Antarctica’s Giant Iceberg Is Cracking — a 19 km Chunk Broke Off

A massive iceberg called A23a — about 3,360 square kilometers and roughly a trillion tons — has stayed largely intact since 2020 while slowly drifting north. It is now heading toward the remote island of South Georgia in the South Atlantic, raising concerns among researchers because it could threaten the island’s penguin and seal populations. Recently, a roughly 19-kilometer-long piece broke off from the iceberg, Andrew Meyers of the British Antarctic Survey reported; Meyers began tracking the iceberg by satellite in 2023. Glaciologist Soledad Tiranti, who is part of the Argentine Antarctic expedition, also shared the news. Science Alert estimated the jagged fragment’s area at about 80 square kilometers — a small portion of what remains.

What You Need to Know About Iceberg A23a

Known as A23a, the iceberg is the largest and oldest in the world; it calved from the Antarctic shelf in 1986. It remained trapped in ice for more than 30 years before finally breaking free in 2020. Its awkward journey north has sometimes been stalled by ocean forces that caused it to rotate in place. The berg has been carried by the Antarctic Circumpolar Current, the planet’s strongest ocean current. Meyers said that although this “monumental specimen” has shrunk over time and lost mass, it still remains relatively intact. He added that other mega icebergs in the past disintegrated “quickly, within a few weeks” once they started losing large chunks. “It’s very hard to say whether it will break apart right now or hold on for a while longer,” Meyers said. He also pointed out that losing this section is unlikely to change A23a’s trajectory toward South Georgia, a crucial feeding ground for seals and penguins.

If the iceberg keeps fragmenting, it would pose “significantly less of a threat to wildlife,” Meyers said. Animals searching for food could navigate more easily among the smaller ice chunks, the scientist added. Soledad Tiranti expects the iceberg to continue moving north, but A23a’s exact course will depend on how local currents influence its movement.