Brunt Ice Shelf in Antarctica Speeds Up After Calving of Giant Iceberg

The recent calving of the massive A-81 iceberg in January 2023 has triggered an unexpected phenomenon on the Brunt Ice Shelf in Antarctica. Prior to this event, the ice shelf’s movement toward the sea averaged between 1 to 2.5 meters (3 to 8 feet) per day. However, in the aftermath of the calving, it is currently advancing at a much swifter pace, averaging approximately 4 meters (13 feet) per day. These noteworthy observations have been detailed in a submission to the prestigious scientific journal, The Cryosphere.

The Brunt Ice Shelf stands as one of the most extensively scrutinized ice shelves worldwide, renowned for its intricate glaciological composition. Calving events on this ice shelf have historically proven difficult to predict due to its complexity. Surprisingly, the recent acceleration of the Brunt Ice Shelf is attributed not to climate change but to the severance of its connection with the seafloor within a region known as the McDonald Ice Rumples. This detachment occurred as a consequence of the A-81 iceberg’s calving.

For the majority of the past 67 years, this connection with the seafloor had acted as a stabilizing force for the ice shelf, allowing it to remain relatively stationary. Remarkably, it is now advancing at a rate typically observed only in ice shelves fueled by exceptionally fast-moving outlet glaciers, akin to the Thwaites Glacier in West Antarctica.

The British Antarctic Survey (BAS) is diligently monitoring this situation through the deployment of GPS equipment on the ice and satellite data. These monitoring efforts play a pivotal role in aiding operational planning at the Halley Research Station, which is strategically positioned on the most secure section of the Brunt Ice Shelf, situated 20 kilometers from the newly formed ice front. Notably, in 2016, as a precaution, BAS relocated Halley Research Station 23 kilometers inland from the Chasm-1 fissure, which ultimately led to the A-81 iceberg’s calving when it began widening.

Currently, Halley Research Station is inactive during the harsh Antarctic winter, devoid of personnel. However, BAS’s operational teams are meticulously preparing for a routine field season scheduled for November 2023, where a team of 40 individuals will be transported to the Brunt Ice Shelf. Their mission is to maintain power supplies and the necessary facilities that enable scientific experiments to function remotely throughout the winter season. Their diligent efforts will persist until they are retrieved by aircraft in February 2024.

Professor Dominic Hodgson, a distinguished BAS glaciologist with over a decade of experience in studying the Brunt Ice Shelf, provides insight into this dynamic situation: “We anticipated the ice shelf’s response to the A-81 calving event. We are closely monitoring its accelerated movement and conducting additional experiments to ascertain when, or if, the ice shelf will reestablish contact with the seafloor. This will be discerned by a stabilization or decrease in ice shelf velocity, which we can monitor in real-time. Our scientific and operational teams continue their vigilant oversight of the ice shelf to ensure safety and the continuation of the scientific endeavors undertaken at Halley.”

Reference: “Brief Communication: Rapid acceleration of the Brunt Ice Shelf after calving of iceberg A-81” by Oliver J. Marsh, Adrian J. Luckman, and Dominic A. Hodgson, Submitted, The Cryosphere. DOI: 10.5194/egusphere-2023-1949

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More about Brunt Ice Shelf Acceleration

• The Cryosphere Journal
• British Antarctic Survey (BAS)
• A-81 Iceberg Calving
• Climate Change and Ice Shelves
• Antarctic Glaciology Research