Thermostats, radiator fins, and the local runaway greenhouse

Abstract

The author has reconsidered the question of the regulation of tropical sea surface temperature. This has been done in general terms through consideration of the tropical heat budget and in specific terms through consideration of an idealized radiative-dynamic model of the tropical general circulation. It is argued that evaportion on its own cannot provide an effective regulating mechanism. Clouds cannot serve as regulators unless there are substantial departures from the observed cancellation between cloud greenhouse and cloud albedo effects. It is found that the main determinant of tropical climate is the clear-sky water vapor greenhouse effect averaged over the entire Tropics. In the absence of dry "radiator fins' maintained by subsidence, the tropical temperature would tend to fall into a runaway greenhouse state that could be stabilized only by heat export to the extratropics. -from Author