It is perhaps no surprise that a climate change 'sceptic' has leaked a draft copy of the volume prepared by working group I for the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, the final version of which is scheduled for publication in September 2013.
The response to the leak of all of 14 chapters of the 'second order draft', will test the crisis management skills of the IPCC in much the same way as the revelation in January 2010 that the Fourth Assessment Report, published in 2007, contained a couple of small but significant errors. On that occasion, the IPCC was slow and reluctant to respond, turning the drafting mistakes into a major crisis. As a registered reviewer of the Fifth Assessment Report, I hope that the IPCC will show that it has learned the lessons of that fiasco, and will respond rapidly and effectively without becoming bogged down in arguments about 'due process'.
Under the arrangements for the review of the second order draft of the report, which drew to a close on 30 November, almost anyone could register to access the documents, as long as they agreed to keep them completely confidential. A number of 'sceptics' seized the opportunity, including Christopher Monckton, who has been boasting of his status as an "expert reviewer".
One of the 'sceptic' reviewers, Alex Rawls, posted copies of each draft chapter on the website of 'Watts Up With That', attempting to justify the breach of confidentiality on the grounds that the "taxpayer funded report" should be "properly in the public domain".
In a move that is reminiscent of the hacker who distributed e-mails from the Climatic Research Unit at the University of East Anglia in November 2009, Rawls has attempted to give a misleading impression of the contents of the draft report by cherry-picking and quoting sections out of context.
Rawls focuses on a sentence that he claims has been significantly added to the second order draft about the potential role of cosmic rays from outer space in affecting levels of cloud cover in the Earth's atmosphere, and hence influencing surface temperature. According to this theory, cosmic rays enter the Earth's atmosphere and nucleate clouds, but periods of high magnetic activity in the Sun deflect the rays away, leading to fewer clouds. 'Sceptics' claim that the magnetic activity of the Sun has been gradually increasing over the past 40 years, so that the skies around the world have become much less cloudy, allowing the Sun's rays to gradually warm the surface.
The quotation highlighted by Rawls, which appears on page 41 in the draft of Chapter 7 on 'Clouds and Aerosols', is:
"Many empirical relationships have been reported between GCR [galactic cosmic rays] or cosmogenic isotope archives and some aspects of the climate system The forcing from changes in total solar irradiance alone does not seem to account for these observations, implying the existence of an amplifying mechanism such as the hypothesized GCR-cloud link. We focus here on observed relationships between GCR and aerosol and cloud properties."
However, Rawls studiously avoids any reference to the following conclusion which appears on page 44:
"Although there is some evidence that ionization from cosmic rays may enhance aerosol nucleation in the free troposphere, there is medium evidence and high agreement that the cosmic ray-ionization mechanism is too weak to influence global concentrations of CCN [cloud condensation nuclei] or their change over the last century or during a solar cycle in any climatically significant way. The lack of trend in the cosmic ray intensity over the last 50 years provides another strong argument against the hypothesis of a major contribution of cosmic rays to ongoing climate change."
It is clear that the second order draft of the working group I report pretty much demolishes every single argument, like the cosmic ray hypothesis, that has been put forward by 'sceptics' against the overwhelming evidence that climate change is being driven by greenhouse gas emissions from human activity.
However, it is important that the IPCC does not allow predictable shenanigans by 'sceptics' to undermine confidence in the Fifth Assessment Report. The review of the second order draft has been carried out in line with the principles of peer review which are used throughout academic science. Reviewers are expected to exhibit high standards of ethical behaviour including maintaining confidentiality. It is disappointing, if not surprising, that 'sceptics' are unable to match such high standards.
Nevertheless, the IPCC must now act quickly to defend the integrity of the draft report, and respond decisively to attempts by 'sceptics' to misrepresent its contents.
Bob Ward is policy and communications director at the Grantham Research Institute on Climate Change and the Environment at London School of Economics and Political Science.