So… where to start? Back in the dim and distant days of a year or so ago, or back to the TAR, there was a problem: temperature trends at the surface and upper atmosphere were incompatible with how the models said they should relate: the models said the upper trends should be larger, obs said otherwise. As it happened (see here and here) the models (and the surface record) ended up triumphant (to somewhat oversell it); and the upper air obs got revised.
But in between the recognition of the problem and its resolution, the CCSP decided to convene a panel to look at the problem and see how it might be resolved. But the CCSP was slow and cumbersome, and has only just got round to releasing the third draft (to be fair, it was probably in the course of working for this report that Mears and Wentz found the big error in S+C’s MSU dataset). I haven’t read the report yet, but I’m guessing from RP Sr’s dislike of it (and his response of dissing the authors) that it will come to the obvious conclusions. Oh all right, I’ll read some of the abstract:
Previously reported discrepancies between the amount of warming near the surface and higher in the atmosphere have been used to challenge the validity of climate models and the reality of human-induced global warming. Specifically, surface data showed substantial global-average warming, while early versions of satellite data showed little or no warming above the surface. There is no longer evidence of such a discrepancy. This is an important revision to and update of the conclusions of earlier reports from the U.S. National Research Council and the Intergovernmental Panel on Climate Change.
I suspect thats as far as most people will get, since most people don’t need to know any more. And from the exec summary: This difference between models and observations may arise from errors that are common to all models, from errors in the observational data sets, or from a combination of these factors. The second explanation is favored, but the issue is still open. Which seems fair enough, but you can see why some people would be unhappy.
But the most fun can be had from reading the list of commenters and then the comments themselves, together with the responses. Those from Douglass are funny, and the responders blow him away. For example:
Douglas ES-8, P13, L262-3, Quote from report: “Since 1979, due to the considerable disagreements between tropospheric data sets, it is not clear whether the troposphere has warmed more than or less than the surface.” Comment: Not true. Do Thorne and Free agree? Response: This is true. It is the considered opinion of the expert author team. Thorne is a member of this team, and, of course, he agrees. Free, who has been consulted at numerous times by the author team and who has participated in some of the meetings of the team, also agrees.
Note that the responders don’t seem to have troubled themselves to spell Douglass correctly. Douglass wrote some stuff with Singer – e.g. Altitude dependence of atmospheric temperature trends: Climate models versus observation which actually got published by GRL. Speaking of Singer, he too commented, and he too has embarassed himself and gets blown away:
Singer ES-17, P18 line 357-364: We don’t see any evidence for the claimed anthropogenic influence in the climate record. The “fingerprint” results claimed in IPCC-SAR have been discredited. Response: The reviewer does not identify “we”? There is a vast literature on fingerprint studies, much of which is reviewed in Chapter 5. None of this literature has been discredited.
Elsewhere, Singer gets “Bottom line: The Reviewer’s unsupported assertion is incorrect.” Oh Lordy, and *then* he goes on about ozone again: “[Singer:] The observed stratospheric temp decrease is difficult to explain by ozone depletion… Response: Again, the Reviewer simply makes unsupported assertions.”
Trenberth also fares somewhat badly in the responses to his comments (for the exec summary; his detailed comments on the chapters look to have been accepted; and his comments on chapter 5 were: “This chapter is pretty good but I only skimmed it” which drew: “Response: Thanks! No change required.”), but for different reasons. E.g. T says The UAH record has once again been revised but the new T2LT values are at odds with surface temperature trends. Chapter 4 falls short in not presenting maps of this difference. Accordingly, this dataset ought to also be discounted. Given the UAH algorithm that is designed to minimize trends, this dataset ought to be given lower weight, but no commentary appears on this issue. Throwing out UAH (ie, Spencer and Christy) would remove most of the niggles that remain, but given the panel that wasn’t likely (later on we find The question of which satellite dataset is the most accurate… is still an open question subject to several different points of view that were represented on the author team.
Sci.env’s own Eric S also comments; as does Haroon Kheshgi, ExxonMobil Research & Engineering Company (which is a bit of fun in itself: I thought Exxon has sworn off actual climate research: it certainly seems very reluctant to talk about it). HK ends up arguing against the use of “strong” in terms of attribution,
MacCracken has a good general comment Overall, from a purely scientific perspective, this assessment provides a very well done scientific overview of the topic. However, this draft does seem to underplay the significance of the most recent papers in helping to resolve the key issues under investigation, specifically in identifying why some of the datasets developed over recent years are very likely to have flaws. which is also my perspective, though I probably couldn’t justify it.
Oooooohhh and it gets better: In that the CCSP assessments are intended to provide information for policymakers [given that they are said to be in response to the relevant section of the US Global Change Research Act], this draft of this assessment seems to me seriously deficient in providing a historical perspective of this issue and a critical evaluation of past claims that have been made about the supposed accuracy of the early versions of the datasets and what the available data were purported to indicate about scientific understanding of climate change. For more than a decade, some of the datasets have been purported to be highly accurate and to indicate that the model simulations must have serious shortcomings. This report shows that those claims, which were made not only in the scientific community but were picked up and loudly exclaimed by some politicians and a number of industrial organizations, were based on a seriously flawed analysis because of flaws in the satellite record. I would urge that, at the least, a table or an appendix be added that gives a timeline of the history of the corrections that have had to be made to the satellite record and that indicates the past claims that should therefore be discounted (and that the IPCC rightly did not accept at the time–leading to some misdirected criticism of their careful approach). By golly there’s good stuff in there! This open commenting is wonderful.
RP Sr rides his usual hobby horses of regional change and ocean heat content, and gets ignored. After a bit more, they clearly get bored with him when he gets on to the “first order” stuff: Quite frankly, the Reviewer’s position on this issue borders on the ludicrous.
But to finish on a happy note, Trenberth says (of chapter 6) Amen to most of this. This is the most important chapter in the whole document. Chapter 6 is dominated by the Met Office (hurrah!) and is called “What measures can be taken to improve our understanding of observed changes?” Well, maybe in another post…
[Update, on a sadder note. RP has completely “jumped the shark” on this one (is that the right expression?). Anyway, he has not one but two more posts on this, and says:
From the abstract, it is clear the removal of an inconvenient data disagreement (the differences in the surface and tropospheric temperature trends) was THE reason for the Committee and the Report. The scientific issues that I raised in my Public Comment were glossed over or ignored, and the conflict of interest issue with respect to the Committee was completely ignored.
If we re-write this somewhat, to replace “removal” with “investigation” or “reconciliation” then the response to the above is “Duh! Of course it was”. The title of the report, “Temperature Trends in the Lower Atmosphere: Steps for Understanding and Reconciling Differences” is just a teensy hint, no?]