Following my GWPF report on Hubert Lamb, there was some criticism (in comments and by email) that I was too soft on Lamb’s successor at CRU, Tom Wigley. These critiques fit the common portrayal of Wigley as an eminence gris, a shadowy figure scheming in the background, putting forward the more reckless younger scientists, while carefully maintaining plausible deniability.
Perhaps. And I can certainly see how this view has developed during the second wave of scepticism that arose with the Hockey Stick Controversy. However, this view tends to distort, if not Wigley’s personal intent, then his rôle in the whole saga.
Wigley is surely one of the most important and curious characters in our whole story. Therefore we should be especially careful not to let accusations of malevolence distract from the problem of his enigmatic rôle. Some may well wish to lay accusations as though of a crime, where intent is crucial to conviction and sentencing. However, this is not our problem. Our problem is the historical problem: the hows and whys of this monumental corruption of our scientific institutions. In this, Wigley’s rôle, rather than his intent, is of primary importance.
For a social phenomenon, a social explanation is the most satisfying. The transformation of the science is easily explained sociologically, where psychology need only come in with its gross emergent social expression—we may call this human nature. If Wigley did not exist, then social forces would have invented him, maybe not at CRU, but somewhere.
Wigley in the economics history of CRU
There are a set of social factors that go a long way towards explaining the successful transformation effected by Wigley at CRU. Indeed, these are of sufficient force that the attribution of a sinister motive or stratagem is hardly required. Consider firstly that many competent and distinguished scientists, however so much they strive, never achieve even one first-author publication in Nature. Such publications are benchmarks of scientific advancement. As far as we know, no historical climatology paper from CRU ever made the grade. Indeed, Astrid Ogilvie (an historical climatologist at CRU from the 1970s) explained by email that it was hard to get their research published in any peer review journals until the specialist journal Climatic Change arrived in 1977. Yet, in 1981, on the CO2 question, Wigley had his name up on top, in Nature, three times in just two months!
The year 1981 is up there with 1976 and 1988 among the most important years in the development of this scare. In that year James Hansen took over at GISS, and that year he won the first New York Times front page headline for warming fears. Meanwhile, over in the UK, but mostly funded by the US taxpayer, Wigley was busy re-orientating the CRU research profile to serve investigations of the science behind these fears. This was never to raise the alarm but only to address the question. And the result? By 1981, reliable and increasing baseline funding had begun to flow from the US Department of Energy’s new ‘CO2 program’. Papers, comments and letters on the topic appeared throughout the 1980s in high impact journals with CRU affiliations in the by lines.
During the 1980s, on the ‘CO2 question’, the reputation of this tiny research unit was made. And on the CO2 question CRU was saved, surviving as it did with contract staff on ‘soft money’ (only excepting the director) and with nothing like the facilities for primary research of NOAA, NCAR, Scripps, Woods hole, NASA and the like. Still, the authority that CRU established on this topic during the 1980s set it up for a boom during the 1990s. That was when local funding finally kicked in after Margaret Thatcher used the climate scare for her belated conversion to environmentalism. Wigley was among the select few scientists invited for a weekend at Chequers to expedite this political transformation. The combined funding that then increasingly flowed into CRU meant that the staff numbers kept climbing until they rose to almost 10 times those under Hubert Lamb. Sure, the peak was after Wigley left in 1993, but it can only be understood in the context of the transformations set in train by Wigley when he took over from Lamb in 1978. Back then Wigley had picked which way the wind was blowing. But, otherwise, the principles of economic history are sufficient to account for the success of the transformation masterfully instigated by him at CRU.
Wigley in the transformation of the climate science
Not only is the social explanation adequate, but the persona eminence gris, of someone carefully guarding against conviction with the calculated pursuit of plausible deniability…this just does not fit our second director of CRU. While at CRU, Wigley was no background figure. In the science, at least, he led from the front. But not as an alarmist. At every level, his answers on the CO2 question were ever moderate. And he went beyond passive deniability to actively arguing against the more extreme views that were tending to attract the limelight.
At CRU, and at least until the mid-1990s, Wigley was not shy about publishing his scepticism in the scientific literature. So many other scientists stand accused of passing in silence while their peers pretended to the scientific foundations of immediate and drastic climate action. Not Wigley. He cannot suffer fools, and those who know him will tell you he loves debate. That he reveled in the cool and calculated demolition of an argument is palpable in some powerful critiques during the 1980s and into the 1990s. And this behavior was tolerated.
This toleration is as important to the story of Wigley as it is to the bigger story. Skepticism was tolerated as a ‘loyal opposition’—including within the IPCC during its first assessment. So long as the scientist maintained support for the investigation of the question, doubters were also tolerated in the preparation of the IPCC supplementary report for the Rio Earth Summit in 1992. They were even tolerated through the early drafting of the Second Assessment. Throughout, the IPCC chairman, Bert Bolin, repeatedly encouraged the emphasis on the uncertainties and the tabling of divergent opinion.
It was only in the very late stages of the second assessment, late in 1995, that a change in the political mood impacted the scientific debate to the extent that intolerance to the normal argy-bargy effected Wigley. But this did not stop him. Not at first. Not until 1996. The year that the Chapter 8 controversy went public was a turning point. After that, from 1997, the year of Kyoto, it is hard to find explicit statements of Wigley’s skepticism. It is his cautiousness from around this time that is often seen as an effort to maintain plausible deniability. That is one way of seeing it. We now know his caution was covering his continuing skepticism. Suspicions that behind the scenes Wigley had his doubts about the empirical science then being used to support warming mitigation were confirmed with the release of the Climategate emails in 2009.
Thus, we can say that, not only was the first director of CRU a skeptic throughout his career, but so too was the second. While Wigley’s later skepticism is famous, at least among those who have followed the Climategate revelations, less familiar is his early skepticism. Thus, while we come to his skepticism of the Hockey Stick in the end, most of the rest of this essay provides some reminders of the depth of his skepticism during the pre-Kyoto days. Here we consider three interventions by Wigley at three distinct levels of the debate. The first is on the question of ‘first detection’, the second on the validity of climate models and the last is on the need for agreement on immediate emissions reductions.
Wigley, the skeptic of detection
In the early 1980s there was a general consensus that even if we might expect dangerous emissions warming, it had not yet arrived. There was no clear sign of it. For those concerned about the threat, this presented a problem because theoretical speculation was considered insufficient to support the drastic mitigation action being proposed. It was also generally acknowledged that policymakers could not be persuaded to take action on emissions until actual ‘detection’ of the climatic effect was achieved. Introducing the section on ‘detection’ in his Carbon Dioxide Review 1982, William Clark explains:
…conventional wisdom holds that nothing will be done about CO2 until, at a minimum, a clear signal of actual warming is detected.(1)
In the 1980s this recognition began to focus some considerable attention on the problem of ‘first detection’. Clark’s introduction to this problem is followed by an essay (by W H Klein) that is only moderately optimistic about the prospects of detection. The critical commentaries that follow include one from the crew at CRU (Kelly, Wigley & Jones). The CRU commentary opens by emphasizing that detection is hindered by uncertainties about the climatic effects of CO2 and that these ‘critically affect our ability’ to achieve detection. Note that the word ‘critically’ in science has the intensity of ‘fatally’. In other words: We can’t detect the effect when we don’t even know what that effect is. Before descending into a demolition of the main essay (and of much of the detection work so far) the CRU folks say that ‘any attempt’ at detection…
…must be underpinned by sound methodology and scientific honesty. If the societal consequences are to be seriously considered by non-scientists, the credibility of our research must be high. (p246)
It was widely acknowledged that the detection problem was not simply to find a correlation between generalized warming and rising CO2 , as any observed warming could be due to natural variability. Yes, there needed to be warming but this warming also needed to be ‘attributed’ to the human cause in some way. The idea was that attribution could be achieved by examining the pattern of the warming. Past generalized warming was found to be unevenly distributed across the globe, and it was proposed that the pattern of this unevenness could tell the tale of the cause. This ‘pattern recognition’ goes back at least to work by Guy Callendar published in the early 1960s, where he speculated that the differential warming across the latitudes during the early 20th century matched the pattern of warming that would be expected if it were caused by increasing greenhouse gas concentrations. By the 1980s this unevenness could be studied across the last few decades in the vertical as well as the horizontal plane, and this is how the analogy came about where a particular pattern would give the human ‘fingerprint’—a unique identifier of the culprit. Thus, the quests for ‘first detection’ became the quest for man’s fingerprint in the sky as it emerged out of the background smudges of natural variability.
Throughout the 1980s, Wigley was able to take a lead with the detection problem. Yet he was never among the optimistic about solving it. In a paper of 1981 Wigley suggested that such detection would not be likely until the end of the century. Later this forecast was pushed out and he continued to hold the view that detection was still a long way off in the ‘detection’ chapter he was asked to write for the IPCC first assessment. There he said that detection should not be expected until there were ½ degree more warming, and that this was not expected for decades to come (in fact, it has not yet arrived). This assessment was repeated in the update that the IPCC prepared especially for the Rio summit in 1992. For the IPCC second assessment, Wigley handed the coördinating lead authorship to Ben Santer, a scientist who had cut his teeth at CRU. In the end, despite significant opposition from other lead authors, but with support from John Houghton, Santer was able to push through (what was widely interpreted as) a weak detection claim. Wigley did come in with powerful support for Santer when the Chapter 8 controversy broke, however one does not find (not yet anyway) a clear statement from Wigley that he considered Santer had shown that the human influences on global climate has been detected. (Indeed, one is pressed to find any experts in the field supporting such a claim.)
So, for Wigley, we can presume that ‘first detection’ had yet to be achieved and probably remained a long way off. With no empirical science yet to support the enhanced greenhouse hypothesis, that only left the speculation based on the models. So, what did he think of them?
Wigley, the skeptic of the model projections
By the early 1990s, skeptics were hounding the modellers over the fact that their models were over-predicting the warming. This criticism was met by IPCC scientists with a remarkable turnaround. In the drafting of the IPCC second assessment, the fact that the models were overstating the rate of global warming was explicitly acknowledged. There were even graphs drawn to show this. However, this acknowledgement of the critics also came with an explanation. The reason the models overshot the actually observed 20th century warming was not that the sensitivity had been set too high but because another human influence had not been taken into account. When it was, all could be set right.
In the 1970s there were those like Reid Bryson who were concerned that human industry might exacerbate the descent into the next (little or big) ice age with all the aerosols thrown up into the troposphere. But it was only in the early 1990s that the greenhouse modellers decided to incorporate this cooling effect. They introduced a dampener to simulate the effect of, in particular, the sulphate aerosols released with CO2 in the burning of fossil fuels. Although this is a local effect and mostly in the northern mid-latitudes, it was still assessed to have a significant global influence. Adjust the models they did…and…voila! they now matched the 20th century global temperature trend, including the pause in the warming during the 1960s and 1970s—before sulphate pollution controls kicked in.
The new IPCC report used CO2+Sulphate results from various modelling groups. In the modelling chapter, Chapter 6, special prominence was given to the recent, impressive results from the team at the UK Met Office led by John Mitchell. Skeptics who were suspicious that this was all too neat and convenient included Pat Michaels. As a reviewer of Chapter 6, he was interested to consult the latitudinal breakdown of the Met Office results so that he could examine how they fared in the polar latitudes—where the aerosol cooling effect should be negligible but the greenhouse warming effect pronounced. He wanted to check to what extent the Met Office results confirmed his own findings, which suggested that runs set with CO2-only low sensitivity better matched the observed pattern than high sensitivity CO2+sulphates runs. His repeated requests for this breakdown were refused. These refusals were firstly on the grounds that the paper cited in the IPCC report was not yet published. Then, after it was published in Nature (10Aug95) the request was still refused for various other reasons. A USA House of Representatives hearing (16Nov95) revealed that the head of the US delegation, Mike McCracken, had been encouraging Mitchell to give up the data. Still he refused. The story was covered in the science press and an editorial in Nature expressed dismay. For a while this little scandal threatened to blow up as a minor international incident.
If Michaels was dubious about empirical validation of these new modelling results, then let’s consider Wigley’s view.
It is common practice when an important paper is published in Nature for a prominent expert in the field to review its significance. As Wigley had published similar CO2+Sulphate results (albeit using a simpler model) a few years earlier, it is not surprising that he was asked to write the accompanying commentary. Read through this and one is discouraged from trusting, not just the Met Office modelling projections, but model projections generally. It finishes thus:
So far climate modellers have had limited success and have had to bear the brunt of criticism from those who are concerned about the role of models in the greenhouse debate. At last, however, it seems that the door is open and the light of credibility is filtering in.
This ungloved backhander suggests that before these new models allowed some filtered light of credibility, the door was closed and modelling had no credibility. Indeed, Wigley talks of how ‘positive results’ from modelling ‘have eluded us before’. In other words, the critics had been right all along. So,…what of these new results? Wigley’s closing remarks complete a review that is highly skeptical of the models empirical grounding, thus suggesting that the light of credibility remains rather dim.
In the new modelling, unresolved problems of the old models remain, including the age-old difficulties in the treatment of clouds and also those introduced more recently with ‘ocean coupling.’ This means that ‘one must view the results circumspectly’ says Wigley. Nor does Wigley leave the reader with much confidence about the way the new human aerosol forcing has been simulated. In fact, the Met Office models ‘do not explicitly include aerosols at all; rather, they simulate their effect by changing the model’s surface albedo or reflectivity’. The well-established indirect effect of aerosols (on cloud reflectivity) is excluded altogether, he says, although their likely over-estimation of the direct effect compensates for this. Still, he thinks this is too small relative to a ‘best-guess values for the total forcing’. But…Does anyone have any idea what total sulphate effect might be?
Wigley’s use of the term ‘best guess’ refers to his own earlier work, and here he clarifies its meaning:
The word ‘guess’ is not used idly here—the uncertainties surrounding the magnitude of aerosol forcing in general and sulphate aerosol forcing in particular are exceedingly large. These uncertainties are central to an assessment of [this work].
But anyway, in terms of model validation, what is the significance of simulating the recent temperature trend? Wigley points out, as many skeptics had already, that, where these various models simulate past global temperatures through adjustments on speculated levels of various types of forcing, this is not the whole story. ‘Although the results show encouraging agreement with observations,’ there remain ‘enormous uncertainties’, says Wigley, around both the CO2 and sulphate effects.
Wigley’s commentary is headlined with the question ‘A successful Prediction?’ It is hard to imagine that anyone could read through Wigley’s review and say that it supports any sort of answer to that question in the affirmative. The same can be said for another commentary by the head of the main modelling group in German, Klaus Hasselmann. The results from the Max Plank Institute of Meteorology lend considerable support to the new IPCC CO2+Sulphate line. Yet, in a discussion that appeared in Science after the publication of the IPCC assessment (‘Are we seeing global warming?’), Hasselmann emphasizes the uncertainties and suggest that we might still be waiting some time before we can properly detect the human warming signal.
Clearly for Wigley, the door might have opened for the models, but the light of credibility was not exactly flooding in. So: What was now left for our loyal skeptic? Despite his view that the human signal was not yet evident, and despite his deep skepticism of the model projections, the models might still be right and the warming might still happen as projected. If so, then: What should we do about it? Should we try to impose drastic emissions reduction targets? Even if this were politically feasible, Wigley said no.
Wigley, the skeptic of emissions mitigation
In May 1995 Wigley submitted a paper to Nature that he had been preparing with two economists. It argued that the cheapest and most desirable ways to respond to expected global warming is not to cut greenhouse gas emissions immediately but to allow ‘business as usual’ growth before taking action in 30 years’ time. Not surprisingly, the paper received a hostile reaction from reviewers. According to Fred Pearce in New Scientist, this ‘resulted in counter-accusations of censorship and a substantial rewrite’. The new version was finally accepted in December and published early in the New Year. The timing of this intervention by a prominent IPCC lead author could not have been worse for the climate convention negotiations. It was published only weeks before the first session of the ‘conference of parties’, where government delegates would be pressed to agree on binding emissions reduction targets. Otherwise, Wigley tried to remain neutral on the politics, and would later protested aggressively when asked to put up his hand in support of Kyoto.
Wigley had resisted claiming detection. Wigley had cautioned against trusting the model projections. And now Wigley is saying, even if the projections are right, then, for the next few decades at least, we should do nothing about it. What was going on here?
Wigley’s (increasingly rocky) middle road
One way to make sense of Wigley’s actions in the 1990s is in terms of his desire to continue on the middle road that he had happily negotiated with the US Department of Energy all through the 1980s. Yes, he had no scruples about continue to fund climate research with the fear-generated money. But this would be only to keeping the question open. It would not be to rush forth and exaggerate the scientific basis for drastic policy action. From the early 1970s, report after report on the possibility of anthropogenic climate change kept recommending, not for action, but only more research. If only this could continue…
At this point it is well worth taking a look at Wigley’s response to a question that serves as a climactic moment in the TV documentary screened in 1990, The Greenhouse Conspiracy. Wigley is asked (at 43:55) whether funding indirectly influences the nature or approach of the research. The answer (at least the one we see) is only implicit and by reference to his own experience at CRU. Wigley explains how CRU is almost complete dependent on ‘soft money’ from external sources. The implication is that CRU can only do the research for which funding is provided…
Funding might influence the subject of investigation, but, when challenged, Wigley will fiercely object to any suggestion that it influences the findings. At CRU he needed to maintain the funding, but this did not push him towards supporting (scientifically unsubstantiated) calls for action on climate change. In fact when these calls grew loud all around, they would jeopardize his chosen course.
The dramatic shift in the politics from 1988 and through the early 1990s impacted all those scientists involved in the research and it affected each in different ways. For Wigley it was that his middle road of ‘more research’ was fast disappearing.
But anyway, even if the political events of the late 1980s did not overwhelm the science, there is still the question of how long this middle course could have been sustained. How long could the fear-generated funding have continued before the bureaucrats and politicians got cynical? Consider how one top science bureaucrat (although not in the UK) reflected on his experiences during the 1970s and 1980s where ‘research policy was the major activity’. Introducing a discussion of environmental scares he says:
Since much of what has laughably been called science policy is a bunfight over who will get the public’s money, I was able to observe the special pleading that goes on…(Preface)
If not for the political shift in the late 1980s, the continuing investigation of the CO2 question would have entered its third decade of special pleading…
Well, is global warming happening or isn’t it?
Whatever happened politically, by the end of the 1980s the pressure must have been growing to answer that question with something more than pleas for still more funded research and a few more years, perhaps decades, to answer it. This situation demanded scientists who could deliver more than Wigley was ever prepared to give. By 1995 his race was run. Another type of character was now required; one prepared to go even further than Santer. Soon enough such characters arrived—and none were more up to the task than Michael Mann. With the differences in their approaches to the science, there is no surprise that Wigley (and other old-school types) would clash with Mann.
The over-riding loyalty of Tom Wigley
The trouble for Wigley in the early 1990s was that the overwhelming influence of the politics meant that it was hard to continue to do the science without taking sides over action on climate change. As the politicization and polarization set in, he resisted. Yet he remained on the side of the good. And this is what is remarkable about him. Others similarly involved in the US research during the 1980s, and similarly moderate in their views, also resisted. But they ended up on the wrong side of the sceptical divide. This was the case for William Nierenberg, who had led a major study that finally reported in 1983 with ‘reason for caution not panic.’ Six years later, his cautioning about panicky policy action had a whole new political significance (see the report & the book). If Wigley felt the same, then what was the difference?
The difference was that Wigley remained loyal to the science. And I think loyalty is the right name for the apparent, overriding sentiment here. From the 1990s onwards, Wigley’s criticism of spurious global warming science could be seen as loyal opposition—moderating the claims that he saw as too extreme. But the other side of this loyalty is what many skeptics came to resent. When the chips were down, Wigley would loyally support and defend global warming research, and the teams of scientists involved, even where he did not seem to support what they were saying. What the skeptic sees as defending the funding, Wigley would see as defending science against the philistines, and defending science against those going in to bat for vested commercial interests. Against the skeptical scientists, he would defend the warming researchers, as though their critics had gone over to the enemy, as though treasonous to science. This explains the way he went in hard to defend Ben Santer against the sceptics in the Chapter 8 controversy.
When the Chapter 8 controversy broke into the public sphere in May and June of 1996, Santer was floundering, reeling under the shock, with support from the IPCC slow and insufficient. Wigley boldly stepped into the breach lashing forth at Fred Singer (among others) in broadcast emails and in the letters pages of Nature. If he were skeptical of the science, then by that time he was keeping it private, while, instead, using an economic argument against immediate emissions reduction.
By the time of the Hockey Stick controversy, early in the new millennium, we know that his skepticism had persisted, only that he was now more discrete about airing it. That his public loyalty hid continuing skepticism is (in my view) one of the great revelations of the Climategate emails.
Consider how the emails reveal Wigley saying that the wide variance in the paleo-reconstructions ‘make me very nervous’ and, if he were ‘on the greenhouse deniers’ side’, then he would be ‘inclined to focus on the wide range of paleo results and the differences between them as an argument for dismissing them all.’ Back in 1985, when there were no ‘greenhouse deniers’ side,’ this was pretty much the reason the CRU crew (Wigley, Jones and Kelly) gave for providing no global trends in their ‘Empirical climate studies’ section of the SCOPE 29 report (the subject of the Villach ’85 conference). Since 1975, most of the major reports addressing man-made global climate change had presented proxy-based graphs of past mean temperature trends on various scales, but Wigley et al refrained from putting them in their report because they are ‘local and poorly dated’ and so…
…we do not know how global mean climate changed, or even if global mean temperature has changed since, say 6,000 BP.
It seems that two decades later Wigley had not changed his view. The leaked emails even show that he was skeptical of the very idea that tree rings could indicate local temperature (he thought it more likely that they measured precipitation, and only temperature in that it correlates with precipitation). But even if trees could be used as thermometers, still he found Mann’s work ‘very sloppy’ and a lot of McIntyre’s critique seemed ‘valid.’ When, in a broadcast email, Michael Mann mocked skeptical criticism of his work, he opens by proclaiming that ‘their supposed “CO2 fertilization” argument is a ruse.’ Wigley is found objecting with reference to an old paper of his on that very topic.
We would never know that Wigley had privately maintained his skepticism if the emails weren’t leaked. By this time there are no published critiques, and no published appeals for ‘sound methodology and scientific honesty’ when it looked like the science has gone astray. If not with the IPCC second assessment, then at least with the third, Wigley’s critical tendencies were restrained in the service of loyalty. And, sadly, we find that this loyalty sometimes took our closet skeptic to extremes, like advocating the conviction and punishment of those who might have inadvertently out-ed themselves: ‘If you think Saiers is in the greenhouse skeptics camp, then, if we can find documentary evidence of this, we could go through official AGU channels to get him ousted.’ There was no out-ing required for the notorious skeptic, Pat Michaels. For him, the idea would be to remove his very legitimacy as a scientist by having his doctorate re-assessed.
What the case of Wigley makes most evident is that the polarization in this debate is not about the science. If it were, then, both before and after Climategate, there is plenty of documentary evidence to place Wigley in the ‘skeptics camp’. And this points to what many skeptical scientists find most disappointing about Wigley, namely, his us-and-them attitude. Despite (or perhaps because of) so much agreement on the science, he can barely maintain civil relations with anyone who had gone over to the dark side. This, in my view, is the source of much of the hostility directed at Wigley. But the more objectionable aspect of this loyalty seems to have come well after his departure from CRU.
Tom Wigley left CRU to take up a position at US NCAR. He left NCAR in 2006 and now lives in South Australia where his interest has moved away from climatological research and towards the promotion of nuclear power. He argues that if we need to reduce GHG emissions then a move toward nuclear generation is more realistic than placing all hope in a shift to renewable energy.
UPDATE JULY 2016
Dr Ben Santer has provided some commentary on this post through recent correspondence on another matter. In April 2016 I asked him for his recollections of the final IPCC SAR lead authors meeting (Asheville, ’95), where, following his presentation of new ‘human fingerprint’ findings, his selection and use of radiosonde data might have come into question. Santer responded that, because he found this post concerning Tom Wigley so offensive, he did not wish to correspond. He asked me to refrain from contacting him in the future. It was with regret that I accepted this decision because, previously (and even in that very correspondence), Santer has made valuable and unique contributions to my research on the development of the Detection and Attribution findings of SAR. Fortunately, before cutting off the correspondence, Santer did provide some detail of his objections, and I responded with an undertaking to insert an update summarizing them.
A summary of Ben Santer’s critique
Santer says that this post provides an inaccurate assessment of Wigley’s scientific contributions, of his tenure as Director of CRU, and of ‘Tom himself’. He says that I have constructed a fictitious character from flawed analysis of stolen emails. Santer notes one particularly offensive fiction, which is where I claim that Wigley’s support of him in the Chapter 8 controversy was ‘motivated solely by loyalty’. According to Santer, one bottom-line conclusion of the Detection and Attribution papers they had both worked on ‘pre-1997’ was that they had ‘positively identified a human fingerprint in observed surface and atmospheric temperature records’. He argues that this was not a conclusion that he ‘forced upon’ Wigley and other co-authors. Santer says that Wigley’s post-Madrid support for Santer was motivated not by loyalty but by science, including his recognition that the criticism of this work by Pat Michaels (and others) was scientifically incorrect. He says that Wigley worked with him on the research required to address the criticism, and to show that it was incorrect.
(Summary of emails sent to BernieL on 15 April 2016)
I will leave to the reader judgement on the potency of this critique, only offering two comments.
Firstly, more fundamental than the validity of Michael’s critique is why this and other criticism could only appear a year after that criticized served to change the advice to policymakers.
Secondly, it is hard to derive any underlying positive attribution from the papers co-authored by the IPCC D&A assessors. (Santer’s ‘pre-1997’ permits consideration of papers written by the assessors, used in the assessment, but published after its completion.) Their equivocating conclusions are no stronger than previous studies or assessments. The ‘human fingerprint’ study critical to Santer’s presentation at Asheville and Madrid was pitched as ‘A search for the human influence…’ when it appeared in Nature, July 1996. It concluded that the trend it found is ‘likely…partially due to human activities, although many uncertainties remain, particularly relating to estimates of natural variability’. There is nothing new in ‘likely…partially…although many uncertainties’ claims. Moreover, another 1996 paper co-authored by Santer presents the unresolved problem of ‘natural variability’ as devastating to any positive attribution claim of fingerprint studies, and this duly informed the over-riding skeptical conclusions of Chapter 8 that were nevertheless excised.
1. p213. See also Proceedings of the Workshop on First Detection of Carbon Dioxide Effects, Harpers Ferry, West Virginia, June 8-10, 1981 where Mike MaCracken says in his introduction: ‘…early observational confirmation that these theoretical estimates are correct will be an essential step in developing a public consensus.’ (p37).