Written evidence submitted by Robin Guenier (IPC0024)

This evidence is a response to the Energy and Climate Change Select Committee’s inquiry concerning the 5th Assessment Review (AR5) of the Intergovernmental Panel on Climate Change (IPCC).

  I have an MA from Oxford University and am a barrister. I’ve been an independent business consultant for several years, specialising most recently in project risk, and was founder chair (now non-executive director) of the medical online research company, Medix UK. In 1996, I was Chief Executive of the Central Computing and Telecommunications Agency reporting to the Cabinet Office. This note is written in my private capacity; it is not intended to represent the views of Medix.

  As a result of experience acquired at Medix, I am familiar with the practical difficulties involved in designing, conducting and analysing surveys of professionals’ opinions in such a way as to be confident that the results of such surveys are an accurate reflection of those opinions. Drawing on that experience, this evidence will address the following question:

“To what extent does AR5 reflect the range of views among climate scientists?”

EXECUTIVE SUMMARY

• Only the WGI Summary for Policymakers (SPM) of AR5 has so far been published. This submission focuses on the three principal SPM findings: (i) warming of the climate system, (ii) human influence on climate and (iii) the implications of continued greenhouse gas emissions.
   
• The submission examines these in the light of the three studies (Doran, Anderegg and Cook) most commonly cited as claiming that most climate experts (usually 97%) agree humans are causing warming. It concludes that the unsatisfactory nature of these studies means they can make only a limited contribution to this submission.
   
• Other evidence, from a 2008 study conducted by Dennis Bray and Hans von Storch, from a more recent American Meteorological Society study, from within the SPM itself and from, in particular, China, is examined and is shown to suggest that the AR5 findings only marginally reflect climate scientists’ views.
   
• The submission concludes: (a) there is insufficient evidence to support a satisfactory answer to the Committee’s question; (b) the only way to establish a satisfactory answer would be to carry out a full, properly conducted worldwide opinion survey (considered likely to be impracticable); and (c) such evidence as does exist indicates that the answer may well be that AR5 reflects climate scientists’ views to only a very limited extent.

1. DIFFICULTIES

  1.1  So far, only part of AR5 has been published: the “Summary for Policymakers” (the SPM), based on “The Physical Science Basis” report from Working Group I (WGI) – the latter available only as a “final draft”. Therefore, it’s not possible to comment on how climate scientists might view AR5 as a whole. Accordingly this submission assumes that the Committee’s question relates only to the SPM.

  1.2  But there’s a difficulty even with this: the SPM covers four essentially discrete matters: “Observed Changes”, “Drivers of Climate Change”, “Understanding the Climate System” and “Future … Change” – each dealing with a range of considerations. Does the Committee’s question refer to the whole SPM or should its parts be considered separately?

  1.3  The phrase “climate scientist” is a third problem. Climate science covers a wide range of scientific disciplines – from, for example, paleoecology to atmospheric physics – each working on different pieces of an extraordinarily complex puzzle. Even closely related disciplines can present a difficulty: in an interview with the BBC in 2010[i], Professor Phil Jones of the University of East Anglia (whose research includes the detection of climate change), when asked whether natural influences could have contributed to global warming, replied, “This area is slightly outside my area of expertise”. If attribution is outside Professor Jones’s expertise, it must be far outside the expertise of, say, an expert on how temperature change affects agriculture. Therefore, as WG1 is concerned exclusively with “The Physical Science Basis”, the opinion of a climate scientist whose expertise is outside that “Basis” is, at best, marginal to the Committee’s question: a problem referred to below as the “Beyond Expertise Problem”.

2.  A SOLUTION

  2.1 These considerations raise complex issues making it virtually impossible to provide a useful answer to the Committee’s question. To simplify matters, this submission will focus on the SPM’s three essential findings:

(i)  “Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia.” (B. – page 2)

(ii)  “It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century.” (D.3 – page 15)

(iii)  “Continued emissions of greenhouse gases will cause further warming and changes in all components of the climate system. Limiting climate change will require substantial and sustained reductions of greenhouse gas emissions.” (E. – page 17)

  2.2  The question now is this: What evidence is there of the extent to which these findings reflect the range of views among climate scientists?

3.  EVIDENCE 

  3.1 As it’s a common claim that a “consensus” of around 97% of climate experts agrees humans are causing global warming, the answer should be easy. Such claims, if valid, would seem to confirm (or at least go a long way towards confirming) that, at least regarding its findings 2.1 (i) and (ii) above, AR5 does indeed reflect the range of views among climate scientists.

  3.2  But whether these claims are valid depends on the quality of the research on which they’re based. Three papers are usually cited: Doran and Zimmerman 2009[ii], Anderegg et al. 2010[iii] and Cook et al. 2013[iv].

              (i)              Doran

This study was based on an opinion poll: 10,257 “earth scientists” were polled, of whom 3,146 responded. However, only about 5% of respondents described themselves as climate scientists and, of these, only 79 had “published more than 50% of their recent peer-reviewed papers on the subject of climate change”. The 97% claim was based on the responses of these 79, i.e. only 2.5% of respondents. But 79 is a barely adequate sample size (certainly inadequate to be representative of all climate scientists), the 50% of recent papers restriction might have excluded knowledgeable respondents and, with a preponderance of respondents (96%) from North America, the sample’s demographic is too limited for global representation. Moreover, the “climate scientist” self-selection is unlikely to have resolved the Beyond Expertise Problem (1.3 above).

These are serious problems. However, the principal problem with Doran is that only two questions were asked, both poorly drafted (the second especially so):

(1) When compared with pre-1800s levels, do you think that mean global temperatures have generally risen, fallen, or remained relatively constant?

(2) Do you think human activity is a significant contributing factor in changing mean global temperatures?

What does “a significant contributing factor” mean? (As there was little human contribution before 1800, even a 5% contribution might properly be regarded as “significant”.) That 97% responded “yes” to these questions does nothing to illuminate the probable view of climate scientists regarding the very precise AR5 findings (2.1 above). For example, Professor Richard Lindzen of MIT (probably the worlds’ leading sceptical scientist), when asked the same questions, responded[v]:

“My answer to (1) is probably, but the amount is surprisingly small -- suggesting that global mean temperature anomaly is not a particularly good index. My answer to (2) would be yes, but dependent on what is meant by significant.”

Moreover, the Doran study does not consider the subject matter of the AR5 findings at 2.1 (iii) (above).

For the above reasons, Doran does little to help this submission. 

              (ii)              Anderegg

Anderegg is more helpful in that it addresses a key matter raised by AR5: whether or not “anthropogenic greenhouse gases have been responsible for most of the “unequivocal” warming of the Earth’s average global temperature over the second half of the 20th century”.

However, there are problems. The first is that, unlike Doran, it wasn’t an opinion poll (no one was asked for a view) but a subjective interpretation of published material of some scientists’ views; selection being based on signatures on pro/anti statements. However Medix’s experience (see the introduction to this submission) is that the only reliable way of determining professionals’ opinion is to ask them directly, and not to try to infer their views from secondary evidence.

Another problem is that 903 “climate researchers” were considered to have accepted the above statement compared with 472 who did not: i.e. 66%, not the claimed 97%. The researchers got to 97% by restricting their findings to researchers “most actively publishing in the field” – i.e. the findings did not cover all “climate scientists”. Further, it was essentially confined to North America, was not concerned with the AR5 findings at 2.1 (iii) (above) and made no attempt to resolve the Beyond Expertise Problem (1.3 above).

For the above reasons, Anderegg is of only limited value regarding the extent to which the principal AR5 findings reflect climate scientists’ views.

              (iii)              Cook

Cook concluded there was “an overwhelming consensus” (over 97%) supporting human causation of global warming. But, like Anderegg, the study was based, not on an opinion poll, but on an attempt to establish scientists’ views by inferring them from secondary evidence. Its methodology was to examine the abstracts of some 12,000 climate-related papers published from 1991 to 2011 (hardly a reflection of current opinion) and to assess the extent to which they endorsed the man-made global warming hypothesis – a subjective interpretation, as authors were not asked about their view. In any case, its main finding “that humans are causing global warming” is almost valueless: does it mean all the warming, most of the warming or some unspecified proportion of the warming? The paper is unclear about this. (Compare that with the clarity of AR5’s “dominant cause … since the mid-20th century” finding.) It’s a methodology that demonstrates why the only way to determine professionals’ current views is to directly ask them clear, unambiguous questions.  

The Cook finding of a 97% consensus that CO2 is a greenhouse gas and that mankind’s emissions have warmed the world to some unspecified extent is one with which many, possibly most, sceptical scientists would agree. In any case, it wasn’t a worldwide study, didn’t attempt to resolve the Beyond Expertise Problem (1.3 above) and, most important, was not concerned with the AR5 findings at 2.1 (iii) above.

For the above reasons, Cook is of only limited value regarding the extent to which the principal AR5 findings reflect climate scientists’ views.

  3.3  Two other studies are rather more helpful: an opinion poll of climate scientists conducted in 2008 (Bray and von Storch 2010[vi]) and an opinion poll of American Meteorological Society (AMS) members conducted in 2012[vii].

              (i) Bray and von Storch

Although 66.5% (of 373 respondents from 35 countries) agreed that “most of present or future climate change is, or will be, a result of anthropogenic causes", only 32% thought "the current state of scientific knowledge is developed well enough to allow for a reasonable assessment of the effects of green-house gases emitted from anthropogenic sources" and only 17.75% that "the state of theoretical understanding of climate change phenomena is adequate". So it would seem that most of the 66.5% based their assessment more on an educated guess than on the science; hardly a position that supports the IPCC.

The stated demographics are unsatisfactory: only 78% of respondents are described as climate scientists and they as being concerned with "physics of the climate system (modelling, model development, data acquisition, theory development, etc.)"; there’s no breakdown of skills explaining how many were climate modellers and how many observational physicists. Therefore it’s unclear what scientific specialties were represented by the sample addressed – which, in any case, was not globally balanced: of 373 respondents, 97% were based in the West – mostly the USA, UK and Germany.

Moreover, the survey doesn’t address issues covered by SPM finding 2.1 iii (above) and is five years old – opinions could have changed since it was conducted, especially regarding the reliability of models, the capability of which was already a matter of concern to many respondents.

              (ii) AMS

Only 52% of respondents thought global warming was happening and was mostly anthropogenic; moreover, at most 34% (and probably less) believed warming was happening, was mostly anthropogenic and would be “very harmful” if nothing were done about it. However, the questionnaire is unsatisfactory in phrasing and structure, making interpretation uncertain; also AMS members may not be representative of “climate scientists” as a whole and certainly not of such scientists worldwide. Nonetheless, like Bray and von Storch, this survey indicates that the principal AR5 findings probably reflect climate scientists’ views to no more than a limited extent.

  3.4  There’s more evidence of this from within the SPM itself. It’s interesting to compare the key SPM finding – “It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century” – with Table SPM.1 (SPM page 5). The latter consists of four columns: of these, column 1 lists various phenomena (e.g. “Warmer and/or fewer cold days and nights over most land areas”) and column 3 consists of assessments of “human contribution to observed changes”. For example, it assesses that a human contribution to “Warmer and/or fewer cold days and nights …” was “very likely” (Note: not “extremely likely”). But “contribution” is a very different concept from the “the dominant cause” of the key AR5 finding: as noted above, a contribution could be relatively trivial. So the assessment that a contribution is “very likely” is hardly a useful finding: many sceptical scientists would agree. This huge difference between the key SPM finding and the Table SPM.1 assessment, suggests that the scientists who compiled the Table may have had a different view about attribution from those who drafted the overall finding.

  3.5  One thing that would seem clear from the above evidence is that there’s widespread scientific agreement that mankind has made a significant contribution to global warming. However, there’s some evidence that it’s a view that may not be shared universally. For example, Ding Zhongli, Vice President of the Chinese Academy of Sciences (described as “the final word on climate science for the Chinese Communist Party”), has observed that a significant relationship between temperature and CO2 “lacks reliable evidence in science” [viii]. And here’s a comment[ix] made in 2010 by Xie Zhenhua, who led China’s delegation at the recent UN climate summit in Warsaw:

"There are disputes in the scientific community. We have to have an open attitude to the scientific research. There's an alternative view that climate change is caused by cyclical trends in nature itself. We have to keep an open attitude."

There’s some evidence that Russian[x], Indian[xi] and possibly Polish[xii] scientists may share this view.

4.  CONCLUSIONS

  4.1 As only a small part of AR5 has so far been published, it’s not strictly possible to answer the Committee’s question. However, even if the question is modified to address that part of AR5 that has been published (the SPM), there are still practical problems – because, for example, of the substantial detail comprised by the SPM. And even the expedient of focusing on the three principal SPM findings fails to provide a satisfactory answer. Taking the SPM findings in turn:

(i)  “Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia.”

Although the evidence (of worldwide opinion) is thin, such as there is indicates that it’s almost certain that climate scientists agree with the first part. However, the phrasing of second part is so vague (“many of the observed changes” and “decades to millennia”) as to be almost meaningless. So scientists’ opinion, even if available, would be of little value.

(ii)  “It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century.”

Human influence on the climate was specifically covered by all the above studies. However, none consulted a representative sample of scientists worldwide and most have not resolved the Beyond Expertise Problem (1.3 above). And even the commonly held view that climate scientists agree that mankind has made a significant contribution to global warming is essentially meaningless (see 3.2 (i) and (iii) above) and, in any case, may not be universally accepted (see 3.5). But, in particular, there appears to be little useful evidence that climate scientists agree with the AR5’s  “dominant cause” finding. 

(iii)  “Continued emissions of greenhouse gases will cause further warming and changes in all components of the climate system. Limiting climate change will require substantial and sustained reductions of greenhouse gas emissions.”

Neither of these claims seems to have been the subject of any significant examination of climate scientists’ opinion – except perhaps the AMS survey (3.3 ii above), which indicates that only a minority of scientists agree with these findings.

  4.2  These difficulties and uncertainties largely stem from the fact that the only way to establish a satisfactory answer would be to conduct a worldwide, properly constructed and correctly implemented opinion survey[xiii], unambiguously covering all the SPM’s main findings. The AMS survey and especially the Bray and von Storch survey got closest to this. But not entirely: for example, Bray and von Storch didn’t cover the AR5 findings at 2.2 iii (above), its sample was inadequate and the study does not seem to have resolved the Beyond Expertise Problem.

The complexity of such a survey and, in particular, the need for an accurate and consistent worldwide response make it unlikely that it would be practicable – consider, for example, translation difficulties.

  4.3  In summary, the inadequacy of useful evidence means that the extent to which the SPM reflects climate scientists’ views is both unknown and likely to continue to be unknown. Therefore it’s impossible to provide a reliable answer to the Committee’s question. However, such evidence as does exist indicates that the answer would probably be that AR5 reflects the range of views among climate scientists to only a very limited extent.

December 2013