The world's largest iceberg washed up in the clear waters of the Southern Ocean (7 photos + 2 videos)
Iceberg A23a with an area of 4,170 sq. km, which broke away from the Filchner ice shelf back in 1986, “woke up” and began to move only this spring. Now, as a result of drift, it has been carried out into the open space of the Southern Ocean. Scientists claim that an ice block the size of Moscow and St. Petersburg combined will one way or another cease to exist, but there are two options for the development of events. 
The first option is that iceberg A23a will soon (several months) reach the Scotia Sea (Scotia), where it will soon melt. The second option is that it will remain in the Weddell Gyre system and will drift for several more years. 
The Antarctic Circumpolar Current is a loop of cold ocean waters up to 30,000 km long that flows around Antarctica
The Weddell Gyre is one of two gyres that exist in the Southern Ocean. It is formed as a result of the interaction of the cold Antarctic Circumpolar Current and the Antarctic continental shelf. 
It is specified that since spring, after the start of active drift along the coast of the Antarctic Peninsula at a speed of 150 km per month, iceberg A23a has covered over 2 thousand km. However, its area remained virtually unchanged. 
Photo from November 15, 2023. Iceberg A23a - in the upper right part, shaped like a tooth
At the moment, A23a is the record holder among icebergs. Before it, the largest iceberg in the world was A76 - before it split into three parts. Large objects such as A23a need to be constantly monitored after liftoff as they can pose a threat to vessels as well as wildlife.
Unlike many large icebergs that break away from Antarctica and float away, A23a has moved only a couple of hundred kilometers since breaking off from the Filchner Ice Shelf in August 1986.
The lack of movement is explained by the fact that it "landed" (or stuck) on the seabed. Icebergs "sit" on the ocean floor when their keel - the part below the surface of the water - is deeper than the depth of the water. However, now a huge iceberg has broken free.
Dr Andrew Fleming, a remote sensing expert from the British Antarctic Survey, told the BBC that he noticed the first signs of movement of iceberg A23a back in 2020.
“It had been stranded since 1986, but eventually it would have shrunk enough in size to lose traction and start moving. We wondered if changing shelf water temperatures could have triggered this, but the general consensus is that it was just time."
There are several ice shelves in Antarctica, marked on this map: Filchner, Shackleton, Ross, etc. The Filchner Shelf is located east of the Antarctic Peninsula (the part that sticks out from the mainland of Antarctica like a small tail).
A23a left the Filchner Ice Shelf in September 1986 and ran aground in the southern Weddell Sea in November 1991. Three decades later, he began to move north.
The previous record holder was A76, which broke off from an ice shelf in the Weddell Sea in May 2021, but it has since split into three pieces.
Record-breaking icebergs replace each other regularly as more and more blocks of ice break off from the Antarctic continent and subsequently break into smaller fragments.
According to the Guinness Book of Records, the largest iceberg in history exceeded 31,000 square meters. km.
This iceberg was spotted 240 km west of Scott Island in the Southern Ocean by the USS Glacier on November 12, 1956.
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