Ice Sheet Model Intercomparison Project (ISMIP6) contribution to CMIP6.

Sophie M J Nowicki,Ayako Abe-Ouchi,Eric Larour,Anthony Payne,Heiko Goelzer,Jonathan Gregory,Helene Seroussi,William Lipscomb,Andrew Shepherd

doi:10.5194/gmd-9-4521-2016

Abstract

Reducing the uncertainty in the past, present and future contribution of ice sheets to sea-level change requires a coordinated effort between the climate and glaciology communities. The Ice Sheet Model Intercomparison Project for CMIP6 (ISMIP6) is the primary activity within the Coupled Model Intercomparison Project - phase 6 (CMIP6) focusing on the Greenland and Antarctic Ice Sheets. In this paper, we describe the framework for ISMIP6 and its relationship to other activities within CMIP6. The ISMIP6 experimental design relies on CMIP6 climate models and includes, for the first time within CMIP, coupled ice sheet - climate models as well as standalone ice sheet models. To facilitate analysis of the multi-model ensemble and to generate a set of standard climate inputs for standalone ice sheet models, ISMIP6 defines a protocol for all variables related to ice sheets. ISMIP6 will provide a 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.

Highlights

Ice sheets constitute the largest and most uncertain potential source of future sea-level rise (Church et al, 2013; Kopp et al, 2014)
Feedbacks, long responses and coupled atmosphere–ocean general circulation models (AOGCMs) over and surrounding the polar ice sheets. This part of Intercomparison Project for Coupled Model Intercomparison Project – phase 6 (CMIP6) (ISMIP6) can be viewed as diagnostic in the sense that all climate models that participate in CMIP6 will be included in this assessment without requiring extra work from the climate modeling centers
This framework works toward the goals of (i) assessing the effect of including dynamic ice sheets in climate models and (ii) improving confidence in projections of sea-level rise associated with mass loss from the Greenland and Antarctic ice sheets

Summary

Introduction

Ice sheets constitute the largest and most uncertain potential source of future sea-level rise (Church et al, 2013; Kopp et al, 2014). Observations indicate that the Greenland and Antarctic ice sheets have contributed approximately 7.5 and 4 mm of sea-level rise over the 1992–2011 period (Shepherd et al, 2012) and that their contribution to sea-level rise is accelerating (Rignot et al, 2011a). Assessing whether the observed rate of mass loss from the ice sheets will continue at the same pace, or accelerate, is crucial for risk assessment and adaptation efforts. In addition to their impact on sea-level change, ice sheets influence the Earth’s climate through changes in freshwater fluxes, orography, surface albedo, and vegetation cover, across multiple spatial and temporal scales (Vizcaíno, 2014). Ice-sheet evolution and iceberg discharge affect ocean freshwater fluxes (e.g., Broecker, 1994), which in turn can affect

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