Hemispheric Symmetry of Planetary Albedo: A Corollary of Nonequilibrium Thermodynamics

Abstract

It is increasingly recognized that the generic climate state is a macroscopic manifestation of a nonequilibrium thermodynamic (NT) system characterized by maximum entropy production (MEP)—a generalized second law. Through a minimal tropical/polar-band model, I show that MEP would propel low clouds to polar bands to symmetrize the planetary albedo, a remarkable observation that may now be explained. The prognosed polar albedo is consistent with the current observation, which moreover is little altered during the ice age of more reflective land and the early Triassic period of symmetric land, suggesting its considerable stability through Earth’s history. Climate models have not replicated the observed albedo symmetry and, given the potency of MEP in propelling clouds, it is suggested that to improve climate models, a higher premium be placed on resolving eddies—thereby encapsulating the NT—than detailed cloud physics.