The sensitivity of a global, coarse-resolution ice-ocean model to a decrease in the thermal conductivity of the snow overlaying Antarctic sea ice (ksant) is investigated. This study was motivated by recent observations made in the eastern sector of the Southern Ocean and in the Bellingshausen, Amundsen, and Ross Seas, which suggest that the value of ksant usually used in large-scale sea ice models is about a factor two too high. When ksant is reduced by half in our model, the average thickness of the Antarctic ice pack decreases by 10 cm (10%) and the geographical distributions of snow and ice thicknesses become more realistic. A strengthening of the Southern Ocean stratification and a concomitant weakening of the Antarctic Bottom Water meridional overturning are also noticed. This ultimately impacts on the sensible heat flux from the ocean to the ice and thus on the rate of thermodynamic ice growth. ¿ 2000 American Geophysical Union