What effect will the Larsen C berg have?

A new paper published at the start of August discusses what impact the loss of the Larsen C iceberg will have on the rest of the ice shelf.

As I have noted in previous posts, iceberg calving (breaking off) is a natural process, and part of the natural cycle of growth and development that all ice shelves undergo. However, the loss of significant portions of ice (in this case approximately 12% of the total volume, around 6,000 km², or an area four times the size of London – enough to cause Antarctica’s former fourth-largest ice shelf to slip down the rankings to number five) can reduce the overall stability of the ice shelf.

Larsen A68
NASA imagery of the Larsen C A68 iceberg breaking off from the main ice shelf in July. From NASA Goddard/UMBC JCET, Christopher A. Shuman via Flickr

This is largely determined by whether or not the calving event will rock the boat enough to cause the ice shelf to become unpinned from two critical ‘pinning points’ which hold the ice in and stabilise it. If that happens, then the ice shelf will be at much greater risk of collapsing in the near future. However, most research suggests that the ice that broke off was ‘passive ice’ and won’t have a huge effect on the stability of Larsen C.

It will be important to monitor the development of new bergs at the calving front (the ‘frontline’ of iceberg creation, so to speak) to keep tabs on whether or not new cracks and calving events are likely to bypass the northern pinning point, Gipps ice rise, and unhinge the shelf.

Scientists will be watching satellite imagery of Larsen closely for clues. While there are several hypotheses about the exact mechanisms, there are still lots of unknowns about how these lead to collapse, and which processes are most important. Current space-borne monitoring systems offer the unique opportunity to watch developments on Larsen C in full: from the propagation of the crack to the calving and (perhaps) collapse of the shelf. This will help glaciologists hone their theories and understand better what exactly causes ice shelves to disintegrate. And of course, that will guide future projections of collapse, which can only be a good thing.

Featured image by Jennifer Pickens via Flickr


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