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Table of contents for Rahmstorf
“According to a new U.N. report, the global warming outlook is much worse than originally predicted. Which is pretty bad when they originally predicted it would destroy the planet.” –Jay Leno
If ever there was a good example of alarmists views being given a free ride by a major journal, then the publication in Science of “Recent Climate Observations Compared to Projections” by
Stefan Rahmstorf, Anny Cazenave, John A. Church, James E. Hansen, Ralph F. Keeling, David E. Parker, and Richard C. J. Somerville is it.
This paper claimed to show that:
The data available for the period since 1990 raise concerns that the climate system, in particular sea level, may be responding more quickly to climate change than our current generation of models indicates.
By way of recap, this paper figured prominently in the Interim Report of the Garnaut Review where it is clearly used as a source of mainstream scientific opinion:
“Developments in mainstream scientific opinion on the relationship between emissions, accumulations and climate outcomes, and the Review’s own work on future business-as-usual global emissions, suggest that the world is moving towards high risks of
dangerous climate change more rapidly than has generally been understood.”
Interest in the current weather has been growing since people have been observing either sharp declines in temperatures since last year, or relative stability in temperatures over about the last 10 years and wondering how these fit into the picture of global warming. I did some posts putting it into context showing last years temperature drop was not unusual here, that a particular 10 year period has been flat here, and that a number of climate indicators are showing decadal stability here.
The Blackboard has been spear-heading rigorous statistical methods for checking IPCC projections and finding post 2001 TAR consistently falsified by climate trends.
Contradicting these findings was the paper by Rahmstorf et al 2007, published in Science, by seven of the leading members of the IPCC scientific team. So, I started to audit this paper to see if this paper does in fact provide a more reliable perspective on the issue of whether climate is changing faster or slower than expected.
A number of bloggers ‘raised concerns’ about the vague description of the methodology, and argued at Niche Modeling and The Blackboard that there were important sources of uncertainty unaccounted for. Other blogs picked up the issue including Peter Gallagher and Mark Lawson.
Stefan Rahmstorf and I exchanged comments at RealClimate.org and here.
His main defense was that the end point uncertainty would only affect the last 5 points of the smoothed trend line with an 11 point embedding. Here the global temperatures were smoothed using a complex method called Singular Spectrum Analysis (SSA). I gave examples of SSA and other methods where the end point uncertainty affected virtually ALL points in the smoothed trend line, and particularly more than 5 end points. Stefan clearly had little idea of how SSA worked. His final message, without an argument, was:
[Response: If you really think you’d come to a different conclusion with a different analysis method, I suggest you submit it to a journal, like we did. I am unconvinced, though. -stefan]
So much for the recap. Keep in mind that the purpose of a scientific exchange like this is to clarify the points of agreement and disagreement and attempt to arrive at a resolution on the validity of the claims. Note the problem I raised is not the only obvious problem either, but just one I worked on. This is not meant to be a personal process. I am grateful for someone to point out errors in my work and would try to understand them, as I would rather not be blowing smoke unintentionally.
This example highlights the power of numbers to resolve an issue. Stefan can have his opinion, and I have opinions too, but the thing I love is the power of numbers to arbitrate and discriminate, and ultimately eliminate the unjustified ones.
Also I was wanting to address the Garnaut Review, as I feel that they are abrogating a duty of diligence by not paying more critical attention to papers such as these. Here was an opportunity to give a specific example of a paper with flaws so obvious that it SHOULD have been dismissed by anyone with statistical training, or background knowledge.
So thank you readers for your patience with this process. I have put a submission into the Garnaut Review supported by documentation from the web sites involved.
Here is a good example of the use of blogs. As the time for comments has closed, I could not submit a critique to Science. It is also better to have a through and open discussion of the issues at hand anyway, before rushing to publication of critical comments, so both can gain a deeper understanding of the finer points. It is unfortunate that Stefan cut the discussion off, but to his credit he was responsive to the actual concerns in the replies he did make.
14 responses so far ↓
On a pedantic point, I have to disagree with you David. Numbers do not have the power to arbitrate and discriminate; only people have those powers. Numbers can also defeat habits of discrimination — even those of good scientists like Ross Garnaut, it seems — by creating an impression of discovery and precision (’conclusiveness’) where neither exists. This, I think, is the important contribution that you and Lucia Liljegren have made to the debate about Dr Rahmstorff’s paper.
Prof. Garnaut’s Interim Review has rather uncritically adopted the Rahmstorff et. al. conclusions that recent trends surprise by overshooting IPCC projection. Accordingly, the Review proposes to build, at public expense, on this shaky foundation a huge edifice of carbon mitigation. This is asking for trouble.
Good policy practice, even in the case of ‘precautionary’ action demands proportionality between the apprehension of a threat and the cost of the avoidance measures. The technical criticisms you make of the Rahmstorff et. al. methods tend to reinforce the naive view that there is nothing in post-1998 temperature trends that even remotely resembles an “overshooting” of the IPCC projections(0.2 deg. per decade). Prof. Garnaut should at a minimum take up Ian Castles’ challenge to defend the Rahmstorff contention, or find another fulcrum for his proposed radical policy levers.
It would be useful if critical analyses of climate science citations made by Garnaut be submitted to the Henry Thornton web site - Garnaut is one of the contributors and I suspect Henry will be willing to add another opinion to that published there.
Bear in mind that Henry Thornton is essentially an economics web page that is read my many in the Australian Government, so material like is is best put there.
I have had politically incorrect articles published there and some of Henry’s readers demanded he remove me as a contributor. Henry resisted admirably.
Just mention when submitting that Henry’s wandering geologist suggested it.
Peter: I agree with you on the first point that numbers can be misused, but its not inconsistent with advocating better numeracy skills throughout society. Also agree with the rest of your comment.
Louis: Thanks for the suggestion. I will put it on the queue after the current work.
David and Peter,
I wonder whether the Statistical Society of Australia Inc. (SSAI) might be
persuaded to take an interest in Rahmstorf et al (2007) and its uncritical
adoption by the Garnaut Review in its Interim Report?
The SSAI has an active interest in �advocating better numeracy skills
throughout our society�, and has what amounts to a manifesto in
support of this objective on its website at http://www.statsoc.org.au/PublicAwareness/.
The page carries a link to the Society�s provocative booklet
�Statistical Success and Disaster Stories�.
In her Comment 2038 on the �Comment on the Slide and Eyeball Method�
on her blog, Lucia characterizes the paper as �dreadful� and argues that the
publication of the paper in �Science� reflects badly on the journal.
In my comments on several blogs I�ve drawn attention to the eminence of the
seven authors, their leading roles in the IPCC and the high prestige of the
institutions with which they are affiliated.
Your submissions to Garnaut and the key posts on �The Blackboard�,
�Niche Modeling� and �RealClimate� could be cited in support of a proposal
that the Society establish a working group of experts to review the use of
statistics in the paper in the light of the criticisms that have been made, and
produce a report that could be published electronically by the Society and
drawn to the attention of appropriate persons and organizations in Australia and
overseas. The report would not necessarily endorse all of the criticisms
that have been made of Rahmstorf et al, but would almost certainly find
the paper seriously wanting.
One point I need to mention is that the SSAI is affiliated with the
Federation of Australian Scientific and Technological Societies, an
activist body which claims to represent the views of Australia�s 60,000
scientists (or whatever the current number is). I�ve been a member of the SSAI
since 1986 and have had some run-ins with FASTS in which I�ve forcefully
pointed out that they couldn�t count me among the 60,000 for whom they claimed
to speak. It might be desirable to assure the SSAI that the purpose of the
proposed exercise would not be to criticize scientists but to draw
their attention, and that of the institutions with which they are affiliated,
of the need for the active involvement of statisticians in many areas of
scientific inquiry = and notably research into climate change.
That would be good indeed. It occurred to me that even the most staunch global warming supporter could be concerned with this paper as it argues for warming faster than the IPCC consensus.
Garnaut is farther to the alarmist position than he pretends, as shown by his boosting of papers that believe the world is warming faster than the IPCC consensus position.
I was under the impress that IPCC was ‘mainstream scientific opinion’. When did it suddenly become too conservative?
Ian, that sound like a good idea. Presumably the Membership of the SSA would have to take this up with the Society. But perhaps others can suggest it would be a public service. Is the Environmental Statistics section the right place to start? Their Chair’s email is listed here: http://www.statsoc.org.au/Sections/Environmental/
Peter, I don’t know any of the officebearers, either in the Environment Section or the Executive Committee (the President is a professor at UNSW, I think that I noticed). I think that it might be best to go directly to the President - I doubt if the Environment Committee could consider taking this forward on their own bat anyway. My first thought was to take this up through the Australian Bureau of Statistics but on reflection, and bearing in mind the sensitivities, I’m inclined to think that that might be putting them ‘on the spot.’
Would you consider writing to the President of the SSAI to make this proposal? You could refer to your submission to the Garnaut Review and to the correspondence that we’re now having. You could note David’s credentials as the author of ‘Niche Modeling.’ And you could say (if you agree with this) that any review should preferably be undertaken by expert statisticians outside government. It does seem to me that the Garnaut Review’s uncritical use of this paper provides the SSAI with an opportunity to intervene in this matter in the national interest.
It would be ideal to have an ongoing, but independent critical input from statistical consultants. One problem with Inhofe Committee was that it ended. It is unacceptable that:
Ian, I like your idea the more I think about it. Given this is the only paper cited in Garnaut as supporting accelerated warming, it is unacceptable that this is merely regarded as a ‘difference in opinion’ and it should be a resolvable question. Is this paper a statistical shocker or not? Stefan’s doesn’t want to talk about it, preferring to refer it to the ‘court of peer review’. Independent review is the next step.
I have just seen Ian Castle’s suggestion about a letter to the President of the SSAI. I have drafted this letter that makes the points he suggests. I will email the letter in the next day or so. If readers of this website have any comments to add, meanwhile, please email me using the link on my website.
My apologies, Ian, for the misplacement of the apostrophe in your name. Peter.
Damn! The link to the letter does not work. Please find the draft at: http://www.petergallagher.com......letter.pdf
Peter,
That looks good. Perhaps there is a need to put in the actual links as they will scroll off the blog.
http://landshape.org/enm/rahmstorf-7-finale/ for summary.
http://landshape.org/enm/rahms.....pcc-error/ for discussion.
Regards
14 Niche Modeling » Global Warming Statistics: OET (ordinary eyeball test). // Jun 9, 2008 at 12:48 am
[...] Experience has shown that it produces reliable results in almost every situation. Moreover, these results are very convincing. So convincing was the OET known as the Hockey Stick that it was used in press releases of Third Assessment Report by the United Nations’ Intergovernmental Panel on Climate Change (IPCC) in 2001 report, featured in the award winning movie “An Inconvenient Truth”, and is still widely used throughout government and science. It has rendered yeoman service in garnering acceptance for the false notion that temperatures are the highest they have been for a million years. Figure: Example of the Ordinary Eyeball Test (OET) from Rahmstorf et al. 2007. One of the most recent examples of the OET is in the publication by seven IPCC lead authors (the Rahmstorf7) of Rahmstorf et al. 2007 in Science. Here it was used as the main scientific support for the notion of a present ‘runaway warming’ using a classic OET method to demonstrate that “the climate system is responding faster than our current generation of models suggest”. So convincing was this OET that on this piece of evidence alone, the Australian Garnaut commission determined that “Developments in mainstream scientific opinion … suggest that the world is moving towards high risks of dangerous climate change more rapidly than has generally been understood”. Recent economic modeling shows that implementing a 90 per cent reduction in carbon emissions by 2050 would alone require closing 3 out of 4 coal fired power stations, and building new clean power stations at a cost of $50 billion dollars. Unfortunately the OET is vulnerable to attacks from the numerate, particularly the claim that uncertainty has not been properly accounted for. Some of the curve has been taken off the Hockey Stick with his studies, but this has not prevented it from remaining in widespread use. The OET must be valid as these papers have been accepted by reviewers in Nature and Science. Some concerns have been raised in a submission to the Garnaut commission pointing out more arcane part of the methodology stems from the same person who developed Hockey Stick (Michael Mann) and that it advocates an even more extreme position than the already quite extreme global warming consensus of IPCC. On questioning about the uncertainty in the OET of the Rahmstorf7 at RealClimate.org, Rahmstorf seemed confused about the operation of the methodology itself, and suggested it concerns be taken to peer review. It never pays to look too closely at an OET. There are a few of the opinion that even papers that have passed Science and Nature’s peer-review processes, and scientific reports such as the IPCC approved by more than 100 governments, could benefit from review of the methodology by at least one expert statistician. But then the statistical deficiencies would be brought to wide public notice and much of the effectiveness of the OET would be lost. [...]
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