Ice shelves are floating extensions of glaciers, some of which can cover more than 20,000 square miles of land . Those glaciers shed ice periodically as a way of balancing the weight they gain when snow falls on their centers. Absent that behavior, they would “just grow and grow and grow — like not cutting your hair,” said Daniela Jansen, a geophysicist with the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research in Germany.

An ice shelf “acts like a cork to hold in the flow of the ice that’s inland of the ice sheet,” said Robert L. Hawley an associate professor of earth sciences at Dartmouth College. If too much of the ice shelf is removed during a calving event, it can’t hold back the rest of the sheet anymore, potentially setting it up for a series of collapses. “It is like you are removing a cork from a champagne bottle,” said Dr. Jansen.

In the case of D28, which gets its name from a classification system used by the United States National Ice Center, there’s no indication that the ice shelf left behind is unstable. And as for sea level rise, “The ice has already been afloat for decades so there will be absolutely no impact on sea level,” Adrian Luckman, chairman of the geography department at Swansea University in Wales, said by email.

Geographic events of this scale “are fascinating reminders of big things happening in remote corners of the planet, even though they are a natural part of the growth and calving cycle of ice shelves,” said Dr. Luckman, who added that we are in “the golden age of satellite earth observation.”