We used modern analog technique applied to Antarctic diatoms to quantitatively reconstruct seasonal sea-ice extent at the Last Glacial Maximum. Winter maximum sea-ice limit occurred around 48 ¿S in the Atlantic and western Indian sectors, around 55 ¿S in the eastern Indian and western Pacific sectors, and around 58--60 ¿S in the eastern Pacific sector of the Southern Ocean. Summer maximum sea-ice extents during the last ice age and today are similar, which contradicts CLIMAP's findings. This implies a reduced summer albedo feedback of the Southern Hemisphere and a greater transfer of heat and moisture from the ocean to the atmosphere than shown by previous qualitative studies. ¿ 1998 American Geophysical Union