Darnell et al. (2025) The interplay of future emissions and geophysical uncertainties for projections of sea-level rise

Identification

• Journal: Nature Climate Change
• Year: 2025
• Date: 2025-10-10
• Authors: Chloe Darnell, Lisa Rennels, Frank Errickson, Tony E. Wong, Vivek Srikrishnan
• DOI: 10.1038/s41558-025-02457-0

Research Groups

• Department of Biological & Environmental Engineering, Cornell University, Ithaca, NY, USA
• Doerr School of Sustainability, Stanford University, Stanford, CA, USA
• Independent researcher, Washington, DC, USA
• School of Mathematics and Statistics, Rochester Institute of Technology, Rochester, NY, USA

Short Summary

This study disentangles the relative contributions of future CO2 emissions and geophysical uncertainties to sea-level rise projections, finding that emissions trajectories become the primary driver of variability by mid-century, while accelerated Antarctic Ice Sheet melting and equilibrium climate sensitivity are key geophysical uncertainties.

Objective

• To quantify and disentangle the relative importance of future CO2 emissions trajectories and geophysical uncertainties (e.g., Antarctic Ice Sheet tipping points) for projections of global mean sea-level rise.

Study Configuration

• Spatial Scale: Global (with specific focus on Antarctic Ice Sheet dynamics).
• Temporal Scale: Future projections, primarily focusing on the period from 2022 to 2100, with a critical period identified between 2065 and 2075.

Methodology and Data

• Models used: A calibrated carbon cycle–climate–sea-level model chain, including components like the BRICK model for sea-level projections and the DAIS model for Antarctic Ice Sheet dynamics.
• Data sources: An ensemble of CO2 emissions trajectories, SNEASY–BRICK calibration results, and simulation outputs from the model chain, including those forced by Shared Socioeconomic Pathways (SSPs). All input data and simulation outputs are publicly available via Zenodo.

Main Results

• Without negative emissions, the CO2 emissions trajectory, particularly the timing of emissions reductions, becomes the primary driver of sea-level variability between 2065 and 2075.
• Accelerated Antarctic Ice Sheet (AIS) melting significantly influences the sensitivity of global mean sea-level rise to time-averaged and integrated temperature changes.
• The most critical geophysical uncertainties associated with the risk of exceeding sea-level thresholds are the threshold corresponding to accelerated AIS melting and the equilibrium climate sensitivity.

Contributions

• Provides a novel disentanglement of the relative importance of emissions and geophysical uncertainties for future sea-level projections.
• Identifies the timing of CO2 emissions reductions as a dominant factor for mid-century sea-level variability, highlighting the urgency of rapid decarbonization.
• Pinpoints specific geophysical uncertainties (AIS accelerated melting threshold and equilibrium climate sensitivity) that are most crucial for assessing the risk of exceeding sea-level thresholds.
• Reinforces the dual need for both adaptation strategies and rapid decarbonization to effectively manage future sea-level rise risks.

Funding

• College of Agricultural & Life Sciences, Cornell University (partially funded C.D. and V.S.)
• US Department of Energy, Office of Science, Biological and Environmental Research Program, Earth and Environmental Systems Modeling, MultiSector Dynamics, Integrated Coastal Modeling (ICoM) project (partially funded V.S.)
• National Science Foundation (NSF) under award no. DMS-2213432 (supported T.W.)

Citation

@article{Darnell2025interplay,
  author = {Darnell, Chloe and Rennels, Lisa and Errickson, Frank and Wong, Tony E. and Srikrishnan, Vivek},
  title = {The interplay of future emissions and geophysical uncertainties for projections of sea-level rise},
  journal = {Nature Climate Change},
  year = {2025},
  doi = {10.1038/s41558-025-02457-0},
  url = {https://doi.org/10.1038/s41558-025-02457-0}
}