Icebergs are endlessly breaking off the Antarctic ice cap and drifting away, but the impact of climate change means this is now happening much more frequently – with larger icebergs than ever before.
A gigantic sheet of ice is currently heading in the direction of South Georgia. Iceberg A23a broke off the Filchner ice sheet in the Weddell Sea in 1986, where it remained stuck to the bottom of the shallow sea for decades – until it began to drift away in 2020.
It travelled for several years aimlessly, before setting a more direct course towards the southern coast of South Georgia, a remote island in the South Atlantic Ocean.
Scientists are closely monitoring the iceberg's progress, not least because South Georgia is an important breeding ground for colonies of penguins, seals and albatrosses.
If the iceberg collided with the island, it could block many animals' access to breeding grounds and foraging waters. Fortunately, this is unlikely to happen, because the island is surrounded by a broad strip of shallow waters – so the iceberg would likely run aground when it approached.
If the iceberg did in fact run aground, this may help the colonies (such as king penguins) living here, as there would be more food in the currents travelling around the iceberg.
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Ice caps grow as snow falls on top of them and gravity pulls them towards the sea. It is here that they lose large volumes of ice as the caps melt. If the ice cap growth continues at the same pace as the loss at the edges, they remain the same size – but as the air and ocean around the south pole have warmed due to climate change, icebergs have been calving off faster and with greater frequency. As the snow on top melts, the ice is weakened. The warmer oceans are also making the ice shelves thinner below. This creates a perfect storm for massive ice blocks to break off from the ice caps.
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The seas around South Georgia have long been assessed as part of iceberg research. Since Antarctica has had a large ice cap for around 34 million years, the island of South Orkney (which lies to the southwest of South Georgia) has witnessed many icebergs pass by. Researchers have even called the waters around it 'Iceberg Alley'.
This week, a new iceberg was discovered drifting about 250km from its point of origin along the base of the Antarctic Peninsula, ricocheting off parts of the coastline. The berg is about 30km long and 17km wide.
Find out more about the recent discoveries around the trajectory of Iceberg A23a in this paper by Utrecht University's Mark Elbertsen.
Main image: A23a, the world's largest iceberg/credit: Getty Images
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