An ice bridge connecting a vast Antarctic ice shelf to two islands shattered on Saturday.
Satellite images from the European Space Agency show a 40-kilometre-long strip of ice, linking the Charcot and Latady islands to the Wilkins Ice Shelf, snapped at its narrowest point.
Scientists fear the collapse will allow ocean currents to wash away more and more of the shelf. They speculate the northern half of the shelf, which is roughly the size of Jamaica, could eventually break free of the Antarctic Peninsula and become a giant iceberg.
The Wilkins Ice Shelf has been moving since the 1990s, but experts say this is the first time one of the links apparently keeping it in place has crumbled.
They suspect climate change is responsible for the collapse of the bridge.
David Vaughan, an expert in glaciers with the British Antarctic Survey (BAS), said the bridge was intact two days ago.
"It's amazing how the ice has ruptured," he told the Reuters news agency. "We've waited a long time to see this."
Last week, U.S. and British scientists reported that Antarctica's Wordie Ice Shelf, which has been retreating in the past 40 years, is now completely gone and more than 8,500 square kilometres have broken off from the Larsen Ice Shelf since 1986.