Trillion ton A-68 Larsen C iceberg could threaten shipping

New satellite images have shown that a trillion ton iceberg which broke off Antarctica has begun to drift farther out to sea.

The huge chunk of ice, dubbed A68, which is around the size of Delaware or four times the size of Greater London, made its final break back in July after a crack began to form in 2014.

It was unclear what would happen to giant mass, as icebergs can remain in place for many years, but experts fear the break could see the berg disintegrate into pieces too small to track on satellite.

If these drift into shipping lanes, they could pose a significant risk to vessels in the region.

 

New satellite images have shown that a trillion ton iceberg which broke off Antarctica has begun to drift out to sea. Experts fear the break could see the berg disintegrate into pieces too small to track on satellite. If these drift into shipping lanes, they could pose a significant risk to vessels in the region

THE BIRTH OF A68

In early July, a huge crack in Antarctica’s Larsen C ice shelf caused a trillion ton iceberg – the third biggest ever recorded – to break off from the icy southern continent.

The huge chunk of ice, dubbed iceberg A-68, measures 5,800 square kilometres (2,240 square miles), making it around the size of Delaware, or four times the area covered by Greater London.

Professor Stef Lhermitte, of Delft University in the Netherlands, shared the latest satellite images of A68 on Twitter.

He said: ‘After some initial back-and-forth movement, Larsen C’s iceberg A68 seems on drift now.’

He added that the iceberg ‘continues to drift’, and posted a graphic comparing A68’s position on Saturday to a another image taken on Wednesday.

The comparison shows a clear drift away from the Antarctic ice shelf.

Scientists have claimed that global warming did not play a role in the calving of the iceberg, according to reports in the Independent.

Dr Natalie Robinson, a marine physicist at New Zealand’s National Institute of Water and Atmospheric Research, told the site it was ‘a “normal”, if relatively large, calving event’ and ‘very different from the collapse of its neighbouring ice shelves’.

But Professor Nancy Bertler, of the Antarctic Research Centre at Victoria University of Wellington, said global warming and the hole in the ozone layer had caused the sudden break-up of ‘numerous ice shelves’ in the region ‘some of which have been shown to have existed for 10,000 years or more’. 

Professor Stef Lhermitte, of Delft University in the Netherlands, shared the latest satellite images of A68 on Twitter. The comparison shows a clear drift away from the Antarctic ice shelf.

National Centre for Earth Observation scientists David Moore shared this up to date image of the region take with the Sentinel 3 satellite on September 16 

National Centre for Earth Observation scientists David Moore shared this up to date image of the region take with the Sentinel 3 satellite on September 16 

In early July, a huge crack in Antarctica’s Larsen C ice shelf caused the trillion ton iceberg – the third biggest ever recorded – to break off from the icy southern continent.

The huge chunk of ice, dubbed iceberg A-68, measures 5,800 square kilometres (2,240 square miles), making it around the size of Delaware, or four times the area covered by Greater London.

New pictures captured via satellite imagery show iceberg A-68 in stunning detail as it drifts from Antarctica, where it could remain in the open sea for years. 

In early July, a huge crack in Antarctica's Larsen C ice shelf caused a trillion ton iceberg  to break off from the icy continent. New satellite images show the iceberg in stunning detail, including this zoomed-in view of  iceberg A-68 (bottom left corner), Antarctica's Larsen C ice shelf (top and righthand segments), taken in late July by the Deimos 2 satellite

In early July, a huge crack in Antarctica’s Larsen C ice shelf caused a trillion ton iceberg to break off from the icy continent. New satellite images show the iceberg in stunning detail, including this zoomed-in view of iceberg A-68 (bottom left corner), Antarctica’s Larsen C ice shelf (top and righthand segments), taken in late July by the Deimos 2 satellite

WAS CLIMATE CHANGE RESPONSIBLE FOR A68

Reporting this week in the Nature journal Climate Change, Dr Anna Hogg and Dr Hilmar Gudmundsson examine the events leading up to this dramatic natural phenomenon.

They also discuss how calving of huge icebergs affects the stability of Antarctic ice shelves.

Their article argues that a calving event is not necessarily due to changes in environmental conditions.

Instead, it may simply reflect the natural growth and decay cycle of an ice shelf.

Despite the iceberg breaking off some time between July 10-12, scientists have struggled to take images of A-68 because Antarctica is currently going through its winter season.

Since the split, researchers have relied on polar satellites like Sentinel-1, which uses radar to peer through thick cloud cover.

But a few clear days in late July gave Spanish satellite firm Deimos Imaging a visible-light view using Deimos-1 and Deimos-2 – a pair of satellites that work as a tag-team.

‘These images are striking – easily the best I have seen since calving,’ Adrian Luckman, a glaciologist at Swansea University and a member of the Antarctic research program Project Midas, told Business Insider.

The team’s Deimos-1 satellite captures wider-angle, medium-resolution images while Deimos-2 takes zoomed-in, very-high-resolution pictures.

When combined the images can capture both vast, wide angle views of the scale of the Larsen C crack, as well as detailed up-close views of individual details.

The team's Deimos-1 satellite captures wider-angle, medium-resolution images (main image) while Deimos-2 takes zoomed-in, very-high-resolution images (insets)

The team’s Deimos-1 satellite captures wider-angle, medium-resolution images (main image) while Deimos-2 takes zoomed-in, very-high-resolution images (insets)

The huge chunk of ice, dubbed iceberg A-68 by scientists, measures 5,800 square kilometres (2,240 square miles), making it around the size of Delaware or four times the area covered by Greater London. This wide-angle view shows iceberg A-68 (central shape) and Antarctica's Larsen C ice shelf (rest of image) and was taken by the Deimos-1 satellite in late July

The huge chunk of ice, dubbed iceberg A-68 by scientists, measures 5,800 square kilometres (2,240 square miles), making it around the size of Delaware or four times the area covered by Greater London. This wide-angle view shows iceberg A-68 (central shape) and Antarctica’s Larsen C ice shelf (rest of image) and was taken by the Deimos-1 satellite in late July

The new images follow the news that cracks were spreading where the A-68 iceberg broke free from the Larsen C ice shelf.

Scientists released satellite footage of the moment the Antarctic Peninsula lost 10 per cent of its area earlier this month.

Since that time, experts have been following the fate of the huge iceberg as a rift has grown between the mainland and the mass of frozen water.

They have found that cracks are still growing on the ice shelf, and if they continue to grow, it’s possible that the ice shelf could collapse.

If all of Larsen C collapses, the ice it holds back might add another 4 inches (10 cm) to global sea levels over the years.

A few clear days in July gave Spanish satellite firm Deimos Imaging a visible-light using Deimos-1 and Deimos-2 - a pair of satellites that work as a tag-team. This image shows Larsen C (left of crack) and iceberg A-68 (right of crack), taken by Deimos-2 in late July

A few clear days in July gave Spanish satellite firm Deimos Imaging a visible-light using Deimos-1 and Deimos-2 – a pair of satellites that work as a tag-team. This image shows Larsen C (left of crack) and iceberg A-68 (right of crack), taken by Deimos-2 in late July

WHAT IS ITS IMPACT?

Icebergs calve from Antarctica all the time, but because this one is particularly large its path across the ocean needs to be monitored as it could pose a hazard to maritime traffic.

The massive ice cube will float in water and by itself will not add to sea levels when it melts.

But the real danger is from inland glaciers.

Ice shelves float on the sea, extending from the coast, and are fed by slow-flowing glaciers from the land.

They act as giant brakes, preventing glaciers from flowing directly into the ocean.

If the glaciers held in check by Larsen C now split into the Antarctic Ocean, it could lift the global water mark by about 10 centimetres (four inches), researchers have said. 

Dr Anna Hogg, from the University of Leeds and Dr Hilmar Gudmundsson, from the British Antarctic Survey, have continued to track the iceberg, known as A68, since the July 12 breakaway.

Using the European Space Agency’s (ESA) Copernicus Sentinel-1 satellite, they have found that, since the calving event, the berg has started to drift away from the Larsen-C.

Open ocean is now clearly visible in the approximately five kilometre gap between the berg and the ice-shelf.

A cluster of over 11 ‘smaller’ icebergs have also now formed, the largest of which is over eight miles (13km) long.  

Dr Anna Hogg, from the University of Leeds and Dr Hilmar Gudmundsson, from the British Antarctic Survey, have continued to track the iceberg, known as A68, since the July 12 breakaway. This Sentinel-1 data shows network of cracks grow on the Larsen-C Ice-Shelf, before and after the colossal iceberg broke free 

The iceberg is  one of the 10 largest icebergs ever recorded. A graphic shows how the iceberg compares in size

The iceberg is  one of the 10 largest icebergs ever recorded. A graphic shows how the iceberg compares in size

These ‘bergy bits’, as the experts are describing them, have broken off both the giant iceberg and the remaining ice-shelf. 

Dr Hogg, an ESA research fellow in the centre for polar observation and modelling at Leeds, said: ‘The satellite images reveal a lot of continuing action on Larsen-C Ice Shelf.

‘We can see that the remaining cracks continue to grow towards a feature called Bawden Ice Rise, which provides important structural support for the remaining ice shelf.

‘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. 

‘It looks like the Larsen-C story might not be over yet.’ 

This image shows the view of the A68 iceberg from a European Copernicus Sentinel-1 satellite image acquired on July 30

This image shows the view of the A68 iceberg from a European Copernicus Sentinel-1 satellite image acquired on July 30

Scientists released satellite footage of the aftermath of the Antarctic Peninsula losing 10 per cent of its area earlier this month. This Sentinel-1 image shows  the colossal iceberg (shown in blue) after it had broken free and the 'bergy bits' described by the experts began to break off

Scientists released satellite footage of the aftermath of the Antarctic Peninsula losing 10 per cent of its area earlier this month. This Sentinel-1 image shows the colossal iceberg (shown in blue) after it had broken free and the ‘bergy bits’ described by the experts began to break off

Using the European Space Agency's (ESA) Copernicus Sentinel-1 satellite, scientists have found that, since the calving event, the berg has started to drift away from the Larsen-C. This image, taken from a video created by the researchers, shows the ice front as it appeared when the crack (bottom right) began to appear in 2014

Using the European Space Agency’s (ESA) Copernicus Sentinel-1 satellite, scientists have found that, since the calving event, the berg has started to drift away from the Larsen-C. This image, taken from a video created by the researchers, shows the ice front as it appeared when the crack (bottom right) began to appear in 2014

Read more at DailyMail.co.uk