The Wegman report

There is apparently a strange thing called the Wegman report. Sadly that link only contains Smokey Joe Bartons comments on selected extracts (does anyone know where the full thing is? Is it published? Also quite what the committee/panel is, is rather vague. [Update! Aha… I should have known: since it was Per who commented on it, and since it reads like it was written by M&M, the dark side pointed me towrds the full thing]). Still, what did they say? (BTW, in case you hadn’t realised, this is yet more HS stuff πŸ™‚

the paleoclimate reconstruction… does not provide insight and understanding of the physical mechanisms of climate
change… What is needed is deeper understanding of the physical mechanisms of climate change
Yup, nothing like stating the bleedin’ obvious. Anything better in there?

evaluation by statisticians should be standard practice. This evaluation phase should be a mandatory part of all grant applications and funded accordingly. Aha! He wants more money and more work for statisticians. Not a particularly odd thing for him to say, but I don’t see hard-pressed cliamte researchers wanting to give up their grant money. Unless there is extra available, perhaps from cancelling the “war on terror”.

authors of policy-related documents like the IPCC report, Climate Change 2001: The Scientific Basis, should not be the same people as those that constructed the academic papers.” Sounds good, but probably naive expressed like that. Who else, apart from people who write climate papers, can assess and synthesise the science?

As statisticians, we were struck by the isolation of communities such as the paleoclimate community that rely heavily on statistical methods, yet do not seem to be interacting with the mainstream statistical community. The public policy implications of this debate are financially staggering and yet apparently no independent statistical expertise was sought or used.” Dubious. It gets said again and again that the HS isn’t a major part of attribution, but no-one listens. Probably a good argument for not letting people who know nowt about climate too close to it. I’m not sure about the isolated bit… maybe it just means Wegman doesn’t know Mann. But then Mann doesn’t know Wegman… does that make W isolated?

As mentioned earlier in our background section, tree ring proxies are typically calibrated to remove low frequency variations. The cycle of Medieval Warm Period and Little Ice Age that was widely recognized in 1990 has disappeared from the MBH98/99 analyses, thus making possible the hottest decade/hottest year claim. However, the methodology of MBH98/99 suppresses this low frequency information. This is weird, and appears to mix up different things. I haven’t seen anyone previously claim that the MBH method suppresses low-f info thats in the proxies. If tree rings don’t have the info, it can’t create it. The assertion about what was widely recognised in 1990 is dubious, and appears to be a re-run of the IPCC ’90 fig 7.1 stuff again (see

Um… so, that was fun, but the full report would be more interesting.

OK, picking a bit from that:

[M&M 2003] … claimed that using the MBH98 methodology and the Northern Hemisphere average temperature index for the period 1400-1980 shows that temperatures in the 15th century exceeded those of the late 20th century. In particular, they claim that MBH98’s incorrect usage of PCA alone resulted in the well-known “hockey stick” shape. This is a bit weird. If using MBH98 produces a warm 15th C, how can they also claim it always produces a HS?

37 thoughts on “The Wegman report”

  1. The report is devestating. It is by premier statisicians and finds the same serious problems that MM found in the Mann work. They also report the same soft issue problems (people not willing to show their data and methods so that they can be checked for accuracy) that MM noted. It’s a crusher for Mann. He is going to look really bad if all he can do is ad hominem against these guys. If he can’t dispute the statistics.


  2. The Wegman Report is very clearly written by top statisticians. It agrees with everything M&M have been saying and shoots MBH down in flames.
    Time for you to decide if you are an honest man, William.

    [It does pretty well endorse all the M&M claims. Indeed it could practically have been written by M&M. Of course it was written at the behest of Barton, well-known for his neutrality in this debate. And (as I’ve detailed) they make several mistakes. It remains to be seen if the report gains much credibility -W]


  3. It’s brutal. Those guys are big guns in stats too. Mike better figure out something better then the ad hom. Better figure out a way to argue the science. They ripped him apart.


  4. TCO, don’t be silly. The report is a damp squib. No surprise that you’d try to hype it though.

    [Tim – stop commenting here, go and fix the problem with Deltoid that won’t let me see the Peiser posting! – W]


  5. there is a background to this. It was Barton that highlighted some of the concerns about MBH, and that lead to turf-wars between congress’ science and energy committee. Science committee won, and thus the NAS commissioned the report.

    However, the recent NRC report conspicuously failed to address some of the principal issues raised by Barton. It seems the Barton report might be very embarrassing for the science committee.

    Interesting to see TL’s opinion that the report is “a damp squib”. Tim’s expertise in statistics is widely known, and I am sure he only needs to educate the good prof wegman for him to realise the error of his ways. The following link should give you some indication of the holes in his statistical knowledge.

    toodle-pip !



  6. An aside: I Googled for toodle-pip and only found this.

    But I appreciate per’s perambulation on the issue, as it is always interesting to see folks pick and choose facts and events to suit their received/chosen/remunerated worldview and then explain them to others.

    May I also point out that this august Committee also said:

    In a real sense the paleoclimate results of MBH98/99 are essentially irrelevant to the consensus on climate change. [pg 66]

    But, being 90-some pp., there should be enough grist for the astroturf bot mill for some time to come, eh per?




  7. Per: It wasn’t just a “turf-wars” between the energy and science committees. It was a war between one of the last of a dying breed of Republicans who actually has some respect for science and the scientific process (Boehlert) and one of the new breed of Republicans who sees science as a tool to be manipulated like any other tools for the ideological and economic interests of themselves and those who fund their campaigns (Barton).


  8. Re: Joel Shore and the difference between Barton and Boehlert –

    Yes, Sherwood Boehlert not only respects science, but actually is a scientist.

    I have found him worthy of respect on just about every issue and will sorely miss him as he is retiring this year.


  9. It gets said again and again that the HS isn’t a major part of attribution, but no-one listens.

    He was talking about public policy implications, but I guess you weren’t listening.


  10. Wait, “It gets said again and again that the HS isn’t a major part of attribution, but no-one listens.”

    Weird, read the IPCC 2001 TAR quite awhile ago, but… by what other limit/metric can one determine magnitude of natural global temp. avg. variation? There really isn’t a choice is there?

    don’t have to look very far to see D/O events, (somewhat negating the ‘unprecedented rate'[of climate change] arguments). Hell, I think on RC ya said that D/O oscillations were evident in antarctic cores, (at the same time as greenland records, thus making us think they’re kinda global) nah?

    [I think you ought to re-read the TAR in that case. Or the AR4 draft -W]


  11. Awww hell, you’re on science blogs, stir up some damn controversey. Screw it, being white kinda sucks…

    from now on I’m gonna be a korean b-boy from taiwan with a white skin but LOTS of attitude!!!


  12. Cytochrome Sea: The problem is that even if we can tell past climates we can’t tell much about the forcings that were in effect at the time so we really don’t get an idea of natural variation.

    Think about this another way, even if the current climate is within the natural variation but we can show that GHGs are driving it higher – would that be a cause for concern? I think it would. The converse is also true, if the current climate is outside the natural variation but it is being driven by something other than GHG would that be useful information? I think it would.

    So while the idea of natural variation is an interesting one and easy to understand it is far better to understand the current forcings in order to predict what will happen in the future.


    I posted more on this at Deltoid, but is there any way that Esper and Moberg can be intreperted to show that the MWP is warmer than current temperatures? If not I would say there is a significant lack of understanding in the report.


    [You’ll find them on the pic at . So, wamer than current is not possible -W]


  13. The defenses of the Mannians are postmodernistic. They can’t argue stats and so they try to argue authority. Good luck trying to say that Wegman lacks the ability to evaluate stats methods. He’s got a lot more ability there then the Mannians. What’s really amusing is how he pulls back the curtain on the opaque language and confusing descriptions that Mann tries to use. That CPS is averaging and CFR PCA and the like. That Mann (while trying to look smart and on high to Barton) actually confuses the meaning of r.


  14. >The peaks in medieval times are at the same level as much of the twentieth century, although the post-1990 warmth seen in the instrumental data (green curve in Fig. 2b) appears to be unprecedented.

    unless you use the instrumental, moberg says the proxies are at the same level as in the past



  15. Per your quote highlights my point very well. If you remove the instrumental then you can say that the levels are the same as much of the 20th century but since the reconstruction ends well before the present you can;t say anything about current levels.

    But what they say is “Both Esper et al. (2002) and Moberg et al. (2005) indicate that current global temperatures are not warmer that the medieval warm period.”

    The reconstruction ends well before the current but yet they use that word. This is not just a little slip. They could have been safe and used Moberg’s wording as you did but they didn’t. The only explanation is that they thought the reconstructions extend to the current time. This shows a distinct lack of understanding of the methodology.


  16. But it moves:

    “We note here that we are statisticians/mathematicians who were asked to comment on the correctness of the methodology found in MBH98/99. In this report we have focused on answering this question and not on whether or not the global climate is changing. We have discussed paleoclimatology only to the extent that it was necessary to make our discussion of the statistical issues clear. The instrumented temperature record makes it clear that global temperatures have risen since 1850 CE. How this present era compares to previous epochs is not clear because the uncertainties in the proxies. However, it is clear that average global temperature increases are not the real focus. It is the temperature increases at the poles that matter and average global or Northern Hemisphere increases do not address the issue. We note that according to experts at NASA’s JPL, the average ocean height is increasing by approximately 1 millimeter per year, half of which is due to melting of polar ice and the other half due to thermal expansion. The latter fact implies that the oceans are absorbing tremendous amounts of heat, which is much more alarming because of the coupling of ocean circulation to the atmosphere. (See Wunsch 2002, 2006).”
    WSS (2006)


  17. Eli, I had scanned that little apologia earlier. It’s interesting in various ways, but on reading it again now I see that the last sentence says that Wehman et al are (in their own words) AGW alarmists!

    Everyone, Lubos is very upset because the Barton/Wegman report is getting very little traction in the media. OTOH it does give him a chance to practice his vocabulary.


  18. Do you all recognize this phraseology?

    “we … were asked to comment on the correctness of the methodology found in MBH98/99. In this report we have focused on answering this question and not on whether or not the global climate is changing.”

    That’s the defining paragraph of a standard business audit letter. It warns that whatever else they saw, they were not charged with reporting in this document.

    They go beyond what they were asked to report, in concluding: “… the oceans are absorbing tremendous amounts of heat, which is much more alarming …”

    It will be interesting to see if they have caught the spirit of inquiry by this contact and begin looking into present day science, and offering to be helpful. Time will tell.


  19. John Cross: thanks for the response. But the idea of natural variation is (I think) pretty important. I disagree when I think you posit that it might be easy to understand, cause I don’t think that it is.

    Keeling himself (I think?) had a paper out about 4 years ago dealing with lunar (tidal)_gravitation and tidal fluxes, and postulated about increased oceanic surface water mixing being able to release more IR heat into the lower tropo. Don’t have the link, but it’s a decent read.

    Okay, a quick pet peeve since I’m posting on William’s blog.

    What is the difference between LW and SW radiation?
    I’ve seen a couple goofy descriptors in physics, but nothing like this. Usually only see LW and SW descriptors in climate or weather related topics. Have mostly seen the descriptors used when speaking to the average Joe, but have seen them in some papers too, and I’m really curious as to whether or not they have a precise definition.?

    Just wondering if there is a defined boundary wavelength,
    separating the two, and if not, why not just say 26 microns and be done with it πŸ™‚ heh… geez…

    [SW is the visible bit (and above). LW is the invisible bit (and below). Happily, they don’t much overlap, which is useful -W]


  20. Eli: good point. Although I think I have a couple questions on Hansen’s thermal inertia of the ocean lag argument (probably because I haven’t read enough though πŸ™‚

    The thing is, thermal expansion will be (for all general purposes of measurement) almost immediate. The measurements do not seem to indicate that this is happening.

    The oceans themselves are pretty awesome though.

    [Thermal expansion occurs not only as the sfc warms but as the warming penetrates into the ocean. Hence delay -W]


  21. WRT to Moberg et al 2005, I think? I located the link to a graph that I thought poignant in their supp. info, I’m not able to access the graphic anymore, anyway, here it is:

    Subscribers should be able to see it, me thinks. IIRC, (granted, unable to see the graph right now) PRE-calibration to the modern instrumental period seemed to yield somewhere along the lines of .2 to .25 degrees K warmer in the MWP period. (on average in Europe…?) Who knows?


  22. cytochrome sea: Bad wording on my part. I did not mean that understanding how the climate changes is easy but rather the metric of natural variation is easy to understand. For example you have an upper line for natural variation and a lower line for natural variation then plot current temperature. If it is above then we are outside, if it is between then we are inside.



  23. This shows a distinct lack of understanding of the methodology.

    Why would a mistake about when a series ended indicate a misunderstanding of methodology?


  24. At this stage it’s probably more about tribalism & egos than science (on all sides). Call me elitist but I’m not too knocked out by Wegman’s credentials as a prof at George Mason U, nor do I think he, who was leader of Reagan’s idiotic “Star Wars Program”, could be seen as an impartial, unbiased person. Sounds like the psycho Republicans like Barton are just calling on the old white guy network…

    [Um. Maybe I’ve taken Wegman too much on faith. Fair point… -W]


  25. NGS: The temperature record in paleo studies come from proxy work (the reconstruction) and current instrumental records used to calibrate the reconstruction. In Esper and Moberg the same process is used with Esper’s proxies ending in 1992 and Moberg’s ending in 1979.

    In both cases the reconstructions show temperatures lower than the MWP. However the reconstructions do not show current temperatures. To show current temperatures you need the instrumental record.

    Wegman appears to think that the reconstructions extend up to the current time or that the temperatures are static from the end of the reconstruction period. If the former he does not understand the need for the two parts of the temperature record, if the latter he doe not understand what the instrumental record is used for.


  26. William, I’m an idiot, and thanks. Makes good sense.

    John Cross, lame of me to nitpick, I was drunk, and apologize.

    Yet I definitely disagree with your July 18th post,”Wegman appears to think that the reconstructions extend up to the current time or that the temperatures are static from the end of the reconstruction period. If the former he does not understand the need for the two parts of the temperature record, if the latter he doe not understand what the instrumental record is used for.”

    Have another read, then have another go. πŸ™‚

    William, again thanks: “[Thermal expansion occurs not only as the sfc warms but as the warming penetrates into the ocean. Hence delay -W]”

    Hey, it’s just a bit difficult for me. Wouldn’t the AGW effect be most prominent near the surface microlayer? The conductive layer would take a pretty big hit too, I think?
    The effect would *slowly* go deeper, yet the expansion would have to be very rapid, no? It’s almost impossible to think that it wouldn’t.


  27. CS – the sfc microlayer will mix quickly into the mixed layer, which is 100m odd deep. The expansion, of course, is instantaneous effectively as soon as whichever bit of ocean warms.


  28. Pssst — William — please educate this editor, his headline writing analogy insults weasels, I’m sure out of ignorance, by suggesting they are like unto …. shudder …. Ick. A political PR professional.

    It’s as misguided or thoughtless as the picture caption (linked at Pharyngula) by the WWF, where someone wrote “nature is revolting” under pictures of flying cephalopods.

    After all, what have weasels and cephalopods done that we should disparage them?


  29. John Cross: I just typed a rather lengthy response but am sobering up a bit and deleted it. I’ll try to be more curt πŸ™‚
    And quote real quick: “Wegman appears to think that the reconstructions extend up to the current time” The proxy recos or the surface temp recos? A quick skim again and it looks like they mainly considered proxies up to ~1980. And presented complaints about calibrating the proxy recos to the mean of 1902-1995 sfc recos, and due to the upward trend present in the latter, considered the calibration (in this case) a “misuse” of the method employed.

    William, re-reading your earlier response ([Thermal expansion occurs not only as the sfc warms but as the warming penetrates into the ocean. Hence delay -W]) it certainly makes sense for most regions, but I’ll still stand by my (inconsequential) remarks about it having the most effect ~the surface microlayer and conductive layer. (due to the higher TEC of water at higher temps above 4C? and all)
    And of course, as the warming penetrates into the ocean, this will reduce the amount of Thermal Expansion for the same quantity of energy. (to a point)

    I suppose vertical mixing assumptions (among other things I’m not considering, cause I don’t know πŸ™‚ must vary quite substantially to give the future ranges of mean sea level rise I’ve seen estimated. (wasn’t considering freshwater melt and isostatic rebound of course)


  30. Wegman was surprisingly aware of ocean heating, for someone who thinks of CO2 in terms of layers in the atmosphere; maybe he was thinking of ocean layering?

    This abstract caught my eye today:

    “… The temperature changes reported here, if they were to hold throughout the abyssal world ocean, would contribute substantially to global ocean heat budgets.”

    I wonder, I have no idea if ‘contribute’ there means add to or just rearrange the amount of heat in the budget.


  31. Eli, thanks, but as I tried to note earlier with, “(wasn’t considering freshwater melt and isostatic rebound of course)”
    but checked out your link. I only see pictures of curves without any substantial information as to how they were derived. (should try to the links but don’t have much time)
    I’m wondering if cyanobacters, carbon soot, direct reflection, anisotropic specular reflection, general specular reflection, etc… are taken into account into the models that produce the curves. (IMHO ‘albeity’ is a WEAK description)(great for astrophysicists, weak for anyone else πŸ™‚

    William, mean sea level rise is looking weirder by the day. Earlier I questioned that the idea of the “thermal inertia” “lag” of the oceans (which, don’t get me wrong, I’m not questioning the amount of KeV stored, only the idea of a “lag” as far as expansion, and I do try to understand the transport mechanisms, (and I was poorly conveying the obvious; due to the inherent thermal expansion coefficient of saltwater, the sea levels might be expanding a bit, yet due to the (how?)(important)rapid vertical mixing, the more rapid the vertical mixing the faster the joules sink, and
    the faster they do, , the less thermal expansion you will get. (do I sound like Yoda there?) Heh, anyway, when I said, “MSL weirder by the day” I was mainly referring to the recent Willis et al paper. It’s recent, and it might turn out to have flaws, but it presents weird hypotheticals, sorta weirdin me out.


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