A23a, the world’s largest and oldest iceberg, has spent most of the past year stuck in one spot, spinning slowly in a circle. Now, just in time for the New Year, it’s gotten its act together and is once again on the move. This is a natural and observable scientific phenomenon and totally not a metaphor for your life.
The mega-berg, which has been rotating about 15 degrees per day just north of the South Orkney Islands since May 2024, has broken free of the Taylor column that held it in place and is moving inexorably towards its eventual destruction in warmer waters.
A Taylor column is a column of water rotating above an underwater mountain and which traps objects on the surface in place. A23a fell into such a trap early last year. Before that, A23a was part of Antarctica’s Filchner Ice Shelf.
It calved from the shelf in 1986 and grounded in shallow water in the Weddell Sea shortly thereafter. Finally breaking free from the ocean floor in 2020, A23a drifted around for several years before heading northward. But the Taylor column caught it, and it’s been slowly completing one rotation every 24 days since. Until mid-December, that is, when scientists noticed it had at last broken its watery shackles.
“It’s exciting to see A23a on the move again,” Dr. Andrew Meijers, an oceanographer at the British Antarctic Survey (BAS). “We are interested to see if it will take the same route [as] the other large icebergs that have calved off Antarctica.”
Depending on how you like to measure your icebergs, A23a spans an area about the size of one Rhode Island, two Londons, or 35,893,440 average-sized sheep standing shoulder to shoulder and snout to tail. Approximately.
