News Excerpt:

The world’s largest iceberg, known as A23a, has become stuck spinning in circles near the South Orkney Islands, approximately 375 miles northeast of the Antarctic Peninsula.

The Journey of A23a:

• A23a is a fragment of a much larger iceberg, A23, which calved from the Filchner Ice Shelf in 1986. 
• At the time, A23 was even larger and housed a research station that had to be abandoned. 
• Later that same year, A23a broke off and became grounded in the Weddell Sea, where it remained for 34 years. 
• In 2020, A23a finally freed itself and began its slow journey through the Southern Ocean.
• By December of 2020, the iceberg was on the move, and it took researchers nearly an entire day to circumnavigate it. 
• However, by spring 2024, A23a had caught the spins, a phenomenon first observed via satellite imagery.

Why is A23a Spinning?

• A23a is currently stuck in an area of the Southern Ocean known as Iceberg Alley, a common pathway for large icebergs.
• Typically, icebergs in this region are pulled into the Antarctic Circumpolar Current, the world’s largest ocean current, which propels them eastward toward warmer waters where they eventually melt.
• However, A23a became caught in a Taylor column, a current that forms around seamounts. 
• The underwater mountain, approximately 62 miles across and rising about 3,280 feet from the sea floor, has created a stagnant cylinder of water above it, slowly rotating the iceberg counterclockwise.

The Impact and Future of A23a

• The duration of A23a’s stay in the vortex is uncertain, but as long as it remains there, it will slowly melt. 
• Despite its size, the iceberg will not contribute significantly to global sea level rise, as it originated from a floating ice shelf. 
• However, if A23a stays in place for an extended period, its melting could impact the marine food chain, particularly plankton and other organisms in the area.
• The phenomenon of Taylor columns and their effects on icebergs is not fully understood, and there is limited data to determine how frequently these currents form or how often icebergs become trapped in them.