Vaughan had predicted the Wilkins shelf would collapse about 15 years from now. The part that recently gave way makes up about 4 percent of the overall shelf, but it's an important part that can trigger further collapse.
There's still a chance the rest of the ice shelf will survive until next year because this is the end of the Antarctic summer and colder weather is setting in, Vaughan said.
Scientists said they are not concerned about a rise in sea level from the latest event, but say it's a sign of worsening global warming.
Such occurrences are "more indicative of a tipping point or trigger in the climate system," said Sarah Das, a scientist at the Woods Hole Oceanographic Institution in Massachusetts.
"These are things that are not re-forming," Das said. "So once they're gone, they're gone."
Climate in Antarctica is complicated and more isolated from the rest of the world.
Much of the continent is not warming and some parts are even cooling, Vaughan said.
However, the western peninsula, which includes the Wilkins Ice Shelf, juts out into the ocean and is warming.
This is the part of the continent where scientists are most concern about ice melt triggering sea level rise.
Free Email News Updates
Sign up for our Inside National Geographic newsletter. Every two weeks we'll send you our top stories and pictures (see sample).
SOURCES AND RELATED WEB SITES