A23a: Giant iceberg on collision course with an island

The world’s largest iceberg is on a collision course with a remote British island, which could endanger penguins and seals.

The iceberg is turning north from Antarctica toward South Georgia, a rugged British territory and wildlife refuge, where it could crash and break into pieces. It is currently 280 kilometers (173 miles) away.

Countless birds and seals died on the icy coves and beaches of South Georgia when giant icebergs prevented them from feeding.

“Icebergs are inherently dangerous. I would be extraordinarily happy if they just didn’t reach us,” Captain Simon Wallace tells BBC News, speaking from the South Georgia government ship Pharos.

Around the world a group of scientists, sailors and fishermen are eagerly examining satellite images to follow the daily movements of this queen of icebergs.

Is known as A23a and it is one of the oldest in the world.

It broke off or broke off from the Filchner Ice Shelf in Antarctica in 1986, but became trapped on the seafloor and then caught in an ocean vortex.

Finally, in December, it broke free and is now on its final journey, hurtling toward oblivion.

Warmer waters north of Antarctica are melting and weakening its vast cliffs that rise up to 400m (1,312ft), higher than the Shard in London.

It once measured 3,900 square kilometers, but the latest satellite images show it is slowly decaying. It is currently about 3,500 square kilometers, approximately the size of the English county of Cornwall.

And large blocks of ice are breaking away, sinking into the waters around their edges.

The A23a could split into vast segments at any time, which could then remain for years, like floating cities of ice sailing uncontrollably around South Georgia.

This is not the first massive iceberg to threaten South Georgia and the Sandwich Islands.

In 2004, one called A38 ran aground on its continental shelf, leaving penguin chicks and seal pups dead on beaches while huge chunks of ice blocked their access to feeding grounds.

The territory is home to beautiful colonies of emperor king penguins and millions of elephants and sea lions.

“South Georgia is in an iceberg alley, so impacts are expected for both fisheries and wildlife, and both are highly adaptive,” says Mark Belchier, a marine ecologist who advises the Georgia government. South Georgia.

Sailors and fishermen say icebergs are a growing problem. In 2023, one called A76 gave them a scare when it was almost grounded.

“Chunks were leaning, so it looked like big towers of ice, a city of ice on the horizon,” says Belchier, who spotted the iceberg while at sea.

Those slabs still persist on the islands today.

“It’s in pieces from the size of several Wembley stadiums to pieces the size of a desk,” says Andrew Newman of Argos Froyanes, a fishing company working in South Georgia.

“Those pieces basically cover the island; we have to fight our way through it,” says Captain Wallace.

The sailors on your ship must be constantly alert. “We have searchlights on all night to try to see the ice; it can come out of nowhere,” he explains.

The A76 was a “game changer,” according to Newman, with “a huge impact on our operations and the safety of our ship and crew.”

The three men describe a rapidly changing environment, with glacial retreat visible year after year and volatile sea ice levels.

It’s unlikely that climate change was behind the birth of A23a because it was born a long time ago, before much of the impacts of rising temperatures we’re seeing now.

But giant icebergs are part of our future. As Antarctica becomes more unstable with warmer ocean and air temperatures, larger chunks of the ice sheets will break off.

However, before its time comes to an end, A23a has left a parting gift to scientists.

A British Antarctic Survey team on the research vessel Sir David Attenborough was found near A23a in 2023.

Scientists rushed to seize the rare opportunity to investigate what mega icebergs do to the environment.

The ship sailed towards a crevice in the iceberg’s gigantic walls, and PhD researcher Laura Taylor collected precious water samples 400 meters from its cliffs.

“I saw a huge wall of ice much higher than me, as far as I could see. It has different colors in different places. Chunks were falling off; it was quite magnificent,” he explains from his laboratory in Cambridge, where he is now based. analyzing the samples.

His work analyzes the impact that meltwater has on the carbon cycle in the Southern Ocean.

“It’s not just water like we drink. It’s full of nutrients and chemicals, as well as tiny animals like phytoplankton frozen inside,” says Taylor.

As it melts, the iceberg releases those elements into the water, changing the physics and chemistry of the ocean.

That could store more carbon deep in the ocean, as particles sink from the surface. Naturally, that would block some of the planet’s carbon dioxide emissions that contribute to climate change.

Icebergs are notoriously unpredictable and no one knows exactly what they will do next.

But soon the giant should appear, lurking on the horizons of the islands, as large as the land itself.