Anthropogenic heat and exergy balance of the atmosphere

Exergy balance of a climate model is discussed from a thermodynamic point of view, using a control volume approach in which the environment and a superficial layer of the earth form the volume, a concentric spherical shell of predominantly gaseous content with a thin layer of the earth. An energy equation that includes anthropogenic heat is suggested based on the mass balance of fossil fuel introduced into the control volume. An exergy balance is also derived for the control volume with this established energy balance. It is argued that the use of temperature as a climate change indicator should be deemphasized since other thermodynamic coordinates including pressure, wind speed, humidity, etc. are equally important. The concept of Equivalent Rate of Evaporation (ERE) is introduced to better estimate the impact of enthalpy of vaporization on climate change. It is argued that both net energy and exergy terms are more accurate representatives of climate change. Exergy is also used as a preferred tool to compare theoretically extractable work from energy resources. For this purpose, we identify source-based exergy components crossing the biosphere, defined as a control volume. The inputs and outputs of energy and mass flows are illustrated to show the net change, with emphasis on anthropogenic exergy destruction. The approach assists in comparing energy reservoirs, defines renewable resources, and provides a more suitable parameter to quantify climate change.