Mysterious formations beneath Antarctic glacier revealed by new study

"In order to understand the ice cycle in Antarctica and how ice gets from the continent into the ocean, we need to understand how it melts from beneath," the scientists claim. That's why they decided to use a remotely operated vehicle to explore the bottom of the glacier. They discovered something there that had never been seen before. The sight of hundreds of metres of formations must have sent chills down their spines.

Scientists discovered strange and unknown shapes at the bottom of the Dotson Glacier in the western part of Antarctica in 2022, but detailed studies on this discovery have only been published now in the journal "Science Advances." The researchers decided to lower a remotely operated vehicle to a depth of about 18 kilometres under the glacier, which travelled about 1,000 kilometres along the ice.

The expedition to the bottom of the drifting ice shelf not only provided the most accurate images of the glacier from below to date but also allowed scientists to identify formations that are hundreds of metres long, which may help better understand the process of glacier melting.

"In order to understand the ice cycle in Antarctica and how ice gets from the continent into the ocean we need to understand how it melts from beneath, a process that is equally important as calving for moving land ice to the ocean," explains Anna Wåhlin, the lead author of the study and an oceanography professor at the University of Gothenburg (Sweden), in an interview with Live Science.

The Dotson Glacier, studied by scientists, is a piece of ice about 50 kilometres wide located on the coast of Marie Byrd Land (West Antarctica). It is considered an area where the ice sheet's collapse could raise sea levels by about 3.4 metres. Previous research shows that warm ocean water is gradually eroding the ice shelf's underside, making its collapse inevitable.

The scientists investigated the exact process by which glaciers melt from below. Using the aforementioned remotely operated vehicle equipped with sonar, they obtained the most accurate image of the lower part of the glacier ever created," reads Live Science. The sonar examination revealed that the glacier melts fastest in places where underwater currents erode its base. Cracks running through the glacier facilitate the movement of the melting ice towards the surface.

The team studying Antarctica was, however, surprised to find that the glacier's base was not as smooth as expected but instead was covered with numerous (teardrop-like) shapes in the peaks and valleys of the ice. Some of them reach lengths of up to about 400 metres and, according to scientists, are formed due to uneven melting as water moves in accordance with the Earth's rotation under the glacier.

"If you look closely at the shapes they are not symmetrical, they are bent a bit like blue mussels, and the reason for that asymmetry is Earth's rotation," explains Wåhlin. The study's lead author explains that this phenomenon is related to the presence of the Coriolis force. "Water moving on Earth is subject to something called the Coriolis force, which is acting to the left of the direction of motion in the Southern Hemisphere," she adds. As a result of this force, a specific spiral pattern called the Ekman spiral is formed, which is mainly visible on the water's surface but can also form when water moves under the ice.

The scientists plan to continue their research in January 2024, but they lost the remotely operated vehicle during the expedition. It got lost under the ice shelf, so the next goal for the team was to reach the glacier with another vehicle and continue their research.