# ISMIP6 wiki page

Welcome to the Ice Sheet Model Intercomparison Project for CMIP6 (ISMIP6) wiki! You are encouraged to use the wiki pages to alter the formulation of numerical experiments, point out any inconsistencies or inaccuracies you find in the data sets, and post results and figures that you'd like others see and discuss. ISMIP6 also has a more official homepage, kindly hosted by CliC.

## What is ISMIP6?

The overall framework for ISMIP6 is designed to deliver projections of the ice sheet contribution to sea level rise. ISMIP6 brings together for the first time a consortium of international ice sheet models and coupled ice sheet – climate models. This effort will thoroughly explore the sea level contribution from the Greenland and Antarctic Ice Sheet in our changing climate and assess the impact of large ice sheets on the climate system. Together with the new glacier CliC (Climate and Cryosphere) targeted activity and projections of thermal expansion (that already sit within the CMIP Coupled Model Intercomparison Project framework), this will allow sea level to become part of the family of variables for which CMIP can provide routine IPCC-style projections. ISMIP6 is explicitly designed to ensure that ice sheet (hence sea level) projections are fully compatible with the CMIP6 (Coupled Model Intercomparison Project-Phase 6) process. ISMIP6 also provides the basis for investigating the feedbacks, impacts, and sea level changes associated with dynamic ice sheets and for quantifying the uncertainty in ice-sheet-sourced global sea level change.

The proposed experiments will both use and augment the CMIP6-DECK (Diagnostic Evaluation and Characetization of Klima), Historical and ScenarioMIP experiments, as summarized in the table below. ISMIP6 will use the standard CMIP AGCM (Atmosphere General Circulation Models) and AOGCM (Atmosphere-Ocean General Circulation Models) experiments for analysis of the climate over and surrounding the ice sheets, and as forcing for the standalone ice sheet models (ISM) projections. Additional sensitivity experiments will be performed with the ISM to investigate the uncertainty associated with these projections arising from ice sheet models. The key output will be an ensemble of historical and future estimates of ice sheet contribution to sea level. To address the feedbacks introduced by interactive ice sheets, we propose that a small number of selected DECK experiments are repeated with coupled AOGCM-ISM, where the ice sheet is an interactive component of the AOGCM. Our assessment of the state of existing AOGCMs is that coupled models including an interactive Greenland ice sheet can realistically be expected for CMIP6, however including the Antarctic ice sheet remains challenging (because of the greater complexity of its response to climate forcing, and the issues associated with simulations of the Southern Ocean). It is for these reasons that ISMIP6 heavily relies on standalone ice sheet models driven offline by CMIP6 climate models for projections of sea level.

 Existing CMIP exp. used by ISMIP6 (AGCM-AOGCM only, no dynamic ice sheet required) New ISMIP6 CMIP6 exp. (Coupled AOGCM-ISM) Standalone ISMIP6 ice sheet model exp. (ISM only) Pre-Industrial Control (piControl) Pre-Industrial Control (piControl-withism) ISM control (piControlforcedism) 1% $\text{yr}^-1$ COTemplate:Sub to quadrupling CO2 (1pctCo2) 1% yr CO2 to quadrupling CO2 (1pctCo2withism) ISM forced by 1pctCo2 (1pctCo2forcedism) for quantification of feedback ScenarioMIP SSP5-8.5 up to year 2300 (ssp5-8.5) ScenarioMIP SSP5-8.5 up to year 2300 (ssp5-8.5withism) ISM for 21st century and up to 2300 sea level forced by ScenarioMIP ssp5-8.5 (ssp5-8.5forcedism) AMIP simulation (amip) ISM for last few decades forced by amip (amipforcedism) CMIP6 Historical Simulation (historical) ISM for the historical period forced by historical (historicalforcedism) Last Interglacial at 127 ky BP (lig127k) ISM for the last interglacial period forced by lig127k (lastInterglacialforcedism) Other ISMIP6 specific experiments to explore uncertainty due to ISM.

## ISMIP6 activities

ISMIP6 Standalone Ice Sheet Experiments > These pages describes the experimental setup for the standalone ice sheet model simulations.

ISMIP6 Coupled Ice Sheet Climate Experiments > This page describes the experimental setup for the coupled ice sheet-climate model simulations

ISMIP6 Meetings > Use this page to find out when and where our next meeting will be!

## ISMIP6 resources

This page describes Datasets that whole ice sheet models can use.