Delhasse et al. (2025) Exploring the Greenland Ice Sheet’s response to future atmospheric warming-threshold scenarios over 200 years

Identification

• Journal: ˜The œcryosphere
• Year: 2025
• Date: 2025-10-10
• Authors: Alison Delhasse, Christoph Kittel, Johanna Beckmann
• DOI: 10.5194/tc-19-4459-2025

Research Groups

• Laboratory of Climatology, Department of Geography, SPHERES research unit, University of Liège, Liège, Belgium
• Physical geography research group, Department geography, Vrije Universiteit Brussel, Brussels, Belgium
• IGE, Univ. Grenoble Alpes, IRD/CNRS/INRAE/Grenoble INP, Grenoble, France
• School of Earth, Atmosphere and Environment, Monash University, Clayton, Kulin Nations, Australia
• Potsdam-Institute for Climate Impact Research (PIK), Member of the Leibniz Association, Potsdam, Germany

Short Summary

This study uses a coupled regional atmospheric-ice sheet model (MAR-PISM) to project the Greenland Ice Sheet's response to various atmospheric warming scenarios and a climate reversal over 200 years, finding that warming beyond +1.4 °C triggers non-linear mass loss, but a rapid climate reversal can stabilize the ice sheet at a reduced state.

Objective

• To investigate the Greenland Ice Sheet's response to various atmospheric warming thresholds (from +0.6 °C to +5.8 °C relative to pre-industrial levels) over 200 years, and to assess its potential for stabilization or recovery if the climate reverts to present-day conditions after an overshoot, while excluding oceanic warming effects.

Study Configuration

• Spatial Scale: Greenland Ice Sheet. Regional atmospheric model (MAR) at 25 km resolution, ice sheet model (PISM) at 4.5 km resolution.
• Temporal Scale: 200 years (1991–2200) for coupled simulations, with PISM initiated in 1961.

Methodology and Data

• Models used: Coupled regional-atmospheric model Atmosphérique Régional Modèle (MAR v3.11.5) and Parallel Ice Sheet Model (PISM).
• Data sources: Atmospheric forcing derived from a Community Earth System Model version 2 (CESM2) simulation under the SSP5-8.5 scenario until 2100, extended to 2200 by randomly sampling 10-year periods to maintain constant mean warming. Ocean conditions were prescribed as unchanged.

Main Results

• Moderate atmospheric warming (+0.6 °C to +1.4 °C relative to pre-industrial levels) leads to a relatively stable Greenland Ice Sheet (GrIS) with sea level rise (SLR) contributions of +8.35 cm to +9.55 cm by 2200.
• Global temperature increases beyond +1.4 °C mark a critical threshold, triggering non-linear mass loss due to feedback mechanisms such as the melt–albedo effect and firn saturation.
• The increase in SLR between +1.4 °C and +2.3 °C warming scenarios is +7.56 cm, accelerating to +15.51 cm between +4.4 °C and +5.2 °C.
• Reversing the climate after exceeding +2.3 °C (e.g., from +5.8 °C in 2100 back to 2000 conditions by 2200) can substantially slow down GrIS mass loss, indicating a trend toward stabilization at a reduced state (approximately 4 % smaller ice sheet area).
• The GrIS exhibits hysteresis behavior, where its surface mass balance (SMB) does not return to initial values even if temperatures revert, due to lower albedo, firn saturation, and a thinner ice sheet.
• The time spent above a temperature threshold appears more critical for irreversible mass loss than the amplitude of the imbalance, within the 200-year timescale.

Contributions

• First study to use a fully coupled regional-atmospheric ice sheet model (MAR-PISM) to evaluate the GrIS response to atmospheric warming thresholds and a climate reversal over a policy-relevant 200-year timescale.
• Highlights the non-linear response of the GrIS to warming beyond +1.4 °C, emphasizing the crucial role of melt-albedo feedback and firn saturation.
• Demonstrates the potential for stabilizing GrIS mass loss at a reduced state through rapid climate reversal, even after overshooting critical temperature thresholds, challenging the notion of a single irreversible threshold.
• Provides insights into the combined effect of the magnitude and duration of warming on GrIS stability, showing that the length of time above a threshold is a critical determinant.

Funding

• Fonds de la Recherche Scientifique – FNRS
• Consortium des Équipements de Calcul Intensif (CÉCI) (grant no. 2.5020.11)

Citation

@article{Delhasse2025Exploring,
  author = {Delhasse, Alison and Kittel, Christoph and Beckmann, Johanna},
  title = {Exploring the Greenland Ice Sheet’s response to future atmospheric warming-threshold scenarios over 200 years},
  journal = {˜The œcryosphere},
  year = {2025},
  doi = {10.5194/tc-19-4459-2025},
  url = {https://doi.org/10.5194/tc-19-4459-2025}
}