A regime change within Amery Ice Shelf cavity by a reversed current in the twenty-first century

The Amery Ice Shelf (AmIS), the third largest ice shelf in Antarctica, has experienced a relatively low basal melting 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 a low-emission scenario and a high-emission scenario to investigate AIS melting by 2100. The melt rate is projected to increase multiple times in 2100. An abrupt increase in melt rate happens in the 2060s in both scenarios. A mechanism that drives the jump of melting is investigated. A redistribution of local salinity (and then 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 a jump of ice shelf melting. This regime change draws our attention to the role of oceanic processes in the basal mass loss of Antarctic ice shelves in climate change.