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
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Will Nitschke:
“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?”
No, because that title would be wrong. Trend in SMB is ***NOT*** the same thing as “trend in the … ice sheet.”
Ice sheets have mass. That mass, M, changes due to inputs (snow less ablation, etc., i.e. SMB), and outputs (flow of mass across the grounding line). dM/dT = SMB (expressed as GT/yr) – D (ice discharge, also GT/yr).
Direct measurements, via the GRACE satellites, show that DM/dt is negative and accelerating (see e.g. Rignot 2011). But these measurements tell you about dM/dt; they don’t (themselves) tell you about SMB and D.
Lenaerts et al measures SMB, based on regional modeling matched against empirical data. They find that d SMB / dT appears to be about zero (Rignot 2011 found a small insignificant negative trend; Lenaerts et al, 2012 shows an insignificant increase).
Meanwhile, D D/dt seems to be increasing (e.g. the discharge *rate* is increasing, so discharge is accelerating) D is “calculated from a time series of glacier velocity and ice thickness” (Rignot, 2011).
And here’s what the AR4 says on the matter (http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch10s10-6-4-1.html):
===
All studies for the 21st century project that Antarctic SMB changes will contribute negatively to sea level, owing to increasing accumulation exceeding any ablation increase (see Table 10.6). ***This tendency has not been observed*** in the average over Antarctica in reanalysis products for the last two decades (see Section 4.6.3.1)
===
*** emphasis mine
In sum: The Lenaerts paper does not contradict the findings that Antarctic ice sheets are losing mass (as indicated by the GRACE satellite DATA). Further, the Lenaerts paper does not contradict the AR4 report, which states that, while SMB is expected to increase, it hasn’t been observed to, yet.
In a nutshell this says precipitation has no trend. Extrapolation says sea level rise is not increasing and logic suggests therefore no increased melt. The only question mark is butress failure.
@BBC:
You’ve basically repeated most of the points I already made, so I will focus on a couple of small things we disagree on. The problem with wanting to talk about MB instead of SMB is that AGW models make certain claims about SMB. It can’t say much about MB because the processes are not well understood in terms of measurement, modelling, etc. (Except in relation to SMB.) The change in MB is highly variable and uncertain. The paper you originally cited, covers only 12 years of data, and 11 of those 12 years don’t show much of a trend. To make matters worse, the high level of annual variability and the short time frame combined, makes any sort of linear trend extrapolation highly uncertain at best. This is why other papers that have looked at the same issue have been hesitant to draw conclusions. Plus your whole argument rests on citing this particular paper. Now, even if the paper was correct, what does it tell us about AGW? Very hard to say…
But the IPCC does reach some conclusions about SMB. It argues that there should be a positive SMB trend and that this will contribute overall, negatively, to sea level rise. The GCM’s have expectations about SMB. Which is why this matter is being discussed in this thread.
Now, the paper under discussion is interesting in the sense that it has the worst possible outcome for Warmists…
IF there was a positive SMB trend then Warmists could say, “See, this is completely consistent with the climate models. This reaffirms the IPCC’s position.”
IF there was a negative trend, you could even spin this and say, “Yeah OK the IPCC climate models got it wrong, but just that mean’s *it’s worse than we thought.*”
Instead there is no SMB trend… So Warmists don’t want to talk about this. There is nothing they can say, it’s the worst of all possible outcomes.
So let’s come back to MB. What can we say? Not much. Most papers are hesitant to draw any conclusions on trends because there is not much data there and it’s highly variable. Rignot et al. (2011) did draw a conclusion, but it looks like a fairly shaky one, since most of the MB loss looks like it happened in ’92-93 and not much has really happened since. But because the paper conflates Greenland MB with Antarctic MB, Warmists aren’t looking at the paper carefully or sceptically.
robert,
Have you looked at the southern ocean SST lately:
http://bobtisdale.files.wordpress.com/2012/02/13-southern.png
The drop in Southern Ocean SST is likely correlated with expanding sea ice.
Meanwhile Vostok temps have been declining for thirty years as well as cloudiness along with increasing high pressure which translates into decreased snowfall at the center of Antarctica which produces adiabatic downslope winds across the Antarctic Peninsula that produce local warming that is studied with the tunnel vision of AGW proponents that ignores what is happening in the remaining 95% of the continent. The IPCC predicted the SMB would be slightly negative because they believed the sea ice would decrease while the snowfall over the continent would increase due to rising relative humidity. The fact is that just the opposite has occurred. Finally, Robert have you looked at the decline in sea level rise since 1998. It is becoming increasingly more difficult to slice a smaller pie to account for melting land ice and thermal expansion.
Sorry I should have wrote 18 years of data, not 12 years. Although that makes my argument stronger…
It’s another of those totally useless models. They are looking for more money to buy a bigger computer than the UK Met Off
>> I wonder how many commenters here ever read the IPCC analysis:”
> Most likely no one.
It seems rather likely that most of you haven’t. Which means you don’t know what you’re arguing against, and explains why you’re fighting strawmen. You appear to be proud of your ignorance.
> The fact that the IPCC is unable to confirm or deny growth or shrinkage
Yes, but try actually *thinking* about that, instead of just writing. You’ve got into your head, somehow, the idea that the IPCC is predicting rapid surface ice loss in Antarctica. And now you realise that you’re wrong.
> http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch10s10-7-4-4.html
> Connolley appears to cite the parts of the IPCC that are convenient to his argument but doesn’t cite the parts that are inconvenient.
I was trying to cite the bits that are relevant. You’ve cited a bit about reactions of the SMB to changes in temperature, in the future. That isn’t relevant to the current observations. The hint is that chapter 10 is called “Chapter 10: Global Climate Projections”.
LC> This paper doesn’t say what you think it does people.
Nice to see that someone is awake. For the rest: SMB != MB. The hint is in the letter “S” which stands for “Surface”.
[snip]
Confirms what we all thought. The hype is baseless.
[Connolley’s] career as a global warming propagandist has now been stopped, following a unanimous verdict that came down today through an arbitration proceeding conducted by Wikipedia. In the decision, a slap-down for the once-powerful Connolley by his peers, he has been barred from participating in any article, discussion or forum dealing with global warming. In addition, because he rewrote biographies of scientists and others he disagreed with, to either belittle their accomplishments or make them appear to be frauds, Wikipedia barred him — again unanimously — from editing biographies of those in the climate change field.
[source]
False. It was temporary. His buddies carried on till his re-instatement recently to the Editorial Board. Smoky mirrors.
Brian H,
I was just reminding folks that Connolley was slapped down for unethical behavior. I understand that Wikipedia has a heavy alarmist slant. But for Connolley to be reprimanded and suspended shows that he is the worst of a bad lot. And note that his punishment for devious one-sided censorship was unanimous.
Now that Connolley is back in his censoring position, I think it is our duty to expose the charlatan in the interests of integrity and freedom of speech, which Connolley does his best to subvert with is Stalinesque deleting of everyone who doesn’t agree with his [repeatedly debunked] CAGW Party line.
> And note that his punishment for devious one-sided censorship was unanimous
You keep reading things in there that are absent. There was no finding of censorship. That you’re happy to lie about things that anyone can easily check says little for your opinion of other commenters and readers here.
Connolley links to a Wiki page that would make any normal person’s eyes glaze over in a matter of microseconds. But his protestations don’t matter. What matters is his suspension. That is a fact. You don’t get suspended for being a good guy, you get suspended for wrongdoing. And his suspension was unanimous.
The link I posted stated that Connolley “rewrote biographies of scientists and others he disagreed with, to either belittle their accomplishments or make them appear to be frauds, Wikipedia barred him — again unanimously — from editing biographies of those in the climate change field.”
That is dispicable character assassination by someone who should never be allowed near a keyboard again. Connolley is just getting a tiny taste of what he does to others. The difference is that Connolley was found guilty. The others were innocent. Their only “crime” was having a point of view that Connolley didn’t like. Dispicable, no?
Why is WUWT the best science site? Because it exposes many of us to science we were unaware of. This post with the back and forth discussion of SMB and MB forces me to do some research into the basics of what is being discussed and I increase my knowledge. Thanks to all on both sides, especially those that provide links to help the learning process.
sunsettommy says:
February 20, 2012 at 3:34 pm
//////////////////////////////////////////////
As you point out, warmer air is unlikely to cause much ice loss. Due to the high latitute the sun will always be weak. Liekwise summer will always be short. For the vast majority of the year, conditions will always remain well below freezing.
Significant ice loss could only be brought about by a warmer ocean and of course, most of Antartica is not ocean ice, but land ice.
It is therefore extremely difficult to see what mechanism could bring about large scale ice loss in Antartica.
Accordingly, it is difficult to see how there could be large sea level rise associated ith ice loss from Antartica. Predictions are wholly unrealistic.
Robert says:
Couldn’t the forces acting on the “Dynamic” ice loss be from geothermal activity then, in addition to warm ocean currents?
Wikipedia: (I know) In January 2008 the British Antarctic Survey (BAS) scientists, Hugh Corr and David Vaughan, reported that 2,200 years ago a volcano erupted under the Antarctic ice sheet. This was the biggest Antarctic eruption in the last 10,000 years. The volcano is situated in the Hudson Mountains, close to Pine Island Glacier.[16][17] The eruption spread a layer of volcanic ash (or tephra) over the surface of the ice sheet. This ash was then buried under the snow and ice. Corr and Vaughan were able to map this ash layer using an airborne radar system and calculate the date of the eruption from the depth of burial of the ash. This method uses dates calculated from nearby ice cores.[17] The presence of the volcano raises the possibility that volcanic activity could have contributed, or may contribute in the future, to increases in the flow of the glacier.[18]
In other articles on this same survey, it says the there is likely ongoing activity? Do the models take into account subglacial, and submarine geothermal activity? I’ve also read that there is geothermal activity acting on some of the Greenland Glaciers. These articles are also increasingly difficult to find.
There actually is a trend in one of the factors – melts have become less pronounced over the years. Uh oh!
So if it’s not snowing more inland, and the melting is accelerating on the perimeter, where is the water going? Sea level rise has dropped by half in the last five years. OK, groundwater has been replenished–that might explain a year or two. Are the oceans getting colder? That’s what we might expect after a decade of cool surface temperatures.
And we have had almost a century of nearly linear sea level rise. Are we to suppose that anthropogenic forcings and resulting feedbacks have combined to produce this linear rate? Or is this better explained as a natural shift between regimes of equilibrium? This is a hell of a way to run a catastophe. –AGF
Ignoring Connolley’s usual ad hominem attacks, it’s not clear to me either that he has much of a grasp of what the IPCC says on the topic of Antarctica until I pointed it out to him. Of course, it’s his right to effectively say the equivalent of, “Yeah the IPCC is not getting this right but their claims are about the future and the future is not now.” OK, yes, true. But would still be nice to have *some* empirical support detectable over the last 30 years of data even if small…?
And I’m still fascinated by the paper cited by BCC which is the basis of the claim for a massive decline in MB in Antarctica. There is only 4 years of ‘reconciled’ GRACE data there and the inter annual variability is as high as 500 Gt. By that I mean one year shows a net loss of 350 Gt. The following year shows a net gain of 150 Gt. A red line is drawn through this short time period pointing downwards (although no obvious trend appears in the actual graphed data), and the authors of the paper conclude there is a massive accelerating ice loss. After drawing this conclusion they introduce a safety net:
“For the same time period, the acceleration in mass loss from the MBM data is 15.1 ± 12 Gt/yr
2. Both estimates have a large uncertainty because of the short period of observation and the large temporal variability in SMB.”
No kidding.
In fields outside climate science – and in fact in most climate science papers I’ve read – when there is an uncertainty as large as that, you say so, and don’t draw a scary conclusion. It would be very interesting to see what one extra year of data does to their results. My suspicion would be that it would significantly change their calculated trend.
new paper: a new “low”?
22 Feb: Sky News UK: Lowering clouds to combat global warming
Clouds around the world may be falling in response to rising global temperatures and having a cooling effect on global warming, according to analysis of satellite data by Auckland University scientists.
The first 10 years of data from the NASA Terra satellite, which uses nine cameras at different angles to produce a stereo image of the world’s clouds, shows their average height has lowered by about 1 per cent, or 30 to 40 metres.
Most of the reduction was due to fewer clouds occurring at very high altitudes, says the study, published in the journal Geophysical Research Letters…
‘We don’t know exactly what causes the cloud heights to lower but it must be due to a change in the circulation patterns that give rise to cloud formation at high altitude,’ Prof Davies said…
‘If cloud heights come back up in the next 10 years we would conclude that they are not slowing climate change,’ Prof Davies said.
‘But if they keep coming down it will be very significant.’
http://www.skynews.com.au/eco/article.aspx?id=721052&vId=
Unfortunately, in your quote from the study above, someone left out a minus sign from the actual study. How did this happen? Your quote above:
“The estimated SMB
trend, integrated over the ice sheet, equals 3+/-2 Gt/y^-2”
The actual quote from the study:
“The estimated SMB
trend, integrated over the ice sheet, equals – 3 +/-2 Gt/y^-2”
___
That little minus sign before the 3 means something, and its a shame it was lost when posted here on WUWT. It means, even within the range of error, Antarctic ice mass was declining somewhere between -5 and -1 GT/yr^2, (just as Grace satellite data showed as well).
@R Gates:
It means, even within the range of error, Antarctic ice mass was declining somewhere between -5 and -1 GT/yr^2, (just as Grace satellite data showed as well).
=================================
Except the range of error is obviously huge, which the authors of the paper admit to themselves. Only 4 years of GRACE data is used, the inter annual variability is enormous, and once you look at the rest of the data you actually see it’s basically flat except for 17 years except for the start year of the analysis.
Doesn’t mean the paper is wrong. We need more data. It’s just hard to see how one could draw any sort of solid conclusion out of that data in a fair and balanced way. My political observation here is if sceptics published a paper along similar lines, Warmists would be calling the authors every name under the sun. The question marks in the analysis would be stark and immediate to them.
JJ says:
February 20, 2012 at 3:18 pm
Brian H says:
“Note that the final number given is for an increase, though it is not statistically significant.”
If it had been a decrease, that would have been the title of the paper and the headline of the press release. “Not statistically significant” would have been buried in the fine print and qualified with “but only just”.
Unfortunately for your hypothesis the trend was for a decrease, Anthony or whoever copied the text accidentally dropped the minus sign. So in this case your cynicism is unfounded!
Still no correction to the error in the “money quote”? Even when pointed out? (see my previous post).
Meanwhile Chinese researchers have concluded no unprecedented warming in China during the last 100 years when the last 2000 years were analyzed. http://earth.scichina.com:8080/sciDe/EN/abstract/abstract505198.shtml