Greenland Ice Sheet Contribution to 21st Century Sea Level Rise as Simulated by the Coupled CESM2.1‐CISM2.1

Laura Muntjewerf,Jan T M Lenaerts,Sarah L Bradley,Miren Vizcaino,Raymond Sellevold,Marcus Lofverstrom,Katherine Thayer‐Calder,Michele Petrini,Meike D W Scherrenberg,Carolina Ernani Da Silva,William H Lipscomb

doi:10.1029/2019gl086836

Abstract

AbstractThe Greenland Ice Sheet (GrIS) mass balance is examined with an Earth system/ice sheet model that interactively couples the GrIS to the broader Earth system. The simulation runs from 1850 to 2100, with historical and SSP5‐8.5 forcing. By the mid‐21st century, the cumulative GrIS contribution to global mean sea level rise (SLR) is 23 mm. During the second half of the 21st century, the surface mass balance becomes negative in all drainage basins, with an additional SLR contribution of 86 mm. The annual mean GrIS mass loss in the last two decades is 2.7‐mm sea level equivalent (SLE) year−1. The increased SLR contribution from the surface mass balance (3.1 mm SLE year−1) is partly offset by reduced ice discharge from thinning and retreat of outlet glaciers. The southern GrIS drainage basins contribute 73% of the mass loss in mid‐century but 55% by 2100, as surface runoff increases in the northern basins.

Highlights

During the past two decades, the Greenland Ice Sheet (GrIS) has lost mass at an increasing rate (Shepherd et al, 2019) and has become a major contributor to global mean sea level rise (SLR) (Chen et al, 2017)
The Greenland Ice Sheet (GrIS) mass balance is examined with an Earth system/ice sheet model that interactively couples the GrIS to the broader Earth system
This paper presents the CESM2.1-CISM2.1 projection of 21st century global climate change and GrIS response, as well as the projected GrIS contribution to global mean sea level

Summary

Introduction

During the past two decades, the Greenland Ice Sheet (GrIS) has lost mass at an increasing rate (Shepherd et al, 2019) and has become a major contributor to global mean sea level rise (SLR) (Chen et al, 2017). The polar ice sheets were identified in the IPCC Fifth Assessment Report as large sources of uncertainty in 21st century SLR projections (Church et al, 2013). The uncertainty in SLR stems partly from insufficient understanding of the complex interactions and feedbacks among ice sheets, surface mass balance (SMB), and climate (Fyke et al, 2018), highlighting the importance of studies with coupled Earth system/ice sheet models (Goelzer et al, 2017; Vizcaino, 2014).

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Conclusion