Antarctic Iceberg: A68
A new iceberg, named A68, in Antarctica has broken away from the Larsen C ice shelf. There is nothing really unusual about this except this iceberg is a gigantic iceberg that has formed as a result of a rapid rift that has developed in the Larsen C ice shelf. Larsen C is a floating platform of glacial ice on the east side of the Antarctic Peninsula and is the fourth largest ice shelf in Antarctica. The size of the ice berg is immense: it is about 5,800 square kilometre (km) of ice that has broken free and is drifting into the Weddell Sea. The berg has around 1,155 cubic kilometres of ice within the block. In early July the iceberg, which is being monitored by the Copernicus Sentinel-1 satellite, the rift or crack was around 200 km long. The distance between the end of the fissure and the ocean was only around 5 kilometres. This was to indicate an imminent shift and break away of the ice sheet. By 10-12 July 2017 the iceberg had broken away from the ice sheet according to NASA. The Larsen C ice shelf has lost around 10% of its size since the iceberg broke away. This crack had initially appeared in 2014.
The breakup of the ice shelf was first reported by the UK Antarctic research project (Project Midas) team. This team monitored the situation on Larsen C and will continue to monitor changes on the ice shelf. Initial monitoring, which is in the very early stages, suggests a new rift may continue in a northerly direction. The research also notes several smaller ice bergs having formed behind iceberg A68.
The iceberg is being monitored by the European Space Agency’s CryoSat satellite (see this link reviewing the situation as of 5 July). When it moves, by ocean currents, the iceberg has an impact the local area by moving sediment on the sea bed. The iceberg is also likely to last many years before it eventually melts. In that time it could become a risk to nearby shipping. Whether the iceberg breaks up into smaller icebergs remains to be seen. Research has shown historical pathways that icebergs tend to follow and this track information is helping to show where A68 may be heading. There is a great image illustrating the historical tracks of icebergs. See below
© Scatterometer Climate Record Pathfinder.
The Larsen ice shelf is divided up into a number of segments (Larsen A – Larsen G). The Larsen C segment is the largest segment of the vast ice shelf which is the fourth largest in Antarctica. What will happen next to the Larsen C ice shelf remains unclear: in 1995 the Larsen A Ice Shelf collapsed following initial ice shelf disintegration. Larsen B Ice Shelf followed a similar pattern by collapsing in 2002 and is likely to have totally disintegrated by 2020. If glaciers, which were once protected by the ice shelf, can now advance into the sea and melt then there could be global implications for raising sea levels.
The A68 iceberg provides evidence and details about how rapidly the environment is changing. This change may have a global impact on sea levels if the ice sheets that were being held back start to flow into the Weddell Sea. The ESA and NASA have much technology to monitor remote changes and record progress almost as it happens. The Larsen B and A ice shelf segments have also shown that large scale ice shelf collapse is possible in relatively short time frames that are expressed in months. The future of how Larsen C will develop, most likely rapidly, over the coming months remains to be seen. It is especially important to review this change in light of the forthcoming Antarctic summer season later this year and into 2018. Whether the summer leads to warmer waters affecting the rest of the ice shelf remains to be seen. Project Midas will continue to monitor the situation.