Antarctica’s deep canyons shape oceans and climate. High-resolution maps show striking regional differences.
Submarine canyons rank among the most striking and complex geological structures on the ocean floor, yet many remain poorly understood, particularly those in remote polar regions like the Arctic and Antarctic. A recent publication in Marine Geology presents the most comprehensive inventory of Antarctic submarine canyons to date, documenting 332 canyon systems, some plunging to depths exceeding 4,000 meters.
This new catalogue, which identifies five times more canyons than earlier surveys, was compiled by David Amblàs of the Consolidated Research Group on Marine Geosciences at the University of Barcelona’s Faculty of Earth Sciences and Riccardo Arosio from the Marine Geosciences Research Group at University College Cork. Their findings suggest that Antarctic submarine canyons could play a larger role than previously recognized in influencing ocean currents, the thinning of ice shelves, and broader climate dynamics, especially in sensitive regions like the Amundsen Sea and areas of East Antarctica.
Submarine canyons: the differences between East and West Antarctica
Submarine canyons, which are deep valleys cut into the ocean floor, are key features that influence ocean processes. They move sediments and nutrients from coastal areas into the deep sea, link shallow and deep water zones, and support ecosystems with high biodiversity. Although around 10,000 submarine canyons have been identified globally, only 27% of the seafloor has been mapped in high resolution, suggesting that many more remain undiscovered. Despite their importance for marine ecology, ocean circulation, and geology, these canyons—particularly those in polar regions—are still not well studied.
“Like those in the Arctic, Antarctic submarine canyons resemble canyons in other parts of the world,” explains David 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.” Moreover, the Antarctic canyons are mainly formed by turbidity currents, which carry suspended sediments downslope at high speed, eroding the valleys they flow through. In Antarctica, the steep slopes of the submarine terrain combined with the abundance of glacial sediments amplify the effects of these currents and contribute to the formation of large canyons.
Amblàs and Arosio’s latest research draws on Version 2 of the International Bathymetric Chart of the Southern Ocean (IBCSO v2), which offers the most comprehensive and detailed mapping of the seafloor in that area. The study incorporates newly available high-resolution bathymetric data and employs a semi-automated technique, developed by the authors, to detect and analyze submarine canyons. In their analysis, they examine 15 morphometric parameters, uncovering notable distinctions between the canyon systems in East and West Antarctica.
“Some of the submarine canyons we analyzed reach depths of over 4,000 meters,” explained David Amblàs. “The most spectacular of these are in East Antarctica, which is characterized by complex, branching canyon systems. The systems often begin with multiple canyon heads near the edge of the continental shelf and converge into a single main channel that descends into the deep ocean, crossing the sharp, steep gradients of the continental slope.”
Riccardo Arosio noted that “It was particularly interesting to see the differences between canyons in the two major Antarctic regions, as this hadn’t been described before. 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 and a greater influence of both erosional and depositional sedimentary processes. In contrast, West Antarctic canyons are shorter and steeper, characterized by V-shaped cross sections.”
According to David Amblàs, this morphological difference supports the idea that the East Antarctica Ice Sheet originated earlier and has experienced a more prolonged development. “This had been suggested by sedimentary record studies,” Amblàs said, “but it hadn’t yet been described in large-scale seafloor geomorphology.”
About the research, Riccardo Arosio also explained that “Thanks to the high resolution of the new bathymetric database — 500 meters per pixel compared to the 1–2 kilometers per pixel of previous maps — we could apply semi-automated techniques more reliably to identify, profile and analyze submarine canyons. The strength of the study lies in its combination of various techniques that were already used in previous work but that are now integrated into a robust and systematic protocol. We also developed a GIS software script that allows us to calculate a wide range of canyon-specific morphometric parameters in just a few clicks”.
Submarine canyons and climate change
In addition to their dramatic appearance, Antarctic submarine canyons play a crucial role in moving water between the deep ocean and the continental shelf. They help transport cold, dense water formed near ice shelves into the deep ocean, where it becomes Antarctic Bottom Water—a key component in regulating ocean circulation and influencing global climate patterns.
These canyons also direct warmer water, such as Circumpolar Deep Water, from the open ocean toward the Antarctic coastline. This movement is a major factor in the melting and thinning of floating ice shelves, which are essential for stabilizing inland glaciers. As Amblàs and Arosio noted, when these ice shelves weaken or break apart, the flow of glacial ice into the ocean accelerates, contributing directly to rising sea levels.
Amblàs and Arosio’s study also highlights the fact that current ocean circulation models like those used by the Intergovernmental Panel on Climate Change do not accurately reproduce the physical processes that occur at local scales between water masses and complex topographies like canyons. These processes, which include current channeling, vertical mixing, and deep-water ventilation, are essential for the formation and transformation of cold, dense water masses like Antarctic Bottom Water. Omitting these local mechanisms limits the ability that models have to predict changes in ocean and climate dynamics.
As the two researchers conclude, “That’s why we must continue to gather high-resolution bathymetric data in unmapped areas that will surely reveal new canyons, collect observational data both in situ and via remote sensors and keep improving our climate models to better represent these processes and increase the reliability of projections on climate change impacts.”
Reference: “The geomorphometry of Antarctic submarine canyons” by Riccardo Arosio and David Amblas, 24 June 2025, Marine Geology.
DOI: 10.1016/j.margeo.2025.107608
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4 Comments
I don’t want to sound ignorant but does the melting ice cause the sea salt to dilute?
“This movement is a major factor in the melting and thinning of floating ice shelves, which are ESSENTIAL for stabilizing inland glaciers.”
One sees this claim, or similar claims, frequently. It is not intuitive that something that wind can move around can offer substantial buttressing to the forward movement to the proverbial “irresistible force” that can grind down rock.
It appears that the support for this idea comes from a paper they cite by Paolo et al. (2015) that relies on low-precision measurements such as “negligible loss at 25 +– 64 cubic kilometers per year.” The uncertainty is more than 2.5X the nominal average value (They don’t explicitly say whether it is 1-sigma or the more commonly used 2-sigma (95% probability). That means that the actual ‘loss’ could even be a gain of more than 39 cubic km per year. Before everyone jumps on the bandwagon and accepts the quoted claim at the top, I think the work needs to be replicated, with higher accuracy. Some glaciers have a nasty habit of episodic surging for generally unknown reasons. There also needs to be research done to be sure that the claimed acceleration correlated with shelf ice thickness is the result of buttressing and not some other factor. That is, they need to prove that the apparent correlation isn’t spurious.
I am not sure if this would help climate change sceptics or not. Does it mean that no matter what we do to reverse climate change, the Arctic and Antarctic ice will melt?
Probably, yes. It all depends on the time scale one is talking about. However, anything more than several decades is very uncertain and probably not worth worrying about because of the rate that technology is advancing. As far as predictions go, there have been several that have claimed that humans only have about a decade to solve the problem(s), made over a decade ago, and the predictions have not happened.