As of May 1 2017, we have observed a significant change in the rift on the Larsen C ice shelf. While the previous rift tip has not advanced, a new branch of the rift has been initiated ~10km behind the previous tip, heading towards the ice-front. This is the first significant change to the rift since February of this year.

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.

It is currently winter in Antarctica, therefore direct visual observation is extremely difficult. Our observations of the rift are based on synthetic aperture radar (SAR) interferometry from ESA’s Sentinel-1 satellites. Although the rift length has been static for several months, it has been steadily widening, at rates in excess of a meter per day. This widening has increased noticeably since the development of the new branch, as can be seen in measurements of the ice flow velocity.

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.

Ice flow velocities of Larsen C in February 2017 and April/May 2017, from ESA Sentinel-1 data.

The MIDAS Project will continue to monitor the development of the rift and assess its ongoing impact on the ice shelf. Further updates will be available on this blog, and on our Twitter feed.

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