The second law of thermodynamics and the global climate system: A review of the maximum entropy production principle

Abstract

[1] The long-term mean properties of the global climate system and those of turbulent fluid systems are reviewed from a thermodynamic viewpoint. Two general expressions are derived for a rate of entropy production due to thermal and viscous dissipation (turbulent dissipation) in a fluid system. It is shown with these expressions that maximum entropy production in the Earth s climate system suggested by Paltridge, as well as maximum transport properties of heat or momentum in a turbulent system suggested by Malkus and Busse, correspond to a state in which the rate of entropy production due to the turbulent dissipation is at a maximum. Entropy production due to absorption of solar radiation in the climate system is found to be irrelevant to the maximized properties associated with turbulence. The hypothesis of maximum entropy production also seems to be applicable to the planetary atmospheres of Mars and Titan and perhaps to mantle convection. Lorenz s conjecture on maximum generation of available potential energy is shown to be akin to this hypothesis with a few minor approximations. A possible mechanism by which turbulent fluid systems adjust themselves to the states of maximum entropy production is presented as a selffeedback mechanism for the generation of available potential energy. These results tend to support the hypothesis of maximum entropy production that underlies a wide variety of nonlinear fluid systems, including our planet as well as other planets and stars. INDEX TERMS: 3220

A thermodynamic hypothesis regarding optimality principles for flow processes in geosystems

“…Under steady-state flow conditions, the average heat flow rate is closely related to entropy production in the Earth-atmosphere system, as shown by Paltridge [1978] and Ozawa et al [2003] and the MEP corresponds to the maximum convective heat transport [Paltridge, 1978]. The latter was further confirmed by Clausse et al [2012] who showed that the temperature distributions on the Earth surface is consistent with a principle (derived from the constructal law) that convective heat flow rate from equator region to the pole region is maximized, or the resistance to heat flow is minimized at a global scale.…”

“…The Earth receives radiation from the hot Sun and transfers the received heat into space. The atmosphere and oceans act as a fluid system that transports heat from the hot region to the cold one with general circulation [Ozawa et al, 2003], because the convection process is more efficient in transferring heat than the conduction process [Bejan, 2000]. Obviously, in this system, the "flow process imposed by its environment" is the heat flow; the heat flow process is the initiator for other flow processes.…”

“…(Heat flows from the high-temperature region to the low temperature region.) The above equation represents the fact that the entropy production by some processes associated with turbulence is completely discharged into the surrounding system through the boundary under steady-state conditions [Ozawa et al, 2003].…”

“…This argument can be further justified as follows. Under steady-state flow conditions, the entropy production in the Earth-atmosphere system is given by Paltridge [1978] and Ozawa et al [2003]:…”

1 Entropy Production by Earth System Processes

“…What Lorenz (1960), Paltridge (1975Paltridge ( , 1978Paltridge ( , 2001) and others (see e.g., review by Ozawa et al 2003) showed with more detailed energy balance model simulations is that several observed features of the climate system, such as the intensity of the atmospheric circulation, the equator-pole temperature difference in surface temperature, and the meridional distribution of cloud cover reflect a state of the climate system which is close to a state of MEP.…”