There is growing concern over a collosal iceberg on a collision course with the British territory of South Georgia, a largely uninhabited South Atlantic island of roughly the same size. 

Measuring 158 kilometers long (98 miles) and 48 km wide, A68a —  as the iceberg is called  —  is believed to be the biggest currently in the Southern Ocean, and one of the largest on record. 

As the iceberg has moved closer to the island over the past weeks, aerial images have shown  it show breaking up. This has sparked concern over the impact of freshwater from the melting ice on local marine life. 

“This is basically an area that’s completely thriving with wildlife,” Professor Geraint Tarling from the British Antarctic Survey (BAS) told DW. “The island has globally significant populations of penguins and seals … Enormous numbers that if they were not there anymore, there would be severe declines in quite a few species.”

Scientists are due to set off for the region next month on the research ship RRS James Cook to assess the impact on local biodiversity. The waters around the island are home to recovering populations of humpback and blue whales. South Georgia is also home to one of the largest numbers of albatrosses in the world.

Two underwater robotic gliders will be used to get as close to the iceberg as possible to measure water temperature, salinity and plankton concentrations. 

Blue whale in the sea

The waters around South Georgia are home to species such as the humpback (above) and the blue whale

‘Iceberg graveyard’

Scientists had expected A68a to shatter after breaking off from the Larsen C ice shelf on the east coast of the Antarctic Peninsula in summer 2017

According to the European Space Agency (ESA), the icy giant has lost at least two large chunks during its long journey, prior to which it was roughly twice the size of Luxembourg. 

Although A68a would be the biggest to hit the island, it would not be the first in the region named the “iceberg graveyard.” In 2004, a smaller iceberg grounded a few kilometers from land. 

What is particularly concerning about this one is not only its size, but its shallow shape, explains Tarling. According to ESA it is only a few hundred meters thick.

A68a iceberg in open waters

The iceberg has been at sea since calving from the Larsen C ice shelf in July 2017

“This one has the potential to go right on the shore and really block those [animal] colonies from getting to their food sources and coming back to get the food back to their pups and chicks.” 

In addition to preventing access to foraging paths to offshore food sources for penguins, seals and albatrosses, it could also disrupt conditions for marine algae at the base of the food chain, says Tarling. “And if that’s not there, then everything that depends on it can’t thrive either.”  

It could also impact creatures on the ocean’s floor, he adds, many of which store carbon in their bodies and secure it in the seabed. “If this is scoured, it gets churned up, it goes back into the water column and then goes back into the atmosphere potentially.”   

Colony of penguins with hills of ice in the background

South Georgia is home to huge colonies of penguins as well as albatrosses that could be adversely affected by the iceberg

The currents will decide where the iceberg goes

While still traveling through the water icebergs of A68a’s size can also have a positive environmental impact through the meltwater they produce, says Grant Bigg, professor in earth systems science at the University of Sheffield in northern England.

They can release plumes of material, sometimes hundreds of kilometres long, which contain iron, picked up while the ice moved over land before reaching the ice shelf. This can fertilize the ocean and support organisms such as phytoplankton.

If the iceberg, which has already traveled an estimated 1,600 kilometers, continues on a direct trajectory at its current speed of one kilometer per hour, BAS predict it could arrive at the island between 10 and 20 days from now. 

“It’s too large to really do anything about it,” says Bigg. “It’s a case of waiting and seeing and hoping the currents will send it around the south [of the island] or break it up.”