Using satellite data and the physics of ice flow, researchers have mapped Antarctica's hidden subglacial bedrock landscape – one of the Solar System's least mapped planetary surfaces – in unprecedented detail, revealing previously unseen geological structures shaping the ice sheet from below. The findings not only improve ice sheet models but can also guide future geophysical surveys and reduce uncertainty in projections of ice loss and sea-level rise. Hidden beneath Antarctica's massive ice sheet lies a complex landscape of mountains, valleys, plains, basins, and lakes. This subglacial topography plays a key role in shaping how Antarctic ice flows and influences the ice sheet's surface, both of which are essential for predicting how the content-scale ice sheet will evolve and contribute to sea-level changes in response to ongoing climate warming. However, much about Antarctica's subglacial landscapes remains unknown, largely due to sparse and limited ground-based and airborne surveys.
To address this gap, Helen Ockenden and colleagues combined high-resolution satellite observations of the ice sheet's surface, limited ice thickness measurements, and Ice Flow Perterbuation Analysis (IFPA), which leverages the physics of how ice flows over underlying bedrock topography, to develop a continent-scale map of subglacial topography. According to Ockenden et al., the map uncovers Antarctica's landscape in unprecedented detail, revealing midsized topographic features (2 to 30 kilometers) beneath the ice sheet that were previously unknown or poorly resolved, including deep and narrow alpine valleys, scoured lowlands, and extensive buried fluvial channels extending hundreds of kilometers. Some of these features may be relics of landforms that predate the modern ice sheet.
Author Robert Bingham told SciPak about the wonder of this discovery: "It is perhaps most surprising that ultimately so much detail of the bed topography – features such as glacial valleys, hills and canyons… – are captured at all in the shape of the ice surface so far above. So much change at the surface is extremely subtle – as 3 km-thick ice passes over a subglacial canyon maybe 100 meters deep, the ice surface elevation typically only falls a handful of meters, a change that is barely noticeable when travelling over the ice surface itself…" What's more, the mesoscale texture of the newly resolved topography allowed the authors to identify patterns of glacial shaping across Antarctica, offering insight into how the ice sheet formed, evolved, and interacted with the underlying landscape. This provides a clearer framework for reconstructing past ice and future ice dynamics. "Although Ockenden et al. provide a detailed map of Antarctica's bedrock landscape at mesoscale, it does not represent the final word on Antarctic geography," writes Duncan Young in a related Perspective. "Similar to mass conservation methods, the analysis relies on major assumptions about mechanisms that are critical for modeling ice sheet evolution, such as ice deformation, basal sliding, and melt and freeze processes at the ice-bedrock interface."
