Antarctica - Larsen C Ice Shelf Getting Ready To Splinter ("Significant Risk To Stability")

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ABSTRACT: An established rift in the Larsen C Ice Shelf, formerly constrained by a suture zone containing marine ice, grew rapidly during 2014 and is likely in the near future to generate the largest calving event since the 1980s and result in a new minimum area for the ice shelf. Here we investigate the recent development of the rift, quantify the projected calving event and, using a numerical model, assess its likely impact on ice shelf stability. We find that the ice front is at risk of becoming unstable when the anticipated calving event occurs. […]

The rift first crossed the Joerg Peninsula suture zone in 2012 and progressed modestly during 2013 into a region which previously appeared to resist transverse fractures (Fig. 2). The rate of rift propagation increased dramatically sometime between January and August 2014, crossing the entire Trail Inlet flow unit (?20km) in just 8 months. We do not have observations within this time period so we cannot say whether the rift propagation during this time period was uniform or was very rapid for only a short15 part of it. Between August 2014 and late January 2015, the rift increased in length at a steady rate of?2.5kmyr?1. From the start of our measurements the width of the rift at the 2010 rift tip position has increased at a more uniform rate than the length, and is still growing at a rate of?40myr?1 (Fig. 2). The area of Larsen C Ice Shelf after the proposed calving event will be 4600km2 less20 than at present for Scenario I, and 6400km2 less for Scenario II (Fig. 1). This amounts to potential area losses of 9 and 12%, respectively. […]

It seems inevitable that this rift will lead to a major calving event which will remove between 9 and 12% of the ice shelf area and leave the ice front at its most retreated observed position. More significantly, our model shows that the remaining ice may be unstable. The Larsen C Ice Shelf may be following the example of its previous neighbour, Larsen B, which collapsed in 2002 following similar events. [more]

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