40 years ago, Iceberg A23-A was the largest iceberg in the world–twice the size of Greater London as a matter of fact. Today, it’s noticeably smaller being around but still larger than New York City.
The year is 1986. The infamous Chernobyl accident happened. Whitney Houston won her first Grammy. Ronald Reagan was President of the United States of America. The Filchner Ice Shelf, a ginormous piece of ice extending off the Antarctic continent into the Weddell Sea, was changing in a big way. One of the icebergs that broke off; A23-A was roughly 4,000 square kilometers big(around 1,540 square miles). After the iceberg detached from Antarctica, it would float around and remain stuck in the Weddell sea for over 30 years.
In 2020, scientists noticed that A23-A would start to get bored of its resting place and set off in search of a new horizon. However, what they didn’t know was how restless this iceberg had become–it would end up travelling across the South Atlantic Ocean.
What’s fascinating for scientists is how unpredictable Iceberg A23-A’s journey continues to be. For context, at the start of 2025, A23-A was still ginormous relative to its current size. For some visual reference, it would have stretched between the Isle of Wight and Normandy. Today, its size pales in comparison, merely stretching not even halfway between Dover to Calais.
The calving (when an iceberg breaks off) and melting of large icebergs in a natural phenomenon and isn’t necessarily directly a result of climate change; however, it is important to note that Antarctica is clearly losing mass faster than it can be replenished. Due to A23-A continuing to move further north into warmer waters as well as hydrofracturing lately (when heavy water sits on top of an iceberg and wants to move downwards), scientists don’t expect A23-A to be around much longer.
Despite the imminent demise of A23-A, scientists are grateful for the opportunity they’ve had to track it over the past 40 years. There have likely been icebergs that have had longer lives; however, A23-A is thought to be the oldest iceberg still alive today. Today, A23-A sits at about 80% smaller than it’s original size.
