NASA
Satellite image of iceberg A23a in the Southern Ocean, showing meltwater on its surface
Satellite photographs show meltwater on the surface of the A23a iceberg accumulating in an unusual way, which could be a sign that the huge block is about to break apart.
Meltwater on a city-sized iceberg in the Southern Ocean is quickly forming a gigantic lagoon on its surface – possibly a sign that it is close to breaking apart.
Scientists are fascinated by the icy colossus, known as , because meltwater is accumulating and holding on to its surface in an unusual way.
Satellite images reveal a edge ice tower that runs along the entire cliff edge of the Antarctic tabular iceberg, giving it the appearance of an immensely sized children’s play pool — except that it covers approximately 800 km², an area eight times larger than Lisbon.
In some places, the dammed water presents a intense blue hue and vivid, suggesting depths of several meters. Along the entire length of the A23a, the volume of water probably amounts to billions of liters – enough to fill thousands of olympic swimming pools.
According to the teacher Douglas MacAyealfrom the University of Chicago, this edge effect is typical of the largest icebergs of the world.
“My theory is thatand the ends are bentwith the nose facing downwards, creating a kind of arched dam on the upper surface that keeps meltwater inside,” explains MacAyeal.
“The curvature probably results from a erosion combination from the cliff face by the waves and the melting ice, and the natural tendency of the cliffs of ice curve even if they would otherwise be perfectly vertical.”
The surface water streaks visible in satellite images are a relic the way the ice once flowed when the iceberg was still attached to the coast of Antarctica, he says.
NASA
Photograph of the iceberg taken by an astronaut on the International Space Station on December 27, 2025
O A23a It’s an old iceberg. stood out from frost platform Filchner-Ronne in 1986 and was then more than five times larger than your current size. For a time, it held the title of the largest iceberg in the world.
In recent years, however, it has moved toward warmer waters and air, and is now in a relentless process of fragmentation.
The enormous volume of meltwater that accumulates on its surface could finally break it. “If this water infiltrates the cracks and freezes again, it will force the block to open,” he says. Mike Meredithfrom the British Antarctic Survey — which ensures that the block will be able to turn into a mush almost from one day to the next.
