Abstract. Disintegration of ice shelves in the Amundsen Sea, in front of the West Antarctic Ice Sheet, has the potential to cause sea level rise by inducing an acceleration of ice discharge from upstream grounded ice. Moore et al. (2018) proposed that using a submarine wall to block the penetration of warm water into the subsurface cavities of these ice shelves could reduce this risk. We use a global sea ice–ocean model to show that a wall shielding the Amundsen Sea below 350 m depth successfully suppresses the inflow of warm water and reduces ice shelf melting. However, these warm water masses get redirected towards neighboring ice shelves, which reduces the net effectiveness of the wall. The ice loss is reduced by 10 %, integrated over the entire Antarctic continent.

Disintegration of ice shelves in the Amundsen Sea has the potential to cause sea level rise by inducing an acceleration of grounded ice streams. Moore et al (2018) proposed that using a submarine wall to block the penetration of warm water into the ice shelf cavities could reduce this risk. We use a global sea ice-ocean model to show that a wall shielding the Amundsen 10 Sea below 350 m depth successfully suppresses the inflow of warm water and reduces ice shelf melting. However, the warm water gets redirected towards neighboring ice shelves, which reduces the effectiveness of the wall.This work has been financed through the German Federal Ministry of Education and Research (Bundesministerium für Bildung und Forschung: BMBF) project ZUWEISS (grant agreement 01LS1612A). We thank in particular Evan Gowan for 125 his comments and his improvements of the manuscript.

<p>The Filchner Trough on the continental shelf in the southern Weddell Sea is a region of great importance for the water mass exchange between the open ocean and the Filchner Ronne Ice Shelf cavity. Observations of the last 20 years and modelling studies show seasonal variations and longer lasting pulses of warm water intruding into the trough and reaching the Filchner Ice Shelf front. In this study, we evaluate the evolution of these intrusions in four climate scenarios defined for CMIP6 and simulated with the AWI Climate Model. We show that a warming climate will lead to more frequent pulses in the mitigation scenarios SSP1-2.6 and SSP2-4.5. For the high emission scenarios SSP3-7.0 and SSP5-8.5, hydrography in Filchner Trough will shift to a substantially warmer state during the second half of the 21st century with a temperature rise of 2°C in the trough until 2100. We demonstrate that the system‘s tipping into a warmer state is primarily caused by changes in the local sea ice formation and the depth of the Antarctic Slope Front. Our results show that a regime shift can be avoided by reaching the 2°C climate goal.</p>