This letter is addressed to scientific colleagues, primarily those on the IPCC list used by Benjamin Santer in his various e-mail letters to me. I have received many letters from others, and this is an efficient way to reply, given my limited time. Following the dictum omnia est divisa in partes tres, I shall report what I have learned about the changes to Chapter 8, then discuss different interpretations of the IPCC Summary's key conclusion, and finally present some policy implications.
In brief, I believe that:
Responsibility for Changes
I have now learned that convening lead author Ben Santer was instructed (prevailed upon?) by IPCC WG-I co-chairman John Houghton to make changes to Chapter 8 following the Madrid meeting. Santer should therefore not be accused of having committed these actions independently, even though he himself has always claimed personal responsibility for the alterations. In reviewing all of my written statements, whether public or private, I do not find any "attack" on Santer; I will say, however, that he has not been forthcoming with the necessary information. We have just now learned from Tom Wigley that he was also involved in making these changes. We may assume that the other two lead authors (Barnett and Anyamba) were simply informed of the changes at some later date but did not raise substantial objections.
This scenario--clearing Santer of responsibility--is in accord with a report in Nature (June 13), which places the responsibility on "IPCC officials." Moreover, I have now obtained a copy of the November 15 letter from the U.S. Department of State to Sir John Houghton, signed by Day Mount (Deputy Assistant Secretary, Acting). It states, inter alia, that "it is essential that chapters not be finalized prior to the completion of discussions at the IPCC WG-I plenary in Madrid, and that chapter authors be prevailed upon to modify their text in an appropriate manner following discussion in Madrid."
I don't know if other chapters of the IPCC WG-I draft report were modified in the same manner as was Chapter 8.
Purpose of Changes
The Nature article quotes the same unnamed IPCC officials as claiming "that the sole reason for the revisions was to tidy up the text, and in particular to ensure that it conformed to a 'policymakers' summary' of the full report that was tortuously agreed by government delegates at the Madrid meeting." The State Department letter confirms this interpretation and contradicts other reasons cited for the changes (for example, by the story in the June 21 issue of Science).
Why did the IPCC make the effort to "conform" the Chapter to the Summary for Policymakers (SPM), when most people would only read the SPM? My guess is: Since the publication of its first assessment report in 1990, the IPCC has been quite sensitive to charges, easily demonstrated by textual comparison, that the SPM did not reflect the underlying scientific report (1).
Were the Changes Substantial?
When I was first apprised of the existence of alterations to Chapter 8 in a mailing from the Global Climate Coalition in May 1996 (2), my reaction was that of surprise. I had attended both the Madrid and Rome meetings and recalled no discussion or announcement of such changes. But after personally comparing the "final draft" (of October 9, 1995) and the printed version (May 1996), I had to conclude that the changes were indeed substantial.
I realize that judgments can differ (3). It would, therefore, be best to have this matter settled by independent reviewers. It may, however, be helpful to quote three key phrases that were deleted from the final draft of Chapter 8:
As the Nature article remarks, "...some phrases that might have been (mis)interpreted as undermining these [IPCC] conclusions ... have disappeared."
In my view, these three phrases, which were subscribed to by the four lead authors, 31 contributors, and numerous reviewers of Chapter 8, should not have been deleted from the IPCC report. **They should have been placed in the Summary for Policymakers.**
Legality of Changes
It is a matter of dispute--but of great importance--whether the text revisions, Houghton's instructions to Santer, or the State Department letter, were in accord with IPCC procedures. I have no fixed opinion and will leave the resolution of this dispute to others, including legal experts.
A separate question is whether IPCC procedures on matters such as peer-review are in accord with accepted scientific standards. For example, a conscientious journal editor would not choose an author's colleague as a referee. The Nature article points out that "the integrity of the reviewing and approval process is ... an essential element in assuring the credibility of the resulting conclusions." The IPCC assigned the role of convening lead author to Ben Santer, who then based much of the conclusion of Chapter 8 on two of his own papers that had not yet appeared in peer-reviewed journals (4). (The comment deadline on Chapter 8 was July 1995; one paper appeared in Climate Dynamics in December 1995, his other paper in Nature in July 1996). Eight of his co-authors are also listed as Chapter 8 contributors. I don't think that one can fairly expect them to be critical of their own work. And indeed, I have seen several scientific notes being submitted for publication, critiquing the two Santer articles, now that these have been published in widely available journals.
There is nothing in the SPM to support or validate the climate models that predict a substantial future warming (5). On the contrary, the estimates of IPCC 1995 are substantially less than those of 1992 or 1990. No mention is made in the SPM of the existence of weather satellite data that show absolutely no warming over the last 18 years. Instead, reliance is placed on an ambiguous phrase: "The balance of evidence suggests a discernible human influence on global climate."
This contrived wording conveys different meanings to different audiences; scientists read it in one way, policymakers in quite another way:
Scientists will accept this phrase and just shrug their shoulders (6). We have known for years now that human activities can affect not only local, but also regional and even global climate. Here are just two examples that are presumed to show an effect of human- induced radiative forcing:
- During the past five decades, there has been a downward trend in the frequency of intense hurricanes, -0.32 intense hurricanes/year per decade, significant at the 2% level. In addition, the mean maximum intensity of hurricanes has been decreasing over the same 50-year period (reference: Landsea et al., Geophysical Research Letters, 23, pp. 1697-1700, 15 June 1996).
- A number of scientific papers have pointed to a statistically significant decrease in diurnal range of temperature over the past decades. This evidence is cited in the recent IPCC report (pp. 144-146).
**Please note:** The existence of such presumed human influences does not by itself validate the climate models. In particular, it cannot be used to claim a substantial temperature rise in the next century--**nor does the IPCC SPM make such a claim.** The likely reason: IPCC scientists would never agree to this. What the SPM does is to report the outcome of climate model calculations. It then implies that the "human influences" somehow validate these models. They do not.
**A key scientific issue:** Can one derive reasonable estimates of the climate sensitivity (defined as the temperature change for a doubling of effective CO2 concentration) from currently available pattern-based analyses? For example, can Northern/Southern hemisphere temperature differences, or the observed stratospheric cooling trend, be used to set numerical limits on climate sensitivity and discriminate among models whose results differ by 300 percent?
The conclusion drawn in Chapter 8 is that one obtains an increasing trend of pattern correlation, R(t), only through the addition of sulfate aerosols in the model calculations. But a straightforward comparison of Figures 8.10(a) and (b) leads to the finding that, if anything, it is the sulfate aerosols that may be causing the increasing trend shown for R(t). Hence, the correct interpretation would be that the anthropogenic greenhouse effect, and hence the climate sensitivity, is negligible.
No great weight should be attached to this conclusion, however, except that the analysis gives little information about the enhanced greenhouse effect. This fact is freely admitted in Section 8.4.2.3 (p. 434): "To date, pattern-based studies have not been able to quantify the magnitude of a greenhouse gas or aerosol effect on climate."
While the IPCC phrase does not in any way confirm a future warming, it does convey such an **impression** to policymakers; indeed, since we do not find any specific disclaimer in the SPM, I suspect that this was the purpose. And judging from the statements by government officials at the Geneva climate meetings in July 1996, this purpose certainly has been accomplished. Acting in good faith, they have to believe that all of the climate disasters linked to a major global warming are likely to come true--unless emissions are drastically curtailed.
The IPCC report has recently been used to justify a policy switch-- from the present voluntary program, based on energy conservation and efficiency improvements, to legally binding (i.e. mandatory) emission targets and time-frames. It should be clearly recognized that mandatory controls mean either the imposition of rationing, or of energy taxes, and/or of mandatory efficiency standards that cannot be economically justified (otherwise they would have been done voluntarily).
The U.S. Government, at the July 1996 Geneva meetings, cited climate science as the reason for this policy shift. This may come as a surprise to IPCC scientists since, if anything, scientific support for mandatory targets is weaker now than it was four years ago when the Climate Treaty was signed. Yet the State Department briefing paper asserts: "The first and foremost reason for launching this new direction is the science." Undersecretary of State Timothy Wirth declared: "The science calls on us to take urgent action" (7). DOE assistant secretary, Dirk Forrister, refers to the science as "convincing and compelling." It is neither; the scientific evidence certainly does not support either statement; nor does the full IPCC report itself.
Some may applaud such a policy shift, but I would hope that scientists, in particularly climate scientists, would not go along with such schemes. We know full well that stabilization of atmospheric CO2 demands a 60 to 80 percent cut in emissions-- worldwide. Yet in a London press conference on June 5, releasing the IPCC report, Houghton called for such mandatory policies, clearly adding a political dimension to his scientific role as IPCC co-chairman. The British Secretary for the Environment, John Gummer, was not hesitant in spelling out a numerical target of over 50 percent, with an emissions cut of 5 to 10 percent by the year 2010 as a first step. He hasn't told the British public how this is to be accomplished.
All sorts of groups seem to favor mandatory control of energy consumption, without paying the slightest attention to the dire consequences this policy would have on lower-income families and on developing nations. I have now seen a June 17 letter in The Times (London) by John Houghton and assorted luminaries, including an ex- Archbishop. It refers to climate change as a "moral issue." It blames the industrialized countries for the problem, and expresses regret that no binding targets on emissions have as yet been adopted. It ends with:
"A change in attitude is required by both Government and individuals, and for this reason we welcome the current initiative of the World Council of Churches in launching a petition on climate change which calls upon the Government to adopt firm, clear policies and targets, and the public to accept the necessary consequences." (These consequences are not spelled out.)
The letter endorses the idea that such policies [i.e. cutting energy use by more than 50 percent] "can contribute powerfully to the material salvation of the planet from mankind's greed and indifference." Not one word about the alleged climate consequences of the enhanced greenhouse effect; no recital of the horrible disasters that are usually trotted out by Greenpeace and Friends of the Earth; just the moral benefits of less energy use. Is this what scientific research has led to?
Conclusions
As far as most politicians are concerned, the science is now settled. There is really no need for further research, and certainly not for any results that might cast doubt on the "scientific consensus." According to the Ministerial Declaration issued in Geneva on 18 July 1996, paragraph 4, the continuing work by the IPCC can now focus on "socio-economic and environmental impacts on developing countries." With the ambiguous IPCC conclusion at hand they can now say to climate scientists: "Ladies and Gentlemen, thank you very much. You've done your job. We don't need you anymore. You can now leave the room. We have more important work to do to figure out how to apportion emissions, a political job that we're perfectly qualified to do without your help."
I believe we have here a clear example of the misuse of science-- and of scientists. If you agree, or have some constructive comments, I would like to hear from you. You may even be interested in joining others in signing the attached Leipzig Declaration.
NOTES
1) See, e.g. The Greenhouse Debate Continued: An Analysis and Critique of the IPCC Climate Assessment, The Science and Environmental Policy Project (S.F. Singer, Ed). Published by ICS Press, San Francisco, Cal. (ISBN: 1-55815-233-4).
2) I am puzzled by statements that one should not accept the fact that changes were made in Chapter 8 because they were first uncovered by an industry-supported group. Does the identity of the messenger alter the facts of the message?
3) I am amazed that anyone insists that only climate scientists with peer-reviewed papers in this subspecialty, i.e. contributors to Chapter 8, can make such a judgment.
4) Chapter 8 ("Detection of Climate Change and Attribution of Causes") lists 19 references to either the (Dec 1995) Climate Dynamics paper (1995a), or the (July 1996) Nature paper (1995b) (sic). The Clim. Dyn. paper is also used as a reference in Chapter 5 ("Climate Models-Evaluation") and Chapter 6 ("Climate Models- Projections of Future Climate"). Note also the modification of Figure 10 of the Climate Dynamics paper when reproduced as Figure 8.10b in the IPCC report.
5) I keep getting e-mail from people who should know better, insisting that the large pre-1940 temperature increase is evidence for the validation of climate models.
6) Most people have difficulty in defining the meaning of this artful phrase; some skeptics call it a big "nothing-burger" that the IPCC came up with because they had nothing else to show. In any case, it is only the latest in a series of vague terms from IPCC summaries. In its 1990 report, the phrase that was supposed to validate climate models was: "broadly consistent"; it is no longer used.
7) Mr. Wirth hasn't always been so solicitous of science. In 1990, then-Senator Tim Wirth boldly asserted, "We've got to ride the global warming issue. Even if the theory is wrong, we will be doing the right thing in terms of economic and environmental policy."
S. Fred Singer