American and European scientists are monitoring an iceberg roughly six times the size of Manhattan that broke off from an Antarctic glacier and is heading into the open ocean.

The iceberg's present location is not in an area heavily navigated by ships, but it could pose a danger to Atlantic shipping during the Antarctic winter, the scientists say.

The iceberg covers about 660 square km (255 square miles) and is up to a third of a mile (500 meters) thick, according to a report from NASA's Earth Observatory. Known as B31, it separated from Antarctica's Pine Island Glacier last November.

"It's one that's large enough that it warrants monitoring," said NASA glaciologist Kelly Brunt in an interview with The Telegraph. "It's like a large sheet cake floating through the Southern Ocean," she added.



The glacial crack that created the iceberg was first detected in 2011, but it only separated from the glacier in November last year. The glacier has been closely studied over the past two decades because it has been thinning and draining rapidly and may be an important contributor to sea level rise.



They say the iceberg has floated across Pine Island Bay, a basin of the Amundsen Sea, and will likely be swept up soon in the swift currents of the Southern Ocean.



"We are doing some research on local ocean currents to try to explain the motion properly. It has been surprising how there have been periods of almost no motion, interspersed with rapid flow," iceberg researcher Grant Bigg of the University of Sheffield in England said in a statement from NASA Earth Observatory.



