In early November, 2013 a large iceberg created an international stir when it broke off the Pine Island Glacier and set adrift in Pine Island Bay. Measuring about 35 km by 20 km (21 mi by 12 mi) in size – roughly the size of Singapore – the calving event was the culmination of a multi-year process of slow cracking and rifting of the glacier.
According to Tom Wagner, NASA’s cryosphere program manager, who spoke to the Earth Observatory in November, 2013, the shelf of Pine Island Glacier has been moving forward at roughly 4 km per year, so calving of this iceberg was not a surprise. Such calving events happen about every five to six years, though Iceberg B-31 is about 50 percent larger than previous ones in this area.
Since the calving, Iceberg B-31 has been drifting very slowly westward towards the Amundsen Sea. The progress has been slow, however. On February 7, 2014 The National Snow and Ice Data Center reported the location of the iceberg at 74°07’S and 105°44’W - roughly 30 miles from the January 10, 2014 location at 74°24’S and 104°33'W.
The Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the Aqua satellite flew over Pine Island Bay on February 5, 2014 and captured this true-color image of Iceberg B-31 in the southern section of the Bay. Its size is virtually unchanged since the calving event, although other ice within the bay has clearly diminished in the warmth of the Antarctic summer.