A new estimate puts maximum global sea level rise from the collapse of the West Antarctic Ice Sheet at 10.5 feet (3.2 meters)—not the 16 feet (five meters) or more predicted in the past.

The latest research indicates that this massive ice sheet is unlikely to disappear completely, limiting the damage as it melts. Glaciologist Jonathan Bamber of the University of Bristol in England and his colleagues modeled the collapse of the ice sheet based on the relative likelihood of a given section vanishing completely.

Their work suggests only those parts of the ice sheet that are grounded below sea level or sloping downwards would collapse. Those parts of the sheet grounded above sea level or on bedrock that slopes upwards would remain in place.

If that theory holds, the maximum sea level rise in the next century would be nearly three feet (81 centimeters), the researchers write in Science.

The results say nothing about disappearing ice sheets elsewhere. Bolivia's Chacaltaya Glacier has already melted away. And Greenland, which holds enough ice to raise sea levels by 23 feet (seven meters), is shrinking. Change can happen quickly. Fossil coral and other records show historic sea level rises of more than six feet (two meters) in as little as 50 years.

Given that West Antarctica, where this ice sheet is located, is warming faster than the rest of the icy continent and gravitational effects from less ice there would change the Earth's rotation and boost sea levels from Boston to Jacksonville by as much as 23 feet (seven meters), residents might want to prepare for a more watery future.

Image Credit: Courtesy of J. Bamber, University of Bristol