17 Entropy and Gaia: Is There a Link Between MEP and Self-Regulation in the Climate System?

Abstract

The Gaia hypothesis posits that the Earth’s climate is self-regulating, while the maximum entropy production (MEP) principle suggests that the climate system self-organizes in a state of maximum entropy production due to turbulent dissipative processes. We explore the relationship between the two by applying MEP to a toy model based on Daisyworld in which the temperature-albedo feedback is dependent on the heat transport rates within the system. We initially assume that the dynamical response of the climate system to di.erential radiative heating is to create heat fluxes such that a steady state satisfying a maximum entropy-production (MEP) condition is obtained. The resulting system, which does not depend on free parameters, turns out to be thermostatic and to favour the existence of two, but not several, daisy species simultaneously. Furthermore, it maximizes the range of luminosity over which daisies exist, that is, the lifespan of Daisyworld. However, if the daisy coverage is assumed to adjust more slowly than the heat fluxes, the range of habitation is narrowed. Imposing a sinusoidal forcing allows more than two species to coexist, but only occasionally and not to a significant extent.