A massive iceberg, once the world’s largest, is on a journey toward its end in the South Atlantic Ocean. Known as A-23a, this iceberg broke off from Antarctica in 1986, grabbing scientists’ attention. Recently, NASA satellite images revealed its striking blue pattern as it floats through the “iceberg graveyard” thousands of kilometers away from its origin.
Originally part of Antarctica’s Filchner Ice Shelf, A-23a calved into a tabular iceberg in 1986, resembling the size of Rhode Island and weighing over a trillion tonnes. After remaining stuck in the Weddell Sea until 2020, it began its northward drift along the Antarctic peninsula, now near South Georgia island. The iceberg has considerably reduced in size to around 781 square kilometers, with parts calving in warmer waters.
Experts believe that A-23a is approaching its demise, especially during the Southern Hemisphere’s summer. The iceberg’s captivating blue coloration is attributed to meltwater accumulating on its surface, gradually breaking it apart. This phenomenon, caused by the flow of meltwater within ice cracks, creates distinctive striations that guide the water movement.
While the sight of white and blue icebergs is familiar, some icebergs in the Weddell Sea have displayed vibrant emerald or jade hues. This coloration may result from ice reflecting the color of phytoplankton in the water or iron oxide-rich dust picked up from Antarctica’s bedrock. In rare cases, icebergs have appeared yellow due to specific light filtration processes.
As icebergs move away from Antarctica into warmer waters, they enter the “iceberg graveyard,” where they begin disintegrating. The Weddell Sea gyre’s clockwise current pulls icebergs northward into the Scotia Sea and the Drake Passage, leading to their gradual demise. A-23a, located at about 54 degrees south latitude, is now at risk due to the warmer waters in the region.
Observations show parts of A-23a breaking off, indicating its ongoing disintegration. This process is expected to continue as the iceberg navigates further into the South Atlantic.