Insofar as the viability of industrial society is at stake, energy supply and climate change are not normal scientific issues. Fossil fuel is the ultimate finite resource, and the atmosphere the ultimate finite sink. There is dispute about the most fundamental issues and values to be promoted or defended. The concept of post-normal science has been introduced for precisely this kind of situation, where "facts are uncertain, values in dispute, stakes high and decisions urgent (Ravetz [1, p. 349])." Although this applies equally to energy supply and climate change, the related knowledge regimes offer a remarkable contrast. Mainstream energy science, on the one hand, has refused to engage in post-normal science. The accredited experts at the International Energy Agency (IEA) and elsewhere have left "peak energy" to mavericks at the fringes or outside mainstream scientific discourse. Consequently, the pressing issue of future energy scarcity has been kept from the public agenda. Official climate science, on the other hand, has embraced post-normal science. But even though the Intergovernmental Panel on Climate Change (IPCC) has been uniquely successful in placing climate change on the public agenda, the inherent ambiguities of post-normal science have plunged climate science into a deep legitimacy crisis. Most people prefer denial and self-deception to an unvarnished vision of the truth when intractable problems such as peak energy and climate change are at stake. In such cases, scientists are in a double bind: they are damned if they do and doomed if they do not engage in post-normal science. (C) 2010 Elsevier Ltd. All rights reserved.