A massive 40-year-old iceberg, once the largest on Earth, is currently drifting into the South Atlantic Ocean, where it is expected to gradually melt away. Known as A-23a, this iceberg broke off from Antarctica back in 1986 and has been a subject of interest for scientists ever since. However, it has recently garnered worldwide attention due to its striking blue appearance as captured in NASA satellite images shortly after the Christmas period.
A-23a, originating from Antarctica’s Filchner Ice Shelf, initially broke away as a 4,000 square-kilometer tabular iceberg equivalent in size to Rhode Island and weighing over one trillion tonnes. Despite remaining stuck in the Weddell Sea until 2020, the iceberg has since embarked on a journey northward along the Antarctic peninsula, currently floating near South Georgia island. Its size has significantly decreased, now measuring approximately 781 square kilometers, following calving events in warmer waters.
According to retired scientist Chris Schuman, it is unlikely that A-23a will survive the Southern Hemisphere’s summer. The vibrant blue hues observed on the iceberg’s surface are believed to be caused by accumulating meltwater, indicative of its deteriorating state. This phenomenon, as explained by experts, results from the interaction of water weight within ice cracks, gradually splitting the iceberg apart.
While blue and white are common iceberg colors, other hues like green, yellow, and even black have also been observed in ice formations. The green tint seen in some icebergs is attributed to the reflection of phytoplankton colors in the surrounding water. Yellow icebergs, on the other hand, likely acquire their hue from iron oxide-rich dust picked up during glacial movements over Antarctica’s bedrock.
As icebergs drift further away from Antarctica into warmer waters, they face disintegration in what is known as the “iceberg graveyard.” The Weddell Sea gyre, a clockwise current, facilitates the movement of icebergs towards regions like the Scotia Sea and the Drake Passage, where the warmer waters accelerate the melting process. A-23a’s current location, around 54 degrees south latitude, places it within the perilous zone where icebergs typically meet their end.
Recent satellite observations indicate significant ice calving events on A-23a, signaling its ongoing disintegration as it navigates through warmer waters. The lifecycle of icebergs, exemplified by A-23a’s journey, underscores the inevitable fate these massive ice structures face as they drift away from their Antarctic origins.