Gaillard Rémi, Peylin Philippe, Cadule Patricia, Bastrikov Vladislav, Chéruy Frédérique, Cuynet Amélie, Ghattas Josefine, Zhu Dan, Guenet Bertrand
Laboratoire de Géologie, Ecole Normale Supérieure, CNRS, Institut Pierre-Simon Laplace, Université Paris Sciences et Lettres, Paris 75005, France.
Laboratoire des Sciences du Climat et de l'Environnement, Institut Pierre-Simon Laplace, Commisssariat à l'énergie atomique et aux énergies alternatives-CNRS-Université de Versailles Saint-Quentin-en-Yvelines, Université Paris-Saclay, Gif-sur-Yvette 91191, France.
Proc Natl Acad Sci U S A. 2025 Jan 21;122(3):e2410226122. doi: 10.1073/pnas.2410226122. Epub 2025 Jan 13.
The insulative properties of soil organic carbon (SOC) and surface organic layers (moss, lichens, litter) regulate surface-atmosphere energy exchanges in the Arctic through a coupling with soil temperatures. However, a physical description of this process is lacking in many climate models, potentially biasing their high-latitude climate predictions. Using a coupled surface-atmosphere model, we identified a strong feedback loop between soil insulation, surface air temperature, and snowfall. Without insulation, the latent heat needed for soil ice thawing leads to a late spring and summer cold bias in surface air temperature (above 2 °C) over Arctic regions. The integration of soil insulation eliminates this bias and significantly improves the simulation of permafrost dynamics. Our findings, including the potential consequences of large perturbations (e.g., fires), highlight the importance of combining soil water freezing with a physical representation of SOC and surface organic layer insulation in Earth system models, to improve Arctic climate predictions.
土壤有机碳（SOC）和地表有机层（苔藓、地衣、凋落物）的绝缘特性通过与土壤温度的耦合来调节北极地区的地表-大气能量交换。然而，许多气候模型缺乏对这一过程的物理描述，这可能会使其高纬度气候预测产生偏差。我们使用一个地表-大气耦合模型，确定了土壤绝缘、地表气温和降雪之间存在一个强烈的反馈回路。如果没有绝缘作用，土壤冰融化所需的潜热会导致北极地区地表气温在春末和夏季出现冷偏差（超过2°C）。纳入土壤绝缘消除了这一偏差，并显著改善了对多年冻土动态的模拟。我们的研究结果，包括大规模扰动（如火灾）的潜在后果，凸显了在地球系统模型中将土壤水冻结与SOC和地表有机层绝缘的物理表示相结合的重要性，以改进北极气候预测。
