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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I look forward to the BBC giving this the same amount of hype that Steig et al 2009 received… I shall not hold my breath though.
Note that the final number given is for an increase, though it is not statistically significant.
That is a 31 year period that the paper evaluated. So those climate scientists who say the minimum climate period required for statistically significant evaluation is 30 yrs must stay mute that the period evaluated is too short.
John
Oopsie.
When will these people learn , your facts are worth nothing, the model is all.
I wish people would stop doing actual science and taken measures of physical things there is no need , all truth is found in the models ‘ For is it not the first commandment of climate scene ‘ when reality and the models differ in value , it is reality which is in error ‘ /sarc off
You left the minus sign off of the 3 in your last sentence. It should read:
“The estimated SMB trend, integrated over the ice sheet, equals -3 +/- 2 Gt y^(-2).”
I’ll assume it was a cut and paste error because of the fonts used. It happened to me just now when I pasted it in.
The scientific credibility of this study is certainly bolstered by the fact that “the modeled Surface Mass Balance is in good agreement with ±750 in-situ SMB measurements” (a.k.a. empirical data). However, I still felt a slight shudder when I read “the map is based on output of a regional atmospheric climate model”.
Let’s hope this proves to be reproducible.
“based on output of a regional atmospheric climate model”? I thought models were GIGO? And how about GRACE?
Look forward to commentary from AR5 WG1 and from Steig et al.
John
Surface Mass Balance (SMB) is not the same thing as mass balance.
Mr. Watts, I believe that you are misinterpreting what this paper says.
For reference, the lead author is also a co-author on the 2011 GRL paper, “Acceleration of the contribution of the Greenland and Antarctic ice sheets to sea level rise”. Monaghan is also a c-author on this paper. If you read this paper ( http://ess.uci.edu/researchgrp/velicogna/files/rignot_etal_grl2011.pdf ) you may better understand the difference between mass balance and surface mass balance (SMB), which is clearly discussed on the first page.
I wouldn’t hold my breath waiting for this to appear on the BS Broadcasting Company!
You might want to check the sign of your ‘money quote’ against the paper.
You might want also to refresh your memories of the definition of mass balance (hint – check the units).
You might want also to compare this result with the IPCC projection.
Remember the old line about the MWP being “not global … only a localized NH fluctuation”?
Weeeellll, that’s been shown false (eg the data at co2science.org) but it begins to look as if it applies to the modern warming period.
In case my above comment was not clear enough:
Mass balance of Antarctica = SMB (water in) less perimeter loss (water out)
So the observation that SMB is more or less constant over the past 30 years says nothing about the perimeter loss, or about the mass balance of Antartica.
For a more complete discussion, including a comparison of two methods of measuring mass balance, I refer you to:
“Acceleration of the contribution of the Greenland and Antarctic ice sheets to sea level rise”
E. Rignot, I. Velicogna, M. R. van den Broeke, A. Monaghan, and J. Lenaerts
http://ess.uci.edu/researchgrp/velicogna/files/rignot_etal_grl2011.pdf
Dang ! 1979-2010, that’s a whole 30 years, which means it’s climate, and not weather; we’re all doomed to ice boredom.
@Brian H
The final number in the paper is negative. The negative symbol is missing in the quote here.
I wonder how many commenters here ever read the IPCC analysis:
(of course, that is complicated by this model being *surface* mass balance, but that distinction is going to go right over your heads).
@ur momisugly Louis Hooffstetter:
Agree strongly with:
” I still felt a slight shudder when I read “the map is based on output of a regional atmospheric climate model”
If a reasonable scepticism is warranted for our current modelling of other complex climate phenomena, it should be here as well. We don’t want to cherrypick our models and undermine the value of broad-based scientific scepticism.
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”.
But the amount of bad ice in the sheet has increased dramatically;>)
BCC says:
February 20, 2012 at 2:57 pm
The paper you referenced quotes an SMB trend of -5.5 +/- 2 Gt/yr/yr
This one quotes an SMB trend of -3.0 +/- 2 Gt/yr/yr.
In other words, pay your money and select whichever figure best suits your view of the world.
Climate “science” in a nutshell……
Okay, the modeled SMB is in good agreement with ±750 in-situ SMB measurements, so that’s some validation. But If it’s a model, how can it “confirm” anything? Shouldn’t this just be a “yay, we’ve got a more realistic model!” sort of hype?
This argument is silly because most of the continent is simply too cold for significant melting.Most of it stays below freezing the entire year.
Just along some shorelines and small areas of the west Antarctica get above freezing for short time periods maybe reach into the 40’s.Not long enough for the feeble above freezing air to penetrate hundreds of feet thick of snow and ice.
A little logic will go a long way here……
William Connolley getting slapped down:
http://opinion.financialpost.com/2010/10/14/global-warming-propagandist-slapped-down
A new, high-resolution surface mass balance map of Antarctica
(1979–2010) based on regional atmospheric climate modeling
…..funded by Tipper Gore
dang computer games…you can make them do and say anything