ICESHEET - a program to create ice sheet reconstructions

Written by Evan J. Gowan (evangowan@gmail.com)

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Version 2.0:
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This version of the code has minor changes to the core component of the program, mainly through loading up the topography and shear stress grids from memory. This results in a substantial increase in computation speed. The main component is a global setup to calculate ice sheets through time, located in the folder global/. This setup has margin reconstructions at 2500 year time intervals for the past 80000 years, and includes the North American, Eurasian, Patagonian and Antarctic ice sheets. 

In order to generate the reconstructions, you first need to run the script "run.sh", which generates the files needed to run ICESHEET. Within run.sh, you can modify which ice sheet you want to calculate, and which times you want to calculate. You also need to modify the settings for the Earth deformation and sea level change file. After you run "run.sh", the running the scripts "run_parallel.sh" or "run_serial.sh" will calculate the ice sheets. If running in parallel, you can change the number of processors within the script. Note, the parallel script requires you to install GNU Parallel.

In order to run with deformed topography, you need to put the deformation grid into the folder deform/. Instructions on how to format the file are in the readme file in that folder.

Make sure to compile icesheet and create_ss_grid before running the scripts!

These scripts make heavy use of Generic Mapping Tools (https://www.generic-mapping-tools.org/), so make sure it is installed before you run the scripts. I have been using GMT 5.4.5, but I assume version 6 will also work (but untested!).

The margin files and shear stress domains and values contained in ICESHEET 2.0 were used to create PaleoMIST 1.0. if you download the Earth deformation files from PaleoMIST 1.0 and put them in the deform/ folder, you can recalculate the ice sheet recontructions. You can download PaleoMIST 1.0 from here: https://doi.pangaea.de/10.1594/PANGAEA.905800

If you use ICESHEET 2.0, please cite the following papers, in addition to the GMD paper:

Gowan, E.J., Zhang, X., Khosravi, S., Rovere, A., Stocchi, P., Hughes, A.L.C., Gyllencreutz, R., Mangerud, J., Svendsen, J.-I., and Lohmann, G., 2021. A new global ice sheet reconstruction for the past 80000 years. Nature Communications, 12, 1199. https://doi.org/10.1038/s41467-021-21469-w

Gowan, E.J., Tregoning, P., Purcell, A., Lea, J., Fransner, O.J., Noormets, R. and Dowdeswell, J.A., 2016. ICESHEET 1.0: a program to produce paleo-ice sheet reconstructions with minimal assumptions. Geoscientific Model Development, 9(5), pp. 1673-1682, doi:10.5194/gmd-9-1673-2016

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Version 1.0:
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This is software to create perfectly plastic ice sheets. I used this to create reconstructions of the Laurentide Ice Sheet (see The NAICE model below). There is a paper on this in Geoscience Model Development. I have included a sample problem with the Greenland Ice Sheet with the scripts that should make it pretty easy to run the program. I usually modify these scripts to suit the problem I am working on. They require Generic Mapping Tools and NETCDF Tools. In particular, ICESHEET requires GMT formatted binary files as input for the basal shear stress and basal topography. Note if you downloaded the version of this file from the GMD website, I forgot to include the shapefiles needed to create the shear stress files, so download it again. Instructions to run this can be found on my website (https://raisedbeaches.net/2016/05/22/icesheet-1-0/).


If you are just starting out, go into the "Greenland_final" folder and run "run_everything.sh". It will check to make sure everything is installed correctly, and you can easily change parameters related to making reconstructions.

ICESHEET is written in Fortran. To compile, you will need to have automake and a Fortran compiler installed. By default it assumes you have gfortran, if you are using a different compiler, go into the makefile files and change it. Note that using the Intel Fortran compiler can result in a speed increase on the order of a factor of two for ICESHEET, if you have it, I definitely recommend it over gfortran!


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If you use this program, please cite the following paper:

Gowan, E.J., Tregoning, P., Purcell, A., Lea, J., Fransner, O.J., Noormets, R. and Dowdeswell, J.A., 2016. ICESHEET 1.0: a program to produce paleo-ice sheet reconstructions with minimal assumptions. Geoscientific Model Development, 9(5), pp. 1673-1682, https://doi.org/10.5194/gmd-9-1673-2016

For a detailed application with the Laurentide Ice Sheet (the NAICE model), see this paper:

Gowan, E.J., Tregoning, P., Purcell, A., Montillet, J.-P., and McClusky, S., 2016. A model of the western Laurentide Ice Sheet, using observations of glacial isostatic adjustment. Quaternary Science Reviews, 139, pp. 1-16, https://doi.org/10.1016/j.quascirev.2016.03.003

Adjustments to the Innuitian ice sheet were done by Sara Khosravi. Details can be found in her master's thesis. A paper is currently in preparation.

Khosravi, S., 2017. Comparison of the past climate in Northern Canada and Greenland. Master's Thesis, University of Bremen and Alfred Wegener Institute, Helmholtz Center for Polar and Marine Research, 70p.


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Here is a list of papers that have made use of ICESHEET in some way (in chronological order). Please let me know if you have used this program and I will add it to the list.

Sejrup, H.P., Hjelstuen, B.O., Patton, H., Esteves, M., Winsborrow, M., Rasmussen, T.L., Andreassen, K. and Hubbard, A., 2022. The role of ocean and atmospheric dynamics in the marine-based collapse of the last Eurasian Ice Sheet. Communications Earth & Environment, 3(1), pp.1-10. https://doi.org/10.1038/s43247-022-00447-0

Simms, A.R., Best, L., Shennan, I., Bradley, S.L., Small, D., Bustamante, E., Lightowler, A., Osleger, D. and Sefton, J., 2022. Investigating the roles of relative sea-level change and glacio-isostatic adjustment on the retreat of a marine based ice stream in NW Scotland. Quaternary Science Reviews, 277, p.107366. https://doi.org/10.1016/j.quascirev.2021.107366

Clark, C.D., Chiverrell, R.C., Fabel, D., Hindmarsh, R.C., Ó Cofaigh, C. and Scourse, J.D., 2021. Timing, pace and controls on ice sheet retreat: an introduction to the BRITICE‐CHRONO transect reconstructions of the British–Irish Ice Sheet. Journal of Quaternary Science, 36(5), pp.673-680. https://doi.org/10.1002/jqs.3326

Lin, Y., Hibbert, F.D., Whitehouse, P.L., Woodroffe, S.A., Purcell, A., Shennan, I. and Bradley, S.L., 2021. A reconciled solution of Meltwater Pulse 1A sources using sea-level fingerprinting. Nature communications, 12(1), pp.1-11. https://doi.org/10.1038/s41467-021-21990-y

Wilton, D.J., Bigg, G.R., Scourse, J.D., Ely, J.C. and Clark, C.D., 2021. Exploring the extent to which fluctuations in ice‐rafted debris reflect mass changes in the source ice sheet: a model–observation comparison using the last British–Irish Ice Sheet. Journal of Quaternary Science. https://doi.org/10.1002/jqs.3273

Gandy, N., Gregoire, L.J., Ely, J.C., Cornford, S.L., Clark, C.D. and Hodgson, D.M., 2020. Collapse of the last Eurasian Ice Sheet in the North Sea modulated by combined processes of ice flow, surface melt, and marine ice sheet instabilities. Journal of Geophysical Research: Earth Surface, p.e2020JF005755. https://doi.org/10.1029/2020JF005755

Hinck, S., Gowan, E.J. and Lohmann, G., 2020. LakeCC: a tool for efficiently identifying lake basins with application to palaeogeographic reconstructions of North America. Journal of Quaternary Science, 35(3), pp.422-432. https://doi.org/10.1002/jqs.3182

Gandy, N., Gregoire, L.J., Ely, J.C., Clark, C.D., Hodgson, D.M., Lee, V., Bradwell, T. and Ivanovic, R.F., 2018. Marine ice sheet instability and ice shelf buttressing of the Minch Ice Stream, northwest Scotland. The Cryosphere, 12(11), pp.3635-3651. https://doi.org/10.5194/tc-12-3635-2018

Kirchner, N., van Dongen, E., Gowan, E.J., Pattyn, F., Noormets, R., Jakobsson, M. and Ingólfsson, Ó., 2018. GRANTSISM: An Excel™ ice sheet model for use in introductory Earth science courses. Journal of Geoscience Education, 66(2), pp.109-120. https://doi.org/10.1080/10899995.2018.1412177

Kirchner, N., Ahlkrona, J., Gowan, E.J., Lötstedt, P., Lea, J.M., Noormets, R., von Sydow, L., Dowdeswell, J.A. and Benham, T., 2016. Shallow ice approximation, second order shallow ice approximation, and full Stokes models: A discussion of their roles in palaeo-ice sheet modelling and development. Quaternary Science Reviews, 147, pp.136-147. https://doi.org/10.1016/j.quascirev.2016.01.032
