Collapse of the WAIS in response to 60 y of currently observed sub-ice-shelf melting in the Amundsen Sea. Field of surface speed of grounded ice body and floating ice shelves, with contours of grounding line and calving front in black and bed topography in blue shading. Region in Amundsen Sea in which ice shelves experience enhanced basal melting during the perturbation phase displayed by magenta rectangle. Region outside model domain hatched. (Lower) Time series of sea-level contribution through ice discharge. After the perturbation period (magenta bar) original ocean conditions with melting strongly below the presently observed values apply.