( CNN ) -- A massive iceberg that broke off an Antarctic glacier in July is now moving toward the open ocean and could pose a threat to busy shipping lanes , researchers reported . The huge berg is estimated to be about 270 square miles ( 700 square kilometers ) in area , about the size of nation of Singapore or double the size of the city of Atlanta . `` An iceberg that size could survive for a year or longer and it could drift a long way north in that time and end up in the vicinity of world shipping lanes in the Southern Ocean , '' Robert Marsh , a scientist at the University of Southampton in England , said in a press release this week . Detecting the dangers of Greenland 's giant icebergs . Marsh is part of a team of scientists who have been given an emergency grant to track the iceberg and predict its path so ships traveling through the area can be alerted . Researchers at the Alfred Wegener Institute , using images from the German Space Agency 's TerraSAR-X satellite , reported in July that the iceberg was separating from the Antarctica 's Pine Island Glacier . It had been kept close to the glacier by sea ice , another researcher , Grant Bigg from the University of Sheffield , told the BBC . But the end of the Antarctic winter has melted some of the sea ice and given the berg a route to the open ocean , he said . `` In the last couple of days , it has begun to break away and now a kilometer or two of clear water has developed between it and the glacier , '' Bigg told the BBC . The calving of the massive berg has been a long process . The crack that produced it was first detected by a NASA plane in October 2011 . The researchers say this will be the first time to track the path of such a massive iceberg , something that will be more important as the effects of global warming increase . Antarctic ice shelves 'tearing apart , ' says study .
# ##s remain in open ocean for a while , researcher says . Sea ice that kept berg close to Antarctica now melting , scientist says . Iceberg separated from glacier in July .