The world’s largest iceberg, A23a, is once again on the move after spending most of the year trapped in a swirling vortex near the South Orkney Islands. This colossal slab of ice, measuring an astounding 3,800 square kilometers (1,500 square miles) and 400 meters (1,312 feet) thick, is more than twice the size of Greater London.
A23a has had a fascinating journey since breaking free from Antarctica’s Larsen Ice Shelf in 1986. Almost immediately, it became lodged on the seafloor of the Weddell Sea, where its immense depth caused its base to scrape along the ocean floor, leaving it virtually immobile for more than three decades.
The iceberg’s story took a dramatic turn in 2020 when it began to drift northward, only to become stuck again this spring in a rotating column of water, or gyre. Now, new observations from the British Antarctic Survey (BAS) indicate that A23a is finally moving again.
Dr. Andrew Meijers, an oceanographer at the BAS, expressed excitement over this latest development. “It’s fascinating to see A23a on the move again after years of stagnation,” he said. “We’re curious to see if it will follow the path of other large icebergs that have calved off Antarctica.”
The iceberg’s next destination is likely the warmer waters of the Atlantic Ocean. Once there, it is expected to break apart into smaller fragments and eventually melt entirely. But before that happens, A23a may have a profound impact on the ecosystems it encounters during its journey.
These colossal icebergs are more than just floating behemoths; they are nutrient-rich platforms that can transform barren ocean regions into thriving ecosystems. When icebergs like A23a melt, they release essential nutrients such as iron, which can fertilize the waters they pass through, boosting productivity and supporting marine life.
Laura Taylor, a biogeochemist with the BAS, was part of a research team aboard the RRS Sir David Attenborough that studied A23a’s influence last year. “We know these massive icebergs act like nutrient delivery systems, helping to create vibrant ecosystems in otherwise unproductive waters,” she explained. “What remains a mystery is how the specific size, shape, and origins of an iceberg like A23a affect this process.”
Scientists are closely tracking A23a’s progress, eager to learn more about how such immense icebergs interact with their environments. As it drifts toward its inevitable demise in warmer waters, A23a’s journey offers a rare opportunity to study the interplay between the frozen giants of the Antarctic and the ecosystems they help sustain.
For now, the world watches as the once-static giant embarks on its final voyage—a stark reminder of the dynamic and ever-changing nature of our planet’s icy frontiers.
