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

B De Boer,A M Dolan,H Goelzer,J Bernales,R S W Van De Wal,E Gasson,N R Golledge,A Abe-Ouchi,P Huybrechts,G Lohmann,J Sutter,I Rogozhina,F Saito

doi:10.5194/tc-9-881-2015

Abstract

Abstract. 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.

Highlights

There is uncertainty in the contribution of the Antarctic ice sheet (AIS) to future sea-level change (Church et al, 2013)
The results presented here are the first steady state simulations of the full domain of the AIS, using coupled shallow ice approximation (SIA)–shallow shelf approximation (SSA) ice-sheet models (ISMs) for the Pliocene Ice Sheet Modelling Intercomparison Project, PLISMIP
The control simulations show a consistent result for all ISMs, all models simulate a lower ice volume for the PD ERA-40/WOD-09 data set compared to the simulation with HadCM3 pre-industrial climatology due to a drier East Antarctic climate in ERA-40

Summary

Introduction

There is uncertainty in the contribution of the Antarctic ice sheet (AIS) to future sea-level change (Church et al, 2013). Studying past intervals with a warmer than present-day (PD) climate can be used to gain a better understanding of the sensitivity of the AIS to predicted future climate warming One such warm interval is the late-Pliocene warm period ( known as the PRISM interval, 3.264 to 3.025 million years before present; Dowsett et al, 2010), which can be considered as a possible analogue for future climate change at the end of this century. This warm period is a well studied interval in Earth’s history using both models During the late-Pliocene, atmospheric CO2 concentrations are estimated to vary between 300 and 450 ppm (e.g. Bartoli et al, 2011; MartinezBoti et al, 2015), an other estimate (Badger et al, 2013) indicates lower concentrations close to the interglacial values found in ice cores (Lüthi et al, 2008)

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