Ji et al. (2026) Reassessing Alpine Permafrost Thermal State by Accounting for Ground Ice

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Identification

• Journal: Earth s Future
• Year: 2026
• Date: 2026-08-01
• Authors: Hailong Ji, Zhuotong Nan, Yuhong Chen, Lihua Chen, Shuping Zhao
• DOI: 10.1029/2025ef007931

Research Groups

Not specified in the provided text.

Short Summary

The study introduces an enthalpy-based metric ($\Delta H'$) to assess permafrost thermal state, demonstrating that it is superior to Mean Annual Ground Temperature (MAGT) because it accounts for the thermodynamic influence of ground ice.

Objective

• To develop and evaluate an alternative metric for permafrost thermal state that integrates both ground temperature and ice content to better predict permafrost persistence and stability.

Study Configuration

• Spatial Scale: Qinghai-Tibet Plateau (QTP).
• Temporal Scale: Simulated warming scenarios (warming rate of $0.4\text{ }^\circ\text{C}$ per decade) and current spatial distribution.

Methodology and Data

• Models used: Process-based model (for controlled warming experiments) and explainable machine-learning analyses.
• Data sources: High-resolution gridded datasets.

Main Results

• Metric Performance: Permafrost traditionally labeled "unstable" (MAGT between $-0.5\text{ }^\circ\text{C}$ and $0\text{ }^\circ\text{C}$) can persist for 30–100 years under a warming rate of $0.4\text{ }^\circ\text{C}$ per decade, depending on ice content.
• Comparison: $\Delta H'$ provides a more uniform scale and higher discernibility in indicating potential permafrost duration compared to MAGT.
• Spatial Analysis (QTP):
  • Western QTP permafrost is less stable than MAGT suggests.
  • Southeast QTP and areas around lakes in endorheic basins are more stable than MAGT suggests.
• Driving Factors: Precipitation, soil coarse fraction, and solar radiation are the primary controls on the spatial discrepancy between MAGT and $\Delta H'$.

Contributions

• Proposes a new enthalpy-based metric ($\Delta H'$) that overcomes the inherent limitations of MAGT by incorporating the latent heat of ground ice.
• Quantifies the role of ground ice in regulating permafrost stability across the Qinghai-Tibet Plateau.

Funding

Not specified in the provided text.

Citation

@article{Ji2026Reassessing,
  author = {Ji, Hailong and Nan, Zhuotong and Chen, Yuhong and Chen, Lihua and Zhao, Shuping},
  title = {Reassessing Alpine Permafrost Thermal State by Accounting for Ground Ice},
  journal = {Earth s Future},
  year = {2026},
  doi = {10.1029/2025ef007931},
  url = {https://doi.org/10.1029/2025ef007931}
}