The world's largest iceberg, as big as Greater London, has been recorded via NASA satellite images executing a pirouette on its route to the Southern Ocean. A23a, a tooth-shaped iceberg has twirled over 360 degrees between December and February near the Antarctic Peninsula.

(Photo : Wikimedia Commons/MODIS Land Rapid Response Team, NASA GSFC)
Iceberg A23a

World's Largest Iceberg Ventures Northward

The British Antarctic Survey (BAS), which examined A23a in December, reported the enormous iceberg is progressing northward at a rate of approximately 30 miles per day.

 
Presently situated between Elephant Island and the South Orkney Islands, A23a is concealed by the South Scotia Ridge in satellite imagery. As it moves forward, it is anticipated to enter the Antarctic Circumpolar Current, where strong westerly winds are expected to propel it northeastward.

This marks its course through 'Iceberg Alley,' a common path leading towards South Georgia, a sub-Antarctic island. The BAS shared an animation on social media, illustrating the iceberg's movements as part of its gradual journey into warmer waters, emphasizing its colossal size, comparable to Cornwall or Rhode Island.

EYOS Expeditions, on-site in January, used a drone to capture aerial images, showcasing the iceberg's immense scale. According to videographer Richard Sidey, A23a is "mind-bogglingly big" and extends as far as the eye can see.

Originating from a 1986 break in an Antarctic ice shelf, A23a had been stationary for three decades after moving a short distance. Recently set free, it is estimated to cover 1,500 square miles, with a volume of 263 cubic miles and a mass of nearly one trillion tonnes, surpassing the size and weight of landmarks such as Greater London or the Eiffel Tower. Scientists revealed its renewed movement in November, propelled northward by wind and ocean currents.

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Waves Breaking of 'Bergy Bits' Off A23a

A23a's precise course will be influenced by the interplay of winds, ocean fronts, and eddies in the upcoming weeks. Many of these massive tabular icebergs typically pass close to the British Overseas Territory of South Georgia, as observed in recent close-up photographs depicting the iceberg's gradual deterioration. Erosion and the breaking off of sections, forming smaller "bergy bits" and "growlers," are evident at the iceberg's edges.

Although A23a currently spans an area of approximately 3,800 sq km (1,470 sq miles), the processes of erosion and melting will accelerate as it journeys further into warmer and rougher waters. Certain sections of the iceberg are already breaking off due to these natural processes.

Similar to coastal erosion on land, waves impact the iceberg, creating gaps that grow over time until the upper part collapses. This results in smaller formations called "stacks," which eventually transform into "stumps" before completely melting away. Despite its substantial size, the melting process will inevitably lead to the eventual loss of A23a, although the timeline for this process is extensive.

As A23a moves north, the risk of disrupting wildlife, especially around South Georgia, looms. If not sufficiently melted upon reaching the island, the massive iceberg may interfere with wildlife, like penguins, depending on its path. 

BAS acknowledges the potential impact, underscoring the iceberg's trajectory's significance. While A23a currently holds the title of the world's largest iceberg, this distinction is temporary, as all icebergs eventually fragment. A76, the former record holder, separated from the Weddell Sea ice shelf in May 2021 and subsequently fragmented into three pieces.



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