Letter to Science: Changes in the Climate Change Report

The controversial text changes (News & Comments, 21 June) made in "Climate Change 1995," the report of the Intergovernmental Panel on Climate Change (IPCC) [1], point to a possible distortion of science for political purposes. If the IPCC conclusions are accepted by governments as being based on solid science and lead to global controls on energy use and generation, drastic economic consequences would follow, impacting mainly on the world's poor.

Dr. Benjamin Santer, convening lead author of Chapter 8, admits to making the actual changes between the final approval of the report in Madrid (in November 1995} and its printing (in May 1996), because "reviewers requested them" [2]. This statement obviously calls for considerable amplification.

The legality of the procedure is still in dispute [3]. It is not clear, for example, who else was involved in making the changes, who decided that changes were necessary, and who approved or edited the changes before the book was printed [4].

Following its own investigation, Nature reports that the responsibility for disputed changes lies with "IPCC officials" [5]. A Richmond Times-Dispatch editorial states on credible authority that the changes "were made at the request of State Department officials, not scientists" [6]. A news story in Nature [7] confirms that a State Department letter of November 15, 1995 "endorsed" changes in the report, but does not explain how the State Department derives such authority.

Did "scientific cleansing" change the tone of the report? The IPCC says No. Nature [5], while clearly favoring the IPCC and impugning its critics, nevertheless concludes that "there is some evidence that the revision process did result in a subtle shift ... [that] tended to favour arguments that aligned with the report's broad conclusions." (Critics of the IPCC would have used much stronger words). The Nature article further admits that "phrases that might have been (mis)interpreted as undermining these conclusions have disappeared" [5].

Why were these changes made? Santer says he "fine-tuned the wording to bring the report into line with the scientific consensus" [2] (emphasis added). IPCC officials quoted by Nature claim the reason for the revisions was "to ensure that it conformed to a `policymakers' summary' of the full report..." [5].

Their claim raises the obvious question: Should not a summary conform to the underlying scientific report rather than vice versa? More important, the policymakers' summary is a political consensus of government delegations not a scientific one. The several pages of the Summary--drafted by the IPCC leadership--were tortuously discussed, line by line, in three days of plenary sessions in Madrid [8].

Why were IPCC officials so anxious to make the scientific report conform to the Summary once its wording had been hammered out? In my view, there may have been two reasons:

1. In the past, the IPCC had been severely criticized in connection with their first climate assessment report of 1990 (and its 1992 addendum), when that earlier Summary clearly departed from the underlying scientific report, thereby portraying the warming issue as much more serious than the data permitted [9].

2. A more basic reason may be that the Summary contains so little to back the political claim of a global warming threat. Ever economical with the truth, the Summary presents the underlying facts selectively and omits relevant information [10]. For example, the Summary does not even mention the existence of 18 years of weather satellite data that show a slight global cooling trend, contradicting all theoretical models of climate warming [11].

In its earlier reports [12], the IPCC used the artful phrase that data and climate models were "broadly consistent." This phrase has now been abandoned. In 1996 [13], it seems to be "balance of evidence for a discernible human influence" on climate. Nothing is new here; we have known for some years that the stratosphere is cooling [14], that the diurnal temperature range has been decreasing [15], etc.--most likely as the result of human influence.

But even if a "discernible human influence" were to exist [16] in the surface temperature record, this does not mean that greenhouse warming will occur at anywhere near the rapid rate calculated from current climate models--although this is exactly what many will be led to believe when they read the Summary and altered report.

S. Fred Singer, distinguished research professor of the Institute for Humane Studies at George Mason University, directs the Fairfax, VA based Science & Environmental Policy Project.

Tel: 703-934-6940

REFERENCES and NOTES

1. The UN-sponsored IPCC acts as the scientific advisor to the governments adhering to the Global Climate Treaty, signed at the 1992 UN Earth Summit in Rio de Janeiro and formally known as the Framework Convention on Climate Change (FCCC).

2. . Weiss, Science 272, 1734 (21 June 1996) gives a valuable but incomplete account of the controversy.

3. "The IPCC: Institutionalized Scientific Cleansing" Memorandum published by the Global Climate Coalition (an industry-supported group) Washington DC, May 23, 1996 (9pp); Frederick Seitz, "A Major Deception on Global Warming", Wall Street Journal, June 12, 1996; D. Wamsted, "Doctoring the Documents?", The Energy Daily 24, May 22, 1996, Washington DC; B. D. Santer, Letter to the Editor, The Energy Daily 24, June 13, 1996; J.T. Houghton, quoted by E. Masood, Nature 381, 546 (13 June 1996).

4. S.F. Singer, Letter to the Editor, The Energy Daily 24, July 3, 1996. Also accessible on the WWW (http://www.his.com/~chyden/SEPP)

5. Editorial, "Climate debate must not overheat", Nature 381, 539 (13 June 1996).

6. Editorial, Richmond Times Dispatch (16 June 1996)

7. E. Masood, Nature 381, 639 (20 June 1996).

8. In the October 9, 1995 draft, the Summary of the IPCC Working Group I (Science) report claimed that historic temperature data "point towards a detectable human influence on global climate." After intensive debate in Madrid, this statement was toned down to: "...balance of evidence suggests that there is a discernible human influence on global climate."

9. "The Greenhouse Debate Continued: An Analysis and Critique of the IPCC Climate Assessment" S. F. Singer (ed.) The Science and Environmental Policy Project, ICS Press, San Francisco, 1992. In the 1990 IPCC report (p.v), the editors admitted to the existence of a "minority of opinions" among scientists who worked on the IPCC report, but whose views they "could not accommodate." Trying to marginalize scientific critics, the Nature editorial [5] refers to "dissent from a dwindling band of skeptics", but some 100 atmospheric scientists have now been willing to sign the "Leipzig Declaration," based on a conference held there in November 1995 to discuss critically the evidence for global warming.

10. S.F. Singer, Science 271, 581 (2 February 1996)

11. R. W. Spencer and J. R. Christy, J. Climate 6, 1194--1204 (1993). The 1996 IPCC report discusses the satellite data fully; its Technical Summary allocates them three lines (p. 27); its Policymakers' Summary does not mention satellites.

12. IPCC 1990: "Climate Change: The IPCC Scientific Assessment" J.T. Houghton, G.J. Jenkins and J.J. Ephraums (eds.), Cambridge University Press; IPCC 1992: "Climate Change: The Supplementary Report to the IPCC Scientific Assessment" J.T. Houghton, B.A. Callander and S.K. Varney (eds.), Cambridge University Press.

13. IPCC 1996 (The Second Assessment): "Climate Change 1995: The Science of Climate Change" J.T. Houghton et al. (eds.), Cambridge University Press.

14. R.W. Spencer and J.R. Christy, J. Climate 5, 847--857 (1992).

15. T.R. Karl et al, Bull.Am.Met.Soc. 74, 1007--1023 (1993).

16. This IPCC conclusion seems to be based mainly on a research paper by B.D. Santer et al, (Clim.Dyn. 12, 77-100, 1995) that was published in December 1995, after the IPCC accepted the final draft report, and well after the draft was printed. The paper claims an "increasing similarity" between observed patterns of surface temperature change and a model-simulated response to a combined sulfate aerosol/CO2 forcing. The correlation coefficient does show an increase over the past 50 years, but shows zero or even negative trends over the past 25 years (see Figure 10). In any case, the coefficient is unimpressively small. There are additional problems with the result that are being addressed in separate publications.
    In a Washington seminar presented to congressional staff on May 21, 1996, B.D. Santer and T.M.L. Wigley distributed a summary article ("Detection and Attribution of a Human Effect on Global Climate") from which the zero and negative trends of Figure 10 had been edited out, leaving only the positive 50-year trend.