World's biggest iceberg spins in ocean trap

A23a, the world's largest iceberg, has been spinning in place just north of Antarctica for several months, trapped in a phenomenon known as a Taylor Column. This iceberg, which is over twice the size of Greater London, has been unable to move despite being in the Antarctic Circumpolar Current, which typically propels icebergs toward warmer waters. Instead, A23a remains stationary, rotating anti-clockwise about 15 degrees a day. It has not grounded again, as there is at least a thousand meters of water beneath it.

A23a broke free from the Antarctic coastline in 1986 but became stuck in the Weddell Sea for three decades before re-floating in 2020. The iceberg's current predicament is due to a vortex created by an underwater feature known as Pirie Bank, which has trapped it in a rotating mass of water. Scientists note that A23a's behavior highlights the significance of understanding seafloor topography, which influences ocean currents and nutrient distribution, impacting the climate system.

The longevity of A23a is unusual for icebergs, which typically fragment and melt away. Its continued spinning may delay its decay, and researchers are uncertain how long this phenomenon will last. The study of such icebergs is crucial for understanding ocean dynamics and climate change, as only a quarter of the Earth's seafloor has been mapped to modern standards.