The IPCC AR5 guidance note on consistent treatment of uncertainties: a common approach across the working groups

Evaluation and communication of the relative degree of certainty in assessment findings are key cross-cutting issues for the three Working Groups of the Intergovernmental Panel on Climate Change. A goal for the Fifth Assessment Report, which is currently under development, is the application of a common framework with associated calibrated uncertainty language that can be used to characterize findings of the assessment process. A guidance note for authors of the Fifth Assessment Report has been developed that describes this common approach and language, building upon the guidance employed in past Assessment Reports. Here, we introduce the main features of this guidance note, with a Climatic Change (2011) 108:675–691 DOI 10.1007/s10584-011-0178-6 M. D. Mastrandrea (*) : K. J. Mach : K. L. Ebi IPCC Working Group II Technical Support Unit, Carnegie Institution for Science, 260 Panama Street, Stanford, CA 94305, USA e-mail: [email protected] G.-K. Plattner IPCC Working Group I Technical Support Unit, University of Bern, Zähringerstrasse 25, CH-3012 Bern, Switzerland G.-K. Plattner : T. F. Stocker Climate and Environmental Physics, Physics Institute, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland O. Edenhofer Potsdam Institute for Climate Impact Research (PIK), P.O. Box 60 12 03, 14412 Potsdam, Germany O. Edenhofer Faculty Planning Building Department, Technical University Berlin, Straße des 17. Juni 145, 10623 Berlin, Germany T. F. Stocker Oeschger Centre for Climate Change Research, University of Bern, Zähringerstrasse 25, CH-3012 Bern, Switzerland focus on how it has been designed for use by author teams. We also provide perspectives on considerations and challenges relevant to the application of this guidance in the contribution of each Working Group to the Fifth Assessment Report. Despite the wide spectrum of disciplines encompassed by the three Working Groups, we expect that the framework of the new uncertainties guidance will enable consistent communication of the degree of certainty in their policy-relevant assessment findings.