In the context of future climate change, understanding the nature and
behaviour of ice sheets during warm intervals in Earth history is of
fundamental importance. The late Pliocene warm period (also known as the PRISM
interval: 3.264 to 3.025 million years before present) can serve as a
potential analogue for projected future climates. Although Pliocene ice
locations and extents are still poorly constrained, a significant contribution
to sea-level rise should be expected from both the Greenland ice sheet and the
West and East Antarctic ice sheets based on palaeo sea-level reconstructions.
Here, we present results from simulations of the Antarctic ice sheet by means
of an international Pliocene Ice Sheet Modeling Intercomparison Project
(PLISMIP-ANT). For the experiments, ice-sheet models including the shallow ice
and shelf approximations have been used to simulate the complete Antarctic
domain (including grounded and floating ice). We compare the performance of
six existing numerical ice-sheet models in simulating modern control and
Pliocene ice sheets by a suite of five sensitivity experiments. We include an
overview of the different ice-sheet models used and how specific model
configurations influence the resulting Pliocene Antarctic ice sheet. The six
ice-sheet models simulate a comparable present-day ice sheet, considering the
models are set up with their own parameter settings. For the Pliocene, the
results demonstrate the difficulty of all six models used here to simulate a
significant retreat or re-advance of the East Antarctic ice grounding line,
which is thought to have happened during the Pliocene for the Wilkes and
Aurora basins. The specific sea-level contribution of the Antarctic ice sheet
at this point cannot be conclusively determined, whereas improved grounding
line physics could be essential for a correct representation of the migration
of the grounding-line of the Antarctic ice sheet during the Pliocene
