A Trillion-Ton Megaberg is Heading for South Georgia Island: Here’s What it Means for the Wildlife That Lives There

A 130-foot towering wall of ice with a surface area larger than Rhode Island is slowly making its way toward a remote island near Antarctica. Imagine if the ice wall from Game of Thrones were mobile and floating through the sea toward your home. That’s what is happening to the penguins and other animals that live on South Georgia Island.

This iceberg, or megaberg, is the largest in the world. Not only is it tall, it’s also thick. Because most of the iceberg is underwater, only its tip is seen floating above the surface. Named A23a by scientists, it’s 920 feet thick and weighs nearly a trillion tons.

What is a Megaberg?

The Antarctic ice sheet covers most of the continent of Antarctica. Antarctica contains 90% of the earth’s ice and 70% of its fresh water. Its ice sheet is so thick in some places it’s nearly three miles deep. When ice begins to melt and crack away from the ice sheet, icebergs form. And when they are as large as A23a, scientists refer to them as megabergs.

An even larger megaberg was created in 2016 when an iceberg larger than 2,200 square miles (that’s bigger than the state of Delaware!) broke from the Antarctic ice sheet and began drifting to the north. This one, named Iceberg A-68 was also headed straight for South Georgia Island, but over the course of a few years, it melted and broke apart before reaching land. As the iceberg melted, it brought freshwater to seawater environments, changing the ecosystems.

What Animals Live on South Georgia Island?

South Georgia Island is a remote and isolated place that is brimming with wildlife. It’s 1,200 miles east of Antarctica and is a British Overseas Territory. The nearest land is the Falkland Islands, about 800 miles away. Thanks to its distance from civilization, South Georgia Island has remained a haven for wildlife with very little human interference.

The island is home to the world’s largest population of king penguins. Over 100,000 pairs of them breed here and raise their young. There are even more macaroni penguins (3 million breeding pairs,) and plenty of gentoo and pinstrap penguins as well.

Aside from penguins, the largest flying bird in the world — the wandering albatross, with a 10- to 12-foot wingspan — can be found here. Other notable animals that live here include Antarctic fur seals and the southern elephant seal.

What Does an Impending Iceberg Mean for the Animals of South Georgia Island?

The biggest threat the animals of South Georgia Island face from a wall of ice is that it may block pathways they use to hunt food. If the megaberg doesn’t begin to melt and break up before it hits the continental shelf, it could get grounded there, blocking wildlife from reaching feeding grounds.

The most vulnerable animals would be at risk, such as seal pups and penguin chicks. These young animals are still dependent on their parents to hunt and bring back food. If the parents have to travel further, it will take them longer to return and they’ll have less to bring back to their young.

Although traveling icebergs are a normal occurrence here and the wildlife has adapted to them, it would still be a challenging time to have the food source blocked during their breeding season. Scientists say that it won’t cause damage to the overall population, but specific colonies could experience higher mortality rates. Also, it would be harmful to already vulnerable species such as the macaroni penguin. This penguin species is listed as a vulnerable species, with a population that has been declining for decades.

Is It a Sure Thing That the Iceberg Will Collide With the Island?

Scientists can’t predict exactly where A23a is headed. It could float past South Georgia Island. Or it could get stuck on the sea floor near the island, blocking the animals from their hunting grounds for months. Eventually, it will keep melting and will break up into smaller icebergs until it completely disappears, filling the ocean with its freshwater. Scientists will continue to monitor the iceberg via satellite to watch its progress.

When Did Megaberg A23a Form?

This massive iceberg is nearly 40 years old, having broken off from the ice sheet in 1986. Scientists kept track of it for decades as it was trapped on the sea floor amid a patch of sea ice. It finally broke free toward the end of 2024, making its slow journey southward. Scientists are studying the water left behind as it passes through the ocean to learn more about how these melting icebergs affect the area’s ecology.

Are Massive Icebergs Becoming More Common?

Chunks of ice commonly crack from the Antarctic ice sheet and float through the sea as icebergs. However, climate change is causing massive icebergs, like A23a, to occur more frequently.