A massive iceberg, known as A-23a, which once held the title of the largest iceberg on Earth, is currently drifting into the South Atlantic Ocean, where it is expected to gradually melt away. This iceberg, which broke off from Antarctica back in 1986, has been a subject of scientific interest for several years. Recently, attention has been drawn to A-23a due to its stunning blue pattern visible in NASA satellite images taken just after Christmas. The vibrant blue color is a telltale sign that the iceberg is nearing the end of its journey as it traverses the “iceberg graveyard,” located approximately 2,800 kilometers from its original calving point.
Originally part of Antarctica’s Filchner Ice Shelf, A-23a split off in 1986, forming a colossal tabular iceberg that was comparable in size to Rhode Island and weighed over one trillion tonnes. Despite being initially stuck in the Weddell Sea for a significant period, the iceberg began moving north along the Antarctic peninsula in 2020. Currently, it is drifting close to South Georgia island and has significantly decreased in size, now measuring about 781 square kilometers as reported by the U.S. National Ice Centre.
According to retired scientist Chris Schuman, A-23a’s chances of surviving the Southern Hemisphere’s summer are slim. The striking blue patches on the iceberg’s surface are likely a result of accumulating meltwater that is gradually fracturing the ice. The blue streaks are believed to be caused by parallel ridges that direct the flow of meltwater on the ice, as explained by National Snow and Ice Data Centre senior research scientist Walt Meier.
While blue and white are common colors observed on icebergs, researchers have also noted icebergs displaying shades of green, yellow, and even black. The green tint seen on some icebergs in the Weddell Sea may be attributed to the reflection of phytoplankton colors in the water. Yellow icebergs, on the other hand, could be due to dust rich in iron oxide picked up from Antarctica’s bedrock during glacial movement.
As icebergs like A-23a move away from Antarctica into warmer waters, they eventually disintegrate in what is known as the “iceberg graveyard.” The Weddell Sea gyre plays a crucial role in pulling icebergs northward and into regions like the Scotia Sea and the Drake Passage, where warmer waters hasten their demise. The NASA Earth Observatory has highlighted that water temperatures around 54 degrees south, where A-23a is located, are particularly hazardous for icebergs.
Recent satellite imagery shows a significant portion of A-23a breaking off, signaling its ongoing disintegration process. As A-23a continues its journey towards warmer waters, its fate in the “iceberg graveyard” seems inevitable.
