1. Ice Sheet Breakout Group Participants: David Holland (scribe) Gudfinna Adalgeirsdottir Patrick Heimbach Ralf Doscher Cornelia Koberle Erica Key

2. Why Include Greenland Ice Sheet (GIS) in ASM? IPCC did not address sea level predictions relating to dynamic glacier response Also (smaller glaciers) not inclued in IPCC ASM with GIS could address this question

3. Why Include Greenland Ice Sheet (GIS) in ASM? Realistic freshwater runoff from GIS to ocean

4. Why Include Greenland Ice Sheet (GIS) in ASM? Global models can do climate prediction but not processes (requiring high res.) ASM can do high res. process studies.

5. Inventory of existing ice sheet models Simple versus complex (shallow ice approximation versus higher order) Simple (not able to simulate fast ice streams) – SICOPOLIS – Glimmer Complex (better, but still missing physics) – CISM-Glimmer – PISM

6. Inventory of existing ice sheet models (At least ) these model available: Simple (not able to simulate fast ice streams) – SICOPOLIS (DMI: coupled ice sheet – atmos.) – Glimmer (used in EU project Ice2Sea) Complex (better, but still missing physics) – CISM-Glimmer (used in US project SeaRise + CCSM) – PISM

7. Interfacing ice sheet model to ASM (coupled physics) initialisation of ice sheets: – hard because long time scales (100,000+ years) surface coupling: unique surface processes, e.g.: – firn densification – surface meltwater refreezing (e.g. moulins!) lateral coupling requires wetting & drying of oceans (grounding line migration) - hard narrow fjords & outlet glaciers require very high resolution O(1 km)

8. Interfacing ice sheet model to ASM (coupled software) standardized interfaces should both EU couplers (OASIS) and US couplers (CPL7, ESMF) be standard? adaptive grids?

9. Interfacing ice sheet model to ASM (un-coupled) Some questions may be more easily addressed without coupling feedbacks – e.g. ocean hosing experiments BUT: assumes that changed ocean, does not affect glacier

10. Data Assimilation for ice sheet model Data sources extremely inhomogeneous DA formal way to synthesize all data to gain dynamical consistent picture DA formal way for parameter estimation – e.g. calving front – e.g. (unknown) basal boundary conditions

11. Paleo Experiments? the natural time scale for ice sheets capability to do regional high res. Paleo simulations to compare with paleo proxies test hypothesis limitation: only time slices are possible