Guo Donglin, Wang Huijun, Romanovsky Vladimir E, Haywood Alan M, Pepin Nick, Salzmann Ulrich, Sun Jianqi, Yan Qing, Zhang Zhongshi, Li Xiangyu, Otto-Bliesner Bette L, Feng Ran, Lohmann Gerrit, Stepanek Christian, Abe-Ouchi Ayako, Chan Wing-Le, Peltier W Richard, Chandan Deepak, von der Heydt Anna S, Contoux Camille, Chandler Mark A, Tan Ning, Zhang Qiong, Hunter Stephen J, Kamae Youichi
Nansen-Zhu International Research Centre, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China.
Key Laboratory of Meteorological Disaster, Ministry of Education/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science and Technology, Nanjing 210044, China.
Proc Natl Acad Sci U S A. 2023 Sep 5;120(36):e2301954120. doi: 10.1073/pnas.2301954120. Epub 2023 Aug 28.
Accurate understanding of permafrost dynamics is critical for evaluating and mitigating impacts that may arise as permafrost degrades in the future; however, existing projections have large uncertainties. Studies of how permafrost responded historically during Earth's past warm periods are helpful in exploring potential future permafrost behavior and to evaluate the uncertainty of future permafrost change projections. Here, we combine a surface frost index model with outputs from the second phase of the Pliocene Model Intercomparison Project to simulate the near-surface (~3 to 4 m depth) permafrost state in the Northern Hemisphere during the mid-Pliocene warm period (mPWP, ~3.264 to 3.025 Ma). This period shares similarities with the projected future climate. Constrained by proxy-based surface air temperature records, our simulations demonstrate that near-surface permafrost was highly spatially restricted during the mPWP and was 93 ± 3% smaller than the preindustrial extent. Near-surface permafrost was present only in the eastern Siberian uplands, Canadian high Arctic Archipelago, and northernmost Greenland. The simulations are similar to near-surface permafrost changes projected for the end of this century under the SSP5-8.5 scenario and provide a perspective on the potential permafrost behavior that may be expected in a warmer world.
准确理解多年冻土动态对于评估和减轻未来多年冻土退化可能产生的影响至关重要；然而，现有的预测存在很大的不确定性。研究地球过去温暖时期多年冻土的历史响应，有助于探索未来多年冻土的潜在行为，并评估未来多年冻土变化预测的不确定性。在此，我们将地表冻融指数模型与上新世模型比较计划第二阶段的输出结果相结合，以模拟上新世暖期（mPWP，约326.4万至302.5万年前）北半球近地表（约3至4米深度）的多年冻土状态。这一时期与预计的未来气候有相似之处。受基于代理的地表气温记录的约束，我们的模拟结果表明，在上新世暖期，近地表多年冻土在空间上受到高度限制，其范围比工业化前小93±3%。近地表多年冻土仅存在于东西伯利亚高地、加拿大北极群岛和格陵兰岛最北部。这些模拟结果与在SSP5-8.5情景下预计本世纪末近地表多年冻土的变化相似，并为在更温暖的世界中可能出现的多年冻土潜在行为提供了一个视角。
