How the IPCC decides which version of climate change to present

The UN’s intergovernmental panel on climate change (IPCC) has just published a new report warning of flooding, storm surges, droughts and heatwaves.  ‘No one will be untouched by climate change’ quotes the Telegraph in its headline.  The reporting is widespread and dramatic, and perhaps it should be.  But there are dissenting voices, including one of the report’s authors, Richard Tol, who withdrew his name because he considered the language of the report summary “alarmist”.

That there should be IPCC scientists who do not agree with the IPCC’s conclusions should not surprise us.  This report was the work of  more than 300 scientists from 70 countries, who in turn were drawing on the research of thousands more climate scientists (it’s quite an industry now).  Chris Field, one of the co-chairs of the working group behind the report, made the point on the Today programme this morning that the report — and particularly its summary — is therefore an exercise in consensus building between hundreds of different opinions.  He said something along the lines of All of the authors think that the report would have been better if it had been closer to their own point of view.

All of which is entirely reasonable.  This is an international body trying to put across a single position for the entire global community of climate experts.  Yet it does make you ponder on the many different versions of the report summary which might have been published.  That the IPCC chose this one, rather than something more optimistic, more pessimistic, more measured or more urgent, does not make it any truer than a dozen other versions of reality they might have proposed.