A melting Antarctica alone could raise oceans by more than 3 feet by the end of the century if greenhouse gas emissions continued unabated, roughly doubling previous total sea-level rise estimates, according to new research.

Scientists previously thought glacial melt in Antarctica would raise sea levels only by a little or only in the far future. But that’s changing as researchers learn more about the different ways the continent’s ice sheets could dump water into the oceans.

The Antarctic retreat could happen much faster and much more than we previously thought.”

The new paper, published in the journal Nature yesterday, comes at a time of increasing concern among sea-level rise researchers about Antarctica.

“The Antarctic retreat could happen much faster and much more than we previously thought,” said David Pollard, one of the lead authors and a researcher at Pennsylvania State University. “This is just the Antarctic contribution to future sea-level rise, but if there’s anything to this, and if we really follow the business-as-usual [emissions] scenarios, then this contribution would exceed all other contributions over next years.”