Beneath nearly two kilometers of the East Antarctica ice sheet, sealed off since the continent froze over at least 34 million years ago, scientists have discovered something that changes the way researchers understand Antarctica’s distant past and its near-term future.
Using ice-penetrating radar collected across multiple aerial survey campaigns, an international team led by Durham University has mapped a vast ancient landscape extending along 3,500 kilometers of the East Antarctic edge, a terrain made up of 31 separate flat surfaces, formed by rivers that once flowed freely across what is now the most remote, ice-covered continent on Earth. The study, published in the journal Nature Geoscience, is the first to map these surfaces at this scale, and what the researchers found is not just a record of a warmer, wetter Antarctic region.
These buried plains appear to actively influence how the ice above them moves today, slowing the flow of glaciers in ways that current climate models have not taken into account, further complicating predictions about how much sea levels will rise as the world continues to warm.
Before Antarctica froze over: How giant rivers formed a lost continent 80 million years ago
These surfaces, some of which are thought to have formed more than 80 million years ago when East Antarctica and Australia were still connected, are thought to have been smoothed over by large rivers before ice submerged the continent about 34 million years ago.
Remarkably, this landscape has remained largely intact, having been preserved under the ice sheet for more than 30 million years. The picture that emerges from this timeline is amazing.
When the flat surfaces now buried under ice first formed, Antarctica was part of the ancient supercontinent Gondwana, sharing land mass with Australia, South America and India. As those continents drifted apart, large rivers carved the topography of what would eventually become East Antarctica.
It is believed that the surfaces were formed by large rivers after East Antarctica and Australia separated about 80 million years ago, and before ice covered Antarctica about 34 million years ago. When the deep freeze eventually arrived, it acted, as one researcher put it, like turning on a refrigerator, locking the landscape in place while the rest of the continent was reshaped by glaciation.
How ice-penetrating radar revealed 31 hidden surfaces beneath the East Antarctic ice sheet
The discovery relied entirely on a technology that has transformed polar science over the past two decades: airborne radar capable of seeing through kilometers of ice to map the rocks and terrain beneath.
Researchers led by Durham University examined radar measurements of ice thickness and found large-scale, never-before-mapped flat surfaces buried under a 3,500-kilometre stretch of East Antarctica’s coast.
The British Antarctic Survey, whose Twin Otter aircraft helped collect radar data, played a key role in collecting and interpreting the subglacial terrain. The scene consists of 31 separate flat surfaces that together cover an area similar to the size of Wells.
From above the ice, none of this is visible. The surface of the East Antarctica ice sheet gives no indication of what lies beneath. It is precisely this invisibility that makes radar the only tool available and is precisely why these surfaces have not been identified for so long.
Why might these ancient river plains be slowing ice loss in Antarctica today?
The most important finding of the study is not historical; It is the present tense. The flat surfaces are now hidden under the ice sheet, separated by deep troughs, through which fast-flowing glaciers are channeled. The ice above the surface moves much more slowly. Dr Jay Paxman, lead author and Royal Society Research Fellow at Durham University, described the mechanism in the official BAS press release: “These flat surfaces we found are likely the remains of ancient river beds that survived under the ice.
Their shape and position now appear to slow the movement of the ice above them, acting almost like brakes on fast-flowing glaciers. “In practice, this means that the ancient terrain acts as a natural regulator, directing fast-moving glaciers across the basins between the flat surfaces while the ice directly above the plains moves much more slowly.
The implications for sea level projections are important because models that do not account for this suppressing effect may overestimate or underestimate how quickly East Antarctica’s ice reaches the ocean.
The potential sea level rise of 52 meters has to do with ancient river beds
The risks associated with this discovery are not abstract. If the ice in East Antarctica melted completely, it would contain enough frozen water to raise global sea levels by up to 52 metres. This number represents a worst-case scenario over time periods extending beyond any near-term climate projections, but it shows why understanding the dynamics of ice loss in East Antarctica is so important. Even a small portion of this melting caused by accelerating climate change over the coming centuries would reshape coastlines across the planet.
Co-author Professor Stuart Jamieson, also from Durham, said analyzing these hidden landscapes in computer models could significantly boost predictions about how Antarctica will respond to rising temperatures. Dr Tom Jordan, a BAS geophysicist and co-author, was frank about the gap the study reveals: “These results show how much of Antarctica’s past remains trapped beneath the ice. Understanding the ancient landscapes that influence ice flow today is crucial if we are to predict how this massive ice sheet will behave in the future.”
What must happen next to reveal the full significance of this discovery
Mapping surfaces from the air is just the beginning. The researchers stress that further exploration is needed to determine how these flat surfaces affected the movement of ice in past warm periods. Drilling to obtain rock samples from beneath the ice can confirm when these areas were last ice-free, vital data for improving climate models. This type of subglacial drilling requires technical effort and is expensive, but the scientific reward will be great.
Samples of rocks and sediments from beneath the ice can reveal plants and organisms that inhabited landscapes before glaciation, confirm the precise timeline of glaciation, and determine whether these surfaces remained stable during warmer glacial periods in the deep past, information that would directly improve the reliability of models that predict Antarctica’s behavior as temperatures rise in the future. The study was supported by the UK Natural Environment Research Council, the Leverhulme Trust, the European Research Council, and international partners including the Alfred Wegener Institute in Germany and the Polar Research Institute in China.
