A trillion-ton iceberg four times the size of London has snapped off the West Antarctic ice shelf

After months of anticipation, one of the biggest icebergs ever recorded has finally broken off the Larsen C ice sheet in the West Antarctic. The iceberg weighs a staggering trillion tons and has an area of 2,239 sq miles (5,800 sq km), making roughly the size of Delaware or four times the size of London.

It was found to have split off from the ice sheet after scientists examined the latest satellite data from the area.

The process, known as calving, occurred in the last few days.

The ice shelf has now decreased in size by 10 per cent, leaving the ice front at its most retreated position ever recorded.

If the glaciers held in check by the iceberg now split into the Antarctic Ocean, it could lift the global water mark by about 10 centimetres (4 inches).

The iceberg, which is expected to be dubbed ‘A68’, is predicted to be one of the 10 largest icebergs ever recorded.

In a statement, Swansea University said: ‘The calving occurred sometime between Monday, July 10 and Wednesday, July 12, when a 5,800-square kilometre (2,200-square mile) section of Larsen C (ice shelf) finally broke away.’

Throughout the Antarctic winter, research teams, led by the University of Swansea and including researchers from British Antarctic Survey (BAS), monitored the progress of a 170 km long ice rift in the ice shelf using the European Space Agency (ESA) Copernicus Sentinel-1 satellites.

According to BAS remote sensing analyst Andrew Fleming, the satellite images have been critical for research planning.

He says: ‘This story has just got even more interesting.

‘Our glaciologists will now be watching closely to see whether the remaining Larsen C Ice Shelf becomes less stable than before the iceberg broke free, and our biologists will be keen to understand how new habitats formed by the loss of the ice are colonised.’

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.

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.

The calving event has potential opportunities for new studies of open ocean and seabed habitats.

According to experts, this calving event will provide unique scientific opportunities for understanding how new biological communities develop and how new species occupy the newly exposed area.

Dr Susie Grant, a marine bio-geographer at BAS, said: ‘At the 2016 meeting of the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) there was international agreement that any newly exposed areas of ocean following ice shelf retreat or collapse could be automatically protected and designated as a Special Area for Scientific Research.’

Commenting on the calving event, Rod Downie, Head of Polar Programmes at WWF, said: ‘The sheer scale of this natural calving event is impressive – we will need to redraw the map of the Antarctic Peninsula.

‘And whilst this is Antarctica doing what Antarctica does, it demonstrates just how fragile the polar regions are. The polar regions drive our oceans and atmosphere.

‘But west Antarctica has experienced some of the most rapid rates of warming on the planet in recent decades, and that’s not good news for iconic species such as Adélie or emperor penguins.

‘This demonstrates why we need to urgently and globally tackle climate change head on, starting in the UK with the UK government outlining how we plan to meet our international commitments to reduce carbon emissions.’

Experts also predict that alongside the main iceberg, several smaller icebergs could break away from the ice sheet.

Data from July 6 revealed that, in a release of built-up stresses, the rift had branched several times.

In a blog, a spokesperson for the MIDAS Project, which is monitoring the ice shelf, said: ‘Using data from ESA’s Sentinel-1 satellites, we can see that there are multiple rift tips now within 5 km of the ice edge.

‘We expect that these rifts will lead to the formation of several smaller icebergs, as well as the large iceberg which we estimate will have an area of 5,800 sq km.’

Professor Adrian Luckman of Swansea University, lead investigator of the Midas project, said: ‘We have been anticipating this event for months, and have been surprised how long it took for the rift to break through the final few kilometres of ice.

‘We will continue to monitor both the impact of this calving event on the Larsen C Ice Shelf, and the fate of this huge iceberg.

‘The iceberg is one of the largest recorded and its future progress is difficult to predict.

‘It may remain in one piece but is more likely to break into fragments.

‘Some of the ice may remain in the area for decades, while parts of the iceberg may drift north into warmer waters.

‘In the ensuing months and years, the ice shelf could either gradually regrow, or may suffer further calving events which may eventually lead to collapse – opinions in the scientific community are divided.

‘Our models say it will be less stable, but any future collapse remains years or decades away.’

Daily Mail
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