CLIMATE CHANGE: AN APPRAISAL OF ATMOSPHERIC FEEDBACK MECHANISMS EMPLOYING ZONAL CLIMATOLOGY.

Abstract

The sensitivity of the earth's surface temperature to factors which can induce long-term climate change, such as a variation in solar constant, is estimated by employing two readily observable climate changes. One is the latitudinal change in annual mean climate, for which an interpretation of climatological data suggests that cloud amount is not a significant climate feedback mechanism, irrespective of how cloud amount might depend upon surface temperature, since there are compensating changes in both the solar and infrared optical properties of the atmosphere. It is further indicated that all other atmospheric feedback mechanisms, resulting, for example, from temperature-induced changes in water vapor amount, cloud altitude and lapse rate, collectively double the sensitivity of global surface temperature to a change in solar constant. The same conclusion is reached by considering a second type of climate change, that associated with seasonal variations for a given latitude zone. Climate models which additionally include ice-albedo feedback are discussed within the framework of the present results.