of Drift.
To get more into Drift issues, there can be Drift in both the equipment, the calibration system for said equipment, and even drift in the human using the calibration system.
Antarctica nothing to see, satellite sea level trends inflated, the only “meat” appears to be in the Greenland data.
Berkely Earth shows Greenland temperature just rising a little bit above 1940s..
http://berkeleyearth.lbl.gov/regions/greenland
The little rise of about 0.6 degrees in 70 years is way below arctic trends expected by climate models, and additionally, BE doesn’t correct for UHI and most of all, the increase is highly correlated with AMO, i.e. mostly natural.
http://upload.wikimedia.org/wikipedia/commons/thumb/1/1b/Amo_timeseries_1856-present.svg/300px-Amo_timeseries_1856-present.svg.png
Dave Wendt says:
December 3, 2012 at 5:07 pm
Many thanks for your comment. Doesn’t sound accurate at the 0.1mm level does it? The problem with satellites is that they take time to go round the earth. If the SLP has changed when you fly past your start point 90 minutes later how do you correct for the IB? The satellites are measuring discrete altitude points in a continuously changing SLP field. Sounds very messy to my relatively stunted mathematical brain. Oh, and wind heaps up the water as well. How do they correct for the effect of wind. Indeed, how do they simultaneously measure the wind at the time they take the altitude measurement?
BTW, “E Pluribus Unum” over the globe – I’m not signing for that.
And Thank you WUWT for showing up another major problem with GRACE, which is also used for measuring aquifer levels and soil moisture content, in support of radical water sustainablility policies.
Here is an interesting PDF on the complexity of ground water fluctuations measured in over 2,000 observation wells in Hungary, at varying depths down to 1,000 meters. The deeper wells sometimes fluctuate faster than the shallow wells, without greater ground permeability to explain it. Don’t let them lob up a couple of satellites and claim the science is settled about Earth’s water tables.
http://itia.ntua.gr/hsj/redbooks/156/hysj_156_01_0345.pdf
http://www.nasa.gov/mission_pages/Grace/multimedia/chart20121129.html
from
http://www.nasa.gov/mission_pages/Grace/news/grace20121129.html
Caption on graph indicates “IJ05_R2 + W12a averaged” , so it appears they did not like the newer, more accurate GAIA adjustment and fudged it by taking the average to blend back in half of the older defective W12a model.
Some more detail on the paper and some excerpted graphs here:
http://www.thegwpf.org/doug-hoffman-ice-surveys-finds-slower-ice-sheet-melting/
“Darren Potter says: CostCo says: “Sorry, what “drifts” are you talking about exactly?”
Drift as in over time equipment gets further away from calibration. Which can induce unknown quantity of error into equipment.”
Right, so what kind of drifts are making the results suspect? TRF is not nearly big enough to change anything for altimetry and for SAR the influence is nil. Mind you that here long time-series were compared and the results matched, so are you proposing that the independent techniques are suffering from some weird drifts that somehow correlate over ling time-periods to make the results match?
“Manfred says: Antarctica nothing to see, satellite sea level trends inflated, the only “meat” appears to be in the Greenland data.
Berkely Earth shows Greenland temperature just rising a little bit above 1940s..”
What do the summer-temperatures say? In addition to warming above sea-level the waters around Greenland have warmed up, which ablates marine-terminating glaciers a lot from below.
CostCo says: “Right, so what kind of drifts are making the results suspect?”
The kinds of Drift that forced Shepherd et al to “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” in hopes of getting past the inaccuracies of each.
The kinds of Drift which causes error ranges larger than the data, and they don’t know to correct for or have a way to correct for.
The kinds of Drift that has NASA admitting to “‘spurious’ errors in current satellite based sea level and ice altimetry”.
The kinds of Drift which has JPL saying they need another space platform.
The kinds of Drift that has you trying to defend the indefensible. 😉
CostCo says: “What do the summer-temperatures say?”
You tell us. But back it up with links, not just claims of 5 times greater.
Then justify to us why we should only listen to what summer-temperatures say.
Zeke says: “Don’t let them lob up a couple of satellites and claim the science is settled about Earth’s water tables.”
Not to worry; that is no longer going to happen.
Two decades ago, some of us (myself being one) might have taking the proponents of Global Warming SCAM at their word. Mistakenly believing that AGW Climatologists/Scientists would never abuse their positions of Trust.
However, after seeing how AGW Climatologists/Scientists are willing to whore themselves for political purposes and funding – by adding bias to data, cherry picking data, lemon picking results, hiding facts counter to their claims (aka hide the decline), and lying (certain mann & peace prize comes to mind); those of us who mistakenly trusted them, will never trust them again.
The burden of absolute Proof now lies with them, as it should have been from day one.
It is greatly and profoundly unfortunate for the lives of the proposers of the ‘GRASP’ proposal in that it, the GRASP proposal, is factually flawed, i.e. a lie, and I posit the “scientists’ involved are like many others, now, hoisting a straw man argument to get NASA and NSF attention only in a futile attempt whose real purpose is to gain millions of US dollars and leverage the flawed perception of national prestige.
Otherwise, the GRASP proposal is an example of fraud and the proposers guilty of fraud and worse.
In their dreams!
Their worst nightmares will visit them, individually, in the course of the coming months. The Department of Treasury agencies move in mysterious ways, but now that the election is behind us the accountants are focused once again on the real value of currency and taxes owed.
Hay. They brought this on themselves. 🙂
About that Shepherd et al paper.
“nicht sogar falsch.” Prof. Wolfgang Ernst Pauli.
Translation: Not even wrong.
CostCo says:
December 4, 2012 at 2:15 pm
What do the summer-temperatures say? In addition to warming above sea-level the waters around Greenland have warmed up, which ablates marine-terminating glaciers a lot from below.
———————————–
Greenland is doing exactly what is expected at current AMO.
Greenland ice sheet melt from Chylek 2007 as reported by Akasofu who states: “present changes of the Greenland ice sheet are smaller than changes observed during the 1920– 1940
http://www.appinsys.com/globalwarming/RS_Greenland_files/image016.jpg
http://www.appinsys.com/globalwarming/RS_Greenland.htm
@Izen:
To get a “Global Average Temperature” one must average. Doesn’t matter if you put it in your comment or not. That folks assert, regularly, that they can get fractional degree (down at 1/100 C range) precision via said averaging reducing the variation in the data is simply a fact. That’s why the data are shown to 1/10 and 1/100 C precision (that is “False Precision” due to systematic error being treated as random error).
Doesn’t matter if you know it, put it in your comment, or not. That’s what is done to the data, and it is an error.
You then go on to present an emphatic overstated falsehood about me, and then react to it. Nice “Straw Man” but really a silly debate tactic. One I don’t accept.
First off, I don’t “reject…all the research in the last sixty decades”. As that’s 600 years, and I don’t think they were doing AGW Scare Grants in the 1400s… But assuming you meant 60 years or 6 decades: In 1940 they were not doing AGW Scare Grants either, and in the 1960s and ’70s it was New Ice Age Scare time. ( I lived through it…) I accept a great deal of the research from the last 600, or even 60 years. Just not the AGW Scare part of it.
As to why I reject the AGW Scare part of it, well, not only all of the stuff on WUWT, but all of the stuff about climate on my own blog. Far too much to put in one comment. Hundreds (thousands?) of pages of it. Only one small part of it is the $Millions hauled in by Al Gore and Mann (nice grants he gets, no?) and all the other flood of money from various NGOs and the UN.
Oh, and that $100 Billion the UN wants as “Carbon Sin Tax”, I’m sure that doesn’t bias their desires one bit. They would be happy to take zero dollars and just fix the carbon “problem”… /sarcoff>;
So that’s just one tiny bit of why I think AGW “science” is deeply flawed. But some of it is reasonably well done. (Though that part tends not to find much warming or much damage from it, if it did happen.)
Now what I do think needs to be “tossed out” is the thoroughly corrupted data sets. Things like the product of GIStemp. ( If you don’t know, I have it running in my office and have looked at ever line of the code. It’s pretty poor. Though the guy they hired to do the Python bit did a nice job of writing the code, but I think it does something that is scientifically silly. – Step 2 IIRC.)
So I’ve sunk a few years of my life into personally checking many of those claims about “the end of life as we know it” and “temperatures known to 1/100 C” and found them terribly wanting. Often (largely?) due to one of: Instrumental data biased, worse corrections, wrong way ‘corrections’, horrid splice artifacts, biased baselines, confounding long term cyclical changes with ‘trend’, and outright scientific malfeasance. (UEA lost their data? REALLY? In High School that would get you an F and taking the class over…) So yes, I think the output product of UEA, NOAA/NCDC, and NASA/ GISS all need to be ’round filed’ and we need to go back to the raw data sheets (IF they can still find real data) and start over. Recognize that data recorded to 1 F (and with no way to tell random error from systematic error) can’t be made any more accurate than 1 F by averaging it together (GIStemp keeps temperatures AS temperatures until the last step when it makes ‘grid box anomalies’ so that whole argument about ‘it is all done with anomalies’ is just bogus).
One Simple Example: The Stevenson Screens were shown by A. Watts et. al. to have a warming bias. This is a systematic error. The paint changes as they age and the temperatures rise. Peterson, of NOAA/ NCDC is on film saying that when they rolled out the MMTS to replace them, they showed a ‘cooling bias’ and it was ‘corrected’. Except that it wasn’t a cooling bias. It was that the Stevenson Screens had warmed over the years of paint fading. So instead of ‘correcting’ a cooling bias they were locking in a systematic warm error.
No amount of averaging or anomaly processing can remove that systematic error bias from the data and it simply is NOT going to be accurate to any finer degree than 1 F (US data and much of the older world data was collected in F, so that’s the raw data precision).
Now we find the satellite data has similar ‘datum’ issues and is also filled with a systematic error. To state that is not to ‘reject all science from the last 60 decades’, or even the last 60 years. It is to reject the data as deeply flawed for saying anything useful about precision as fine as mm.
Now look at the computer models that are so wrong (even compared to the wrongly over warm data we have) and it’s pretty clear they are broken too. We’ve fallen below their lowest band of prediction (or projection or hand waving or whatever new word of the day you pick this week…) and we’ve had a 16+ year standstill in the ‘warming’. (Golly, no instrument change splice artifact and things stop “warming’…) So it’s pretty darned clear that the models are useless for prediction.
Which makes basing policy on those predictions pretty dumb.
But you go on:
As I have no connection with the fossil fuel industry other than using their product, I really don’t care much about their paycheck. However, you ought to realize that Oil doesn’t fund the anti-AGW side much. It spends more money on the AGW folks. Why? Because they want to kill off the competition. Coal. Exxon uses CO2 for tertiary oil extraction and some years back was lamenting that they would soon have to purchase it. Gee, now if they could only get their competition, coal, to pay THEM to take away that nasty CO2 and “sequester it”…
And look at the total funding flowing to the AGW parade (measured in hundreds of millions) vs the skeptics (largely volunteer or occasionally getting small $1000 sized or smaller donations). Pretty clear where the money is at. Just measure Al Gores wallet… Oh, and check out the investments in “alternative energy companies” that got a chunk of ‘bail out money’ and then folded. Does the name Solyndra mean anything to you? Yeah. “Friends of Democrats” getting bailout money and subsidy money by the truckload.
If you “follow the money”, it’s very clearly about 100 : 1 on the “pro AGW” side and going to the politically connected. Even from the oil companies. (Coal not so much…)
That you subscribe to the canard of oil funding skeptics makes it pretty clear you’ve not actually looked at the money flows.
As to the ‘thermodynamic consequences of CO2″: Since they are substantially nil, I have no fear of what they would do to anything. We have existence proofs from all of past history that the planet can be in an ice age at 7000+ ppm and hotter than now at lower CO2. It just doesn’t have control of the thermostat. (Position of the continents, orbital mechanics, solar changes, and the occasional big BANG from space do… with water vapor being the dominant control / working fluid in the system).
So please, keep your innuendo and straw man smears to yourself. They have nothing to do with me or my beliefs, and even less to do with the reality of climate.
The reality of climate it that at present it is extraordinarily stable, but after 12,000 years of so of ‘reasonably warm’ we’re on the cusp of a decent into the next glacial. There’s an existence proof of no ‘tipping point’ to warmer (the Holocene Optimum that was about 2 C warmer than now) and one of a clear ‘tipping point’ to colder (that glacial we just had). Look at the temperature graph for the last 10,000 years and it’s a clear hump. We’re on the ‘lower lows and lower highs’ side of things. The LIA was colder than the prior cold period. This Modern Optimum is lower than the prior warm period ( Greenland ice core data). The only really good news is that it takes 100,000 years for the slide to cold to build up the full ice sheet, and there’s about a 1500 year cycle, so we could well be in the slide into the next ice age and not know it. Things change that slowly on the long fall, and cycle faster on the 1500 year range.
So, believe it or not, I desperately hope CO2 driven global warming is correct. It’s the only thing that can possibly prevent our entry into the next glacial period during the next 1000 to 2000 years. I’d like to burn every scrap of carbon fuel we can during that time. If we’re really really lucky, it will slow the decline. Unfortunately, there is no evidence that it will work, as we have those prior glacials with higher CO2.
Unfortunately, we live on a ‘water world’ and convection, evaporation, and condensation drive things. Not a trace gas of no importance to weather.
Oh, and sending $100 Billion to the UN, a few $100 Billion to “Friends of Congress” for investing in their
pocketscompanies, and more $100 Billions to owners of ‘carbon exchanges’ (like Al Gore and friends) will not change the climate either… which leaves me wondering why that’s what they keep proposing for the ‘fix’…Me? I’m going back to my self funded ‘research’ into climate data and not expecting to see even $10 from an “Oil Company”. ( I sometimes get donations at my blog. Last year I bought a ‘smoker’ and I’ve managed to get good at doing BBQ in it… Just to put some scale on the money thing… It’s measured in low 3 digits / year…) So when you go snarking about all the money on the skeptic side, well, it’s really a hoot…
Now to catch up the rest of the comments…
“Darren Potter says: CostCo says: “Right, so what kind of drifts are making the results suspect?”
The kinds of Drift that forced Shepherd et al to “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” in hopes of getting past the inaccuracies of each.
The kinds of Drift which causes error ranges larger than the data, and they don’t know to correct for or have a way to correct for.
The kinds of Drift that has NASA admitting to “‘spurious’ errors in current satellite based sea level and ice altimetry”.
The kinds of Drift which has JPL saying they need another space platform.
The kinds of Drift that has you trying to defend the indefensible. ;)”
There are no unknown drifts that are “larger than the data” so your point is moot. We have three independent techniques that see the same thing, which increases the confidence in these results a lot. I’m willing to bet that satellites not used in this study, for example CryoSat-2, will corroborate these results. I think it’s fantastic that ice sheet monitoring has progressed so far it has given the remoteness and sizes of the continental ice sheets.
“Manfred says: Greenland is doing exactly what is expected at current AMO.”
Well is it really? Check this Nature-paper:
http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1481.html
…where it is stated that:
“We show that many land-terminating glaciers underwent a more rapid retreat in the 1930s than in the 2000s, whereas marine-terminating glaciers retreated more rapidly during the recent warming.”
The marine-terminating glaciers have been retreating more rapidly today, possibly due to increased underwater melting. The marine-terminating glaciers are exactly the ones that are responsible for most of the ice-loss and the retreats of their calving fronts have caused them to flow faster, dumping more ice into the ocean. Got any evidence for arguing this is within “normal variability”?
‘E.M.Smith says: So, believe it or not, I desperately hope CO2 driven global warming is correct. It’s the only thing that can possibly prevent our entry into the next glacial period during the next 1000 to 2000 years. I’d like to burn every scrap of carbon fuel we can during that time. If we’re really really lucky, it will slow the decline. Unfortunately, there is no evidence that it will work, as we have those prior glacials with higher CO2.”
That’s a reckless attitude as you’re basically suggesting doing geoengineering of Earth with a compound that stays in the atmosphere for a very long time, i.e. a non-reversible experiment in human timescales. Using something that stays in the air for only a couple of years would be infinitely wiser as then it would be possible to withdraw the forcing quickly if something bad starts happening. For example, what will you do if it turns out that your increased atmospheric CO2 is going to trigger a new ice age through shutdown of the thermohaline circulation in North Atlantic? A hypothetical example but it demonstrates your approach to geoengineering is reckless.
Does that mean that the data series was regularly “recalibrated” so that each resultant “trend to date” maintained the desired 3.2 mm/yr gradient?
CostCo:
I see that at December 5, 2012 at 1:03 am you have abandoned the hopeless task of trying to defend the indefensible paper by Shepherd et al. and, instead, you try to scare-monger about Greenland ice loss. You write
So, you say, “The marine-terminating glaciers have been retreating more rapidly today, possibly due to increased underwater melting.”
Well, that is possible. Or it may possibly be due to the breath of dragons. Or it may be possibly due …
There is no more reason to be concerned at the present glacier retreat being predominantly “marine-terminating glaciers” than there was to be concerned that the previous glacier retreat was predominantly land-terminating glaciers. The Greenland ice continues to retreat at a rate which is trivial.
Simply, Manfred is right when he says, “Greenland is doing exactly what is expected at current AMO”; i.e. it is losing ice at a trivial rate.
Richard
“richardscourtney says: The Greenland ice continues to retreat at a rate which is trivial.”
Yes, but ice-loss is accelerating at a rate that is not trivial, i.e. five-fold in just 20 years. The ice-stream acceleration has been witnessed further and further north and there’s still room for more acceleration in the coming years. A millimeter per year in sea-level from Greenland only is not that far away if acceleration continues.
“richardscourtney says: I see that at December 5, 2012 at 1:03 am you have abandoned the hopeless task of trying to defend the indefensible paper by Shepherd et al. ”
Should I “defend” against the negligible TRF-error and Anthony erroneously chose to highlight on WUWT instead of the findings of this landmark paper? (where’s the redaction of that BTW?). Or do I also need to defend against the (non-existing) drifts-that-cannot-even-be-named that might derail the results? LOL I say.
But additional ice loss in September in the Arctic leads to .. MORE COOLING of the Arctic ocean through evaporation losses! (At latitudes north of 82 latitudes, there is NO extra absorption of solar energy when the sun is less than 5 degrees above the horizon. All but 5% of the solar energy is reflected from the water.
More Arctic evaporation (in August and September and October) leads to more snow in Europe and Russia and Siberia and China in October and November and December …..
(By the way, more Antarctic sea ice in September (at record levels this year) reflects more solar energy from latitudes 60 south and leads to … MORE COOLING! )
So, is this the tipping point starting the next ice age that you want?