New satellite images provide a bird’s eye view of the massive iceberg that broke away from the Brunt Ice Shelf in Antarctica on Sunday night.
The frozen block has a thickness of 490 feet (150 metres) and an area of 600 square miles (1,550 km²) – almost the size of Greater London.
It broke off at a huge crack that bisected the ice shelf, known as Chasm-1, which had been growing by about 2.5 miles (4 kilometers) each year since 2012.
The incredible images were taken by a Copernicus Sentinel-2 satellite, which orbits the poles in a mission managed by the European Space Agency (ESA).
New images show the massive iceberg that broke away from the Brunt Ice Shelf in Antarctica on Sunday night from space
The frozen block has a thickness of 490 feet (150 metres) and an area of 600 square miles (1,550 km²) – almost the size of Greater London. The left image was taken on the 20 January 2023, and the right on 24 January 2023
What’s a calving event?
Glacier calving is a natural occurrence caused by the forward motion of a glacier making its end unstable.
During a calving event, part of the end of a glacier drops off, often forming an iceberg.
Calving of glaciers is often accompanied by a loud cracking or booming sound before blocks of ice up to 60 meters (200 ft) high break loose and crash into the water.
The entry of this ice into the water can cause large and dangerous waves.
GPS sensors began to pick up movement at Chasm-1 between 7pm and 8pm on Sunday, when it extended to roughly 40 miles (60 kilometers), across the entire shelf.
At the time, 21 staff with the British Antarctic Survey (BAS) were working in the Halley Research Station just 12 miles (19 km) away.
Fortunately, all of them were completely safe, and had been preparing for this eventuality for some time.
In 2016, continuous growth of Chasm-1 prompted the BAS – the national polar research institute – to relocate their site 14 miles (23 kilometers) inland.
The Halley VI Research Station consists of eight units which each sit on skis so they can be easily maneuvered away from the edge of the ice shelf when needed.
It has been unoccupied during the last six winters because of the complex glaciological situation which makes the impact of calving events unpredictable.
However, staff are deployed there between November and March to maintain the facilities that allow them to monitor experiments remotely during the winter.
The glaciologists have since confirmed that the area of ice the station is situated on remains unaffected by the recent calving event, and there is no need for evacuation.
Those currently on site are due to be collected by aircraft around 6 February.
At the time, 21 staff with the British Antarctic Survey (BAS) were working in the Halley Research Station just 12 miles (19 km) away, as indicated by the red square. Fortunately, all of them were completely safe, and had been preparing for this eventuality for some time.
The Halley VI Research Center (pictured) is an internationally important platform for atmospheric and space weather observations in a climate-sensitive zone.
PhD student Ben WAllis, who processed the new images, also said that the channel between the Brunt Ice Shelf and the new berg is about (3 km) wide at its northern end (pictured).
Mr Wallis tweeted: ‘Before the calving Chasm 1 was filled with a mélange of young ice formed from multiyear sea-ice and meteoric ice from compacted snow. This is now disintegrating while the large berg remains intact’
The satellite images of the new iceberg were processed by Ben Wallis, a PhD student at the University of Leeds, who also shared them on Twitter.
A colony of thousands of Emperor Penguins is known to live on the Dawson-Lambton glacier tongue, which sits immediately west of the Brunt Ice Shelf.
Some of the penguins started life in the Halley Bay colony, which was largely killed off in 2016 when part of the ice shelf collapsed.
Therefore, concerns had been raised as to whether they had been disrupted by the recent calving event.
But Mr Wallis confirmed that the sea-ice they call home is still intact, and stains from their poop, or ‘guano’ can even be seen in the images.
He also said that, as of yesterday, the channel between the Brunt Ice Shelf and the new berg is about (3 km) wide at its northern end.
He tweeted: ‘Before the calving Chasm 1 was filled with a mélange of young ice formed from multiyear sea-ice and meteoric ice from compacted snow.
‘This is now disintegrating while the large berg remains intact.’
A colony of thousands of Emperor Penguins is known to live on the Dawson-Lambton glacier tongue, which sits immediately west of the Brunt Ice Shelf. Mr Wallis confirmed that the sea-ice they call home is still intact, and stains from their poop can even be seen in the images
GPS sensors began to pick up movement at Chasm-1 between 7pm and 8pm on Sunday, when it extended to roughly 40 miles (60 km) long – across the entire shelf.
The iceberg broke off at a huge crack that bisected the ice shelf, known as Chasm-1 (pictured), which had been growing by about 2.5 miles (4 km) each year since 2012.
The iceberg separated from the ice shelf due to a spring tide in what’s known as a ‘calving event’.
This is a completely natural process that happens regularly in the frozen continent, and is not linked to climate change.
Professor Dominic Hodgson, BAS glaciologist, said: ‘This calving event has been expected and is part of the natural behavior of the Brunt Ice Shelf.
‘Our science and operational teams continue to monitor the ice shelf in real-time to ensure it is safe, and to maintain the delivery of the science we undertake at Halley’.
Calving is caused by the forward motion of a glacier making its end unstable so that part of it falls off, often forming an iceberg.
The process enables glaciers to balance out the accumulation of new snow and ice.
While this won’t be the largest iceberg to split off from Antarctica, it’s the biggest chunk the ice shelf has lost since observations began over 100 years ago in 1915. Pictured: Chasm-1
Chasm-1 (pictured) had lain dormant for the 25 years prior to 2012, when satellite monitoring revealed it was starting to move.
The weekend’s ‘calving event’ was completely natural – not at all linked to climate change – and caused by a spring tide. Calving is a natural occurrence caused by the forward motion of a glacier making its end unstable.
HOW DO SCIENTISTS MONITOR THE BRUNT ICE SHELF?
Scientists use a network of 16 GPS instruments to measure any deformation of the Brunt Ice Shelf, which causes cracks, which report updates every hour.
These include the Sentinel 2 satellites from the European Space Agency, NASA Worldview satellites, US Landsat 8 and TerraSAR-X.
They also utilize on-site drone footage, as well as ground penetrating radar to image the subsurface.
The data has provided scientists with a number of ways to measure any cracks with high precision.
They have also used computer models and bathymetric maps to predict how close the ice shelf was to calving.
While this won’t be the largest iceberg to split off from Antarctica, it’s the biggest chunk the Brunt Ice Shelf has lost since observations began over 100 years ago in 1915.
Chasm-1 had lain dormant for at least 35 years prior to 2012, when satellite monitoring revealed it was starting to move.
In 2015 and 2016, scientists used ice-penetrating radar technologies and satellite images to determine the path the fracture could take, and the speed it could grow.