How do the ice sheets affect atmospheric and oceanic circulations?
The general effects of ice sheets on the atmosphere and oceans were discussed above. Clearly, changes in either the albedo of the surface (through a change in snow facies extents), or changes in the geometric shapes of the ice sheets will alter their climatic effect and perturb the global climate system. Usually these changes are discussed in the extreme cases of glacial periods, when surface temperatures in central North America or Europe fell an average of 10 to 12 degrees Celsius, but smaller changes in ice sheets will also perturb the climate (Dawson, 1992). The relationship is probably highly non-linear; the climate record from Greenland ice cores shows that dramatic climate changes can occur in much less than a decade (Alley et al., 1993). Remnants of vast armadas of icebergs have been detected in the western North Atlantic, well beyond the reach of ice sheets (Heinrich, 1988). It has been suggested that the melting of these icebergs would introduce a sufficient quantity of fresh
