11 february 2010

Open letter of Dutch researchers on the IPCC and on errors in the climate report of 2007

[The letter was published in an abridged version in the Dutch daily NRC Handelsblad of 10 February 2010 and is online in extenso at www.sense.nl/openbrief ]

Errors in the IPCC climate report are currently being used by certain parties to discredit climate science as a whole. In the Dutch Parliament, climate scientists have recently been denigrated as “cheaters”and a “Climate Mafia. Such qualifications have no basis in fact and are out of order. That the IPCC is not infallible does not mean that its main conclusions are either untrue or distorted. The IPCC ought nonetheless to be more generous in the rapid and open recognition and correction of its errors.

The purpose of this letter from the world of scientific research is to set right the picture that has developed. We ask that the discussion keep closer to the facts. We will discuss here the main message of climate science, the way the IPCC works and the qualitative standards of the IPCC. We will conclude with suggestions for the improvement of our work and for restoration of the damaged trust in climate science.

The climate problem

Since 1990 there has been a rapid increase both in knowledge about human-caused climate change and in the seriousness of the phenomenon. The natural sciences have reached a good understanding of important components of the climate system. We know that the amount of greenhouse gases in the atmosphere have increased sharply since the industrial revolution. That these greenhouse gases in the atmosphere play a major role in the temperature at the earth’s surface is elementary physics. Through the increase of greenhouse gases, the balance of the earth’s thermal radiation is altered and as a result this surface very probably warms up. A global warming of more than 0.5°C in the past century has already been observed. As a result of the posterior effect of the already accumulated greenhouse gases in the atmosphere, the global average temperature is expected to increase in the decades to come by at least 1°C.

The increase of greenhouse gases comes principally through the way coal, oil and natural gas are used and through deforestation. Uncertainties about future emissions of greenhouse gases and the effects they may have are considerable. Studies of highly reputed research groups show that unhindered continuance of the emission of greenhouse gases will by 2100 increase the warming trend by between 1.1 and 6.4°C (compared to the period 1980-1999). Given the fact that there are numerous tipping points in the climate system, this can have partly unpredictable and possibly far-reaching and irreversible consequences for man and nature.

The Copenhagen Accord stipulates that dangerous disruption of the climate system must be prevented and that therefore the globally average warming must be limted to no more than 2°C (in relation to the pre-industrial period). Research shows that this is economically and technically possible by measures to reduce emissions and by changes in consumption patterns.

The IPCC and the 2007 Climate Report

In 1988, the World Meteorological Organization (WMO) and the United Nations Environment Progrmme UNEP) established the Intergovernmental Panel on Climate Change (IPCC), whose goal was to regularly provide policy makers with a carefully prepared overview of the state of knowledge of the climate problem. The IPCC is an open network organization which makes use of well known experts from the entire world, aove all from universities – including most Dutch universities – and of research institutions such as the Dutch meteorological institute (KNMI), the Dutch Center for Energy Research (ECN) and the Planning Office for the Living Environment (PBL). In the IPCC, 194 countries work together, including The Netherlands.

The IPCC issues a climate report roughly every six years, most recently in 2007. This report contains three sections: The Natural Science Basis (Working group I), Impacts, Adaptation and Vulnerability (Working Group II); and a section on solutions, Mitigation of Climate Change (Working Group III). The 2007 reports were written by about 44 writing teams, with a total of 450 main authors. The authors were selected on the basis of their expertise, with participation of all 194 countries. Another 800 research scholars have contributed texts on specific aspects. The entire process of the IPCC is supported by four Technical Support Units (TSUs), each with 5-10 members.

Errors in the IPCC Report

We have taken note of the consternation caused by the errors discovered in the Report of 2007, above all in the report of Working Group II. The incorrect year for the disappearance of Himalayan glaciers and the incorrect percentage of “land completely below sea level” are examples of errors which ought be frankly recognized and corrected. However, they in no way detract from the report’s main conclusion: that humankind very probably is changing the climate, with serious long-term consequences.

In the heated discussions about these errors, questions have been raised about the quality and integrity of the IPCC. The qualitative standard of the IPCC appears to be not always unimpeachable. But the idea that there has been intentional manipulation of scientific knowledge has no basis in fact. We also reject emphatically the notion that the report’s main conclusions depend on dubious sources. The list of references of the roughly 3,000 page report comprises 18,000 sources, the vast majority of them in peer-reviewed scientific studies. The IPCC maintains a clear guideline on the responsible use of so-called grey sources. This guideline was not properly followed in the Himalaya reference, leading to error. Adherence to this guideline in future reports requires extra vigilance.

Maintenance of quality in the IPCC

The notion that the IPCC lacks a good procedure to guarantee quality is incorrect. The procedures for guaranteeing quality in IPCC work is established in a guideline for the so-called peer-review process. This guideline is subject to periodic evaluation and revision. On the IPCC website , one can also find for each chapter all the steps in the writing and reviewing process: the First Order Draft with the commentaries of many researchers attached, the revised Second Order Draft, in which all these comments are integrated, and the commentaries of scientists and representatives of different countries on this revised version. In the latest report, 2,500 referees made all together about 90,000 commentaries on the 44 chapters. For each comment, the authors concerned indicate with arguments how they have reacted to each commentary. Moreover, there are review-editors whose task is to make sure that all commentary has been correctly and honestly handled and incorporated. As the conclusion of the procedure, they sign a declaration to that effect.

The IPCC guideline also prescribes how writing teams have to proceed with sources that are not peer-reviewed and with as yet unpublished work. This guideline recognizes that scientific journals do not contain much about matters such as how many emission reducing measures are possible in various sectors and countries, and about the vulnerability of those sectors and countries for climate change. This knowledge often is found in reports of research institutes or of workshops and congresses or in publications of a particular industry and of other organizations, the so-called grey sources. The IPCC guideline demands that grey sources must be critically examined. Every writing team is obliged to thoroughly check quality and validity before a finding from a grey source can be used. Copies of as yet unpublished sources must be given to the IPCC secretariat for examination by others if they so wish.

We conclude that the IPCC procedures are transparent and thorough even if not always infallible. The writing of IPCC reports and the qualitative vigilance remains the work of human being. Guarantee of an error-free report is an unreachable ideal, desirable as it is. It is of course essential to continually reevaluate the procedure and where necessary to sharpen it by learning from discovered errors.

Where do we go from here?

In the meanwhile, public and political confidence in the scientific basis of climate policy has been dented by the picture that has come about and the – in our view disproportionate – uproar. This is worrying, because the climate question is serious and urgent. Despite the errors, the chief conclusions of the IPCC that we have sketched remain standing.

The IPCC ought to be more generous in the rapid and open recognition and correction of errors. To do this, the IPCC should maintain an erratum on its site of all errors that come to light after publication. Moreover, there should be a clear distinction between on the one hand errors in the reporting of knowledge and on the other new insights. New insights are established and assimilated in the next climate report and would not appear in the erratum.

Climate research and the reporting of the IPCC on the state of knowledge provide a scientific basis for climate policy. The quality and balance of the knowledge offered and the explicit acknowledgement of uncertainties is for us, as for the IPCC, of the highest importance.

Given the recent uproar, we find it important to examine how we can contribute to the search for a resultion. We in the world of scientific research shall commit ourselves to a critical evaluation – if possible with involvement of the Royal Dutch Academy of Science -- of the entire IPCC process. This should lead both to a better prevention of errors and to a proper correction of errors as soon as these are established.

February 10, 2010

01. Prof. Wim Turkenburg, Universiteit Utrecht
02. Prof. Rik Leemans, Wageningen Universiteit
03. Prof. Hans Opschoor, Institute of Social Studies, Den Haag
04. Dr. Bert Metz, European Climate Foundation / voormalig co-voorzitter IPCC Werkgroep III
05. Prof. Rien Aerts, Vrije Universiteit Amsterdam
06. Prof. Theo Beckers, Universiteit van Tilburg
07. Prof. Frans Berkhout, Vrije Universiteit Amsterdam
08. Prof. Frank Biermann, Vrije Universiteit Amsterdam
09. Prof. Kornelis Blok, algemeen directeur Ecofys, Utrecht / Universiteit Utrecht
10. Prof. Henk Brinkhuis, Universiteit Utrecht
11. Dr. Stefan Dekker, Universiteit Utrecht
12. Prof. Peter Driessen, Universiteit Utrecht
13. Prof. Klaas van Egmond, Universiteit Utrecht
14. Prof. Nick van de Giesen, TU Delft
15. Prof. Joyeeta Gupta, Vrije Universiteit Amsterdam
16. Prof. Jan Hendriks, Radboud Universiteit Nijmegen
17. Dr. Ton Hoff, directievoorzitter ECN, Petten
18. Prof. Bert Holtslag, Wageningen Universiteit
19. Prof. Jef Huisman, Universiteit van Amsterdam
20. Dr. Gjalt Huppes, Universiteit Leiden
21. Prof. Bart van den Hurk, Universiteit Utrecht / KNMI
22. Prof. Ekko van Ierland, Wageningen Universiteit
23. Dr. Ron Janssen, Vrije Universiteit Amsterdam
24. Prof. Pavel Kabat, Wageningen Universiteit
25. Prof. Gert Jan Kramer, TU Eindhoven
26. Prof. Carolien Kroeze, Wageningen Universiteit / Open Universiteit Nederland
27. Prof. Maarten Krol, Wageningen Universiteit
28. Dr. Lambert Kuijpers, TU Eindhoven
29. Dr. Lucas Lourens, Universiteit Utrecht
30. Prof. Pim Martens, Universiteit Maastricht
31. Prof. Arthur Mol, Wageningen Universiteit
32. Prof. Henri Moll, Rijksuniversiteit Groningen
33. Prof. Paul Opdam, Wageningen Universiteit
34. Prof. Paquita Perez Salgado, Open Universiteit Nederland
35. Dr. Ad Ragas Radboud Universiteit Nijmegen
36. Dr. Max Rietkerk, Universiteit Utrecht
37. Prof. Lucas Reijnders Universiteit van Amsterdam
38. Prof. Jan Rotmans, Erasmus Universiteit Rotterdam
39. Prof. Paul van Seeters, Universiteit van Tilburg
40. Prof. Anton Schoot Uiterkamp, Rijksuniversiteit Groningen
41. Dr. Appy Sluijs, Universiteit Utrecht
42. Prof. Geert de Snoo, Leiden Universiteit
43. Prof. Gert Spaargaren, Wageningen Universiteit
44. Prof. Jef Vandenberghe, Vrije Universiteit Amsterdam
45. Prof. Anne van der Veen, Universiteit Twente
46. Prof. Pier Vellinga, Wageningen Universiteit
47. Prof. Herman Verhoef, Vrije Universiteit Amsterdam
48. Dr. Pita Verweij, Universiteit Utrecht
49. Prof. Martin Wassen, Universiteit Utrecht
50. Prof. Ernst Worrell, Universiteit Utrecht
51. Prof. Sjoerd van der Zee, Wageningen Universiteit
52. Prof. Bert van der Zwaan, Universiteit Utrecht

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