The world’s largest iceberg, A23a, has shattered into multiple large fragments after drifting for nearly four decades, scientists confirmed this week. The break-up, reported by the British Antarctic Survey, marks the end of an iconic ice mass that has been closely monitored since it broke off from Antarctica in 1986.
Originally weighing nearly a trillion metric tonnes and covering an area of 3,672 square kilometers, A23a was once comparable in size to Rhode Island. It remained stuck on the sea bed of the Weddell Sea for over 30 years before ocean currents dislodged it in 2020. Earlier this year, it ran aground on the continental shelf near South Georgia Island, raising concerns about potential disruptions to local wildlife, but it floated free again in May.
According to Andrew Meijers, an oceanographer at BAS, the iceberg is now rapidly breaking apart due to exposure to warmer waters in the Southern Antarctic Circumpolar Current Front. Satellite imagery shows large chunks, some as vast as 80 square kilometers, shearing off from the main body. The current size is estimated at 1,700 square kilometers, but it is diminishing quickly.
The disintegration reduces the risk to South Georgia’s ecosystem, which hosts critical populations of penguins, seals, and seabirds. However, the resulting icebergs could pose navigation hazards in a region frequented by ships. The RAF’s Operation Cold Stare has been monitoring the situation to aid maritime safety.
This event is part of a natural cycle of iceberg calving, but it occurs against a backdrop of accelerated ice loss in Antarctica. Human-induced climate change is warming ocean waters and altering currents, leading to increased melting and calving from ice shelves. Antarctica loses approximately 150 billion tonnes of ice annually, contributing to global sea level rise.
A23a’s break-up follows similar fates of other large icebergs like A68 and A76, which also disintegrated around South Georgia. The new largest iceberg, D15a, is currently stationary near the Antarctic coast, but scientists expect more such events as the climate warms.
Research conducted on A23a, including recent samples analyzed in the UK, will provide insights into the ecological impacts of large iceberg meltwater releases. Understanding these processes is crucial for predicting future changes in polar regions and their global implications. The rapid fragmentation of A23a underscores the dynamic and fragile nature of polar ice in a warming world, emphasizing the importance of ongoing scientific observation and climate action.