As part of an open discussion on the critical issue of energy, sustainability and climate change, MRS Energy & Sustainability—A Review Journal (MRS E&S) has published a paper in which Cambridge (UK) engineering professor M.J. Kelly argues that it is time to review the current efforts to reduce carbon emissions, some of which "represent total madness." This paper is one of a series of articles in MRS E&S that, with varying opinions, address this controversial topic.