Antarctica’s Glacial Border Shifts Many Kilometers Every Day with the Tides

The Cryosphere, 26 September 2023

The “grounding line” of the southern Ronne Ice Shelf in Antarctica can migrate up to 15 kilometers daily with changing tides, which can flush ocean water several kilometers inland under the ice sheet and increase melting. In less stable Antarctic regions, such as the Thwaites Glacier, this process is known to have driven long-term historic grounding line retreat. The grounding line marks the boundary between the grounded ice sheet and floating ice shelf. The movement of this line allows researchers to measure the health and stability of an ice sheet. This study develops a new method for monitoring Antarctic grounding lines from satellite data, observing shifts that occur over several minutes to hours, with significant impacts on ice shelf behavior. During rising tides, the flow of water lifts the more buoyant ice shelf off the sea bed and temporarily shifts the grounding line inland, before it returns to its seaward position at low tide. Understanding these daily shifts in grounding line position can help scientists better project Antarctica’s long-term response to climate change and how much global sea levels will rise.

https://tc.copernicus.org/articles/17/4079/2023/