What is our Focus Group About? 

Focus Group Statement (Task F2):

Although the net loss of ice from ice sheets to the ocean is a major contributor to historical and projected future sea-level rise, sea level does not change uniformly.  The Earth responds to changes in land ice mass through a combination of adjustments to its gravitational field and rotational axis, and viscoelastic deformation of the crust and mantle, termed Glacial Isostatic Adjustment (GIA). These GIA effects induce geographically varying distribution of melt water and result in regional sea-level change that can vary from the global mean rate by 50% or more.  In ISMIP6, intercomparison results were presented solely as equivalent changes to global mean sea level, and evaluation of regional sea-level effects were left to other researchers.  To improve upon the status quo, in this activity we propose to integrate the production of regional sea-level projections directly into the ISMIP7 project. This task will be done by processing the ice-sheet mass change output from the ISMIP7 experiments using GIA models to produce regional sea level projections. Similar to ice-sheet modeling, there are many groups engaged in GIA and sea-level modeling with differing methodologies and models of differing complexity.  In this activity we will organize an additional model intercomparison exercise to coordinate these groups to produce regional sea-level projections from the ISMIP7 ensemble.  This activity will include the following tasks: (a) Preparation of ISMIP7 output for use by sea-level models, (b) Developing and testing protocols, (c) Coordination and analysis of submissions from sea-level models with different complexity and fidelity. Our primary deliverable will be a publication summarizing projections of regional sea-level change caused by future ice-sheet changes, focusing on regional variability and uncertainty at critical coastal cities and regions.

Focus Group Goals:

1. Establish protocol for bedrock adjustment in ice-sheet models

2. Define methodology for calculating global mean sea-level contribution from ice sheets

3. Provide estimates of regional sea-level change