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

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.