Extended Data Fig. 8: Predicted Antarctic ice-volume changes and global-mean sea-level contributions.

a, Changes in AIS volume predicted in a simulation with Northern Hemisphere ice cover fixed at the 40 ka configuration within ICE5G²⁷ (solid red line) and in simulations with evolving Northern Hemisphere ice adopting the ICE5G²⁷ (solid black line), ICE6GC³¹ (dashed black line) and ANU³⁰ (cyan line) ice histories, as well as two composite ice histories in which ice cover over North America and Greenland in ICE5G has been replaced by regional GLAC1D²⁹ models (blue lines). The dashed red line represents a simulation in which the Northern Hemisphere ice sheets are fixed at the modern configuration rather than at the 40 ka configuration throughout the simulation. In this case, marine-based sectors of the AIS start on even shallower bedrock, and hence the predicted ice-sheet growth is larger at the LGM, while the ice loss during the deglaciation occurs later and is of even smaller magnitude than in the original simulation. Note that this is not a realistic starting configuration. b, As in a, but expressed as a global-mean sea-level-equivalent (GMSLE) relative to the modern state. This is calculated by taking the ice above floatation thickness in Antarctica relative to the palaeo bedrock topography at each time step in the model, and dividing by the area of the modern ocean. Note that a and b are not directly proportional because as the bedrock topography in Antarctica evolves the volume of ice above floatation in marine sectors also changes. Blue (a) and red (b) vertical bands represent the timing of MWP and AID events, as in Fig. 2a, c, respectively.