ICE-6G
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| ICE-6G | |
|---|---|
| Name | ICE-6G |
| Developer | NASA, University of Tasmania, Utrecht University |
| Initial release | 2013 |
| Latest release | 2013 |
| Type | Glacial isostatic adjustment model |
| License | Proprietary/academic |
ICE-6G is a glacial isostatic adjustment (GIA) and global ice-sheet reconstruction used in geodesy, paleoclimate, and Earth-system science. It provides time-dependent ice thickness, surface elevation, and continental water storage for the Late Pleistocene and Holocene, informing studies across International Association of Geodesy, Intergovernmental Panel on Climate Change, and National Oceanic and Atmospheric Administration communities. The model underpins analyses in GPS, GRACE, and sea-level rise research.
Overview
ICE-6G reconstructs the spatiotemporal evolution of continental ice sheets and associated sea-level changes from the Last Glacial Maximum to the present, integrating constraints from radiocarbon dating, varves, luminescence dating, marine sediment cores, and cosmogenic nuclide records. The framework is widely used by researchers at institutions such as Cambridge University, Princeton University, Harvard University, and Massachusetts Institute of Technology to interpret signals in datasets from missions like Gravity Recovery and Climate Experiment and GRACE Follow-On. ICE-6G outputs feed into studies referencing IPCC Fifth Assessment Report, IPCC Sixth Assessment Report, and assessments by the United Nations Framework Convention on Climate Change.
Development and Methodology
Development combined expertise from teams led by researchers at University of Melbourne, University of Toronto, and Australian National University with collaborators at NASA Goddard Space Flight Center and European Space Agency. Methodologically, ICE-6G couples ice-sheet reconstructions with viscoelastic Earth models described in literature from Lambert Glacier/Antarctica studies and works citing James H. Adams-style rheology (note: author examples). Input datasets include ice-margin chronologies from North American Ice Sheet Complex, Laurentide Ice Sheet, Fennoscandian Ice Sheet, and Antarctic compilations used by International Polar Year projects. Computational techniques draw on approaches implemented in codes developed at University of California, Santa Cruz and ETH Zurich for loading history inversion, employing viscosity profiles inspired by studies from Scripps Institution of Oceanography and Woods Hole Oceanographic Institution.
Ice Sheet and Glacial History Reconstructions
ICE-6G provides reconstructions for major ice bodies: the Laurentide Ice Sheet, Fennoscandian Ice Sheet, Cordilleran Ice Sheet, Greenland Ice Sheet, and portions of the Antarctic Ice Sheet. Output chronologies align with stratigraphic records from North Atlantic Ocean cores, terrestrial datasets from Great Lakes, Scandinavia, and Iceland, and geomorphological evidence cataloged by United States Geological Survey and Geological Survey of Canada. The reconstruction synthesizes sea-level indicators such as coral reefs, barrier islands, and shelf sedimentation documented in regional studies across Mediterranean Sea, Baltic Sea, and Bering Sea margins.
Geophysical and Climatic Applications
ICE-6G is applied to interpret geodetic signals measured by Global Positioning System, VLBI, and Satellite Laser Ranging networks, and gravity variations observed by GRACE. It informs crustal deformation models used in analyses associated with Plate Tectonics features like the Mid-Atlantic Ridge and passive margins near Eastern Canada. Climate research groups at NOAA Geophysical Fluid Dynamics Laboratory, Met Office Hadley Centre, and Lamont–Doherty Earth Observatory use ICE-6G boundary conditions to force coupled models such as CMIP5 and CMIP6 experiments, linking paleo-ice history to paleoclimate records from Greenland Ice Core Project and EPICA cores. Sea-level change reconstructions using ICE-6G have been cited in regional impact studies by agencies including UNESCO and World Meteorological Organization.
Model Validation and Comparisons
Validation against independent proxies involves comparisons with datasets from Holocene sea-level indicators, tree-ring chronologies, and peat stratigraphy compiled in regional atlases by NOAA and PAGES. ICE-6G is often benchmarked against alternative reconstructions such as GLAC-1D, Peltier’s ICE-5G, and models developed by groups at Utrecht University and University of Toronto. Intercomparisons examine fit to GPS uplift rates, relative sea level curves from British Isles, Mediterranean, and North American databases, and gravity trend residuals in analyses published in journals including Nature, Science, and Journal of Geophysical Research.
Limitations and Uncertainties
Uncertainties stem from sparse chronological constraints in regions like Antarctic Peninsula and Siberia, assumptions about Earth rheology inferred from seismic tomography by groups at Caltech and ETH Zurich, and limited resolution of past ice-margin positions documented by British Antarctic Survey and Scott Polar Research Institute. Limitations include simplifications in ice dynamics relative to full thermomechanical models used by teams at University of Oslo and Los Alamos National Laboratory, and sensitivity to choices of mantle viscosity profiles cited in work by Yale University researchers. As a result, regional sea-level predictions constrained by ICE-6G carry uncertainties addressed in assessment reports by IPCC and regional panels of the International Union for Quaternary Research.