Preprints
https://doi.org/10.5194/egusphere-2024-1287
https://doi.org/10.5194/egusphere-2024-1287
17 Jun 2024
 | 17 Jun 2024
Status: this preprint is open for discussion.

Current reversal leads to regime change in Amery Ice Shelf cavity in the twenty-first century

Jing Jin, Antony J. Payne, and Christopher Y. S. Bull

Abstract. The Amery Ice Shelf (AmIS), the third largest ice shelf in Antarctica, has experienced relatively low rates of basal melt during the past decades. However, it is unclear how AmIS melting will respond to a future warming climate. Here, we use a regional ocean model forced by different climate scenarios to investigate AmIS melting by 2100. The areally-averaged melt rate is projected to increase from 0.7 m·yr−1 to 8 m·yr−1 in the low-emission scenario or 17 m·yr−1 in the high-emission scenario in 2100. An abrupt increase in melt rate happens in the 2060s in both scenarios. The redistribution of local salinity (hence density) in front of AmIS forms a new geostrophic balance, leading to the reversal of local currents. This transforms AmIS from a cold cavity to a warm cavity, and results in the jump in ice shelf melting. While the projections suggest that AmIS is unlikely to experience instability in the coming century, the high melting draws our attention to the role of oceanic processes in basal mass loss of Antarctic ice shelves in climate change.

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Jing Jin, Antony J. Payne, and Christopher Y. S. Bull

Status: open (until 17 Aug 2024)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2024-1287', Anonymous Referee #1, 24 Jul 2024 reply
Jing Jin, Antony J. Payne, and Christopher Y. S. Bull

Model code and software

AME025 configuration Jing Jin, Christopher Bull, and Antony Payne https://doi.org/10.5281/zenodo.10797900

Jing Jin, Antony J. Payne, and Christopher Y. S. Bull

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Short summary
The Amery Ice Shelf cavity is one of the largest cold cavities filled by relatively cold Dense Shelf Water. However, in this study, we show that warm intrusion of modified Circumpolar Deep Water flushes the Amery cavity, which changes it from a cold cavity to a warm cavity and leads to an abrupt increase in basal melt rate in the 2060s. The shift to the warm cavity is attributed to a freshening-driven current reversal in front of the ice shelf.