Shocking footage reveals a giant iceberg is close to calving off

Experts are concerned the huge calving event, which would create an iceberg with an area of more than 5,000 km², roughly the size of Delaware or Wales, could leave the entire shelf unstable, Joinfo.com reports with reference to Daily Mail Online.

This, they warn, could contribute dramatically to sea level rise.

‘Iceberg calving is a normal part of the glacier life cycle, and there is every chance that Larsen C will remain stable and this ice will regrow,’ said Dr Paul Holland, ice and ocean modeller at British Antarctic Survey.

‘However, it is also possible that this iceberg calving will leave Larsen C in an unstable configuration.

‘If that happens, further iceberg calving could cause a retreat of Larsen C. We won’t be able to tell whether Larsen C is unstable until the iceberg has calved and we are able to understand the behaviour of the remaining ice.

‘The stability of ice shelves is important because they resist the flow of the grounded ice inland.

‘After the collapse of Larsen B, its tributary glaciers accelerated, contributing to sea-level rise.’

Satellite observations from February 2017 show the growing crack in the ice shelf which suggests that an iceberg with an area of more than 5,000 km² is likely to calve soon.

Researchers from the UK-based MIDAS project, led by Swansea University, have reported several rapid elongations of the crack in recent years, and today revealed it is up to 1500m wide in parts.

BAS scientists are involved in a long-running research programme to monitor ice shelves to understand the causes and implications of the rapid changes observed in the region, and shot the footage as they flew over the ice shelf on their way to collect science equipment.

During the current Antarctic field season, a glaciology research team has been on Larsen C using seismic techniques to survey the seafloor beneath the ice shelf.

Because a break up looks likely the team did not set up camp on the ice as usual.

Instead they made one-off trips by twin otter aircraft supported from the UK’s Rothera Research Station.

Ice shelves in normal situations produce an iceberg every few decades.

There is not enough information to know whether the expected calving event on Larsen C is an effect of climate change or not, although there is good scientific evidence that climate change has caused thinning of the ice shelf.

Once the iceberg has calved, the big question is whether Larsen C will start to retreat.

An ice shelf is a floating extension of land-based glaciers which flow into the ocean. Because they already float in the ocean, their melting does not directly contribute to sea-level rise.

However, ice shelves act as buttresses holding back glaciers flowing down to the coast.

Larsen A and B ice shelves, which were situated further north on the Antarctic Peninsula, collapsed in 1995 and 2002, respectively.

This resulted in the dramatic acceleration of glaciers behind them, with larger volumes of ice entering the ocean and contributing to sea-level rise.

Elsewhere in the Antarctic, shocking new satellite image has revealed the march of a giant crack dubbed the ‘Halloween crack’.

Taken by the European Space Agency’s Copernicus programme, which is aimed at Earth Observation, the data was instrumental in the recent decision to temporarily close down the British Halley VI research station in Antarctica.

The crack is located on the Brunt Ice Shelf – a floating ice sheet that moves steadily towards the ocean where it occasionally calves – when chunks of ice break off glaciers to make an iceberg.

The crack first appeared last October, when the Halley VI base of the British Antarctic Survey was only 17km from it.

Information from two satellites – Sentinel-1 and Sentinel-2, were used to monitor the crack’s development.

A company called Enveo, which uses satellite data to monitor to study the frozen parts of the world, also helped with the observations.

In November and December, the crack was growing in length by as much as 600 metres per day.

While the Halley Research station had to move because of this, it was designed to be relocated if the ice becomes dangerous.

The station already had to relocate 23km inland during Antarctica’s last summer months because of another chasm (crack) which had lain dormant for more than three decades but became active again in 2013.

Dr Hilmar Gudmundsson, the survey’s lead scientist, said: ‘The frequency of Sentinel-2 images and Sentinel-1 radar products allows us to follow in detail and almost in real time the development of the crack as it grows week by week.’

The two Sentinel satellites are being used to monitor three cracks – the Halloween crack, which is now growing at 200 metres per day, and two other ice chasms.

The satellites are also being used to detect any new cracks that may arise.

The Sentinel-2 satellite has been programmed so that it takes images every time it flies over the cracks so that there’s a maximum chances of photos without clouds in them.

Other satellites, Sentinel 1-A and Sentinel 1-B, have also been recording data with two crossing tracks.

This allows researchers to map the growing rift and, showing how the ice shelf is deforming at the tip of the growing crack.