An assessment of the foundational assumptions in high-resolution climate projections: the case of UKCP09

The United Kingdom Climate Impacts Programme’s UKCP09 project makes high-resolution projections of the climate out to 2100 by post-processing the outputs of a large-scale global climate model. The aim of this paper is to describe and analyse the methodology used and then urge some caution. Given the acknowledged systematic, shared errors of all current climate models, treating model outputs as decision-relevant projections can be significantly misleading. In extrapolatory situations, such as projections of future climate change, there is little reason to expect that post-processing of model outputs can correct for the consequences of such errors. B Roman Frigg [email protected] Leonard A. Smith [email protected] David A. Stainforth [email protected] 1 Department of Philosophy, Logic and Scientific Method, LSE, Houghton Street, London WC2A 2AE, UK 2 Centre for Philosophy of Natural and Social Science (CPNSS), LSE, Houghton Street, London WC2A 2AE, UK 3 Centre for the Analysis of Time Series (CATS), LSE, London, UK 4 Pembroke College Oxford, Oxford, UK 5 The Grantham Research Institute on Climate Change and the Environment, LSE, London, UK 6 Department of Statistics, University of Chicago, Chicago, IL 60637, USA 7 Department of Physics, University of Warwick, Coventry CV4 7AL, UK 8 Environmental Change Institute, University of Oxford, South Parks Road, Oxford OX1 3QY, UK