Strong Ocean Melting Feedback During the Recent Retreat of Thwaites Glacier

• Published in: Geophysical Research Letters
• Main Authors: Holland, Paul R., Bevan, Suzanne L., Luckman, Adrian J.
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Geophysical Union 2023
• Subjects: Thwaites Glacier
• Online Access: http://nora.nerc.ac.uk/id/eprint/534329/; https://nora.nerc.ac.uk/id/eprint/534329/1/Geophysical%20Research%20Letters%20-%202023%20-%20Holland%20-%20Strong%20Ocean%20Melting%20Feedback%20During%20the%20Recent%20Retreat%20of%20Thwaites%20Glacier.pdf; https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2023GL103088

Accelerating ice loss from Thwaites Glacier is contributing approximately 5% of global sea-level rise, and could add tens of centimeters to sea level over the coming centuries. We use an ocean model to calculate sub-ice melting for a succession of Digital Elevation Models of the main trunk of Thwaites Glacier from 2011 to 2022. The ice evolution during this period induces a strong geometrical feedback onto melting. Ice thinning and retreat provides a larger melting area, thicker and better-connected sub-ice water column, and steeper ice base. This leads to stronger sub-ice ocean currents, increasing melting by over 30% without any change in forcing from wider ocean conditions. This geometrical feedback over just 12 years is comparable to melting changes arising from plausible century-scale changes in ocean conditions and subglacial meltwater inflow. These findings imply that ocean-driven ice loss from Thwaites Glacier may only be weakly influenced by anthropogenic emissions mitigation.