At Lewandowsky’s blog here, conspiracy theorist John Mashey has challenged Deming’s “get rid of the MWP” recollection claiming that:
Nobody in 1995 would have been worried about “getting rid of the MWP,” although they might have wanted to dispel the idea the Lamb schematic was Truth. They had years before abandoned the schematic… Anyone citing this schematic as credible any time after 1992 might be likened to a flat-earther clinging to Anaximander.
Although the climate community now pretends that the IPCC 1990 graphic never existed or was a one-off, variants of this graphic continued in use by leading climatologists through 1996, because, as Crowley complained in a Climategate email, “there was no alternative”. This doesn’t prove that Deming’s recollection is valid, only that Mashey’s argument that “nobody in 1995 would have been worried about “getting rid of the MWP” is without support.
In today’s post, I’ll review two of the most relevant contemporary publications by the UC Global Research Information Office – a 1991 article by Bradley and Jack Eddy, an older contemporary, and a 1996 article by Tom Crowley, both using variants of the IPCC 1990 graphic. I’ll also review interesting 2007 Climategate correspondence in which Bradley and Crowley reflect back on these articles.
Bradley and Eddy 1991
In 1991, Eddy and Bradley published “Changes in time of the temperature of the earth” pdf(Earthquest 1991, Vol 5 No 1), a publication of the US Global Climate Research Information Office. Although Bradley, regarded as notoriously vain in the Climategate emails, has a comprehensive bibliography of his publications, this 1991 publication isn’t listed.
Eddy and Bradley 1991 presented six figures representing global temperature over scales ranging from 140 years to 180 million years. One of their figures was a slight modification of the IPCC 1990 Figure 7.1 bottom panel (the “Lamb” graphic); two other figures either matched or were only slight modifications of the top two IPCC 1990 panels.
Eddy and Bradley provided the following overall description of these reconstructions:
“reconstructions of the longer history of past variations of surface temperature are obtained through the chemical analyses of dated sediments of various kinds are as such are themselves regionally or even site specific.. A compilation representative of what is known today is shown in this set of graphs, which portray a sampling of estimated surface temperatures through the last 180 million years of earth history”.
Their most birds-eye graphic (see below) showed 180 million years (attributed to L.A> Frakes, Climates through Geologic Time, 1979). This showed “a global cooling trend since the time of the Cretaceous, when global surface temperatures were 8-10 deg C warmer than today” and shows that even the interglacials of the Pleistocene are cool in geological time.
Their second panel (see below) showed temperatures for the past 850,000 years and closely matches the IPCC 1990 Figure 7.1 top panel (also shown below for comparison). Bradley and Eddy attribute it to an equatorial Pacific O18 proxy series from Shackleton and Opdyke (Quat Res, 1973), referring also to the iconographic version of this series in W.C. Clark, Carbon Dioxide review, 1982.
Top- Eddy and Bradley, 1991 Figure 2; bottom – IPCC 1990 Figure 7.1 top panel
Their third panel (not shown) shows a 150,000 year series, derived from Vostok dD isotopes (Jouzel et al 1987), a series shown in other contemporary multiscale panels. Their fourth panel showed 18,000 years and is said to be a modification of the IPCC 1990 Figure 7.1 middle panel. They say that this graphic is ‘estimated from a variety of sources, principally isotope ratios from Greenland ice cores”, but also mention the use of “European lakes”, stating that, during the Holocene maximum “summer temperatures may have been 1-2 deg C warmer than the present era”. Again, the corresponding IPCC 1990 panel is shown for comparison.
Top – Eddy and Bradley, 1991 Figure 4; bottom- IPCC 1990 Figure 7.1 middle panel.
Their fifth panel was a 1000-year graphic, clearly in the Lamb lineage. They describe their graphic as “modified from J.T. Houghton et al, 1990”. As above, the corresponding IPCC graphic is shown. [Update note: as Tom Curtis observed below, Bradley bodged (to borrow the Briffa phrase) the Lamb graphic by reducing the MWP estimate by about 0.25 deg C; Curtis asserted that the dashed lines in the Bradley graphic “clearly” show the bodge. In my opinion, the existence of the Bradley bodge would have been more evident if it had been mentioned in the caption or running text.] Bradley also modified the schematic in the period after 1600, varying the squiggles somewhat.
top – Eddy and Bradley, 1991 Figure 4; bottom – IPCC 1990 Figure 7.1 bottom panel.
They described its construction as follows:
Variations in surface air temperature estimated from a variety of sources including temperature-sensitive tree growth, indices and written records and accounts of various kinds, largely from western Europe and eastern North America. Of note is a possible protracted global warming through the Medieval period, when surface temperatures may have averaged about 0.3 deg C warmer than the AD1900 reference. It was followed by a longer period of much colder conditions, loosely termed the Little Ice Age, when the estimated global mean temperature may have fallen about 0.5 deg C below the reference norm, reflecting global temperatures almost 1 deg C lower than the values attained during the middle of the current century, modified from J.T. Houghton et al, 1990.
Their final panel (not shown) was the CRU temperature history (then covering about 140 years).
Given the recent blog criticism of my incorrect attribution of the Lamb graphic in a 2005 blog post and contemporary presentation (ignoring that I had correctly attributed the graphic by June 2005 and subsequently), it is ironic to read Raymond Bradley’s thorough confusion on this point in Climategate emails.
Phil Jones had been trying to figure out the provenance of the IPCC 1990 Figure 7.1 bottom panel. In very early January 2007, Bradley (CG1 – 760. 1167752455.txt) wrote to Jones that Bradley himself had originated the Lamb-style graphic and that Chris Folland (“Dork” Folland in Bradley’s contemporary terminology in CG2-4621) had used it in IPCC 1995 (elsewhere complaining at the time that Dork Folland had been insufficiently deferential to Bradley’s pearls of wisdom):
I believe this graph originated in a (literally) grey piece of literature that Jack Eddy used to publish called “Earth Quest”. It was designed for, and distributed to, high school teachers. In one issue, he had a fold-out that showed different timelines, Cenozoic, Quaternary, last 100ka, Holocene, last millennium, last century etc.
The idea was to give non-specialists a perspective on the earth’s climate history. I think this idea evolved from the old NRC publication edited by L. Gates, then further elaborated on by Tom Webb [see Webb 1991 here] in the book I edited for UCAR, Global Changes of the Past. (This was an outcome of the wonderful Snowmass meeting Jack master-minded around 1990).
I may have inadvertently had a hand in this millennium graph! I recall getting a fax from Jack with a hand-drawn graph, that he asked me to review. Where he got his version from, I don’t know. I think I scribbled out part of the line and amended it in some way, but have no recollection of exactly what I did to it. And whether he edited it further, I don’t know. But as it was purely schematic (& appears to go through ~1950) perhaps it’s not so bad….
They also seem to have fabricated a scale for the purported temperature changes. In any case, the graph has no objective basis whatsoever; it is purely a “visual guess” at what happened, like something we might sketch on a napkin at a party for some overly persistent inquisitor….. (so make sure you don’t leave such things on the
What made the last millennium graph famous (notorious!) was that Chris Folland must have seen it and reproduced it in the 1995 IPCC chapter he was editing. I don’t think he gave a citation and it thus appeared to have the imprimatur of the IPCC. Having submitted a great deal of text for that chapter, I remember being really pissed off that Chris essentially ignored all the input, and wrote his own version of the paleoclimate record in that volume.
There are other examples of how Jack Eddy’s grey literature publication was misused. In a paper in Science by Zielinski et al. (1994) [v.264, p.448-452]–attached– they reproduced [in Figure 1c] a similarly schematic version of Holocene temperatures giving the following citation, “Taken from J. A. Eddy and R. S. Bradley, Earth-quest 5 (insert) (1991), as modified from J. T. Houghton, G. J. Jenkins, J. J. Ephraums, Climate Change, The IPCC Scientific Assessment (Cambridge Univ. Press, Cambridge, 1990).”
But I had nothing to do with that one!
So, that’s how a crude fax from Jack Eddy became the definitive IPCC record on the last millennium!
Crowley quickly disputed Bradley’s recollection, pointing out that he did not believe that Eddy (and Bradley) had ‘”cooked up” that figure … purely out of thin air’. Crowley reported that he had used a version of the Lamb graphic in Crowley and Lowery 2000. The Climategaters quickly recognized that the graphic originated with Lamb, rather than Bradley, though the Climategate correspondence shown thus far did not trace it as far back as the Lamb 1965 later identified at Climate Audit.
At Lewandowsky’s blog, conspiracy theorist John Mashey asserted that use of the IPCC-Bradley graphic “after 1991” would only be done by someone adhering to the “Aniximander” plan:
Anyone citing this schematic as credible any time after 1992 might be likened to a flat-earther clinging to Anaximander. Think of the schematic as a flat-earth temperature sketch, which by 2005 got retroactively elevated (by a few people) and promoted as Absolute and Unchanging Truth being hidden by a cabal of climate scientists, just as the way NASA is hiding the absolute truths known by the Flat Earth Society. There we find The Conspiracy:, the active faking of the whole space program, not just Apollo! It has a good FAQ. They show a newer map than Anaximander, still flat.
Mashey didn’t explain exactly what happened in 1992 to exclude Eddy and Bradley’s 1991 publication from membership in the Aniximander plot. The IPCC 1992 report is almost totally silent on the MWP: its only mention of the topic was a passim comment about Briffa’s Tornetrask reconstruction as follows:
in this region [Scandinavia] for a “Medieval Climatic Optimum” (S7, p 202) around 870-1110, another warm period around 1360-1570, and a “Littie Ice Age” (S7, p202) period around 1570-1750.
The Briffa reconstruction cited by IPCC 1992 was, of course, his Tornetrask reconstruction, which Briffa had “bodged” to reduce the MWP – a topic later of interest at CA. (This data recurs in the recent Esper et al 2012 article, discussion of which is long overdue here.) But I am not aware of anything in 1992 (either in the IPCC report or elsewhere) evidencing that climate scientists had resiled from the Eddy and Bradley 1991 summary.
Bradley and Jones (Holocene 1993) was a sort of opening shot by the Hockey Team. It did not discuss the MWP, but did question the concept of the Little Ice Age, citing the inconsistency of a number of NH proxies. (From a 2012 AR5 perspective, it seems to me that the concept of a global Little Ice Age is now relatively widely accepted in the paleoclimate community and, to that extent, Bradley and Jones 1993 took an incorrect fork in the road, though I recognize that this interpretation might not be widely shared within the climate “community”.)
Hughes and Diaz (1994) extended the Bradley and Jones 1993 project to the MWP. It was cited by AR4 as authority against the MWP concept. However, Hughes and Diaz 1994 primarily relied on tree ring chronologies that had been homogenized in a way that removed all centennial variability. Although it has been widely cited by climate scientists, its flawed methodology meant that its conclusions did not follow from its data – a point that ought to be evident even to climate scientists. In the review of AR4, both Jan Esper and myself, using identical arguments and in unusual agreement, argued against AR4 relying on Hughes and Diaz 1994, but our criticism was ignored. Nonetheless, the criticisms are valid. BTW draft versions of AR5 admit the concept of a “Medieval Climate Anomaly” and are far more accepting of the idea of a global reorganization of climate than AR2 and AR3, but that’s a different story.
While Hughes and Diaz criticized the concept of a MWP, through 1995, neither they nor anyone else had presented an alternative to the Lamb graphic and variants of the Lamb graphic continued to be used in academic literature. As Bradley noted in his 2007 Climategate email, the Eddy and Bradley 1991 version was used in Zielinski et al (Science 1994.)
[Update: Oct 10] Jean S observes in comments below that a version of the Lamb graphic was used in Mayewki et al (JGR) 1993, a presentation of GISP2 ice core results. The bottom two panels of Mayewski et al 1993 are shown below.
[Update: Oct 10] Bradley’s recollection of Zielinski et al 1994 was only partly correct. Zielinski et al re-drew from IPCC 1990 bottom and middle panels as shown below:
Zielinski et al 1994 Figure 1. Caption stated: Composite of the postulated variation in Northern Hemisphere surface temperatures from the present to 7000 B.C. (35) Temperature change was determined by a deviation from the mean value at the turn of the last century. (35 – Taken from J. A. Eddy and R. S. Bradley, Earthquest 5 (insert) (1991), as modified from J. Houghton, G. J. Jenkins, J. J. Ephraums, The IPCC Scientific Assessment (Cambridge Univ. Press, Cambridge, 1990).
Here is a parsing of the Zielinski bottom panel, showing the scale as a grid over the figure, together with the MWP and Holocene Optimum maxima.
Additional adherents to the Aniximander plan revealed by these articles are: G. A. Zielinski, P. A. Mayewski, L. D. Meeker, S. Whitlow, M. S. Twickler, M. Morrison, D. A. Meese, A. J. Gow, R. B. Alley, K. K. Ferland, M. R. Legrand, and J. P. Steffensen, twelve of the most prominent ice core specialists of the time, and Christian Hass and Michael Kass.
The last authors meeting for the IPCC Second Assessment Report was held in Madrid in Novermber 1995, but the report itself would not be published until June 1996.
In winter 1996, during this hiatus, Tom Crowley, a very prominent climate scientist, re-visited the multi-scale temperature history (covered in 1991 by Eddy and Bradley) for Consequences, a peer-reviewed publication by the US Global Climate Change Research Office. Crowley’s 1996 article had three named peer reviewers: including Anthony Broccoli, the present editor of Journal of Climate; William Ruddiman, another prominent and prolific climate scientist; and Lisa Sloan.
Like Eddy and Bradley 1991, Crowley 1996 presented temperature histories over scales varying from the instrumental period to geological time. It drew directly on the Eddy and Bradley 1991 graphics for the three panels in the IPCC 1990 report.
Crowley’s longest-scale graphic (his Figure 6 – not shown here – derived from Crowley et al 1990) covered 120 million years and was even more schematic than the corresponding graphic in Bradley and Eddy.
Crowley’s next scale (his Figure 5 shown below) covered the 850,000 years of the Pleistocene. Crowley attributed this graphic to Imbrie et al 1984, a book section in Milankovitch and Climate (1984), edited by Berger and others. However, the data itself appears unmistakeably to be the same series as in the corresponding graphic in Eddy and Bradley 1991 (see above) and thus ultimately derived from the same data as the top panel of the IPCC 1990 graphic.
Crowley 1996 Figure 5
Crowley’s next scale (his Figure 3) was 125,000 years; it was attributed to Bradley and Eddy 1991, based on Jouzel et al 1987 (Vostok dD).
Crowley’s next scale (his Figure 2) was the 15,000 year period covered by the IPCC 1990 middle panel. Again, Crowley attributed his figure to Eddy and Bradley 1991.
Crowley 1996 Figure 2
Crowley’s final scale (his Figure 1) was the 1000-year period of the IPCC 1990 bottom panel. Crowley’s version was a re-drawing of the corresponding Eddy and Bradley 1991 figure (which Crowley acknowledged). Both figures are shown below for comparison.
Crowley’s caption was as follows (drawing on the corresponding caption in Eddy and Bradley 1991):
Figure 1 Example of regional variations in surface air temperature for the last 1000 years, estimated from a variety of sources, including temperature-sensitive tree growth indices and written records of various kinds, largely from western Europe and eastern North America. Shown are changes in regional temperature in° C, from the baseline value for 1900. Compiled by R. S. Bradley and J. A. Eddy based on J. T. Houghton et al., Climate Change: The IPCC Assessment, Cambridge UniversityPress, Cambridge, 1990 and published in EarthQuest, vol 5, no 1, 1991.
Thus, if Mashey were correct in his allegation that users of the Lamb graphic after 1992 were adherents to the Aniximander plan, Crowley, his reviewers (Ruddiman, Broccoli and Sloan) and his editor (Eddy) would have to be counted among the adherents to the Aniximander plan.
In June 1996, a few months after Crowley 1996, the IPCC Second Assessment Report was finally published. Its Chapter 3 combined assessment of recent instrumental data and assessment of paleoclimate data. Coordinating lead authors include names familiar from Climategate: Neville Nicholls, Tom Karl, David Parker; Phil Jones was listed as a “Key Contributor”. It cited both Bradley and Jones 1993 and Hughes and Diaz 1994 and took the very disbelieving views of those articles, as, for example, the following:
it is not yet possible to say whether, on a hemispheric scale, temperatures declined from the 11-12th to the 16-17th century. Nor, therefore, is it possible to conclude that global temperatures in the Medieval Warm Period were comparable to the warm decades of the late 20th century.
Crowley’s reflections in 2007 on the prior events are instructive. He explained in 2007 (CG1-760) that he used this graphic in 1996, because “even though I didn’t like it – there was not an alternative”:
I might also point out that in a 1996 Consequences article I wrote – and that Fred Singer loves to cite — Jack [Eddy] (who was the editor of the journal) basically shoehorned me into re-reproducing that figure even though I didn’t like it – there was not an alternative. in the figure caption it has a similar one to Zielinski except that it states “compiled by R.S. Bradley and J.A. Eddy based on J.T. Houghton….so that puts a further twist on this because it point to Houghton not Bradley/Eddy as the source. Jack must have written that part of the figure caption because I don’t think I knew those details.
Deming in Context
In March 2005, shortly after the publication of our GRL article criticizing the MBH hockey stick, David Deming recounted the following story containing the now notorious phrase “get rid of the MWP”:
With the publication of the article in Science [in 1995], I gained significant credibility in the community of scientists working on climate change. They thought I was one of them, someone who would pervert science in the service of social and political causes. So one of them let his guard down. A major person working in the area of climate change and global warming sent me an astonishing email that said – We have to get rid of the Medieval Warm Period.
I first learned of Deming’s recollection from an article by Deming posted at the SEPP website here. Deming later published a version of this article in a lower-tier journal (Journal of Scientific Exploration); this version was subsequently cited by Huang et al in a 2008 GRL article here. In 2006, Deming gave similar testimony to a Senate Committee (see here.) I first referred to Deming’s story in a March 2005 blog post. Ross and I also referred to it in contemporary presentations in which we sought to explain the remarkable prominence of the MBH hockey stick in the IPCC (2001) report, where it appears on no fewer than 6 occasions.
In previous reflections on this topic (most recently in 2007 here), I had made the (to-me-obvious) point that it would be difficult to motivate policy makers or the public with any sense of urgency using the Lamb graphic.
Crowley’s Climategate recollection clearly shows the frustration of Hockey Team scientists in 1996: they felt (incorrectly IMO) that Bradley and Jones 1993 and Hughes and Diaz 1994 had refuted concepts of the Little Ice Age and MWP, but had nothing to substitute in its place. Thus, Bradley in 1991 and Crowley in 1996 had both ended up using the Lamb graphic – reluctantly but used nonetheless. It seems entirely plausible to me that Hockey Team scientists in 1995-96 really did want to “get rid of the MWP”. Even as late as 2007, Overpeck, as an IPCC Coordinating Lead Author, still wanted to “deal a mortal blow to the MWP” (see CA post here).
Mashey contested the validity of Deming’s story on the basis that “Nobody in 1995 would have been worried about “getting rid of the MWP,” although they might have wanted to dispel the idea the Lamb schematic was Truth. They had years before abandoned the schematic.” However, it seems to me that the closer re-examination of the documents carried out here, if anything, adds circumstantial support for Deming’s recollection (I emphasize circumstantial). Mashey’s claim that no one used the Lamb graphic after 1992 is refuted on its face by Crowley 1996. This doesn’t prove that Deming’s recollection is valid, only that Mashey’s argument that “nobody in 1995 would have been worried about “getting rid of the MWP” is completely imaginary.
Postscript: Ross and my criticism of the Mann graphic was not on the basis that the Lamb graphic was “right”, but only that the Mann reconstruction had used questionable methods, did not live up to its warranties of statistical skill and robustness and therefore did not permit Mann or the IPCC to assert with statistical confidence that 1998 was the warmest year of the millennium. (Our actual argument has been misconstrued by both supporters and critics alike.) We did not preclude the possibility that someone could show that 1998 was the warmest year of the millennium using better data and statistics, only that Mann et al hadn’t done so. Subsequently, mainly at Climate Audit, I’ve argued that other Hockey Stick reconstructions are also defective, but that’s a long and different story.