Gergis’ Two Medieval Proxies

Jun 3, 2012 – 10:27 PM

IPCC AR5 (First Draft) cited Gergis et al as follows:

New paleo records from Australasia provide evidence of MCA warming around 1250–1330 CE, [my bold] somewhat later than maximum medieval warmth described from many Northern Hemisphere regions (Gergis et al., submitted). Following peak medieval warmth in the early 1300s, a cooling trend reaching a temperature anomaly of approximately 0.5 ± 0.18°C below the 1961–1990 CE climatology during the peak of the LIA, 1830–1859 CE (Gergis et al., submitted).

In addition, the Gergis reconstruction was one of a number of regional reconstructions compared to model simulations.

The “New” Paleo Records
What are the “new paleo records from Australasia” that shed this new light on the medieval period?

Gergis et al has only two proxies in the period 1250-1318: tree ring series from Tasmania and Oroko Swamp, NZ, both from Ed Cook. Neither of them are “new’. Nor is a third long proxy, Law Dome O18 (screened out by Gergis.)

The “New” Gergis Proxies in IPCC AR4
Not only are the “new” Gergis proxies not new; they were prominently displayed in the AR4 section on SH proxies. Indeed they are the only two long proxies so displayed. The commentary in AR4 is as follows:

The paucity of SH proxy data also means that uncertainties associated with hemispheric temperature estimates are much greater than for the NH, and it is more appropriate at this time to consider the evidence in terms of limited regional indicators of temperature change (Figure 6.12).

The long-term oscillations in warm-season temperatures shown in a tree ring reconstruction for Tasmania (Cook et al., 2000) suggest that the last 30 years was the warmest multidecadal period in the last 1 kyr, but only by a marginal degree. Conditions were generally warm over a longer period from 1300 to 1500 (Figure 6.12). Another tree ring reconstruction, of austral summer temperatures based on data from South Island, New Zealand, spans the past 1.1 kyr and is the longest yet produced for the region (Cook et al., 2002a).


Figure 2. Excerpt from IPCC AR4 Figure 6.11, showing Tasmania and Oroko NZ tree ring chronologies.

The two long series illustrated in AR4 come from the same two sites as the two long Gergis series.

In fact, the Gergis version of Cook’s Tasmania series appears to be identical to the version used by IPCC, as shown in the panel below, where the Gergis versions is overprinted onto the IPCC graphic (rescaling by eye). It appears that Gergis used a newer and somewhat different version of Cook’s Oroko Swamp series, but the differences are not material other than Gergis has values post-1957, while AR4 didn’t. The original article says that logging impacted post-1957 growth; Gergis says that her post-1957 have been adjusted for post-1957 logging (citing a pers comm from Cook), but the adjustment itself is not shown or discussed in the referenced artice.)

Figure 3. IPCC Figure with Gergis series overprinted (rescaled by eye). Top – Tasmania: Gergis overlay in cyan is indistinguishable; bottom Oroko NZ – overlay in red.

Thus, the statement in AR5 that the Gergis results for the medieval period come from “new paleo records” is untrue. I wonder if reviewers picked this up.

Mann and Jones 2003

IPCC AR4 referred to Mann and Jones 2003, which included a SH reconstruction, as a primary SH reference, noting that they used “only three series”.

There are markedly fewer well-dated proxy records for the SH compared to the NH (Figure 6.11), and consequently little evidence of how large-scale average surface temperatures have changed over the past few thousand years. Mann and Jones (2003) used only three series to represent annual mean SH temperature change over the last 1.5 kyr.

Remarkably, and I hadn’t noticed this until just now, IPCC AR4 didn’t show the Mann and Jones SH reconstruction, for reasons that will become clear below.

Mann and Jones 2003 also screened SH proxies, but with interestingly different results than Gergis. They started with 5 long proxies: Tasmania tree rings, Oroko, Law Dome plus two South American proxies – Quelccaya O18 and a Chilean tree ring series. Whereas Gergis rejected Law Dome and kept Oroko, the screening procedure of Mann and Jones did the opposite: it rejected Oroko and kept Law Dome. Their screening was based on decadal correlation to local instrumental temperature. They reported that Law Dome had a (decadal) correlation of 0.76 to instrumental temperature, while Oroko had negative correlation (-0.25). These results were plotted on Figure 1 of Mann and Jones 2003, shown below;


Excerpt from Mann and Jones 2003 Figure 1, showing SH proxies. Correlations to local temperature also shown (decadally smoothed comparison)

Reconstructions – Law Dome vs Oroko
Using Law Dome O18 rather than Oroko led Mann and Jones to SH temperature reconstruction that didn’t have a Hockey Stick, as shown in the excerpt from Mann and Jones 2003 shown below.


Figure . SH reconstruction from Mann and Jones 2003 Figure 2. Caption: “b) SH reconstruction based on 2 indicators back tovAD 200 (thick blue) and 3 indicators back to AD 470 (blue- dotted). Other weighting schemes shown using color convention of (a) [areal and hemispheric correlation weighting (green), areal weighting only (magenta), local-correlation weighting only (cyan)] Shown for comparison is multi-century composite of previous reconstructions discussed in text (thick black).

This reconstruction wasn’t illustrated in AR4. Instead, IPCC commented on the reconstruction as follows:

The recent proxy-based temperature estimates, up to the end of the reconstruction in 1980, do not capture the full magnitude of the warming seen in the instrumental temperature record. Earlier periods, around AD 700 and 1000, are reconstructed as warmer than the estimated level in the 20th century, and may have been as warm as the measured values in the last 20 years.

Now compare the Mann and Jones reconstruction with the Gergis reconstruction which is shown in AR5 (First Draft) as part of its panel graphic comparing regional reconstructions to models, as shown below. Both have rather small amplitudes; however, the Gergis reconstruction has a small Hockey Stick.


Figure 1. Excerpt from IPCC AR5 Figure 5.9. Caption: “Figure 5.9: Regional temperature reconstructions, comparison with model simulations over the past millennium (1001–1999 CE)…”

Law Dome
Much of the difference between the Mann and Jones 2003 and the Gergis reconstruction arises merely from the presence/absence of the Law Dome O18 series, as can be seen by comparing the Law Dome O18 series (shown below) with the Mann and Jones 2003 SH reconstruction.


Figure . Law Dome O18 record. Plotted from LD2.1yyr data set sent by email by Tas van Ommen on 2006-03-14.

If you compare the Law Dome series shown here with the Mann and Jones 2003 SH reconstruction, you can see how the Law Dome series directly affects its results. And thus why screening Law Dome out and replacing it with Oroko leads to a very different result. Although Gergis carried out an elaborate ensemble of 3000 permutations, none of these permutations included Law Dome.

In passing, I’ll remind readers of my efforts as an IPCC AR4 reviewer to get the IPCC authors to show the Law Dome data (which I’d received in March 2006 just before review comments) – see CA post here.

CRU’s Tim Osborn led the movement against showing the data. He wrote (709. 1153233036.txt) presenting the problem:

(1) Jones/Mann showed (and Mann/Jones used in their reconstruction) an isotope record from Law Dome that is probably O18 (they say “oxygen isotopes”). This has a “cold” present-day and “warm” MWP (indeed relatively “warm” throughout the 1000-1750 period). The review comments from sceptics wanted us to show this for obvious reasons.

Osborn and the IPCC authors wanted not to show it also apparently “for obvious reasons”, a picture being worth a thousand words.

Law Dome also plays an interesting role in Mann et al 2008 – one that I hadnt appreciated before, but will re-visit. Mann et al 2008 used Law Dome O18, but did not use the long Law Dome O18 series that he had used in Mann and Jones 2003 (with its inconvenient MWP) – which would have had an impact on the sparse SH network. Instead Mann’s version of Law Dome O18 went only from 1761-1970 (!) It is a truncation of an obsolete version. I’ll discuss this backstory in another post as well.

The above graphic shows a 2003 version of Law Dome O18 (which Tas van Ommen sent me in 2006.) Despite the overwhelming importance of O18 as a paleoclimate proxy and the importance of Law Dome as a high-accumulation (high-resolution) core, the Law Dome O18 record shown here has never been archived (or even published by the authors.) The authors have been unfortunately diverted by other projects. [Note: June 4 – the Law Dome 2.1kyr O18 series does not turn up on a search of the Australian Antarctic Data Center under “law dome”. However, the existence of the series is reported at the NASA Global Change Directory, which contains a link to a webpage
which states “The file you have tried to download is not yet available for public access. Contact the Australian Antarctic Data Centre, using the request form, for further details.” Van Ommen says by email that he has not received requests for the data, but will reconsider the matter.]

I will discuss the puzzling history of this important proxy in a follow-up post.

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Myles Allen Calls For “Name and Shame”

May 31, 2012 – 9:10 PM

Myles Allen, a declared supporter of open data archives, has, in blog comments here, proposed “name and shame” as a first tactic against data obstructionists (as opposed to FOI).

Journal editors can and should enforce a simple “disclose or retract” policy if a result is challenged, and almost all of them do: if any don’t, then the solution is to name and shame them, not set up a parallel enforcement system.

I partly agree with this; I’ve used FOI primarily as a last resort. And in the case of climate scientists and journals that withhold data unashamedly, I believe that it remains a valuable tool of last resort. Obviously I’ve not been shy about naming data obstructionists at Climate Audit, though this longstanding effort has typically encountered resentment rather than encouragement from the community. Perhaps Allen will add his voice in more direct communications with editors rather than just at blog comments. Regardless, it’s nice to get even some moral support, since, for the most part, the community has united in solidarity behind data obstructionists.

By coincidence, Myles’ comments come in the midst of another data non-archiving incident that I haven’t reported on. Continue reading →

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Myles Allen and a New Trick to Hide-the-Decline

May 26, 2012 – 10:08 PM

Myles Allen has written here blaming Bishop Hill for “keeping the public focussed on irrelevancies” like the Hockey Stick:

My fear is that by keeping the public focussed on irrelevancies, you are excluding them from the discussion of what we should do about climate change

But it’s not Bishop Hill that Myles Allen should be criticizing; it’s John Houghton who more or less made the Hockey Stick the logo of the IPCC. Mann was told that IPCC higher-ups wanted a visual that didn’t “dilute the message” and they got one: they deleted the last part of the Briffa reconstruction – Hide the Decline. If, as Allen now says, it’s an “irrelevancy”, then Houghton and IPCC should not have used it so prominently. And they should not have encouraged or condoned sharp practice like Hide the Decline.

In the run-up to AR4, I suggested that, if the topic was “irrelevant”, as some climate scientists have said, then IPCC should exclude it from the then AR4. Far from trying to keep the topic alive in AR4, I suggested that it be deleted altogether. I guess that there was a “consensus” otherwise. If Allen wants to complain, then he should first criticize IPCC.

Bishop Hill links to a presentation by Myles Allen to a 2011 conference on Climategate, which like every other such handwringing introspection by climate “communicators”, notably failed to invite any of the major CRU critics – people who might actually have given them some insight into Climategate. In his presentation to climate communicators, Allen gave his own version of Hide the Decline. Allen showed the graphic below, sneering that the entire effect of Climategate was 0.02 deg C in the 1870s.

Needless to say, Allen’s graph has nothing to do with Hide the Decline and the Climategate dossier. Allen’s graph shows the CRUTEM temperature index from 1850, not the 1000 year reconstructions in which Hide the Decline occurred. CRUTEM was only mentioned a couple of times in the Climategate dossier. Climategate was about the Hockey Stick, though this point was misunderstood by Sarah Palin and now, it seems, Myles Allen.


Figure 1. Allen in front of temperature history.

In contrast, here’s a graphic from Richard Muller’s 2011 lecture. Unlike Allen, Muller understood Hide the Decline, which is shown here in one of its manifestations. (This is the WMO graphic; the more important Hide the Decline was in the IPCC Third and Fourth Assessment reports.) Hide the Decline is not 0.02 deg C in the 1870s; it was Briffa, Mann and Jones deleting the inconvenient portion of the Briffa reconstruction after 1960. And it wasn’t a microscopic difference. This difference is large enough that it might well have “diluted the message” that Houghton and others wanted to convey.

Figure 2. Muller in front of WMO hockey stick – a 1000 year reconstruction. Left – Hide the Decline; right – actual data.

While one would hope and expect that Myles Allen would have had a better factual grasp on Climategate issues than Sarah Palin, it seems that we’ve been disappointed.

Allen’s decision to show temperature data rather than Hockey Stick reconstructions cleverly draws attention away from the problems of those reconstructions. The Climategate emails have a apt phrase for Allen’s technique. Showing an unrelated dispute about a temperature graphic rather than the decreasing Briffa reconstruction is itself just another …. trick to hide the decline. 🙂

Update: Lucia responded to Myles ALlen in the comments as follows:

[Myles Allen said]

I appreciate that people like yourself who have devoted a lot of time to the analysis of paleoclimate data find it irritating when scientists who don’t work in that area dismiss it as uninformative.

First: communication tip: You need to learn to post complete thoughts. Uninformative about what? Everything? Climategate? Or the thermometer record? Or the strength of evidence for AGW? Depending on how I read your mind, you may be saying something true or utterly false. If you are going to lecture people on communicating science you might want to stop making readers guess which you mean.

Second: It seems to me you are misunderstanding what SteveMc writes. He’s not saying he is irritated that someone thinks paleo data is uninformative. He is saying that you suggest the “whole affair” (i.e. climategate) is an argument about the thermometer record. The fact is: climategate is not merely or even mostly about the thermometer record.

And I stand by the assertion that, thanks to the sloppy coverage the affair received in the media, it wasn’t just Sarah Palin who got the impression that the instrumental temperature record was seriously compromised

I would suggest that the main reason for this “sloppy coverage” was that reporters turned to people trying to rebut those discussing climategate at blogs and in forums. Some people people who (like you) might prefer to discuss the thermometer record rather than misbehavior of scientists or what “hide the decline” meant, diverted the discussion to the thermomeber record.

I strongly suspect the behavior of the scientists who wanted to suppress discussion of climategate succeeded in giving the media the incorrect impression that climategate was about the thermometer record is one of the reasons much of the media, some politicians, and Sarah Palin developed the impression climategate is about the thermometer record. That you can show they were confused about what people at blogs and forums were posting about merely shows you don’t know what it was about.

I would also suggest the only thing that can come of you continuing to try to convince people it was about the thermometer records is for people to explain that which you do not wish to be discussed: The Hockey Stick, misbehavior or scientists and the various whitewash investigations.

OTOH: If you simply wish to communicate that the topics that are central to climategate are not important to our understanding of climate change- that would be fine. But if you wish to make the case that the hockey stick doesn’t matter, then you need to make that clearly. Unfortunately for you, clear exposition requires discussion of the hockey stick!

A proper exposition might be to
a) Discuss what the hockey stick “is” with a little history.(Accuracy would be useful here. Mention it was used as background at IPCC meetings, and in Gore’s talk.)
b) Discuss why this shape is not important to our understanding of climate change. Show versions with and without the decline– and explain why even if the decline exists we do believe the world is warming. Do this by
c) Explaining the thermometer record.

Don’t try to take the tack of inaccurately claiming that climategate is actually about the thermometer record. If you take that tack, you’ll find yourself trying to defend your position– downgrading much of what you seemed to present rather strongly as your opinion, and burying your arguments in favor of your opinion deep in comments at a blog. (I’d note: I think much of your argument amounts to “changing the subject”– but that’s another matter.)

Moreover, I would like to point out that unless say what paleo is uninformative about your claim that paleo is not important (at all) seems a bit thin. Climate blog addicts can easily see see that on May 26, 2012 you are chiding Bishop Hill for discussing the Hockey Stick and providing lengthy explanations of its lack of importance while Real Climate’s front page is simultaneously running a post on discussing Hockey Sticks (See
Fresh hockey sticks from the Southern Hemisphere, May 22). It’s quite likely some will suspect that your opinion that the hockey still is uninformative (about something you don’t quite spit out) is maybe not entirely correct.

Third: Returning to “first”. When I watched your talk, I was struck by your tendency toward vagueness. Based on what you write in your defense in comments, I learn that the allusion to “the data” at minute 2:37 likely meant “the thermometer record” and “impact of the whole affair” (i.e. climategate) must have meant “impact of portions of the climategate discussions that relate to the thermometer record”. Your talk is riddled with these types of vague ambiguities. The consequence is that– on the whole– what your talk appears to communicate is false. If the audience comes away thinking you are suggesting that climategate was not about the paleo records, and that you think the only impact of climategate is a small tweak on the thermometer record, then the fault for their misunderstanding you falls on you for communicating rather badly.

Next time you want to make a presentation telling reporters that they shouldn’t focus on the paleo record but rather the thermometer record, you might be wise not to try to turn that into a talk about how the media got climategate wrong. Try to bite off less– stick to just discussing the thermoter record and why you think it tells us that the world has warmed and it’s because of man.

If you want to discuss climategate and how scientists failed to communicate their position, you have a hard row to hoe. Much of the reason scientists communicated the issues in climategate badly is they didn’t want to talk about them. Scientists mistake was to respond to journalists by trying to change the subject; others with plenty of ink keep talking all the whining in the world isn’t going to get people to stop discussing the topic. You can keep trying to do that: it isn’t going to work any better in 2012 than it did from 2009-2011.

Update 2: Myles Allen replies to Lucia:

I am not suggesting that the whole affair is about the surface temperature record. What I was complaining about, and I think that was clear from the talk, was that the public were given the impression that the affair compromised the data we actually use for detection and attribution, when in fact it didn’t. The “sloppy software” people found turned out to be nothing to do with the surface temperature record, the issues raised with tree-ring reconstructions turned out to be long-standing ones that Keith Briffa published on in the late 1990s, and in any case most detection and attribution studies make no use of tree-ring data at all. Scientifically, the UEA e-mails didn’t really change anything: no published dataset had to be withdrawn or revised, apart from that error in HadCRUT that I highlighted. And I stand by the assertion that I don’t think that is a message that has got across to the public.

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Schmidt’s “Conspiracy Theory”

May 16, 2012 – 5:06 PM

Schmidt’s recent post on Yamal advocated the following “conspiracy theory”:

McIntyre got the erroneous idea that studies were being done, but were being suppressed if they showed something ‘inconvenient’. This is of course a classic conspiracy theory and one that can’t be easily disproved. Accusation: you did something and then hid it. Response: No I didn’t, take a look. Accusation: You just hid it somewhere else.

One aspect of Schmidt’s response is beyond laughable. I agree that the best way of disarming suspicion is to show data: “take a look”, as Schmidt says. However, if Schmidt thinks that the conduct of the scientists involved in the various data refusals, obstructions and FOI refusals constitutes “take a look”, then he’s seriously in tin foil country. Comical Gav indeed.

Although I find it hard to believe that Schmidt is unfamiliar with the past incidents that gave rise to suspicion that adverse results and data have been withheld or not reported, I’ll review a couple of important ones. These do not, in any sense, constitute an inventory of incidents. They are ones that are either familiar in part to CA readers or which illustrate an important aspect of the problem.

Continue reading →

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New Data from Hantemirov

May 15, 2012 – 7:31 AM

Yesterday, I received updated Yamal data (to 2005) from Rashit Hantemirov, together with a cordial cover note. As CA and other readers know, Hantemirov had also promptly sent me data for Hantemirov and Shiyatov 2002. There are 120 cores in the data set, which comes up to 2005. I’ve calculated a chronology from this information – see below. Continue reading →

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Schmidt on FOI

May 14, 2012 – 4:41 PM

In yesterday’s post (as noted), I only responded to one aspect of Schmidt’s Yamal article, as it contains numerous extraneous spitballs, each of which takes time to respond to.

In yesterday’s post, I focused on points of agreement or points where agreement ought to be possible. In a subsequent RC comment, Schmidt complained that I had failed to respond to his “main point”, which now appears to be his ruminations on the UK Freedom of Information Act. Continue reading →

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Stocker’s Earmark: An Update

May 14, 2012 – 10:09 AM

Interesting news at Bishop Hill. A UK minister informed David Holland’s MP that the extra secrecy measures at IPCC, arising from the instigation of Phil Jones and persistence of Thomas Stocker, arose unintentionally and as a “drafting error”. Continue reading →

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Schmidt’s Rant on Yamal

May 13, 2012 – 2:59 PM

Two days ago, NASA blogger Gavin Schmidt posted an extended rant against me at Real Climate, a rant directed in part at my recent post on Yamal.

I’ve now looked through his post carefully and, beneath Schmidt’s fulminations, did not find any rebuttal to any points actually made in my post, as I’ll discuss in detail below. Much of Schmidt’s post fulminates against my criticism of inadequate disclosure of adverse results. This is a large topic in itself that provides a context to the Yamal controversy, but the exposition of this context is lengthy and, in my opinion, the Yamal issues are sufficiently discrete that they can be considered on their own, as I shall do in this post. Continue reading →

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Steig’s “Hockey Stick”

May 12, 2012 – 3:56 PM

I’m writing a response to Gavin Schmidt’s rant about Yamal, which I should finish by tomorrow. Schmidt’s rant does not refute anything in my Yamal post. Indeed, Schmidt barely touches on the actual content of my post. Most of his post has nothing to do with Yamal.

In the present post, I’ll deal with the following spitball: Continue reading →

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“Misconceived”

May 11, 2012 – 8:35 AM

In the FOI request under appeal, one of the two outstanding issues is my request for a copy of the Wahl and Ammann version, as submitted to Lead Author Briffa and used in the AR4 First Draft. East Anglia has argued that Briffa received the article under conditions of ordinary academic confidentiality. My counter-argument is that he received them in his capacity as an IPCC Lead Author. And that, in any event, he certainly didn’t treat the article as “confidential” since he cited it in the IPCC First Draft. Under IPCC policies, IPCC Lead Authors were required to place unpublished articles in an online archive available for reviewers. The lugubrious history of Wahl and Ammann has attracted attention in the community critical of the Team, see e.g. Bishop Hill’s excellent Caspar and the Jesus Paper.

If I were in East Anglia’s shoes, I wouldn’t have wasted two seconds fighting this FOI request. I’d have told Wahl and Ammann that we didn’t think that we received the article on a “confidential” basis since it was expected to be used in IPCC, that we had had enough headaches and didn’t want to have one more fight, and therefore we expected them to acquiesce in our decision. If I were the UEA administration, I’d have asked Jones and Briffa to agree with this decision and get Wahl and Ammann to cooperate. That’s what any sane person in the private sector would have done.

Instead, East Anglia has contested every step of the FOI, which has now reached the Tribunal.

As with all legal proceedings, they take on a life of their own after a while and so it is with this case. In today’s post, I’ll discuss an interesting fact-law issue arising out of East Anglia’s submission to the Tribunal on May 9. Continue reading →

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