A new amazing discovery was made by scientists under Antarctica: massive landforms, some as tall as the Eiffel Tower, and are five times bigger than the ones left behind by Scandinavia and North America former ice sheets, and could be part of the explanation of the thinning of the Antarctic ice shelves, and even greatly influence the region’s stability.
Due to the ancient ice sheets found at the Northern Hemisphere, scientists already knew that landforms could grew for many meters below the surface, with the Scandinavian Ice Sheet being one of the largest glacial masses of the Pleistocene epoch (between 2 588 000 and 11 700 years ago), achieving an amazing size of ice surface of around 6.6 million square kilometers at its peak.
Bellow the ice sheet, with a thickness of about 3000 meters, various landforms begin to shape, and during thousands of years, they mitigated a cycle of evaporation and precipitation to keep on the ice cycling through the ocean. But now, that the ice sheet has retreated, the complex landforms, known as eskers, have finally been exposed.
Below you can see similar landforms located in Western Sweden.
Although it was long for speculated that similar features should be beneath our current ice sheets, no one could have guessed and prepared the scientists from the Université de Bruxelles in Belgium and the Bavarian Academy of Sciences in Germany for the Antarctica discovery.
The landforms found under Antarctica, with five times the size of the ones found at the Scandinavian Ice Sheet, are so huge that compared to it, all others seem irrelevant. By using a combination of both satellite imagery and airborne and ground based radar data, they were able to identify distinct “radar reflectors” under the Ice Sheet.
The reflections are clear indicators of large protrusions cutting into the ice flow above, that look much like the ancient eskers found at Scandinavia, but much larger! But how exactly did they come to be?
After studying a feature known as subglacial conduits, usually found under large ice sheets, funnel meltwater out towards the ocean, and the closer they get to it, the wider they become. That widening makes room to the accumulation of sediments over time, ultimately forming eskers.
“As the conduits widen, the outflow velocity of the subglacial water decreases, which leads to increased sediment deposition at the conduit’s portal. Over thousands of years, this process builds up giant sediment ridges – comparable in height with the Eiffel tower – below the ice”, the team explains in a press release.
“Active sedimentation in subglacial water conduits seems to drive the formations of eskers – elongated ridges of gravel which are commonly observed today in areas where former ice sheets have retreated”.
We might not be able to stop the thinning of the Antarctic ice sheet, but a better understanding of how it happens could at least help us to predict what will happen next.