A joint Australian–French study has discovered the calving of a massive iceberg from the Mertz Glacier in the Australian Antarctic Territory. The iceberg, 78 kilometers long and 33 to 39 km wide with a surface area of 2,500 square kilometers, broke off the Mertz Glacier after being rammed by another massive iceberg, 97 kilometers long.
The new ice berg represents about half the length of the glacier tongue. Satellite imagery shows the iceberg separation occurred on 12 / 13 of February.
This calving event was detected by a joint French-Australian team working on a project called “CRACICE” (Cooperative Research into Antarctic Calving and Iceberg Evolution). The CRACICE team is carrying out a long-term study on how fractures developing in the Mertz Glacier Tongue lead to iceberg calving, and the fate of the icebergs and remaining glacier tongue. Their work involves surveys using satellite data and GPS beacons deployed on the glacier to measure the evolution of the rifts and the calving process.
The team has followed the development of two major rifts cutting across the tongue, from opposite sides, over many years. The rifts had almost joined, when a similarly massive iceberg, B9B, collided with the eastern flank of the tongue leading to the final separation.
The future behavior of the two icebergs is of great interest, according to the researchers. Satellite images show that the recently-calved Mertz iceberg is moving into the Adélie Depression, a coastal basin situated between the Mertz Glacier and the French Antarctic station of Dumont D’Urville to the west. This depression is one of the major sites of dense water formation which drives the world’s deep ocean circulation.
The dense water is formed from ocean water that circulates onto the continental shelf and interacts with the glacier tongue, and by high rates of sea ice formation within the Mertz Glacier polynya to the immediate west of the former glacier tongue. The future position of the two giant icebergs will likely affect local ocean circulation, the extent (and timing?) of the polynya, sea ice production, and deep water formation. It also has important implications for the marine biology of this region. A number of on-going field and research activities will follow up this calving event and its impact on the local environment.
The ACE CRC is a unique collaboration between core partners the Australian Antarctic Division, CSIRO Marine and Atmosphere, the University of Tasmania, the Bureau of Meteorology and a consortium of supporting partners. It is funded by the Australian Government’s Cooperative Research Centre Program.