That's the conclusion of three research teams that have modeled the behavior of the continent's Pine Island Glacier, or PIG, which at 60,000 square miles contains almost 20 percent of the ice flowing from Antarctica into the ocean.
Data collected by satellites and aircraft have revealed the glacier has been thinning and its velocity increasing in recent years, the researchers said.
"You can think of PIG like a ball. It's been kicked and it's just going to keep on rolling for the foreseeable future," Hilmar Gudmundsson from the British Antarctic Survey told the BBC.
The main driver of its movement is not air temperature, the scientists said, but warm ocean waters getting under and eroding the glacier where it leaves the land and becomes a floating ice shelf.
This creates an unstable architecture that, once created, can put the glacier into an irreversible decline, they said.
"Even if you were to reduce melt rates, you would not stop the retreat," Gudmundsson said.
The melting glacier is seen as a major contributor to sea level rise, and could raise the world's oceans by as much as 0.13 inches to 0.39 inches in just the next 10 years, the scientists predict.