Iceberg A23a sounds like it should have a vintage horror movie catchphrase like “It came from West Antarctica!” or “Zombie iceberg on the loose!” The veteran iceberg had been quietly minding its own business since it first broke off from an Antarctic ice shelf in 1986. It spent decades stuck in one place, but now A23a is on the move and satellites are tracking its journey.
A series of satellite images from the European Space Agency’s Copernicus Sentinel-1 mission traces the iceberg’s movements from November 2 to November 26.
The berg seems to be in a hurry. ESA said it “has put a spurt on and is heading quickly away from Antarctic waters.” That pep in its step is due to winds and currents pushing it along.
Just how big is A23a? With an area of about 1,550 square miles, it’s four times the size of New York City or roughly the size of the Hawaiian island of Oahu. The iceberg’s official moniker comes from a naming system that involves the Antarctic quadrant it came from followed by a sequential number. The big “A” designates the Bellingshausen/Weddell Sea area. The little “a” at the end is added when an iceberg breaks apart and the pieces get sequential letters.
A23a is imposing, but it doesn’t pose a threat to humanity. The iceberg’s great escape traces to 2020 when it began to lose its connection to the seafloor. No longer anchored, the icy chunk began to move in the Weddell Sea along northwest Antarctica. “Scientists say that it is not unusual for icebergs to become grounded, but over time they shrink enough to unground and float,” said ESA. A23a was just a late bloomer.
The National Oceanic and Atmospheric Administration is also keeping a space eye on the iceberg. The NOAA-20 weather satellite captured a scenic view of A23a drifting in the Southern Ocean north of Antarctica. The agency shared the image on X on Friday.
Iceberg A23a will likely end up in the South Atlantic Ocean, said ESA. That would put it in a region known as “Iceberg Alley.” Many icebergs from the Weddell Sea float there, where warmer waters peck away at their bodies. Some large icebergs persist for quite a while, as with infamous berg A68a. A68a was seen as a threat to sensitive wildlife on South Georgia Island in 2020. That iceberg eventually shattered without damaging the ecosystem. Satellites helped track the movements and eventual demise of A68a, just as they are doing now with A23a.
A23a is currently recognized by Guinness World Records as the largest iceberg on the planet. The big berg won’t reign forever. “The record for the largest current iceberg changes hands most years, as new icebergs are calved off the Antarctic continent and subsequently break into smaller fragments,” said Guinness. A23a last held the title in early 2021, but was eclipsed by a bigger berg named A76. A76 later broke up into pieces, a common fate for an iceberg. That may be the ending that awaits A23a after decades of treading water. Until then, it will hold court on the ocean as one of Earth’s natural wonders.
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