Yet Another Incorrect IPCC Assessment: Antarctic Sea Ice Increase
by Chip Knappenberger
March 8, 2010
Another error in the influential reports from the Intergovernmental Panel on Climate Change (IPCC) reports has been identified. This one concerns the rate of expansion of sea ice around Antarctica.
While not an issue for estimates of future sea level rise (sea ice is floating ice which does not influence sea level), a significant expansion of Antarctic sea ice runs counter to climate model projections. As the errors in the climate change “assessment” reports from the IPCC mount, its aura of scientific authority erodes, and with it, the justification for using their findings to underpin national and international efforts to regulate greenhouse gases.
Some climate scientists have distanced themselves from the IPCC Working Group II’s (WGII’s) Fourth Assessment Report (AR4), Impacts, Adaptation, and Vulnerability, prefering instead the stronger hard science in the Working Group I (WGI) Report—The Physical Science Basis. Some folks have even gone as far as saying that no errors have been found in the WGI Report and the process in creating it was exemplary.
Such folks are in denial.
As I document below, WGI did a poor job in regard to Antarctic sea ice trends. Somehow, the IPCC specialists assessed away a plethora of evidence showing that the sea ice around Antarctica has been significantly increasing—a behavior that runs counter to climate model projections of sea ice declines—and instead documented only a slight, statistically insignificant rise.
How did this happen? The evidence suggests that IPCC authors were either being territorial in defending and promoting their own work in lieu of other equally legitimate (and ultimately more correct) findings, were being guided by IPCC brass to produce a specific IPCC point-of-view, or both.
The handling of Antarctic sea ice is, unfortunately, not an isolated incident in the IPCC reports, but is simply one of many examples in which portions of the peer-reviewed scientific literature were cast aside, or ignored, so that a particular point of view—the preconceived IPCC point of view—could be either maintained or forwarded.
Background
The problems with the IPCC’s handling of the trends in Antarctic sea ice was first uncovered and presented a week or two ago in an article posted over at the World Climate Report—another blog with which I have been involved with for a long time.
…
The First Order Draft of Chapter 4 contained the following illustration of Southern Hemisphere sea ice, along with the caption “Sea Ice extent anomalies … the Southern Hemisphere based on passive microwave satellite data… [l]inear trend lines are indicated for each hemisphere….the small positive trend in the Southern Hemisphere is not significant. (Updated from Comiso, 2003).”
Figure 1. Figure 4.4.1b from the IPCC AR4 Chapter 4 First Order Draft.
Notice two things, 1) the figure depicts monthly ice extent anomalies from November 1978 through October 2004, and 2) the trend through them seems to be statistically significant (i.e. the confidence range does not include zero), given in the illustration as 9089.2 +/- 2970.7 km2/year or 0.735 +/- 0.240%/dec.
Yet, for some reason, the accompanying text claims that the trend in Figure 4.4.1b is insignificant (AR4 First Order Draft, page 4-14, lines 9-10):
The Antarctic results show a slight but insignificant positive trend of 0.7 ± 0.2% per decade.
This inconsistency was brought to the IPCC Chapter 4 authors’ attention by several IPCC commenters. Commentor John Church wrote “I do not understand why this trend is insignificant – it is more than three times the quoted error estimates” and Stefan Rahmstorf wrote “How can a trend of 0.7 +/- 0.2 be ‘insignificant’? Is not 0.2 the confidence interval, so it is significantly positive?” The IPCC responded to both in the same manner “Taken into account in revised text.”
And boy did they ever!
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So, to be added to the ever growing “gate” list: Ice-gate? Antarctic-gate?
Sorry, the S.D. of this data is TOO HIGH. There is NO statistically discernable trend in this data.
ANYONE saying there IS, is a STATISTICAL MORON.
Use Student’s T or Mann-Whitney (Non parametric) and analyze by year or by decade.
NOT significant.
The fact that none of these so called “experts” do this, makes their work COMPLETELY INVALID!
Many people often confuse ‘statistical significance’ and ‘significance for whatever practical purpose’. This may be the case here as well.
However, while laymen can sometimes be excused for being careless with terms, scientists never can.
We didn’t have Anarctica-gate already or did we?
Thanks, Chip, great article!
Hide the incline
Mannian statistics?
After all we’ve learned in the past few months , this should come as no surprise . What else will come up ?
Does anyone really believe we can measure sea ice area or extent within an accuracy of +/-0.2%.
If these measurements are accurate to within 3% I would be impressed. Especially given the measurements go back 30 years and likely use different methods of measurements (or different satellites).
It’s enough to say we see no evidence of any decrease in sea ice. The latest assessments reduction in confidence is actually more believable to me (of course, their tactic of reporting less confidence in data they don’t agree with, and reporting higher confidence in data they agree with is disturbing).
Climate Science really needs to do a better job in estimating and reporting the uncertainty of their measurements, as well as their assumptions underlying any calculated data in their algorithms. This goes for those on both sides of the debate.
Even with temperature, we are arguing over tenths of a deg C over a century with poorly sited equipment, land use changes, equipment changes and all subject to cherry picking . In 30 years lets see where we (you) are ( I won’t be around).
This month to month, year to year, even decade to decade comparisons is not very productive., and takes away from the real issue, the science behind warming attributed to CO2 (more specifically, anthropogenic CO2)
I’ve not read this story yet but the first thing to jump out is the date.2004 The last time I checked it was 2010 What happened to the last 5 plus years???
Presumably, similar forensic analysis is required for the whole of AR4 WG1.
I can’t wait for the dissection of the papers which show that CO2 is the main climate driver and the papers which consider and rule out ‘natural’ climate forcing. Oh, I forgot, maybe they don’t exist.
There is no end to this group of scientists cooking the books.
Nothing to see here, we all know that evidence for man-made global warming is overhelming. The debate is over and we must act NOW [before we uncover more reasons not to act…] in order to avoid the catastrophic consequences.
Oy. When faced with a series of choices they just “happened” to pick the right set of individual choices to end up with a minimization.
Hey, the good news is next time they’ll admit in AR5, with loud rejoicing, that since their previous report the antarctic pack is now in recovery mode. Right? Riiiight?
I do mediations. Some small and some large (millions). Perhaps instead of this winner takes all situation we should propose a middle ground. Propose the release a statement that: ‘… the AGW scientists and the Skeptical Scientists have agreed that, using PNS sources, the AGW theory is 98% BS but that the 2% is significant and further studies should continue but at a reduced scale’. We could site PNS sources such as: Postman Pat(Sociological), The Day of Triffids(Biological), Day the earth Stood Still(physics),
Trend-Gate?
Do the climate modellers have a rate of decline they are predicting for the antarctic ice? Shouldn’t we also be comparing the rate of actual incline against the predicted rate of decline, not just against zero?
You’ve heard of Doctors without Frontiers (Sans Frontiers)….’
Have you heard of ‘Scientists Sans Data’?
I suspect there may be some confusion here about error bars and statistical significance. If the sea ice was measured perfectly then the error bars of the ice measurement could be zero, but given the up and down fluctuation of the ice from year to year, an increase over a few years still might not be significant, it might still just be the random increase and decrease of the ice. Though this whole story still seems to be very hurtful to the IPCC’s credibility.
This is one of the reasons that I find the proclamation that the Southern Hemisphere is undergoing unprecedented warming is highly suspect. The Warmists know that there are very few weather stations in the Southern Hemisphere, and the ones in New Zealand and Australia are manned by radical warmists, so they can draw such conclusions with little accoutabiliry and in spite of Antarctic and oceanic satellite data that is contradictory.
Forgive me if it’s already been answered before, but why has it taken so long for the above-mentioned as well as other recent inaccuracies to be discovered?
Max Hugoson (14:05:08) : ….”Use Student’s T or Mann-Whitney (Non parametric) and analyze by year or by decade.
NOT significant.”
Correct me if I’m wrong, (I’m not a statistician.) but didn’t they run it monthly as opposed to yearly or decade? And doesn’t that alter the statistical significance? Again, IDK, but I believe that was the complaint in the full article.
At any rate, statistical or not, I would attach significance to it because any increase in sea ice in the SH at all, by inference, runs counter to a lot of the alarmist claims.
we need to have a common label for the AGW crowd.
Start calling them “WARMERS”.
Reply: No. We explicitly recommend not calling people derogatory names. I personally use the term AGW proponent. ~ ctm.
Ahh, here it is….. an excerpt from the full article…
“Notice two things, 1) the figure depicts monthly ice extent anomalies from November 1978 through October 2004, and 2) the trend through them seems to be statistically significant (i.e. the confidence range does not include zero), given in the illustration as 9089.2 +/- 2970.7 km2/year or 0.735 +/- 0.240%/dec.
Yet, for some reason, the accompanying text claims that the trend in Figure 4.4.1b is insignificant (AR4 First Order Draft, page 4-14, lines 9-10):
The Antarctic results show a slight but insignificant positive trend of 0.7 ± 0.2% per decade.”
EPA says 100,000 km2 per decade is statistically insignificant.
In the Greenhouse Gas Endangerment Finding, Response to Comment 2-111, EPA says this (Volume 2 of Responses to comments available here: http://www.epa.gov/climatechange/endangerment.html)
In the April version of the TSD, EPA stated: “Antarctic sea ice extent shows no statistically significant average trends according to IPCC (2007d). However, the U.S. National and Snow and Ice Data Center [NSIDC] states that Antarctic sea ice underwent a slight increase from 1979 to 2007 (NSIDC, 2009).” EPA acknowledges these two sentences, taken together, may confuse the reader. And we are also aware of updated data from NSIDC. So we have revised the TSD to provide more clarity. It now reads: “For the period 1979––2008, Antarctic sea ice underwent a not statistically significant increase of 0.9% (about 100,000 km2; 42,000 mi2) per decade (NSIDC, 2009).”
This is from the article,
“Notice two things, 1) the figure depicts monthly ice extent anomalies from November 1978 through October 2004, and 2) the trend through them seems to be statistically significant (i.e. the confidence range does not include zero), given in the illustration as 9089.2 +/- 2970.7 km2/year or 0.735 +/- 0.240%/dec.”
Just because the confidence range does not include zero, does not mean that the result is statistically significant.