Thermodynamic Efficiency and Entropy Production in the Climate System

TL;DR

This paper offers a thermodynamic perspective on the climate system, analyzing efficiency, entropy production, and energy cycles to enhance climate modeling and understanding of climate change.

Contribution

It introduces a formal thermodynamic framework for the climate system, linking efficiency, entropy production, and energy cycles with new theoretical insights.

Findings

Lower bound to entropy production related to system efficiency

Re-interpretation of maximum entropy production principle

Thermodynamic tools for climate change analysis

Abstract

We present a new outlook on the climate system thermodynamics, studying some of its macroscopic properties in terms of the 1st and 2nd laws of thermodynamics. We review and clarify the notion of efficiency of the climate system by constructing formally an equivalent Carnot engine with efficiency eta, and show how the Lorenz energy cycle can be framed in a macro-scale thermodynamic context. Then, by exploiting the 2nd law, we prove that the lower bound to the entropy production is eta times the integrated absolute value of the internal entropy fluctuations. An exergetic interpretation is also proposed. Finally, the controversial maximum entropy production principle is re-interpreted as requiring the joint optimization of heat transport and mechanical work production. These results provide new tools for climate change analysis and for climate models' validation.