Sea ice is an important factor in controlling the exchange of energy between the ocean and atmosphere in the polar regions and has an important impact on climate. A climate model has been developed which enables analysis of the effect of changes in sea ice on the ocean-atmosphere energy exchange and atmospheric temperature. The model results described here show that opening small areas of open ocean (leads) within the winter ice pack has a large impact on the atmospheric temperature of the polar regions. This effect is due to changes in the sensible heat flux between the surface and atmosphere resulting from leads. Thus leads within the ice pack may have significant impact on short and long term climatic variations. ¿ American Geophysical Union 1988