Massive iceberg threatens South Georgia's unique ecosystem
The world's largest iceberg, A23a, is dangerously approaching the South Atlantic archipelago, posing a threat to the unique ecosystem, reports Science Alert. The massive block covers an area of about 3,900 square kilometres, making it three times the size of New York City. Its ice cover is up to 300 metres thick in some places, and its mass may reach a trillion tonnes, threatening penguins and seals, among others.
A23a, the gigantic iceberg, is currently about 270 kilometres from South Georgia and the surrounding islands. Its potential grounding could threaten millions of penguins, seals, and unique marine species found nowhere else in the world. This is not the first time a massive iceberg has threatened the natural environment of this region. In 2004, a fragment of another iceberg, A38-B, blocked access to food sources for penguins and seals for several months, putting them at risk of starvation.
The world's largest iceberg A23a
"Icebergs are inherently dangerous. I would be extraordinarily happy if it just completely missed us," said Simon Wallace, captain of the Pharos ship that approached the iceberg, as quoted by Science Alert.
A23a broke off from the Filchner-Ronne Ice Shelf back in 1986, but remained anchored at the bottom of the Weddell Sea for decades. Only gradual melting allowed it to begin its slow journey towards the Southern Ocean in 2020, and in 2023, after years of being trapped by ocean currents, it set out again towards open waters.
The iceberg is drifting in the Antarctic Circumpolar Current. This is a cold ocean current that flows uninterruptedly around Antarctica from west to east. The current is now pushing A23a towards the islands located at the southwestern edge of the Atlantic Ocean. According to scientists' forecasts, A23a is heading towards the so-called "iceberg alley," and if it reaches South Georgia, it could have serious consequences for fisheries and wildlife.
However, the consequences of A23a's melting could be more complex. Previous research suggests that melting glaciers deliver iron to the oceans, which could promote the development of phytoplankton and the absorption of carbon dioxide from the atmosphere.
"We know that these giant icebergs can provide nutrients to the waters they pass through, creating thriving ecosystems in otherwise less productive areas," explained Laura Taylor, a biogeochemist from the British Antarctic Survey, as quoted by Science Alert. "What we don't know is what difference particular icebergs, their scale, and their origins can make to that process."
