On about 14 million square kilometers, just under twice the size of the United States, Antarctica is covered with ice caps. This real freshwater tank, the largest in the world, is revealed for the first time using an exceptional underground map of details.
Ironically, scientists know more about the surface of other planets, very distant, than about the Antarctic ice cap, whose ice can reach almost 5 km in thickness. However, a better understanding of these large masses could, for example, help researchers more accurately calculate how quickly the melting of the ice on Earth’s southernmost continent could affect the rise in sea level. A new mapping is now trying to open this path.
Published in mid-January in the journal Science, a study presents the most detailed map ever made on the entire subglacial terrain of Antarctica. An unknown landscape, buried under a thick and vast layer of ice, appears for the first time in the eyes of humans.
Unsuspected forms
Created from satellite images and computer simulations of the movement of the ice, this exceptional map reveals « thousands of previously hidden reliefs » and provides countless details about the surrounding valleys, mountains and canyons.
« It’s as if, before, you had a pellet pixel film camera, and now you have a properly enlarged digital image of what is really happening, » explains Helen Ockenden, co-author of the study and geoscientist at Grenoble Alpes University, to the BBC.
A card that can still be improved
Previous attempts to map this ice behemoth used radar instruments, dragged behind snowmobiles or suspended from airplanes, whose radio waves penetrated the cap and were reflected, but only along the journeys made. The areas above which vehicles and aircraft had not passed, sometimes several tens of kilometers wide, had thus remained blank of data.
« If you imagined that the Scottish Highlands or the European Alps were covered in ice and that the only way to understand their form was to occasionally fly over the region several kilometers apart, you could in no way see all those steep mountains and valleys that we know are there, » summarizes Scottish glaciologist Robert Bingham, one of the four authors of the study.
Their method has unearthed, among other things, 30,000 hills and a huge canal, about 400 kilometers long. But this map is not yet perfect, says the quartet, which sees it only as a first glimpse of the soclerocheux. « We guess what’s underneath, but it’s not the whole story, » conclude the researchers, eager to learn more.
source : geo.fr
