Fissure on the Brunt platform in Antarctica.
“Impressive”. The most complete and detailed map ever made of the underground region of the frozen continent reveals thousands of hitherto unknown hills and mountain ranges.
A new map has just revealed the landscape beneath the ice of Antarctica with an unprecedented level of detail — something that scientists say could significantly expand our understanding of the icy white continent.
According to the study in Science, researchers used satellite data and the physics of glacier movement in Antarctica to estimate what the continent might look like beneath the ice. They found evidence of thousands of hills and mountain ranges hitherto unknown. According to the team, maps of some of Antarctica’s hidden mountain ranges are clearer than ever.
Although these maps may contain inaccuracies, researchers believe the new details could help clarify how Antarctica will respond to climate change and what that will mean for sea level rise.
“It’s as if before we had an analog camera, with a grainy image, and now we have a digital image, much enlarged, of what’s really going on,” the researcher told BBC News. Helen Ockendenfrom the University Grenoble-Alpes (France), lead author of the study.
Thanks to satellites, scientists now have a good understanding of Antarctica’s icy surface, but what lies beneath the ice remains largely a mystery. mystery. In fact, more is known about the surface of some planets in the Solar System than about much of the “dark side” of Antarctica — the topography beneath the ice sheet. Now, researchers say they have what they believe to be the most complete and detailed map ever made of this underground region.
“It really excites me to look at this and see, at one glance, the entire floor of Antarctica,” said glaciologist Robert Bingham of the University of Edinburgh, co-author of the study. “I think this is impressive.”
New approach
Traditional measurements from the ground or air use radar to “see” under the ice — which, in some spots, is almost 5 km thick — typically along isolated survey lines or paths. But these paths can be tens of kilometers apart, forcing scientists to fill in large gaps.
“If we imagine the Scottish Highlands or the European Alps covered in ice and the only way to perceive their relief were occasional flights, separated by several kilometers, there would be no way to identify all those mountains and steep valleys that we know exist”, said Bingham.
To overcome the problem, the researchers adopted a new approach: they combined satellite data on the ice surface with physical knowledge of how it moves and compared these results with records obtained in previous surveys.
“It’s a bit like kayaking on a river: When there are rocks underwater, eddies sometimes appear on the surface, which give clues about what’s underneath,” explained Ockenden of the University of Grenoble-Alpes. “Ice obviously flows differently to water, but still, when it flows over a rise or hill in bedrock, this is reflected in both the topography of the surface and the speed of the flow.”
Although the main mountain ranges of Antarctica were already known, this new methodology revealed tens of thousands of previously unknown hills and ridges, as well as much more precise details of mountains and canyons buried beneath the ice.
“I think it’s really interesting to look at all these new landscapes and see what’s there,” Ockenden said. “It’s like when you first see a topographic map of Mars and think, ‘Wow, this is fascinating, this looks a bit like Scotland’ or ‘This doesn’t look like anything I’ve ever seen’.”
One of the most intriguing discoveries is a deep channel excavated from the bed of Antarctica in an area known as the Maud Subglacial Basin. The channel is, on average, 50 meters deep, 6 km wide and stretches for almost 400 km.
The new map prepared by the researchers, however, is unlikely to be definitive. It is based on assumptions about exactly how the ice moves, which, like any method, involves uncertainties. Furthermore, there remains much to discover about the rocks and sediments beneath the ice sheet.
Still, other researchers agree that, combined with additional surveys on land, in the air and in space, the map represents an important advance.
“It’s a really useful product,” said Peter Fretwell, a senior researcher at the British Antarctic Survey in Cambridge, who was not involved in the new study but has been extensively involved in previous mapping. “It gives us the opportunity to fill in the gaps between these surveys,” he added.
According to the authors, a more detailed understanding of ridges, hills, mountains and channels can improve computer models that project how Antarctica may change in the future. This is because these landforms ultimately determine the speed at which the glaciers above move and the pace of their retreat in a warming climate.
This point is crucial because the future rate of melting ice in Antarctica is considered one of the biggest unknowns of climate science.
“[Este estudo dá-nos] a clearer picture of what will happen in the future and how quickly Antarctic ice will contribute to global sea level rise,” agreed Fretwell.
