Scott Saleska agreed in cordial terms that this site was attempting to carry out “evidence-based” analysis without deferring to perceived authority. He then asked us to characterize, in our words, exactly what our position was – he agreed that we didn’t contest “basic science”, but then asked (politely) if it was reasonable to say that we contested “consensus science”. The focus of this site has been on millennial paleoclimate reconstructions, since that’s what I specialize in. I acquiesce in some discussion of water vapor feedback and things like that, but I haven’t expressed views on these matters. We may get there some day but we haven’t so far.
In order to answer Scott Saleska’s question, in order to say whether I agree or disagree with “consensus science” in respect to millennial reconstructions (or what aspects I agree or disagree with), the first thing to do is obviously to define what is meant by “consensus science” in respect to millennial paleoclimate?
Not every opinion expressed by a dendroclimatologist is part of “consensus science” (which I take to be defined by IPCC). For example, Martin Wilmking has reported positive and negative responders at latitudinal treeline, a result that he stated would have major impact on the millennial reconstruction project. This finding is not cited nor discussed nor incorporated in IPCC 4AR and thus, even though articulated by an excellent dendroclimatologist, cannot be counted as being part of “consensus science”. In the same vein, certain views and recommendations by the NAS Panel (e.g. bristlecones should be avoided in temperature reconstructions), that are disregarded by IPCC (and even themselves) by using such reconstructions cannot be said to be part of “consensus science”, even though the point of view has been expressed by an important committee.
I think that the “science” is defined by its set of methods and procedures, rather than through genuflection to a particular squiggle (the HS), and accordingly, I have drafted the following list (in no particular order) of what I believe to be the salient elements of “consensus science” in the millennial reconstruction field (and to a lesser extent gridcell calculations) that are discussed at this blog. (I will probably edit and revise this list as I think some more about it):
1. The urban heat island effect in the 20th century is less than 0.05 deg C.
2. In December 1941, although there is no contemporary documentation of the event, all ships around the world synchronously converted from measuring SST using canvas buckets to engine inlets, thereby requiring a 0.3 deg C step adjustment in SST measurements. [This view is held despite the fact that 90% of SST measurements in 1970, for which the measurement method is known were made, were still being made with buckets.]
3. The following position is acceptable: “We have 25 or so years invested in the work. Why should I make the data available to you, when your aim is to try and find something wrong with it?
4. Data collected by a scientist with public funding is his personal property. Funding agencies pay the scientist for his expertise, imagination, and insight to be able to make some advance in our understanding of how nature works, not for raw data sets.
5. Computer codes developed in paleoclimate studies funded by NSF are the personal private property of the scientist.
6. It is prudent to rely on statistical studies carried out by non-statisticians without ever subjecting these studies to a statistical or other audit.
7. If a methodology used in a study in found to be faulty, it is acceptable to keep using the results. [Mann's PC1 is used in the following studies illustrated by IPCC: MBH99, Mann and Jones 2003, Rutherford et al 2005, and remarkably, Osborn and Briffa 2006, Hegerl et al 2006].
8. Calculating a verification r2 statistic for a reconstruction is an incorrect and foolish thing to do.
9. It is acceptable practice to report favorable verification statistics and not report failed statistics.
10. It is acceptable practice to calculate confidence intervals based on calibration period residuals in an inverse regression using 20 or more proxies, even if the verification r2 is much less than the calibration r2.
11. Bristlecone and foxtail ring widths are a valid temperature proxy.
12. The Yamal ring width chronology is a valid temperature proxy, but the Polar Urals ring width chronology isn’t.
13. It is acceptable practice to inspect a data set of (say) treeline white spruce chronologies and report on and archive only the chronologies that go up in the 20th century.
14. Even if two reconstructions have substantial proxy overlap, the reconstructions may be called “independent” if one or more proxies or one or more authors are different.
15. Studies since the TAR draw increased confidence from additional data showing coherent behaviour across multiple indicators in different parts of the world with upper treeline ring width chronologies showing a consistent increase in ring widths in response to warmth in the 1990s and 2000s.
16. If a reconstruction does not record recent warmth, it is acceptable to truncate the reconstruction in 1960 and use the instrumental record afterwards.
17. The following is an acceptable scientific explanation: “In the absence of a substantiated explanation for the decline, we make the assumption that it is likely to be a response to some kind of recent anthropogenic forcing. On the basis of this assumption, the pre-twentieth century part of the reconstructions can be considered to be free from similar events and thus accurately represent past temperature variability.”
18. It is a good idea for an assessment report on a controversial topic to be done by one of the parties to the controversy.
19. Examination of underlying data is not relevant to the duties of an IPCC reviewer.
I’m sure that readers will have additional suggestions which I may incorporate (but please try to maintain the above tone).
The question for Scott Saleska and others: (1) do you feel that it is unfair to include any of the above points in describing the millennial paleoclimate “consensus”? [this is a draft list and not locked in stone] (2) do you support all (or any) of the above elements of the “consensus” on millennial proxy reconstructions?
If the consensus on these points were to be reversed, as I believe that it ought to be, then one could begin the process of assessing the impact of the above positions on detection and attribution studies, the tuning of GCMs etc. I would be surprised if there was no knock-on effect whatever, but have not studied the matter so far.