Antarctic climate and ice-sheet configuration during the early Pliocene interglacial at 4.23 Ma

Published: Sep 1, 2017 by The PISM Authors

Title Antarctic climate and ice-sheet configuration during the early Pliocene interglacial at 4.23 Ma
Authors N. Golledge and others
Venue Climate of the Past

Whether a ‘tipping point’ will be reached in the next few centuries, in the dynamics of various parts of the Antarctic ice sheet (AIS) as it responds to a warming world, is the most difficult prediction question. It is an extreme challenge to models. How complete a model must be, so as to resolve the relevant behavior of the (real) dynamical system, is unknown. A negative result from modeling (i.e. no tipping points seen in model runs) has minimal value because a more-complete, or merely different, model may show a tipping point. Insisting that a model include all possibly-relevant mechanisms is unfeasible to the point of silliness. Tipping-point questions can be asked about the past states of the AIS, though using existing observations to resolve these questions is extraordinarily difficult. This paper uses GCM/RCM and ice-sheet modeling to recreate conditions of the early to mid-Pliocene when atmospheric CO2 concentrations were similar to present day. The focus of PISM application is on modeling grounding-line motion, ice shelf basal melt near the grounding line, and basal sliding. A novel method here, relative to other AIS modeling literature, is an autocorrelation analysis of time series for (modeled) ice mass to find early-warning signs of impending tipping points. A precursor to tipping-point-type destabilization, proximately by classic marine-based ice-sheet retreat, appears to be prolonged surface lowering in response to warm air temperatures.


Latest news

Version 1.2

We are pleased to announce the release of the Parallel Ice Sheet Model (PISM) v1.2.

MPI-M Hamburg, Germany: open postdoc for coupled atmosphere-ocean-ice sheet model

The Max Planck Institute for Meteorology (MPI-M) contributes to the BMBF project “From the Last Interglacial to the Anthropocene: Modeling a Complete Glacial Cycle” (PalMod,, which aims at simulating the climate from the peak of the last interglacial up to the present using comprehensive Earth System Models. Phase II of this project has an open position Postdoctoral Scientist (W073). The successful candidate will be part of a local team performing and analysing long-term transient simulations covering the last glacial and the transition into the Holocene with an interactively coupled atmosphere-ocean-ice sheet model. Additionally, the candidate will contribute to the continued development of this model. The model system consists of the MPI-Earth system model, the ice sheet model PISM, and the solid-earth model VILMA.

AWI PostDoc: Antarctic Ice Sheets in warming climates

Dr. Lohmann’s group at AWI is seeking a postdoc to work with PISM and the multi-scale Earth system model AWI-ESM. See