Sea levels on Earth would rise about 70 m (230 ft) if all the ice in Antarctica were to melt.
If all the ice covering Antarctica, Greenland, and mountain glaciers around the world were to melt, sea level would rise about 70 meters (230 feet). The ocean would cover all the coastal cities. And land area would shrink significantly. But many cities, such as Denver, would survive.
However, all the ice is not going to melt. The Antarctic ice cap, where most of the ice exists, has survived much warmer times.
The concern is that portions of the Greenland and West Antarctic ice caps may disappear. We do not know how much or how quickly this could happen, because we do not know exactly how it will happen.