Iceberg A23a trapped by vortex, defying rapid melting predictions

The world's largest iceberg, A23a, is stuck in a trap where it may remain for several years, thus avoiding rapid melting. According to the BBC, scientists have observed that A23a has been rotating in place north of Antarctica for months instead of drifting with the ocean current. The phenomenon known as the Taylor column causes this unusual behaviour.

“A23a is an iceberg that simply refuses to die,” Professor Mark Brandon told the BBC, pointing out the unusual fate of the enormous ice mass with a surface area of 3,600 square kilometres and a mass of nearly a trillion tonnes. The iceberg, which broke off from the Filchner-Ronne Ice Shelf in West Antarctica in 1986, was trapped on the shallows of the Weddell Sea for years. It only began to drift north toward warmer waters in 2020 slowly.

A23a's journey picked up pace in April 2023 when the iceberg entered the Antarctic Circumpolar Current. This cold, fast-moving ocean current flows uninterrupted from west to east around Antarctica. Scientists predicted that it would push A23a towards the South Orkney Islands, located at the southwest edge of the Atlantic Ocean.

Experts also expected that the enormous ice mass, fragmented by warmer air and surface waters, would disappear within a few months, sharing the fate of other icebergs that have broken off Antarctica. However, this did not happen. According to researchers, A23a has become trapped in a state that may last for several years.

According to the BBC, the so-called Taylor column has stopped it. A Taylor column is a type of vortex from which objects find it difficult to free themselves. In the case of A23a, the iceberg is rotating in place, counterclockwise, at around 15 degrees per day. It is unknown how long it will remain in this state.