World’s biggest iceberg is on the move: Huge TRILLION-tonne ‘megaberg’ twice the size of Greater London has broken free – and is now drifting in the Southern Ocean

The world’s biggest iceberg is officially on the move. 

A23a is double the size of Greater London and weighs nearly a trillion tonnes. 

The megaberg has been grounded on the seafloor for over 30 years and recently began spinning on the spot. 

Now, experts from the British Antarctic Survey (BAS) have confirmed that A23a has finally broken free from its position north of the South Orkney Islands. 

It is now embarking on a new journey, as it begins drifting in the Southern Ocean. 

‘It’s exciting to see A23a on the move again after periods of being stuck,’ said Dr Andrew Meijers, an oceanographer with the BAS.

‘We are interested to see if it will take the same route the other large icebergs that have calved off Antarctica have taken. 

‘And more importantly what impact this will have on the local ecosystem.’  

The megaberg has been grounded on the seafloor for over 30 years and recently began spinning on the spot. Now, experts from the British Antarctic Survey (BAS) have confirmed that A23a has finally broken free from its position north of the South Orkney Islands

A23a is roughly double the size of Greater London and weighs nearly a trillion tonnes 

The iceberg originally calved from Antarctica’s Filchner Ice Shelf back in 1986. 

It then remained grounded on the seabed in the Weddell Sea, before beginning its slow journey north in 2020. 

In February this year, the iceberg became trapped in a Taylor Column – a phenomenon where rotating water above a seamount traps objects in place. 

This kept A23a spinning on the spot, delaying its expected rapid drift north. 

Now, images captured by satellites overhead have confirmed that the iceberg has broken free. 

BAS experts now expect it to continue its journey into the Southern Ocean, following the Antarctic Circumpolar Current. 

This is likely to drive it towards the sub-Antarctic island of South Georgia. 

Warmer conditions in that region will likely lead to the break up of A23a into smaller icebergs, which will eventually melt. 

The iceberg originally calved from Antarctica’s Filchner Ice Shelf in 1986. It then remained grounded on the seabed in the Weddell Sea, before beginning its slow journey north in 2020

In February this year, the iceberg became trapped in a Taylor Column – a phenomenon where rotating water above a seamount traps objects in place

Alongside the satellites, the megaberg is being studied by researchers on board RRS Sir David Attenborough. 

Laura Taylor, a biogeochemist on board the vessel, hopes to study the impact of the iceberg on local ecosystems. 

She said: ‘We know that these giant icebergs can provide nutrients to the waters they pass through, creating thriving ecosystems in otherwise less productive areas. 

‘What we don’t know is what difference particular icebergs, their scale, and their origins can make to that process.

‘We took samples of ocean surface waters behind, immediately adjacent to, and ahead of the iceberg’s route. 

‘They should help us determine what life could form around A23a and how it impacts carbon in the ocean and its balance with the atmosphere.’