Larsen C ice shelf that set free huge iceberg in Antarctic is still changing and could destabilise even more, scientists say

The iceberg has gradually moved away from the shelf in recent weeks

A picture of the iceberg taken at the end of July (A. Fleming/British Antarctic Survey)

The huge iceberg that detached from the Larsen C ice shelf is travelling away from it, according to scientists that are tracking it.

And ice shelf is continuing to change after the iceberg detached, with more cracks appearing in its surface.

The Larsen C ice shelf lost 10 per cent of its surface when one of the biggest icebergs ever seen – about a quarter of the size of Wales, or four times as big as London – detached from it on 12 July. Since then, researchers Anna Hogg from the University of Leeds and the British Antarctic Survey's Hilmar Gudmundsson have been tracking both, watching the iceberg's movements from satellites.

They have seen the iceberg drift about five kilometres from the shelf that it detached from, meaning that the gap is now clearly visible. And more than 11 other smaller icebergs have broken off from both the shelf and the big iceberg itself.

Damage is continuing on the main ice shelf, and Dr Hogg said that "the Larsen-C story might not be over yet". Satellite images show that cracks are continuing to grow towards a feature on the shelf called the Bawden Ice Rise – an important support for the shelf that could detach, causing yet another dramatic event.

"If an ice shelf loses contact with the ice rise, either through sustained thinning or a large iceberg calving event, it can prompt a significant acceleration in ice speed, and possibly further destabilisation," she said.

The calving itself might not be the result of changes in the environment conditions, the two researchers report in a study published in Nature Climate Change. But the changes might bring about major alterations to the environment themselves.

"Although floating ice shelves have only a modest impact on of sea-level rise, ice from Antarctica's interior can discharge into the ocean when they collapse. Consequently we will see increase in the ice-sheet contribution to global sea-level rise," Dr Gudmundsson said.

"With this large calving event, and the availability of satellite technology, we have a fantastic opportunity to watch this natural experiment unfolding before our eyes. We can expect to learn a lot about how ice shelves break up and how the loss of a section of an ice shelf affects the flow of the remaining parts."