 The Antarctic sheet is the largest known single mass of ice . It covers almost 14 million km2 and some 30 million km3 of ice . Around 90 % of the fresh water on the planet 's surface is held in this area and if melted would raise sea levels by 58 metres . The continent @-@ wide average surface temperature trend of Antarctica is positive and significant at > 0 @.@ 05 ° C / decade since 1957 . 
