A massive iceberg that had been blocking traditional shipping routes to McMurdo Station, the National Science Foundation’s research station in Antarctica, snapped in two seemingly overnight. The B-15A iceberg seemed to be intact in the Terra MODIS image recorded on October 7, 2003. But Moderate Resolution Imaging Spectroradiometer (MODIS) images starting on October 9 show the iceberg in two pieces. The largest section, top, is about 75 miles long, and the shorter section, called B-15J, is 20-25 miles long. On December 15, 2003, B-15A fractured again. The new iceberg, B-15K, is visible on the left edge of B-15A beginning on December 16, 2003. It is about 37 miles long and 4 miles wide.
The B-15A iceberg broke off the Ross Ice Shelf in 2000 and drifted to its present location. It was one of the largest icebergs scientists had ever observed breaking from the shelf. It and a second large iceberg, C-19, trapped sea ice in the passage that supply ships typically used to get to the research station on Ross Island. C-19 swung out to sea in 2002, freeing some of the trapped ice. Scientists at the University of Wisconsin-Madison who first noticed the recent break say that it is unclear how B-15A’s break-up will affect previously trapped ice.
The Ross Ice Shelf is a vast field of snow and ice extending from the continent into the Ross Sea on the western Pacific coast of Antarctica. As glaciers slide off the continent and push the shelf out, the outer edges crumble into a myriad of icebergs such as B-15A.
In this series of images, starting on October 7, 2003, the B-15A iceberg points out into the Ross Sea. After the break, it began to drift away from the B-15J iceberg, which is slowly rotating and moving next to the smooth white Ross Ice Shelf. The B-15K iceberg began to move away from the B-15A iceberg after breaking off on December 15. The C-16 iceberg, which broke off the Ross Ice Shelf in the same event as the B-15 iceberg, sits to the left of B-15J.