New video footage of the massive A81 iceberg that broke away from the Brunt Ice Shelf in Antarctica in January has been released. While before and after satellite images were released of the iceberg when it broke away, the new footage shows the massive scale of the iceberg for the first time.
Recorded by a team at the British Antarctic Survey leaving the Halley Research Station, they witnessed the iceberg begin its journey into the Weddell Sea. The Halley Research Station used to be located on the part of the ice now floating away in the form of the A81 iceberg itself. It’s continuing to move and is currently 150km south of where it broke from the ice shelf.
The A81 iceberg has been monitored since 2012 when a crack, known as Chasm-1, was discovered in the ice shelf. Scientists had been predicting the break in the ensuing decade, which finally happened in January 2023. Now, two months on, the iceberg has travelled 150km, heading into the Weddell Sea. After the initial break, the European Space Agency (ESA) satellite Copernicus captured before and after images.
According to researchers in January, it was reported to be “five times the size of Malta”. Now it’s said to cover an area the size of Greater London, England. Both descriptions are accurate, with the iceberg having an area of around 1550km², but naturally, the British Antarctic Survey will describe its size compared to a British city. In this case, London. The capital of the United Kingdom.
The footage above shows the scale of the iceberg poking its head above the water to great effect. But with an estimated 90% of any given iceberg existing underwater, A81 is truly a colossal iceberg. And with an iceberg of this size, there are major ecological implications.
As it melts, it will release a lot of nutrients that can potentially benefit microscopic plants at the lowest end of the region’s food chain. But as well as the positive effects, there are also negative ones. Its melting will also introduce a lot of freshwater into the sea. An iceberg of this size can dilute the salt content of the ocean, making the underwater conditions unsuitable for many types of phytoplankton and the zooplankton that feed on them.
These can then have knock-on effects further up the food chain in animals such as fish, birds, seals and even whales.
A81 isn’t the most enormous iceberg out there, though. There’s also A76a, one of three icebergs created when the giant A76 iceberg split apart after breaking from the Filchner-Ronne ice shelf in 2021. A76a is the largest iceberg on earth, around twice the size of A81. It is also being closely monitored.
Where’s it going?
A81’s break-off was predicted early on. The Halley Research Station, where the team was leaving when they recorded the giant iceberg, used to exist on ice that now forms part of A81. Several months before Chasm-1 extended across the ice shelf, the research station was relocated 23km from its previous location. The A81 iceberg is expected to follow the Antarctic coastal current around the Weddell Sea, as has been the case with previous icebergs.
[Related reading: This robot is filming the ocean under a Florida-sized glacier in Antarctica]
A76a, on the other hand, has a potentially more devastating trajectory with significant disruptions to wildlife along its journey. Being twice the size of A81, A76a has even more potential to dilute the salinity of the water through which it passes, causing ecological imbalances with massive effects. But wildlife isn’t the only concern with A76a.
Our major concern at the moment is the possible risk for vessels operating in the region as the iceberg begins to break up and calve smaller chunks of ice. It looks as though A76A may end up heading west of South Georgia, not east where A68 broke up, but there is still so much uncertainty around this. We will be watching its movement closely.
– Dr Mark Belchier, Government of South Georgia and Sandwich Island
You can find out more about the A81 and A76a icebergs on the British Antarctic Survey website.