Enormous iceberg heads towards island in South Atlantic
An iceberg 158 kilometers long (98 miles) and 48 km wide is on course to hit the British territory of South Georgia, a largely uninhabited island of roughly the same size in the South Atlantic.
Named A68a, the iceberg is believed to be the biggest currently in the Southern Ocean and one of the largest on record.
While it could still break apart or change course, scientists fear there is a strong possibility it will collide with the island, potentially disrupting biodiversity there.
“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.”
The island is also a hotspot for recovering populations of humpback and blue whales and is home to one of the largest numbers of albatrosses in the world.
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 chunks during 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.
“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.”
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.”