Thermodynamics of climate change: generalized sensitivities

Abstract. Using a recent theoretical approach, we study how global warming impacts the thermodynamics of the climate system by performing experiments with a simplified yet Earth-like climate model. The intensity of the Lorenz energy cycle, the Carnot efficiency, the material entropy production, and the degree of irreversibility of the system change monotonically with the CO₂ concentration. Moreover, these quantities feature an approximately linear behaviour with respect to the logarithm of the CO₂ concentration in a relatively wide range. These generalized sensitivities suggest that the climate becomes less efficient, more irreversible, and features higher entropy production as it becomes warmer, with changes in the latent heat fluxes playing a predominant role. These results may be of help for explaining recent findings obtained with state of the art climate models regarding how increases in CO₂ concentration impact the vertical stratification of the tropical and extratropical atmosphere and the position of the storm tracks.