Scientists have uncovered previously unseen patterns beneath a floating ice shelf in Antarctica, following an expedition to create the most detailed image ever of the glacier’s underside.
The peculiar teardrop shapes were found below Dotson Ice Shelf in West Antarctica in 2022 when a remotely operated vehicle (ROV) plunged 10 miles (17 kilometres) under the glacier and travelled over 600 miles (1,000 km) along the underside of the ice.
The findings from this unprecedented survey were published on Wednesday (July 31) in the journal Science Advances.
“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,” study lead author Anna Wahlin, a professor of oceanography at the University of Gothenburg, told Live Science.
Dotson Ice Shelf is a 30-mile-wide (50 km) slab of floating ice seven times the size of New York City, situated on the coast of Marie Byrd Land in West Antarctica.
It forms part of the West Antarctic ice sheet, which has dramatically calving glaciers that could cause sea levels to rise by approximately 11 feet (3.4 m) if they eventually drive the entire sheet to collapse.
The ice shelf is gradually being eroded, with warm ocean water seeping underneath and detaching it from the land, making its eventual collapse a certainty, according to previous studies.
To delve deeper into the threats facing the 1,150-foot-thick (350 m) ice shelf, the scientists deployed an ROV beneath the ice to sonar scan the glacier’s underside, creating the most comprehensive image of the glacier’s underside to date.
As anticipated by the researchers, the survey revealed that the glacier is melting fastest where underwater currents are wearing away at its base, and fractures within the glacier are facilitating the melt’s ascent to the surface.
However, they also unexpectedly found that the glacier’s base is not smooth but dotted with teardrop shapes protruding from peaks and valleys in the ice. Some of these shapes are up to 1,300 feet (400 m) long.
Scientists believe the peculiar patterns are formed by uneven melting as water, influenced by Earth’s rotation, moves across the glacier’s underside.
“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,” Wahlin explained. “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. If we are correct, there is a force balance in the layer closest to the ice where friction is balanced by the Coriolis force.”
This results in a spiral flow pattern known as an Ekman spiral, typically seen when winds travel over surface water but can also be created by water travelling over ice.
