Mega Iceberg Weighing 1,000,000,000 Tonnes & Twice The Size Of London Heading Straight For a British Island
An enormous iceberg twice the size of Greater London, known as A23a, is drifting ominously towards the remote British island of South Georgia in the South Atlantic Ocean. Often referred to as a ‘megaberg,’ it is the largest iceberg currently in existence, weighing a staggering one trillion tonnes. This icy behemoth poses potential dangers, not to the island’s tiny human population of around 30 to 40 residents, but to its rich biodiversity, including penguins and seals.
Titanic Journey Through Time and Waters
A23a first separated from Antarctica back in 1986, breaking free from the Filchner-Ronne Ice Shelf. For decades, this massive iceberg remained stuck in the Weddell Sea due to its sheer size, essentially becoming a stationary part of its frozen surroundings. However, in 2020, the iceberg became unanchored from the seabed and began moving freely through the ocean.
Its progress was temporarily halted in 2024 when it became trapped in a phenomenon called a ‘Taylor Column.’ This vortex of rotating water essentially left A23a swirling in place for months. However, the iceberg has since freed itself from this watery prison and is currently on a collision course with South Georgia.
A Threat to Wildlife
While the sparsely populated island might remain physically intact, A23a poses a significant danger to the area’s wildlife as it drifts closer. South Georgia is home to millions of penguins, seals, and other marine species, whose survival depends on unhindered access to feeding grounds.
British Antarctic Survey physical oceanographer Andrew Meijer has expressed concerns about the iceberg’s potential impact, stating that “A23a could dramatically increase mortality rates among penguins” by blocking key foraging routes in the shallow waters near the island. Meijer, who observed the iceberg in 2023 from the RRS Sir David Attenborough, dramatically described it as “a Game of Thrones-style wall of ice that towers above the ship.”
For penguins, whose survival hinges on efficiently feeding their chicks, a detour around the massive ice block would expend additional energy and mean less food for their offspring. This could have devastating consequences for the island’s ecosystem, which is already vulnerable to climate change.
Meltdown in Warmer Waters
However, the iceberg’s march northward spells more than ecological disruption—it also heralds its eventual demise. As it drifts into warmer waters, the melting of A23a is accelerating. Initially measuring a colossal 1,500 square miles, the iceberg has already shrunk to approximately 1,350 square miles, as satellite images reveal.
According to oceanographic studies, large icebergs like A23a typically generate significant freshwater input as they melt, which disrupts local salinity levels in the surrounding ocean. This freshwater dilution could impact marine currents and ecosystems around South Georgia.
Scientists predict that A23a will continue to break apart into smaller fragments. While smaller pieces may not seem as imposing, they can still obstruct shipping lanes and threaten local wildlife due to their unpredictable nature.
Under Close Watch
The iceberg’s approach is being closely monitored via satellite by research teams worldwide, including the British Antarctic Survey and NASA. Per reports released on January 23, A23a is approximately 173 miles away from South Georgia. Dr. Peter Fretwell from the British Antarctic Survey told The Guardian that scientists are less concerned about the iceberg hitting the island directly and more alarmed about it getting lodged on the seafloor near shallow waters. “The iceberg, if grounded, could stay in place for years, impacting wildlife on an ongoing basis,” he warned.
Looking Ahead
Beyond its immediate threat to South Georgia’s ecosystem, A23a offers a stark reminder of the increasing effects of climate change. Antarctica has been losing an estimated 150 billion metric tons of ice annually since the early 2000s, according to NASA. These losses not only contribute to rising sea levels but also set massive icebergs like A23a adrift, creating complex risks for marine life and human economies alike.
While all eyes are on South Georgia for now, the global community has an opportunity to study A23a’s trajectory and impact as a harbinger of broader environmental challenges.
