
Iceberg loses world's biggest title claim after 80 per cent ice loss
An iceberg that was once labelled as the biggest in the world has been breaking apart in the Southern Ocean--to such an extent that it no longer holds that title, according to the Cooperative Institute for Research in the Atmosphere (CIRA) and the British Antarctic Survey (BAS).
Leaders often lose their position at the top, and that doesn't just apply to sports, weather, military or government.
In this case, it refers to an iceberg called A23a. The massive 'berg was once roughly the size of Rhode Island, accumulating a weight of close to one trillion metric tonnes, holding the title of the world's biggest slab of ice for most of its time since first breaking off of Antarctica's Filchner-Ronne Ice Shelf in 1986.
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However, that is no longer the case. According to a new report from the British Antarctic Survey (BAS), A23a has undergone significant shrinkage in recent months--losing about 80 per cent of its mass since May, scientists with the organization said.
“The iceberg is rapidly breaking up, and shedding very large chunks, themselves designated large icebergs by the U.S. National Ice Center that tracks these," Andrew Meijers, an oceanographer at BAS, told CNN in an email last week.

Iceberg A23a no longer holds the distinction of being the world's largest. (Getty Images/Juergen Brand/1942436797-170667a)
Losing size at a rapid pace since May
According to CNN, A23a carried a weight of close to one trillion metric tonnes in January, measuring 3,672 square kilometres. Fast forward to September, and the mega-sized iceberg has been dethroned from its No. 1 status as the world's largest. It now measures just 1,700 square kilometres, or roughly 20 per cent of its original size from the beginning of the year.
A23a, or the "megaberg" as it was once called, has been quickly falling apart since it became lodged in a current flowing counterclockwise around South Georgia Island in the South Atlantic Ocean.
Scientists have been closely monitoring A23a since the detachment of it from the Filchner-Ronne Ice Shelf in Antarctica 39 years ago.
Also given the moniker of the "queen of icebergs," A23a first split away from Antarctica's Filchner-Ronne Ice Shelf, adjacent to the Weddell Sea in 1986. Shortly after breaking away, the iceberg ran aground, becoming entangled in the seabed in the Weddell Sea for more than three decades. It then earned the biggest iceberg in the world title for years to come.
Which iceberg is now the world's largest?
A23a's most-recent reign at the top wasn't the only time it was considered to be the world's largest iceberg. When it wasn't the largest in the world since the 1980s, A23a was behind, for a short time, A68 from 2017 to 2020, and A76 in 2021.
Meijers said A23a is encountering a "similar fate" as other megabergs, including A68 in 2021 and A76 in 2023, which also apart near South Georgia in the southern end of the Atlantic Ocean. However, A23a has stayed together as a single ice slab for longer than A68 and A76.
And the shrinkage of A23a means the new titleholder for the globe's largest iceberg is D15a, which measures around 3,000 square kilometres. According to Meijers, D15a is “fairly static on the Antarctic coast near the Australian Davis base.”
While A23a is still holding on to the world’s second-largest iceberg position, the BAS oceanographer said that status will likely “rapidly change” as it continues to “fragment in the coming weeks.” He noted that warmer water temperatures and the forthcoming southern spring will likely lead to it crumbling into “bergs too small to track further."
Antarctic ice vulnerable to climate change effects
Antarctic ice is increasingly vulnerable to warming ocean waters and changing weather patterns, and for some time, scientists have been raising the alarm regarding the amount of ice being lost from western Antarctica.

Iceberg A23a. (Getty Images/Juergen Brand/942436790-170667a)
However, because iceberg calving is a natural process, there is a lack of megabergs for scientists to know with any certainty that they are increasing as the planet warms, Meijers said.
He quickly mentioned that ice shelves have seen trillions of tonnes of ice vanish because of an increase in the creation of icebergs and melting over the past few decades. Much of that is attributed to warming ocean water and the alterations in ocean currents, Meijers added.
Thumbnail is of A23a, courtesy of Getty Images/Juergen Brand/1942436797-170667a.
With files from Scott Sutherland, a meteorologist and science writer at The Weather Network.