As an update to our earlier articles on the subject, it seems that the very large rift in the Larsen C ice shelf in Antarctica is continuing to grow — with a new second branch of the rift (15 kilometers long) now growing in the direction of the ice front, and thus a near-future calving event.
Picture: The current location of the rift on Larsen C, as of May 1 2017. Labels highlight significant jumps. Tip positions are derived from Landsat (USGS) and Sentinel-1 InSAR (ESA) data. Background image blends BEDMAP2 Elevation (BAS) with MODIS MOA2009 Image mosaic (NSIDC). Other data from SCAR ADD and OSM.
Once this occurs, a roughly 180-kilometer-long iceberg will be released, which will thus represent one of the largest icebergs ever recorded. There remains only about 20 kilometers of ice tethering the Larsen C ice shelf to Antarctica.
The head of the UK’s Project Midas, Professor Adrian Luckman of Swansea University College of Science, commented: “While the previous rift tip has not advanced, a new branch of the rift has been initiated. This is approximately 10 km behind the previous tip, heading towards the ice-front.”
The press release provides more:
“This is the first significant change to the rift since February of this year. Although the rift length has been static for several months, it has been steadily widening, at rates in excess of a metre per day.
“It is currently winter in Antarctica, therefore direct visual observations are rare and low resolution. Our observations of the rift are based on synthetic aperture radar (SAR) interferometry from ESA’s Sentinel-1 satellites. Satellite radar interferometry allows a very precise monitoring of the rift development.
“Researchers say the loss of a piece a quarter of the size of Wales will leave the whole shelf vulnerable to future break-up. Larsen C is approximately 350m thick and floats on the seas at the edge of West Antarctica, holding back the flow of glaciers that feed into it.”
So to be clear on that, the event itself won’t notably affect anyone outside of Antarctica, but is very notable because of the size of the iceberg in question, and because it likely presages the disintegration of the Larsen C ice shelf (this is what happened with Larsen B ice shelf, among others).
Professor Luckman continued:
“When it calves, the Larsen C Ice Shelf will lose more than 10% of its area to leave the ice front at its most retreated position ever recorded; this event will fundamentally change the landscape of the Antarctic Peninsula. We have previously shown that the new configuration will be less stable than it was prior to the rift, and that Larsen C may eventually follow the example of its neighbour Larsen B, which disintegrated in 2002 following a similar rift-induced calving event.”