Statement by ICSU on the controversy around the 4th IPCC Assessment

This statement is endorsed by the Officers of the International Council for Science (ICSU, February, 2010). ICSU is a non-governmental organization representing a global membership that includes both national scientific bodies (119 members) and international scientific unions (30 members). The statement does not necessarily represent the views of all individual Members. See www.icsu.org

As a scientific organization with global representation and active engagement in global environmental change research including climate change, the International Council for Science (ICSU) has been closely following the ongoing controversy concerning the Intergovernmental Panel on Climate Change (IPCC). Important issues have been raised in relation to both the interpretation of scientific knowledge, especially in making predictions of future developments, and the procedures used by the IPCC in its assessment.

With more than 450 lead authors, 800 contributing authors, and 2500 reviewers from more than 130 countries, the IPCC 4th Assessment Report represents the most comprehensive international scientific assessment ever conducted. This assessment reflects the current collective knowledge on the climate system, its evolution to date, and its anticipated future development. It is now apparent, and given the scale of the enterprise not surprising, that some errors did occur in part of the report. However, in proportion to the sheer volume of the research reviewed and analyzed, these lapses of accuracy are minor and they in no way undermine the main conclusions. It should be noted that the errors were initially revealed and made public by scientists and the misinterpretations can now be corrected accordingly. Rather than compromising the integrity and credibility of the science of climate change, this series of events is in itself a demonstration of the vigour and rigour of the scientific process.

In any area of science it is important that errors, or previous assumptions that change in the light of new evidence, are openly admitted and corrected. This is especially the case for the IPCC reports, which have broad and deep implications for societal choices and policy. Lessons should be learnt from the current controversy. The IPCC processes are tried and tested but they are not infallible (and have never been presented as such by the scientific community). In the light of recent events, it is timely to review these processes to see whether modifications can be made that i) reduce the chance of errors being introduced in the first place, and ii) optimise the mechanisms for identifying and correcting errors that do inadvertently remain in the final IPCC reports. The procedures for the IPCC assessments engage not only the scientific community, but also governmental agencies. They are complicated and not always easily understood by those not directly involved. It is important to continue to strive to make these processes as transparent and accountable as possible.

The identified errors in the IPCC report are regrettable but, in the context of the complex IPCC process, understandable. That these errors have resulted in attempts to discredit the main conclusions of the report, accusations of scientific conspiracies, and personal attacks on scientists is unacceptable. Scientific assessments, such as those of the IPCC, are a crucial basis for making the decisions that will shape our society now and in the future. Scientists, governments, and other societal stakeholders need to work together to ensure the quality and relevance of such assessments. We need to learn from the current controversy and make improvements where necessary. We should be grateful to the many thousands of scientists who give freely of their time to contribute to the IPCC and other scientific assessments. And we should continue to be critical but constructively so and in ways that openly recognize the strengths and limitations of the scientific process itself.