The colossal iceberg A23a, a frozen titan over five times the size of New York City, has been caught in a massive whirlpool and may remain trapped there for years.
Iceberg A23a, spanning about 4,248 square kilometers, is slightly larger than the state of Rhode Island and dwarfs New York City by fivefold. This mammoth iceberg broke away from Antarctica’s Filchner-Ronne Ice Shelf in 1986 but became lodged in the Weddell Sea after grounding on the seafloor. It finally drifted away from the icy continent in 2020, as reported by Newsweek.
Instead of heading towards the warmer waters of the South Atlantic via the Antarctic Circumpolar Current, A23a is now ensnared in a swirling ocean current known as the Taylor Column. Currently situated north of the uninhabited South Orkney Islands, this behemoth rotates counterclockwise at about 15 degrees per day. Consequently, rather than slowly melting as anticipated, this giant iceberg could endure until it escapes the grip of the Taylor Column. “A23a is the iceberg that refuses to die,” remarks polar expert and Open University professor Mark Brandon.
The Taylor Column phenomenon occurs when a fluid, such as ocean water, flows over a submerged object, creating a rotating system similar to Earth’s own rotation. In this case, the whirlpool results from a seabed protrusion known as the Pirie Bank. Such an obstacle causes the current to split and form a rotating vortex above it, trapping the iceberg in a continuous spin.
According to Mike Meredith, a professor at the British Antarctic Survey, Taylor Columns can also form in the air. They can range from a few centimeters in a lab tank to colossal structures like this one, capable of capturing an entire iceberg.
Currently, A23a has evaded the typical fate of Antarctic icebergs, which is to melt away. Last year, Antarctica experienced its lowest winter sea ice extent on record, falling nearly 1.8 million square kilometers below average. The continent is losing ice at an accelerating pace, with sea ice disappearance increasing sixfold in the 30 years leading up to 2020. Research published in Nature in 2018 revealed that Antarctica lost approximately 3 trillion tons of ice between 1992 and 2017, with the rate of loss surging from 76 billion tons per year before 2012 to 219 billion tons per year in recent years.
The melting of Antarctic ice significantly contributes to global sea level rise, with current estimates attributing 0.4 millimeters of annual sea level increase to Antarctic ice loss alone. Should the West Antarctic Ice Sheet collapse entirely, global sea levels could rise by several meters, impacting coastal communities worldwide.
