Scientists have announced that the world’s largest iceberg, A23a, has started moving for the first time in over three decades. The colossal Antarctic iceberg, spanning almost 4,000 square kilometers (1,500 square miles) and weighing nearly a trillion metric tonnes, is currently drifting past the northern tip of the Antarctic Peninsula.
Since calving off West Antarctica’s Filchner-Ronne Ice Shelf in 1986, A23a has been mostly stranded after its base became stuck on the floor of the Weddell Sea. However, recent satellite images reveal that strong winds and currents have set the iceberg into motion.
British Antarctic Survey glaciologist Oliver Marsh expressed the rarity of witnessing an iceberg of this size on the move and emphasized that scientists will be closely monitoring its trajectory. As A23a gains momentum, it is expected to be propelled into the Antarctic Circumpolar Current, directing it toward the Southern Ocean along a path known as “iceberg alley,” where similar icebergs are commonly found.
The reason behind the iceberg’s sudden movement remains unclear. Marsh suggests that over time, A23a may have slightly thinned, gaining the necessary buoyancy to lift off the ocean floor and be carried by ocean currents. Notably, A23a is one of the world’s oldest icebergs.
There is speculation that A23a could again become grounded, potentially at South Georgia island, posing a threat to the region’s rich wildlife. The island is home to millions of seals, penguins, and seabirds that breed and forage in the surrounding waters. The colossal iceberg could potentially cut off access to essential feeding grounds.
In 2020, a similar scenario unfolded with another giant iceberg, A68, raising concerns about a collision with South Georgia. Fortunately, A68 broke up into smaller pieces, averting a catastrophe. Scientists believe a similar fate could await A23a.
Despite the warmer conditions in the Southern Ocean, Marsh warns that an iceberg of this scale has the potential to survive for an extended period. There is a possibility that A23a could make its way farther north, posing a disruption to shipping routes near South Africa.
The international scientific community is now closely monitoring the unprecedented movement of A23a, with potential implications for the delicate ecosystem of the Antarctic region.
