The Role of Polar Regions in Global Climate, and a New Parameterization of Global Heat Transport

Abstract

Such role as polar regions may have in determining global climate obviously depends on the transport of heat between polar regions and other latitudes. We review the way such transport affects climate sensitivity and stability within the context of simple energy balance models, noting that climate sensitivity in most such models is too small to readily permit the functioning of the Milankovitch mechanism, for example. We then turn to the development of new heat transport parameterizations wherein radiative equilibrium distributions of temperature with latitude are adjusted on the basis of recently noted properties of Hadley cells and baroclinically unstable eddies. The simplest application of this adjustment tends to underestimate the observed pole-equator temperature differencem‐the error being confined almost entirely to high latitudes (in effect the parameterization overestimates the heat flux). Including the effects of static stability clinging with latitude virtually eliminates the discrepancy. This situation is remarkable since heat transport by both stationary waves and ocean currents has been ignored. The implications of this are discussed. Moreover, it is found that climate sensitivity and stability for the new transport parameterization can he different from what is obtained with simpler models, and appears capable of simulating the sensitivity called for by existing climate data.