World's Largest Iceberg Crumbles! Trillion-Tonne Megaberg Shatters After Years of Stability

The Journey of the World’s Largest Iceberg

At the start of this year, the world's largest iceberg, A23a, was more than twice the size of Greater London. As we enter September, scientists are watching with concern as this massive ice structure is nearing its end. Known as one of the oldest and largest megabergs ever recorded, A23a has been breaking apart in warmer waters and may disappear within weeks.

Shaped like a tooth, A23a has been drifting north through the South Atlantic Ocean for months. Now exposed to increasingly warmer waters and large waves, the former 'king of the seas' has rapidly disintegrated. According to Mr. Andrew Meijers, a physical oceanographer at the British Antarctic Survey (BAS), A23a has been 'breaking up fairly dramatically' as it moves further north. He described the process as 'rotting underneath,' with the water being too warm for the iceberg to maintain its structure.

In early 2024, A23a weighed around one trillion tonnes—about 100 million times the weight of the Eiffel Tower in Paris. At its peak, the iceberg spanned 1,540 square miles, which is more than twice the size of Greater London. It was also an astonishing 1,312 feet thick. Today, it measures 683 square miles and 37 miles at its widest point, according to AFP analysis of satellite images. This means it is less than half its original size.

In recent weeks, chunks of about 150 square miles have broken off, while smaller pieces still pose a threat to ships. Waves crashing against the iceberg create gaps that grow larger over time, leading to collapses and the formation of smaller 'stacks' and 'stumps.' As it continues to drift north, carried by ocean currents, the surrounding waters become warmer, and the iceberg will soon melt away completely.

Mr. Meijers expects this process to continue in the coming weeks, with A23a becoming unrecognizable within a few weeks. Scientists were surprised by how long the iceberg managed to stay intact. Most icebergs don’t make it this far, but A23a’s sheer size allowed it to last longer and travel further than most.

How Icebergs Form

Icebergs are pieces of freshwater ice that have detached from glaciers or ice shelves and float in the ocean. They form when parts of ice shelves or glaciers break off—a process known as 'calving.' This natural phenomenon contributes to ice loss at the edges of glaciers and ice sheets.

A23a is the largest remaining fragment of an iceberg that broke free from the Antarctic Filchner Ice Shelf in August 1986. Initially, it moved only a few hundred miles before becoming stuck on the ocean floor, remaining stationary for 30 years. Icebergs 'ground' on the ocean floor when their keel is deeper than the water’s depth. A23a finally broke free in 2020 and began moving north, though its journey was occasionally delayed by ocean forces that kept it spinning in place.

The iceberg was carried by the powerful Antarctic Circumpolar Current, the world's most significant ocean current. In March, it ran aground near South Georgia Island, raising concerns about potential impacts on penguin breeding and feeding grounds. Fortunately, A23a dislodged in late May and continued its journey northward.

The Significance of Icebergs

Icebergs play a crucial role in marine ecosystems. When they break off from floating ice shelves, they do not contribute to rising sea levels, similar to how melting ice cubes do not raise the liquid level in a glass. Some icebergs contain iron-rich sediment, known as 'dirty ice,' which can fertilize the ocean by providing nutrients to marine organisms such as phytoplankton.

However, icebergs can also pose dangers to ships, as seen in the tragic sinking of the RMS Titanic in 1912. Icebergs can reach heights of over 300 feet above the sea surface and have masses ranging from 100,000 tonnes to more than 10 million tonnes. Those smaller than 16 feet are called 'bergy bits,' while those under 3 feet are 'growlers.'

The Future of Icebergs and Climate Change

Scientists note that the rate at which icebergs are lost from Antarctica is increasing, likely due to human-induced climate change. This trend raises concerns about the future of Antarctic wildlife and the broader implications for ocean ecosystems.

As A23a continues its final journey, it serves as a reminder of the delicate balance between nature and climate change. Its dramatic fragmentation could signal not just its demise, but also a larger transformation in our oceans. The fate of icebergs like A23a highlights the urgent need to understand and address the impacts of global warming on polar regions.