At about the same time everyone was getting excited about the possibility of a massive iceberg displacing as much as four million acres off the coast of the Antarctic Peninsula, nature itself made headlines for a potentially equally large iceberg breaking off from the Pine Island Glacier.

Drilling through to a depth of 3,445 feet, this appeared to be an iceberg measuring about 12 square miles, about the size of Las Vegas. In fact, the iceberg, according to published images and data, is about twice as big as a 1989-200 Bahrein-sized iceberg and only 16% the size of the recently discovered iceberg off the Pacific coast of Antarctica, so its significance remains to be seen. “My guess is it is of the same age as the 1989-200 Bahrein-sized one,” said Michael Studinger, lead scientist of the European Union’s Joint Polar Satellite System (JPSS) team, which first detected the iceberg. That would make it 100 years old. There are as yet no obvious signs of anyone being hurt by the iceberg, however.

Despite its appearance to be double the size of the recently discovered chunk of ice off the western coast of Antarctica, the iceberg would not be able to move much. “When it does eventually break free, it will most likely take with it a large amount of ice and will drift north, near the tip of the Antarctic Peninsula,” Studinger said in a statement. The iceberg will extend the rift in the glacier, speeding up its retreat.

Pine Island Glacier is about 1,200 miles south of the Antarctic Peninsula, where it lies on the large Western Flank of the Antarctic ice sheet. The glacier runs roughly perpendicular to the ocean. What is most significant about this last ice sheet movement is the speed with which it happened. “It happened all of a sudden and then [the iceberg] broke completely apart,” noted Studinger. “There are no indications of the glacier moving in a slow clockwise direction, whereas in earlier calving events it has moved faster.” Studinger said that what is visible on the surface is a “huge belt of ice.”

The unexpected sea-level rise is already having a negative impact on people’s homes. Already, a few small islands off the coast of northeast Australia have been completely swallowed by rising seas and dunes of salt are covering the flats. At least 10 new islands are likely to form due to the forced drift of glaciers.

As Antarctica is slowly disintegrating, it has been slower to leave land than Greenland, where it last year became the first continent in 4,000 years to lose more land mass, said UC Berkeley geologist Jay Zwally. More recent animations by NASA show that over the past few years the two Antarctic ice sheets have retreated at rates that suggest they are becoming more vulnerable to melting, though the forces pushing the ice sheets toward the ocean remains relatively low compared to historic levels.

Zwally cautioned that rates of retreat are expected to continue for at least another decade, and are not necessarily a bellwether of ultimate sea-level rise. However, the rise in recent measurements tells us that Antarctica has left land much faster than previously estimated, he said. “The glaciers definitely aren’t just sitting there still,” Zwally said. “What happens when they start flowing southwards faster is not completely clear yet.”