Why models run hot: results from an irreducibly simple climate model

Lord Christopher Monckton of Brenchley & Tom Tamarkin, Fusion4Freedom founder, at the Ninth Annual Conference on Climate Change after Lord Monckton’s keynote address; July 2014, Las Vegas, Nevada, USA.

Christopher Monckton • Willie W.-H. Soon •
David R. Legates • William M. Briggs

Received: 27 August 2014 / Accepted: 12 November 2014 / Published online: 8 January 2015
 Science China Press and Springer-Verlag Berlin Heidelberg 2015


An irreducibly simple climate-sensitivity model is designed to empower even non-specialists to research the question how much global warming we may cause. In 1990, the First Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) expressed “substantial confidence” that near-term global warming would occur twice as fast as subsequent observation. Given rising CO2 concentration, few models predicted no warming since 2001. Between the pre-final and published drafts of the Fifth Assessment Report, IPCC cut its near-term warming projection substantially, substituting “expert assessment” for models’ near-term predictions. Yet its long-range predictions remain unaltered. The model indicates that IPCC’s reduction of the feedback sum from 1.9 to 1.5 W m-2 K-1 mandates a reduction from 3.2 to 2.2 K in its central climate-sensitivity estimate; that, since feedbacks are likely to be net-negative, a better estimate is 1.0 K; that there is no unrealized global warming in the pipeline; that global warming this century will be <1 K; and that combustion of all recoverable fossil fuels will cause <2.2 K global warming to equilibrium. Resolving the discrepancies between the methodology adopted by IPCC in its Fourth and Fifth Assessment Reports that are highlighted in the present paper is vital. Once those discrepancies are taken into account, the impact of anthropogenic global warming over the next century, and even as far as equilibrium many millennia hence, may be no more than one-third to one-half of IPCC’s current projections.

Keywords Climate change  Climate sensitivity Climate models  Global warming  Temperature feedbacks  Dynamical systems

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