Future Sea Level Change Under Coupled Model Intercomparison Project Phase 5 and Phase 6 Scenarios From the Greenland and Antarctic Ice Sheets

Antony J Payne,Ayako Abe‐Ouchi,Martin Rückamp,Heiko Goelzer,Christopher M Little,Sophie Nowicki,Tong Zhang,Xavier Fettweis,Andy Aschwanden,Eric Larour,Thomas Kleiner,Aurélien Quiquet,Ronja Reese,Torsten Albrecht,Michiel Van Den Broeke,Tyler Pelle,Frank Pattyn,Daniel P Lowry,William H Lipscomb,Matthew J Hoffman,Thomas Zwinger,Donald Slater,Xylar Asay‐Davis,Ralf Greve,Isabel Nias,Sainan Sun,Peter Kuipers Munneke,Philippe Huybrechts,Patrick Alexander,Andrew Shepherd,Ricarda Winkelmann,Victoria Lee,Nicholas R Golledge,Jonathan M Gregory,Christopher Chambers,Fiammetta Straneo,Luke D Trusel,Angelika Humbert,Jonas Van Breedam,Erika Simon,Joshua Cuzzone,Thomas J Bracegirdle,Nicolas C Jourdain,Cécile Agosta,Youngmin Choi,Gunter Leguy,Nicole‐Jeanne Schlegel,Reinhard Calov,Alice Barthel,Christophe Dumas,Tore Hattermann,Denis Felikson,Mathieu Morlighem,Rupert Gladstone,Lev Tarasov,Chen Zhao,Benjamin K Galton‐Fenzi ,H L Seroussi ,Tamsin Edwards ,Stephen Price ,Sébastien Le Clec’h ,R S W Van De Wal ,Richard I Cullather ,Robin Smith

doi:10.1029/2020gl091741

Abstract

AbstractProjections of the sea level contribution from the Greenland and Antarctic ice sheets (GrIS and AIS) rely on atmospheric and oceanic drivers obtained from climate models. The Earth System Models participating in the Coupled Model Intercomparison Project phase 6 (CMIP6) generally project greater future warming compared with the previous Coupled Model Intercomparison Project phase 5 (CMIP5) effort. Here we use four CMIP6 models and a selection of CMIP5 models to force multiple ice sheet models as part of the Ice Sheet Model Intercomparison Project for CMIP6 (ISMIP6). We find that the projected sea level contribution at 2100 from the ice sheet model ensemble under the CMIP6 scenarios falls within the CMIP5 range for the Antarctic ice sheet but is significantly increased for Greenland. Warmer atmosphere in CMIP6 models results in higher Greenland mass loss due to surface melt. For Antarctica, CMIP6 forcing is similar to CMIP5 and mass gain from increased snowfall counteracts increased loss due to ocean warming.

Highlights

The overall aim of this paper is to assess whether the stronger future warming shown by many Coupled Model Intercomparison Project phase 6 (CMIP6) models (Forster et al, 2019; Meehl et al, 2020) compared with CMIP5 has a significant impact on future Global Mean Sea Level Rise (GMLSR)
Details of the experimental protocols employed can be found in Nowicki et al (2016) and Nowicki et al (2020) and employed a carefully chosen sub-sample of six CMIP5 models for each ice sheet
These protocols were primarily employed by ice sheet modelling groups to generate projections using forcing from the CMIP5 ensemble, which are reported in Goelzer et al (2020b) for GrIS and Seroussi et al (2020) for AIS, groups conducted experiments using forcing from the CMIP6 ensemble as summarised in Tables 1 and 2

Summary

Introduction

The overall aim of this paper is to assess whether the stronger future warming shown by many CMIP6 models (Forster et al, 2019; Meehl et al, 2020) compared with CMIP5 has a significant impact on future Global Mean Sea Level Rise (GMLSR). Goelzer et al (2020b) and Seroussi et al (2020) present detailed analyses of the latter set of experiments for GrIS and AIS, respectively In both cases, a great deal of attention was paid to sampling the CMIP5 ensemble effectively, so that the CMIP5 models used to provide climate forcing both represented the presentday climate of the ice sheets well and sampled the range of future projections of the overall ensemble. A great deal of attention was paid to sampling the CMIP5 ensemble effectively, so that the CMIP5 models used to provide climate forcing both represented the presentday climate of the ice sheets well and sampled the range of future projections of the overall ensemble Details of this procedure can be found in Barthel et al (2020). Global warming as manifested in regional atmospheric and oceanic change can impact the ice sheet mass budget, and contribution to GMSLR, in a number of ways

Objectives

Discussion

Conclusion