Simulating the Antarctic ice sheet in the late-Pliocene warm period: PLISMIP-ANT, an ice-sheet model intercomparison project

摘要

In the context of future climate change, understanding the nature andbehaviour of ice sheets during warm intervals in Earth history is offundamental importance. The late Pliocene warm period (also known as thePRISM interval: 3.264 to 3.025 million years before present) can serve as apotential analogue for projected future climates. Although Pliocene icelocations and extents are still poorly constrained, a significantcontribution to sea-level rise should be expected from both the Greenland icesheet and the West and East Antarctic ice sheets based on palaeo sea-levelreconstructions. Here, we present results from simulations of the Antarcticice sheet by means of an international Pliocene Ice Sheet ModelingIntercomparison Project (PLISMIP-ANT). For the experiments, ice-sheet modelsincluding the shallow ice and shelf approximations have been used to simulatethe complete Antarctic domain (including grounded and floating ice). Wecompare the performance of six existing numerical ice-sheet models insimulating modern control and Pliocene ice sheets by a suite of fivesensitivity experiments. We include an overview of the different ice-sheetmodels used and how specific model configurations influence the resultingPliocene Antarctic ice sheet. The six ice-sheet models simulate a comparablepresent-day ice sheet, considering the models are set up with their ownparameter settings. For the Pliocene, the results demonstrate the difficultyof all six models used here to simulate a significant retreat or re-advanceof the East Antarctic ice grounding line, which is thought to have happenedduring the Pliocene for the Wilkes and Aurora basins. The specific sea-levelcontribution of the Antarctic ice sheet at this point cannot be conclusivelydetermined, whereas improved grounding line physics could be essential for acorrect representation of the migration of the grounding-line of theAntarctic ice sheet during the Pliocene.