Documentation for PISM, the Parallel Ice Sheet Model

NEWS: PISM version 1.0 is out!

PISM v1.0


Modeled ice flow speed on the Olympic Peninsula, Washington state, USA, for conditions near the LGM.

The Parallel Ice Sheet Model PISM v1.0 is open source and capable of high resolution. It has been widely adopted as a tool for doing science.

Features include:

Application of the Month

December 2017

Reconstructions of the time-dependent geometry of ice sheets over the last ice-age cycle (100kyr) can draw from two categories of data. On one hand there are constraints from observations of GIA (glacial isostatic adjustment) and of eustatic sea-level through marine sediment stratigraphy. These are constraints on ice geometry but via temporal and/or spatial integration. On the other hand there is high temporal resolution, but geographically local, information in ice cores about climate over the same period. The former category informs the output (ice thickness and grounding line) of the ice sheet evolution equations while the later inform the input (source term).

Like Stuhne & Peltier (2015), this paper connects the two categories using PISM. Because climate-record-driven applications of PISM, such as the SeaRISE project, already use well-posed simulations, a reconciliation of the two data categories is necessarily a temporal/spatial inversion. Here the goal is close fit to the GIA+eustatic-record-based ICE-6G_C ice thickness reconstruction from tuned (“nudged”) climate-input-driven PISM runs. These authors analyze the amount of surface mass balance correction, applied using hypothesized characteristic time scales, needed to reduce the error between PISM output and ICE-6G_C. An example of the usefulness of this methodology is in diagnosing the origin of Meltwater Pulse 1B (-11kyr). They suggest it is more likely to have been in North America than in Antarctica, its origin in the ICE-6G_C reconstruction.

2017/12/19 17:16 · Ed Bueler

Latest News


LARMIP is the Linear Antarctic Response to basal melting Model Intercomparison Project. PISM is one of several participating models. The goal is to use the newest models to compute a linear-response sea level contribution to inform the IPCC-AR6. Find all necessary materials at

2017/11/26 19:56 · Ed Bueler

PhD opportunity in ice-ocean interaction (modeling)

The Geophysical Institute of the University of Alaska Fairbanks is seeking a PhD student for the recently funded NSF project “Understanding the controls on spatial and temporal variability in ice discharge using a Greenland-wide ice sheet model”. The overall goal of this project is to develop novel parameterizations of ice-ocean interaction that are suitable for large scale ice-sheet modeling. The interdisciplinary project is co-led by Andy Aschwanden (UAF; ice sheet modeling) and Patrick Heimbach (U Texas at Austin, ocean modeling) and comprises two PhD positions, one focussing on the ocean side (see separate announcement) and the other on the ice sheet side (this posting). The student here at UAF will implement and test parameterizations within the framework of the Parallel Ice Sheet Model (PISM) but will closely collaborate with U Texas, including mutual visits.

We seek motivated candidates with a degree (preferably a M.Sc. or equivalent) in geosciences, physics, mathematics, engineering or related fields. Basic experience in numerical modeling, good oral and written communication skills are a prerequisite.

For more information, please contact Andy Aschwanden (

2017/11/21 09:32 · Ed Bueler

Openhub's summary of the PISM project

We think PISM has pretty-good open-source-software cred. But don't take our word for it. Here is the automatically-generated nutshell (here, on 4 November 2017) at

In a Nutshell, Parallel Ice Sheet Model (PISM)…

  • has had 6,867 commits made by 21 contributors representing 76,716 lines of code
  • is mostly written in C++ , with a well-commented source code
  • has a well established, mature codebase, maintained by a large development team, with stable Y-O-Y [year-on-year] commits
  • took an estimated 19 years of effort (COCOMO model), starting with its first commit in September, 2006, ending with its most recent commit 2 days ago
2017/11/04 23:28 · Ed Bueler

PISM v1.0 is out

This release has substantial changes to the code base, but users will not see many large differences. The goal of most code changes was to improve modularity and usability, making PISM easier to use, maintain and extend.

User-visible changes include the following.

  • New mass transport code makes it easier to “balance the books”.
  • PISM's grids are no longer transposed (y,x versus x,y).
  • Adds an optimized implementation of the GPBLD flow law for the Glen n=3 case.
  • Adds von Mises calving.
  • Adds more diagnostic quantities (127 spatially-variable fields and 38 scalar variables in total).
  • Better code, better documentation, more regression and verification tests.

For a more complete list of changes since v0.7, please see CHANGES.rst in the source release.

If you already have a Git repository for PISM then upgrade by doing

git fetch origin
git checkout master

in the PISM source tree. (Or get a new tagged .tar.gz or .zip at Then run

make install

in the build directory.

Please see the Installation Manual for detailed instructions.

Help with installation and usage is available through

2017/10/19 18:16 · Constantine Khroulev


PISM is jointly developed at the University of Alaska, Fairbanks (UAF) and the Potsdam Institute for Climate Impact Research (PIK). For more about the team see the UAF Developers and PIK Developers pages.

UAF developers, who are in the Glaciers Group at the GI, are supported by NASA's Modeling, Analysis, and Prediction and Cryospheric Sciences Programs (grants NAG5-11371, NNX09AJ38C, NNX13AM16G, NNX16AQ40G, NNX17AG65G) and by NSF grants PLR-1603799 and PLR-1644277.

home.txt · Last modified: 2018/09/20 15:49 by Ed Bueler
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