IMPACT OF THE GREENHOUSE-EFFECT ON SEA-ICE CHARACTERISTICS AND SNOW ACCUMULATION IN THE POLAR-REGIONS

An extensive analysis has been made of the simulated sea-ice behaviour for current and doubled carbon dioxide levels for both polar regions. The sea-ice variations were computed as a component of the overall pe rformance of a global climatic model. This model simulated the major c limatic processes, but used an elementary oceanic representation known as the Q-flux parameterization. For simplicity, dynamical processes w ere omitted from the sea-ice formulation. For current conditions the s ea-ice extent, thickness, seasonal and interannual variability were re asonably simulated, particularly for the Northern Hemisphere. The majo r deficiency was the lack of regions with very thick sea-ice, which is known to be generated in the real world by dynamical interactions. Ve ry substantial reductions occurred in the sea-ice thickness, and to a lesser extent in sea-ice area, under greenhouse conditions, with the m ajor impact being in summer. Water mass accumulation over the great ic e-sheets agreed moderately well with limited observations for control conditions. An increase in accumulation rate was simulated for both po lar regions in the greenhouse experiment. The results indicate that, o verall, a first-order representation of sea-ice behaviour is obtainabl e with a thermodynamics-only sea-ice parameterization.