Uh, oh. Another talking point bites the dust.
Leif Svalgaard writes in to tell me of a significant new paper. While Gore, Hansen, Branson, and a gaggle of hangers on just finished a publicity stunt tour of Antarctica to tell us all how terrible the ice loss is there, the data says otherwise. No trend!
A new, high-resolution surface mass balance map of Antarctica
(1979–2010) based on regional atmospheric climate modeling
J. T. M. Lenaerts, M. R. van den Broeke, W. J. van de Berg, E. van Meijgaard,
and P. Kuipers Munneke
Received 17 January 2012; accepted 21 January 2012; published 21 February 2012.
Abstract: [1] A new, high resolution (27 km) surface mass balance (SMB) map of the Antarctic ice sheet is presented, based on output of a regional atmospheric climate model that includes snowdrift physics and is forced by the most recent reanalysis data from the European Centre for Medium-Range Weather Forecasts (ECMWF), ERA-Interim (1979–2010). The SMB map confirms high accumulation zones in the western Antarctic Peninsula (>1500 mm y^-1) and coastal West Antarctica (>1000 mm y^-1), and shows low SMB values in large parts of the interior ice sheet (<25 mm y^-1). The location and extent of ablation areas are modeled realistically.
The modeled SMB is in good agreement with ±750 in-situ SMB measurements (R = 0.88), without a need for postcalibration. The average ice sheet-integrated SMB (including
ice shelves) is estimated at 2418 ± 181 Gt y^-1. Snowfall shows modest interannual variability (s = 114 Gt y^-1), but a pronounced seasonal cycle (s = 30 Gt mo-1), with a winter maximum. The main ablation process is drifting snow sublimation, which also peaks in winter but with little interannual variability (s = 9 Gt y^-1). Citation: Lenaerts, J. T. M.,
M. R. van den Broeke, W. J. van de Berg, E. van Meijgaard, and P. Kuipers Munneke (2012), A new, high-resolution surface mass balance map of Antarctica (1979–2010) based on regional atmospheric climate modeling, Geophys. Res. Lett., 39, L04501,
doi:10.1029/2011GL050713.
Here’s the money quote:
[15] We found no significant trend in the 1979–2010 ice
sheet integrated SMB components, which confirms the
results from Monaghan et al. [2006]. The estimated SMB
trend, integrated over the ice sheet, equals –3+/-2 Gt/y^-2
Read the full paper here
UPDATE: One of my readers emailed me today to say that I had left off a minus sign in the last paragraph where it says: 3+/-2 Gt/y^-2 which should read –3+/-2 Gt/y^-2 instead. Corrected, my apology for the error, which originated in this original email from Dr. Leif Svalgaard:
That missing minus sign doesn’t change the conclusion in the paragraph of “We found no significant trend in the 1979–2010 ice sheet integrated SMB components, “ but some alarmist types are apparently all atwitter and looking for nefarious motives. What is typical of that criticism, is that it’s just another coward saying nasty things without the courage to put his/her name behind the words of criticism.
Here’s the fun part, you can open up the PDF that Leif Svalgaard provided here. Then go to paragraph [15] and highlight the relevant text listed above that this blogger and the Tamino crowd are all upset about, and then paste it into notepad or the comments box below and watch the minus sign disappear!
Apparently it is some oddly formatted character they used, and gets stripped on copy/paste, which is why Dr. Svalgaard accidentally sent it to me that way. Another “evil and devious skeptic plot” bites the dust. – Anthony
UPDATE2: Dr. Leif Svalgaard confirms in comments here – Anthony
For those whining about it being a model based study, quoting from the conclusions……“Without additional calibration, the modeled SMB agrees very well with 750 in-situ SMB observations….
For those worrying about what this paper actually states, look at figures 3 & 4 and understand the different scaling. You can visualize the math from there. Then also ask yourselves, is sublimation consistent with the CAGW hypothesis? Further, look again at figure 3. The only graphed component which has a discernible trend is melt!!……. which way is that going? Is that consistent with the CAGW hypothesis?
With all the attacks accumulating on William Connoley, few people have yet realized the substantial error in the post by Anthony Watts (or at the very least, that it gives a misleading impression of what is happening to Antarctica to people who don’t understand the terminology). It only takes a slight amount of courage or honesty for everyone to admit this, and does not depend on how much you like the IPCC, Connoley, Michael Mann, the climategate e-mails, or whatever else.
The total mass budget involves estimating the difference between surface mass balance (input) and perimeter fluxes (output). That said, Antarctica is almost certainly losing ice (contributing to sea level) in its net effect. The IPCC 2007 report is rather outdated on this subject and observational ability has improved tremendously since that time. See for example Rignot et al (2011, GRL); Velicogna, I., (2009, GRL), and there are large regional changes, especially in the Antarctic Peninsula & West Antarctica that are changing rapidly (e.g., Cook and Vaughan, 2010; Ivins et al., 2011). It would be nice to see some WUWT summaries of these papers…
yawn,
You’re a noob here, so I’ll explain it for you. On this site threadbombing is making multiple comments that have little or no redeeming purpose, other than to monopolize the conversation with science-free, fact-free nonsense from site pests. Just like most of your comments, in fact.
A few observations on the various papers cited here:
“We found no significant trend in the 1979–2010 ice sheet integrated SMB components, which confirms the results from Monaghan et al. [2006].”
The following is not a surprise and consistent with “Acceleration of the contribution of the Greenland and Antarctic ice sheets to sea level rise” – http://ess.uci.edu/researchgrp/velicogna/files/rignot_etal_grl2011.pdf
The conclusion of this paper s that “The magnitude of the acceleration suggests that ice sheets will be the dominant contributors to sea level rise in forthcoming decades, and will likely exceed the IPCC projections for the contribution of ice sheets to sea level rise in the 21st century [Meehl et al., 2007].”
The implication being that even if SMB is relatively stable, MB is decreasing. This presumably implies that there is some empirical support for an increase in ice calving. What else could it be?
The conclusion reached by Rigno et. al, needless to say, is the opposite of the expectation of IPCC AR4, where GCM modelling is expecting to see an increasing SMB trend.
The main game in town is SMB, not MB. If MB is accelerating but SMB has no trend, then it seems difficult to reconcile this with GCM atmospheric modelling. Now if someone disagrees, I’d be interested in a different point of view. However, I would seek clarification on how MB acceleration can be explained in terms of AGW theory when there is no observable SMB trend.
In summary:
Rigno et al agrees with Lenaerts et al, on no trend in SMB but reaches the opposite conclusion of the IPCC AR4 report. On the other hand IPCC AR4 expected to see an increasing SMB trend, according to GCM’s, which is not observed by Lenaerts el al, either. So if the GCM’s are correct, it just hasn’t happened (yet) as predicted.
So you have a bunch of authorities who all basically disagree with each other in one way or another where it matters, which is sea level rise attributable to GW. Such is climate science.
Jeeeze, it’s almost like that whole “Greenhouse Effect” thingy is only working inside the computer models. What’s an honest climate scientist to do? I guess you could claim that the missing heat is lost in the measurement errors. That usually works when something I design doesn’t work as I predicted it would, Ha, Ha….
Maybe the NULL HYPOTHESIS (i.e. the climate varies naturally and the GHE has no impact on the average temperature) is correct ????
After several decades looking for the signature of the GHE all I’m hearing is EXCUSES, and of course name calling and requests for more tax dollars to study the “problem”.
Cheers, Kevin (denier)
Surface Mass Balance is different from total Mass Balance.
Dynamic loss is glaciers accelerating which is where most ice sheets lose their ice. This paper does not look at that. Noobs…
So the paper doesn’t say what was implied in the write up and what many of the posters believe it does. [snip. After Gleickgate, that comment is inappropriate. ~dbs, mod.]
This thread and the comments with the abstract are not correct. This was not an assessment of mass balance of the ice sheet. It was modelling the surface mass balance. These are two different things.
It is idiotic to jump on a high horse and confound the two when they’re very different. Shame on everyone here for not reading the article or taking the time to learn anything at all on the subject before commenting.
snowfall: a pronounced seasonal cycle (s = 30 Gt mo-1), with a winter maximum.
That surprises me a bit. I’d expect a summer maximum for snowfall. Less sea ice, weaker katabatic winds = more ocean influence in summer.
Also for the record, this is creating a dataset that goes into complete mass balance surveys such as Rignot et al 2011. It is one component of Mass Balance for the whole ice sheet.
Antarctic Mass Balance = Ice Input – Ice Output
Ice Input comes through the SMB and the SMB is nearly 0 so the Antarctic Mass Balance then equals 0 minus ice outputs through calving and accelerating glaciers (Pine Island Glacier for Example).
Rignot et al. 2008 and Rignot et al. 2011 use INSAR Flux budget method to calculate the Mass Balance of the ice sheet by measuring the Output and comparing it to the SMB. They find losses are huge because of dynamic ice loss from accelerating glaciers.
Uh-oh: http://dotearth.blogs.nytimes.com/2012/02/20/peter-gleick-admits-to-deception-in-obtaining-heartland-climate-files/
Peter Gleick Admits to Deception in Obtaining Heartland Climate Files
By ANDREW C. REVKIN
Peter H. Gleick, a water and climate analyst who has been studying aspects of global warming for more than two decades, in recent years became an aggressive critic of organizations and individuals casting doubt on the seriousness of greenhouse-driven climate change. He used blogs, congressional testimony, group letters and other means to make his case.
Now, Gleick has admitted to an act that leaves his reputation in ruins and threatens to undercut the cause he spent so much time pursuing. His summary, just published on his blog at Huffington Post, speaks for itself. You can read his short statement below with a couple of thoughts from me:
OFF TOPIC-
Pter Gliek admits it. Go to Dot Earth.
@Robert says:
Surface Mass Balance is different from total Mass Balance.
Dynamic loss is glaciers accelerating which is where most ice sheets lose their ice. This paper does not look at that. Noobs…
=========================
Obviously we’re all noobs here Robert. But since you’re a clever fellow, could you explain the relationship between MB, SMB and GCM modelling? In relation to AGW, the main game in town is, obviously, SMB and not MB.
(How’s that for packing a lot of acronyms into one sentence? 😉
Yawn: We don’t distrust science at all. We distrust studies if and when there is reason to do so. That Yawn is what science should do. If it can’t hold up to scrutiny then it isn’t science. If you have some meaningful reason to doubt this study, then your comments will be appreciated here.
If the grounding line remains constant then SMB = MB.
If the point where the ice floats rather than sitting on bedrock (even if below sea level) moves toward shore then it is possible to have a positive surface mass balance while the overall mass balance is negative.
The paper discussed in this WUWT post is about SMB only.
There tends to be an awful lot of confirmation bias in reports like this, with people leaping onto anything that may confirm their views.
I suggest something simple – posts like this should always contact one of the paper’s authors to ask what it really means before doing a write-up. This would eliminate a great deal of baseless speculation. I do not know the difference between MB and SMB, so I will not comment, but it is clear that a lot of other people also do not know, but are willing to comment anyway.
Robert wrote;
“This was not an assessment of mass balance of the ice sheet. It was modeling (sic) the surface mass balance. These are two different things.”
Agreed, however the surface of the ice is the only place where the interactions of sunlight, warm air and warm water can possibly melt the ice and thus reduce its volume. So, if it is not being observed there how exactly is the rest of the ice volume decreasing? Indeed the GHE Hypothesis specifically states that “extra energy” from the “effect” warms the SURFACE. Are you asserting that IR “backradiation” penetrates deeply into the ice and melts it from below? X-rays might do that, but I strongly doubt that relatively unenergetic IR radiation posses this additional magic trait. However it appears a pretty tricky beast that can cause warming for decades and then stop working for additional decades.
If I try to drill a hole through a 10 foot thick concrete wall and my drill bit fails to penetrate the surface by more than 0.01 inch does the remaining 9.99 foot of hole magically drill itself?
Noobs, indeed, please see my reference to name calling.
Cheers, Kevin (recently upgraded to a denying noob)
Will Nitschke says:
February 20, 2012 at 6:00 pm
“In relation to AGW, the main game in town is, obviously, SMB and not MB.”
Not true. Dynamic ice losses are due to warming oceans causing grounding line retreat subsequently accelerating glaciers and carrying more ice to the sea. Warming oceans is definitely related to AGW. Noob.
Silly rabbit! The fact is in the other hat!
It’s not mass, it’s area that’s important. And area has been increasing rapidly while mass holds steady, which is a sign of the flattening of the Antarctic. Yes, the world will soon be following this flattening trend until the whole thing is flat. And then trade and commerce will be paralyzed because ships will no longer be able to sail around the world. Woe be to us all!
Robert says:
Not true. Dynamic ice losses are due to warming oceans causing grounding line retreat subsequently accelerating glaciers and carrying more ice to the sea. Warming oceans is definitely related to AGW. Noob.
================================
Did you make that up or can you cite a paper for that claim? Just curious. I don’t have a problem if you write, “I speculate that it might be caused by…” but Warmists always post messages as if their proclamations were authoritative…
Also, since a number of Warmists here are arguing that SMB is irrelevant (when exactly the opposite is in fact true), and the basis of this claim is the paper by Rignot et al, and their analysis is based on data from 1992-2010, are they aware that if you remove the 1992 year there is probably no trend for the rest of the data? In fact, there is possibly mass balance gain as well? Would you consider an analysis robust if you toss 1 year out of 12 from the data set and this reverses the conclusion?
(With Warmists, you have to be very careful about not what they argue, but what information they leave out of the discussion…)
Anything is possible: The point isn’t about the trend of SMB, or whether it’s up or down; the point is that Mr. Watts is interpreting this paper to mean that there is no (significant) trend in the mass balance of the Antarctic. The paper says no such thing. Also: Other recent papers (some of which are co-authored by the authors of this paper) say quite the opposite.
In conclusion: This isn’t about cherry picking, this is about either misunderstanding, or choosing to misrepresent, the findings of this paper.
DocMartyn: Among other things, the 36.3 Gt/y you cite is actually 36 Gt per year PER YEAR (for Greenland + Antarctica). It’s an acceleration. So, your equation is wrong. Besides, we agree: There’s going to be ice in Antarctica for a long time to come. But problems arise if even only *some* of Antarctica melts.
Will Nitschke says:
February 20, 2012 at 7:12 pm
“When a glacier is in balance or flowing at its balance velocity, net mass will remain balanced. However, when a glacier accelerates while near or at its balance velocity, the outputs resultantly increase but the inputs do not, thereby shifting the glacier regime to one of negative mass balance or net ice loss. This situation is particularly important because accelerated ice flow is the key method through which the Antarctic ice sheets incur a net ice loss. Accelerations such as these occur through two primary mechanisms. The first of which is caused by surface melt water reaching the glacial bed causing basal lubrication therefore reducing the frictional forces at the bed and thus increasing ice flow (Bell 2008).
The second mechanism refers to when the forces at the downstream terminus of a glacier or ice stream are disturbed or altered. This can occur through removing buttressing ice shelves or by shifting the glacier’s grounding line (point where glacier ice reaches floatation). The presence of an ice shelf provides a longitudinal compressive force which slows the flow of ice streams. If removal of this compressive force occurs, velocity of ice streams increase. This has been observed directly by Scambos et al (2004) and Rignot et al (2004) through both visual observations (Scambos) and radar interferometry (Rignot).
In terms of a grounding line retreat, an inland shift of the grounding line causes less backpressure through increased calving and basal melting. This process results in increased glacier velocities and subsequent inland thinning as more ice is being pulled from the accumulation zone (Bell 2008). In a warmer climate, one would expect that surface melting would increase, making the first mechanism more likely, however because of Antarctica’s climate and the omnipresence of ice shelves and calving glaciers there, the second mechanism actually dictates the ice losses from Antarctica. Evidence has already been presented which supports the theory that it is warm ocean water in West Antarctica which is in actuality enabling this second mechanism (Shepherd, Wingham and Rignot, 2002).”
Shepherd, Wingham and Rignot’s article is called “Warm ocean is eroding West Antarctic Ice Sheet” GRL 2004
Will Nitschke says:
February 20, 2012 at 7:12 pm
Warm Ocean is Eroding West Antarctic Ice Sheet
Geophysical Research Letters
2004
Also see the following:
“This situation is particularly important because accelerated ice flow is the key method through which the Antarctic ice sheets incur a net ice loss. Accelerations such as these occur through two primary mechanisms. The first of which is caused by surface melt water reaching the glacial bed causing basal lubrication therefore reducing the frictional forces at the bed and thus increasing ice flow (Bell 2008).
The second mechanism refers to when the forces at the downstream terminus of a glacier or ice stream are disturbed or altered. This can occur through removing buttressing ice shelves or by shifting the glacier’s grounding line (point where glacier ice reaches floatation). The presence of an ice shelf provides a longitudinal compressive force which slows the flow of ice streams. If removal of this compressive force occurs, velocity of ice streams increase. This has been observed directly by Scambos et al (2004) and Rignot et al (2004) through both visual observations (Scambos) and radar interferometry (Rignot).
In terms of a grounding line retreat, an inland shift of the grounding line causes less backpressure through increased calving and basal melting. This process results in increased glacier velocities and subsequent inland thinning as more ice is being pulled from the accumulation zone (Bell 2008). In a warmer climate, one would expect that surface melting would increase, making the first mechanism more likely, however because of Antarctica’s climate and the omnipresence of ice shelves and calving glaciers there, the second mechanism actually dictates the ice losses from Antarctica. Evidence has already been presented which supports the theory that it is warm ocean water in West Antarctica which is in actuality enabling this second mechanism (Shepherd, Wingham and Rignot, 2002).
We should all now at least remotely understand that mass balance changes in Antarctica aren’t reliant on surface melting but rather depend on dynamic responses such as the 2nd mechanism.”
@BCC:
In conclusion: This isn’t about cherry picking, this is about either misunderstanding, or choosing to misrepresent, the findings of this paper.
======================
What if the heading of the post was changed to:
“New paper: A high-resolution surface mass balance map of Antarctica suggests “no significant trend in the 1979–2010 ice sheet. Inconsistent (to date) with IPCC global climate modelling.”
Would you be happier?
Also Mr Watts could add this disclaimer:
“While most studies relating to Mass Balance of the Antarctic continent remain uncertain and it is not possible to draw significant conclusions due to a high degree of inter annual variability, it should be noted that Rignot et al (2011) suggests otherwise; however, the linear trend in that paper is sensitive to the start date of the analysis, and therefore may not be robust.”
I would argue that if the heading was changed and the disclaimer was added, it would make the post more balanced. I think it’s always a good idea to qualify claims as much as possible.
@Robert:
Warm Ocean is Eroding West Antarctic Ice Sheet
=============================
Are we talking about the West Antarctic Ice Sheet or are we talking about MB and SMB of the Antarctic continent?
Because if I wrote a post that showed data that, say, sea level was dropping off the coast of Brisbane, I’m sure you would be furious with me, because it would only be fair to discuss global sea level change and not sea level change in Brisbane.
So now you point to a paper about the West Antarctic Ice Sheet which is pretty much the only coastal region that has seen any significant degree of warming. (With warming of around .5C over 50 years.) Keep in mind that most of the low latitude coast has an average temperature of -12C and the high latitude coast an average temperature of -17C. The Antarctic peninsula can get as warm as 1C on average at the summer peak. Just not sure how you extrapolate what’s happening in that region to the mass balance of the entire continent. I would not want to accuse you of cherry picking, but…