ACPD Atmospheric Chemistry and Physics Discussions ACPD 1680-7375 Copernicus GmbH Göttingen, Germany 10.5194/acpd-10-3699-2010 Thermodynamics of climate change: generalized sensitivities Lucarini V. 1 2 3 Fraedrich K. 4 Lunkeit F. 4 Department of Meteorology, University of Reading, Earley Gate, P.O. Box 243, Reading RG6 6BB, UK Department of Mathematics, University of Reading, Whiteknights, P.O. Box 220, Reading RG6 6AX, UK Department of Physics, University of Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy Meteorologisches Institut, Klima Campus, University of Hamburg, Grindelberg 5, 20144 Hamburg, Germany 09 02 2010 10 2 3699 3715 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys-discuss.net/10/3699/2010/acpd-10-3699-2010.html The full text article is available as a PDF file from http://www.atmos-chem-phys-discuss.net/10/3699/2010/acpd-10-3699-2010.pdf

Using a recent theoretical approach, we study how the impact of global warming of the thermodynamics of the climate system by performing experiments with a simplified yet Earth-like climate model. In addition to the globally averaged surface temperature, the intensity of the Lorenz energy cycle, the Carnot efficiency, the material entropy production and the degree of irreversibility of the system are linear with the logarithm of the CO<sub>2</sub> concentration. These generalized sensitivities suggest that the climate becomes less efficient, more irreversible, and features higher entropy production as it becomes warmer.

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