#68a

A ~6,000 sq km iceberg has broken away from Antarctica.

The iceberg was spotted by a US satellite on Wednesday while passing over a region of Antarctica known as the Larsen C Ice Shelf. Scientists have been monitoring this ice shelf, and in particular a large crack in the ice, for over a decade. In 2014, it was noted that the rift was accelerating in size and thus, the eventual separation from the shelf was seemingly inevitable. The iceberg is estimated to be around 200m thick and it is expected to remain quite stationary in the short term; however, it will need to be monitored as oceanic currents and winds may eventually push the berg to the north where it could become a shipping hazard. Despite some misinformation, the impact of this event on sea level rise will not be significant as the ice was already 'floating' in the water (throwback to Archimedes' principle!).

What does this mean for the Larsen C Shelf?

At the moment, not much.

Larsen C is a shelf of floating ice which was formed by glaciers flowing down the eastern side of the Antarctic Peninsula into the ocean; where the glaciers meet the water, their fronts ‘combine’ to make one single protrusion. Over time, the shelves seem to strive for equilibrium between the accumulation of new ice and the loss of old ice, so the calving of icebergs is quite a natural phenomenon. However, like much of the Earth’s natural processes, rising global temperatures (both atmospheric and oceanic) have acted as a catalyst, increasing the rate of melting and berg formation. Of note, Larsen C is now at its smallest extent since the end of the last ice age some 11,700 years ago.

Is Climate Change to blame?

It is not yet known, or at least substantiated, if climate change played a role in the calving of this iceberg, but two nearby, smaller shelves, Larsen A and Larsen B, disintegrated around the turn of the century and a warming climate very probably had a role in their demise.

Over the coming weeks, months and years, research scientists will be closely watching this new addition and also focusing on the Larsen C shelf itself. They will be particularly interested to assess the stability of the shelf post-calving and monitor the rates of both melting and calving going forward.

Previously, there was speculation that the crack, which spread across the shelf from a pinning point known as the Gipps Ice Rise, looked as though it might sweep around behind another such anchor called the Bawden Ice Rise. If this had occurred, it could have instigated a significant increase in the movement of the shelf's seaward movement once the berg came off.

As it is, scientists are not now expecting a big change in the speed of the ice, but only time will tell.

Jean