Ocean tides trigger ice shelf rift growth and calving

Area of Science:

• Glaciology
• Oceanography
• Antarctic Research

Background:

• Tabular iceberg calving significantly impacts ice-shelf extent, influencing ocean circulation and ice-sheet stability.
• Understanding the processes leading to calving is crucial for predicting future ice loss and sea-level rise.

Purpose of the Study:

• To present detailed observations of a rift on the Brunt Ice Shelf, East Antarctica, from 2017-2023.
• To analyze the factors controlling rift propagation and the timing of iceberg calving.

Main Methods:

• Detailed rift observations from 2017-2023 on the Brunt Ice Shelf.
• Application of a viscoelastic rheological model to estimate stresses and fracture thresholds.
• Analysis of environmental factors including ocean tide height, wind speed, and iceberg collision events.

Main Results:

• Rift propagation was influenced by the rate of change of ocean tide height, wind speed, and an iceberg collision in August 2021.
• A viscoelastic rheological model indicated a critical fracture threshold was exceeded in early 2019.
• The final calving event on January 22, 2023, occurred during a spring tide peak.

Conclusions:

• Ocean tides directly influenced the timing of the Brunt Ice Shelf calving event.
• Ice-shelf calving is a complex process influenced by both short-term environmental factors and long-term ice dynamics.