Article (Scientific journals)
Recent warming trends of the Greenland ice sheet documented by historical firn and ice temperature observations and machine learning
Vandecrux, Baptiste; Fausto, Robert S.; Box, Jason E. et al.
2024In The Cryosphere, 18 (2), p. 609-631
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Keywords :
Earth-Surface Processes; Water Science and Technology
Abstract :
[en] Abstract. Surface melt on the Greenland ice sheet has been increasing in intensity and extent over the last decades due to Arctic atmospheric warming. Surface melt depends on the surface energy balance, which includes the atmospheric forcing but also the thermal budget of the snow, firn and ice near the ice sheet surface. The temperature of the ice sheet subsurface has been used as an indicator of the thermal state of the ice sheet's surface. Here, we present a compilation of 4612 measurements of firn and ice temperature at 10 m below the surface (T10 m) across the ice sheet, spanning from 1912 to 2022. The measurements are either instantaneous or monthly averages. We train an artificial neural network model (ANN) on 4597 of these point observations, weighted by their relative representativity, and use it to reconstruct T10 m over the entire Greenland ice sheet for the period 1950–2022 at a monthly timescale. We use 10-year averages and mean annual values of air temperature and snowfall from the ERA5 reanalysis dataset as model input. The ANN indicates a Greenland-wide positive trend of T10 m at 0.2 ∘C per decade during the 1950–2022 period, with a cooling during 1950–1985 (−0.4 ∘C per decade) followed by a warming during 1985–2022 (+0.7 ∘ per decade). Regional climate models HIRHAM5, RACMO2.3p2 and MARv3.12 show mixed results compared to the observational T10 m dataset, with mean differences ranging from −0.4 ∘C (HIRHAM) to 1.2 ∘C (MAR) and root mean squared differences ranging from 2.8 ∘C (HIRHAM) to 4.7 ∘C (MAR). The observation-based ANN also reveals an underestimation of the subsurface warming trends in climate models for the bare-ice and dry-snow areas. The subsurface warming brings the Greenland ice sheet surface closer to the melting point, reducing the amount of energy input required for melting. Our compilation documents the response of the ice sheet subsurface to atmospheric warming and will enable further improvements of models used for ice sheet mass loss assessment and reduce the uncertainty in projections.
Research center :
SPHERES - ULiège [BE]
Disciplines :
Earth sciences & physical geography
Author, co-author :
Vandecrux, Baptiste 
Fausto, Robert S. 
Box, Jason E. 
Covi, Federico 
Hock, Regine 
Rennermalm, Åsa K. 
Heilig, Achim 
Abermann, Jakob 
van As, Dirk
Bjerre, Elisa 
Fettweis, Xavier  ;  Université de Liège - ULiège > Département de géographie > Climatologie et Topoclimatologie
Smeets, Paul C. J. P.
Kuipers Munneke, Peter 
van den Broeke, Michiel R. 
Brils, Max
Langen, Peter L. 
Mottram, Ruth 
Ahlstrøm, Andreas P. 
More authors (8 more) Less
Language :
English
Title :
Recent warming trends of the Greenland ice sheet documented by historical firn and ice temperature observations and machine learning
Publication date :
12 February 2024
Journal title :
The Cryosphere
ISSN :
1994-0416
eISSN :
1994-0424
Publisher :
Copernicus GmbH
Volume :
18
Issue :
2
Pages :
609-631
Peer reviewed :
Peer Reviewed verified by ORBi
Tags :
CÉCI : Consortium des Équipements de Calcul Intensif
Tier-1 supercomputer
Funders :
FWF - Austrian Science Fund [AT]
NSF - National Science Foundation [US-VA]
NESSC - Netherlands Earth System Science Centre [NL]
AU - Aarhus Universitet [DK]
DFG - Deutsche Forschungsgemeinschaft [DE]
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since 13 February 2024

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