Article (Scientific journals)
Diverging future surface mass balance between the Antarctic ice shelves and grounded ice sheet
Kittel, Christoph; Amory, Charles; Agosta, Cécile et al.
2021In The Cryosphere, 15 (3), p. 1215-1236
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Keywords :
SMB; Antarctic; future
Abstract :
[en] The future surface mass balance (SMB) will influence the ice dynamics and the contribution of the Antarctic ice sheet (AIS) to the sea level rise. Most of recent Antarctic SMB projections were based on the fifth phase of the Coupled Model Intercomparison Project (CMIP5). However, new CMIP6 results have revealed a +1.3 ∘C higher mean Antarctic near-surface temperature than in CMIP5 at the end of the 21st century, enabling estimations of future SMB in warmer climates. Here, we investigate the AIS sensitivity to different warmings with an ensemble of four simulations performed with the polar regional climate model Modèle Atmosphérique Régional (MAR) forced by two CMIP5 and two CMIP6 models over 1981–2100. Statistical extrapolation enables us to expand our results to the whole CMIP5 and CMIP6 ensembles. Our results highlight a contrasting effect on the future grounded ice sheet and the ice shelves. The SMB over grounded ice is projected to increase as a response to stronger snowfall, only partly offset by enhanced meltwater run-off. This leads to a cumulated sea-level-rise mitigation (i.e. an increase in surface mass) of the grounded Antarctic surface by 5.1 ± 1.9 cm sea level equivalent (SLE) in CMIP5-RCP8.5 (Relative Concentration Pathway 8.5) and 6.3 ± 2.0 cm SLE in CMIP6-ssp585 (Shared Socioeconomic Pathways 585). Additionally, the CMIP6 low-emission ssp126 and intermediate-emission ssp245 scenarios project a stabilized surface mass gain, resulting in a lower mitigation to sea level rise than in ssp585. Over the ice shelves, the strong run-off increase associated with higher temperature is projected to decrease the SMB (more strongly in CMIP6-ssp585 compared to CMIP5-RCP8.5). Ice shelves are however predicted to have a close-to-present-equilibrium stable SMB under CMIP6 ssp126 and ssp245 scenarios. Future uncertainties are mainly due to the sensitivity to anthropogenic forcing and the timing of the projected warming. While ice shelves should remain at a close-to-equilibrium stable SMB under the Paris Agreement, MAR projects strong SMB decrease for an Antarctic near-surface warming above +2.5 ∘C compared to 1981–2010 mean temperature, limiting the warming range before potential irreversible damages on the ice shelves. Finally, our results reveal the existence of a potential threshold (+7.5 ∘C) that leads to a lower grounded-SMB increase. This however has to be confirmed in following studies using more extreme or longer future scenarios.
Research center :
Sphères - SPHERES
Disciplines :
Earth sciences & physical geography
Author, co-author :
Kittel, Christoph  ;  Université de Liège - ULiège > Département de géographie > Climatologie et Topoclimatologie
Amory, Charles 
Agosta, Cécile
Jourdain, Nicolas C
Hofer, Stefan
Delhasse, Alison ;  Université de Liège - ULiège > Département de géographie > Climatologie et Topoclimatologie
Doutreloup, Sébastien  ;  Université de Liège - ULiège > Département de géographie > Climatologie et Topoclimatologie
Huot, Pierre-Vincent
Lang, Charlotte
Fichefet, Thierry
Fettweis, Xavier  ;  Université de Liège - ULiège > Département de géographie > Climatologie et Topoclimatologie
Language :
English
Title :
Diverging future surface mass balance between the Antarctic ice shelves and grounded ice sheet
Publication date :
2021
Journal title :
The Cryosphere
ISSN :
1994-0416
eISSN :
1994-0424
Publisher :
Copernicus, Katlenberg-Lindau, Germany
Special issue title :
The Ice Sheet Model Intercomparison Project for CMIP6 (ISMIP6)
Volume :
15
Issue :
3
Pages :
1215-1236
Peer reviewed :
Peer Reviewed verified by ORBi
Tags :
CÉCI : Consortium des Équipements de Calcul Intensif
European Projects :
H2020 - 869304 - PROTECT - PROjecTing sEa-level rise : from iCe sheets to local implicaTions
Funders :
F.R.S.-FNRS - Fonds de la Recherche Scientifique [BE]
CÉCI - Consortium des Équipements de Calcul Intensif [BE]
UE - Union Européenne [BE]
CE - Commission Européenne [BE]
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