A23a: World's Largest Iceberg Has Been Spinning In One Place For Eight Months
The iceberg broke free from the Antarctic coastline in 1986 but got stuck in the bottom-muds of the Weddell Sea, according to the report.
In a remarkable phenomenon that has piqued the interest of the scientific community, the world's largest iceberg, A23a has been spinning on one spot near Antarctica for the last eight months instead of racing along with Earth's most powerful current.
Scientists say the frozen block, which is more than twice the size of Greater London (3,600 sq km), has been captured on top of a huge rotating cylinder of water.
It's a phenomenon oceanographers call a Taylor Column - and it's possible A23a might not escape its jailer for years, BBC News reported.
"Usually you think of icebergs as being transient things; they fragment and melt away. But not this one," observed polar expert Prof Mark Brandon.
"A23a is the iceberg that just refuses to die," the Open University researcher told BBC News.
In One Place for Three Decades
The iceberg broke free from the Antarctic coastline in 1986 but got stuck in the bottom-muds of the Weddell Sea, according to the report.
For three decades it was a static "ice island". However, in 2020 it started moving again, slowly at first, before accelerating its speed northward, towards warmer air and waters.
The Berg That Won't Move
In early April this year, A23a floated into the Antarctic Circumpolar Current (ACC) - a juggernaut that moves a hundred times as much water around the globe as all Earth's rivers combined, the BBC News report stated.
This was expected to rev up the near-trillion-tonne berg’s movement into the South Atlantic and eventual demise.
Instead, A23a went precisely nowhere. It remains in place just north of South Orkney Islands, turning in an anti-clockwise direction by about 15 degrees a day. And as long as it does this, its decay and end will be delayed.
What Is Stopping A23a?
It has been stopped in its tracks by a type of vortex, first described in the 1920s by a brilliant physicist, Sir G.I. (Geoffrey Ingram) Taylor, and named the Taylor Column after him.
Prof Taylor demonstrated how a current that meets an obstruction on the seafloor can - under the right circumstances - separate into two distinct flows, generating a full-depth mass of rotating water between them.
In this instance, the obstruction is a 100km-wide bump on the ocean bottom known as Pirie Bank. The vortex sits on top of the bank, and for now A23a is its prisoner, the BBC News reported.
No one can predict how long A23a will continue to perform its spinning-top routine.
