Some tentative conclusions based on current and historical observations of the ocean/atmospheric system as constrained by one boundary condition, ice extent on the sea. Ice extent influences the global system by regulating heat exchange between ocean and atmosphere, and by influencing the intensity of polar heat sinks. In the Arctic, where data are good, sea-ice variations counter observed trends of global circulation; in the Antarctic, although evidence is meager, sea ice is larger in area, and both annual and long-term variations reinforce trends of global circulation intensity. Changes in arctic atmospheric heat advection may advance the melting as much as 6-8 kcal/sq cm, about 10 percent total annual heat advection. In the Antarctic, the annual melting of the ice-pack ring is crucial: two weeks late reduces oceanic heating 4 percent; two weeks early increases it 7 percent. More data for this study would be useful. 21 pp. Ref.