Antarctica. Credit: Oleksandr Matsibura, Shutterstock
A vast network of 332 giant submarine canyons, some plunging over 4,000 metres, has been revealed beneath Antarctica’s icy waters in the most detailed mapping of the region to date.
The high-resolution bathymetric survey, led by David Amblàs of the University of Barcelona and Riccardo Arosio of University College Cork, identified five times more canyons than previous studies. The findings, published on Science Daily, highlight how these immense valleys influence ocean circulation, ice shelf stability, and global climate patterns.
Antarctica’s hidden corridors
Submarine canyons are vast valleys carved into the ocean floor, often transporting sediments and nutrients from the coast to the deep sea, creating habitats rich in biodiversity. Globally, scientists have identified around 10,000 such canyons, but only 27 per cent of the Earth’s seafloor has been mapped in high resolution, meaning the real total is likely far higher.
Antarctic canyons stand out for their size and depth. “Like those in the Arctic, Antarctic submarine canyons resemble canyons in other parts of the world,” explained Amblàs. “But they tend to be larger and deeper because of the prolonged action of polar ice and the immense volumes of sediment transported by glaciers to the continental shelf.”
In Antarctica, many are formed by turbidity currents – fast-moving flows of suspended sediment that erode the seabed. The steep slopes and abundance of glacial sediment amplify these currents, contributing to the canyons’ vast scale.
East vs West Antarctica
The research revealed striking contrasts between the two main Antarctic regions.
“Some of the submarine canyons we analysed reach depths of over 4,000 metres,” said Amblàs. “The most spectacular of these are in East Antarctica, which is characterised by complex, branching canyon systems.” These often start with multiple canyon heads near the continental shelf edge, converging into a single deep channel that drops sharply into the ocean depths.
According to Arosio, “East Antarctic canyons are more complex and branched, often forming extensive canyon-channel systems with typical U-shaped cross sections.” This suggests prolonged development under sustained glacial activity.
By contrast, West Antarctic canyons are shorter, steeper, and typically V-shaped, indicating different geological processes. Amblàs said this morphological divide supports the theory that the East Antarctic Ice Sheet is older and has had a longer period of development, a conclusion previously suggested by sedimentary records but not by large-scale seafloor mapping until now.
“When the shelves weaken or collapse, continental ice flows more rapidly into the sea and directly contributes to the rise in global sea level,” Amblàs warned.
Amblàs and Arosio stress that current ocean circulation and climate models, including those used by the Intergovernmental Panel on Climate Change (IPCC), do not yet accurately reproduce the small-scale processes occurring in and around submarine canyons.
Next steps for Antarctic exploration
The researchers argue that further high-resolution mapping is essential, as large parts of Antarctica’s seabed remain unexplored. They recommend combining detailed mapping with both in-situ observations and remote sensing, which could reveal more canyons and help scientists better understand their role in ocean and climate systems.
This discovery adds urgency to Antarctic research at a time when ice shelves are already under threat from rising temperatures. It also poses a question for the scientific and political community: if such massive and climate-critical structures have remained hidden until now, what other key features might still be undiscovered?
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