Position analysis: the Antarctic ice sheet and sea level

The rate at which ice discharges from the great ice sheets into the oceans is presently the greatest source of uncertainty in projections of global mean sea level rise. Reducing the uncertainty of ice sheet behaviour is important since the two great parts of Antarctica – the East and West Antarctic ice sheets – hold around 70 per cent of the world’s fresh water and more than 90 per cent of its ice. If the ice sheet melted completely, global mean sea level would rise by about 60 metres, although the likelihood of this occurring over the next two centuries is low.