A23a, the world’s largest iceberg, has baffled scientists by getting trapped in a spinning vortex just north of Antarctica, instead of drifting away as expected. This iceberg, larger than Greater London, was supposed to be racing north in the powerful Antarctic Circumpolar Current, but instead, it’s caught in a giant rotating water column called a Taylor Column, causing it to spin in place and delay its melt. This unusual phenomenon, discovered in the 1920s, is keeping A23a from breaking apart or moving, making it the iceberg that just won’t quit!
This unusual event is known as a Taylor Column, named after the physicist Sir G.I. (Geoffrey Ingram) Taylor who first described it in the 1920s. Taylor Columns can trap objects in their swirling waters for a long time, and A23a might be stuck for years to come.
Professor Mark Brandon, an expert on polar ice, pointed out how unusual this is. Normally, icebergs break apart or melt away over time, but A23a seems to defy this pattern. It’s like the iceberg that just won’t go away, according to Brandon.
A23a has a long history. It broke off from the Antarctic ice shelf in 1986 and got stuck in the Weddell Sea, remaining almost stationary for 30 years. It wasn’t until 2020 that it started drifting again, heading north towards warmer waters.
In April of this year, A23a entered the Antarctic Circumpolar Current (ACC), one of the strongest ocean currents on Earth. Scientists expected this current to push A23a quickly towards warmer regions, but instead, the iceberg has stayed put, slowly spinning in a counter-clockwise direction each day.
The iceberg isn’t stuck on the seafloor—there are about 1,000 meters of water underneath it. Instead, it’s caught in a Taylor Column caused by an underwater bump known as Pirie Bank. The current meeting this bump creates a swirling column of water, trapping A23a in its place.
Professor Mike Meredith from the British Antarctic Survey finds this phenomenon fascinating. Taylor Columns can occur in the air too, like in the swirling patterns of clouds over mountains. This iceberg’s spinning routine is an extraordinary example of how ocean currents and seafloor features interact.
How long A23a will continue to spin is uncertain. In similar situations, scientists have seen floating instruments remain trapped in these columns for years. Understanding the ocean’s seafloor and these swirling columns is important because they affect water movement, nutrient distribution, and climate systems. Currently, only a small fraction of the world’s seafloor is mapped in detail, so there’s much more to discover about these hidden ocean features.
