IT is as certain as we can be in science that we will lose the Antarctic ice sheet within the next 200-500 years, leading to a devastating rise of about four metres in sea level. Worse, the process is now irreversible. Two separate studies --- one by the NASA used satellite and airborne radar data for the past 40 years, and the other by European Space Agency's CryoSat2 satellite that measured the height of the glaciers --- have both come to very similar conclusions. The Antarctic is losing ice from the glaciers at approximately 160 billion tonnes a year.