A23a: A giant iceberg on a collision course with an island

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

The iceberg is spinning north from Antarctica towards South Georgia, Britain’s rugged territory and wildlife haven, where it could break up and break into pieces. It is currently 173 miles (280 km) away.

Countless birds and seals have died on South Georgia’s icy bays and beaches when past giant icebergs stopped feeding on them.

“Icebergs are inherently dangerous. I would be extremely happy if it passed us by completely,” Sea Captain Simon Wallace told BBC News, speaking from the South Georgia government vessel Pharos.

Around the world, a group of scientists, sailors and fishermen are anxiously checking satellite images to track the daily movements of this iceberg queen.

That’s right known as A23a and is one of the oldest in the world.

It broke off from the Filchner ice shelf in Antarctica in 1986, but got stuck on the sea floor and then got caught in an ocean eddy.

Finally, in December, he broke free and is now on his final journey, hurtling into oblivion.

Warmer waters north of Antarctica melt and weaken its huge cliffs, which rise to 1,312 feet (400 m), taller than the London Shard.

It once covered an area of ​​3,900 square kilometers, but recent satellite images show that it is slowly collapsing. Now it is about 3,500 square kilometers, which is about the size of the English county of Cornwall.

And large ice sheets break off, plunging into the water at the edges.

The A23a can break into huge segments any day, which can then hang for years like floating cities of ice that cruise out of control around South Georgia.

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

In 2004, one called A38 washed up on the continental shelf, leaving penguin chicks and seal pups dead on beaches as huge chunks of ice cut off their access to feeding grounds.

The area is home to valuable colonies of royal emperor penguins and millions of elephants and seals.

“South Georgia is in the iceberg lane, so impacts to both fisheries and wildlife are to be expected, and both have great adaptive capacity,” says Mark Belchier, a marine ecologist who advises the South Georgia government.

Sailors and fishermen say icebergs are a growing problem. In 2023, one called A76 spooked them as it came close to landing.

“Pieces of it were falling over, so they looked like big ice towers, an ice city on the horizon,” says Mr Belchier, who saw the iceberg while at sea.

These plates still lie around the islands today.

“It goes from the size of several Wembley stadiums to pieces the size of your table,” says Andrew Newman of Argos Froyanes, a fishing company based in South Georgia.

“These pieces basically cover the island – we have to get through it,” says Captain Wallace.

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

According to Mr Newman, the A76 was a game-changer, having “a huge impact on our operations and ensuring the safety of our vessel and crew”.

All three describe an environment that is changing rapidly, with glaciers retreating every year and unstable sea ice levels.

Climate change is unlikely to have caused the birth of A23a because it spawned so long ago, before the warming effects we are seeing now.

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

Still, until his time is up, A23a left scientists with a parting gift.

A team from the British Antarctic Survey on the research vessel Sir David Attenborough nears A23a in 2023.

Scientists have tried to use a rare opportunity to study what mega-icebergs are doing to the environment.

The ship sailed into a crack in the iceberg’s giant walls, and Laura Taylor, Ph.D., collected precious water samples 400 meters from its cliffs.

“I saw a massive wall of ice far above me, as far as I could see. It has different colors in different places. Pieces were falling off – it was very beautiful,” she explains from her laboratory in Cambridge, where she is currently analyzing the samples.

Her work examines how meltwater affects the carbon cycle in the Southern Ocean.

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

As the iceberg melts, it releases these elements into the water, changing the physical and chemical composition of the ocean.

This can store more carbon deep in the ocean as particles sink from the surface. This would naturally stop some of the planet’s carbon dioxide emissions, which contribute to climate change.

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

But a behemoth, looming on the horizon of the islands, should appear soon, the size of the territory itself.