Highly restricted near‐surface permafrost extent during the mid-Pliocene warm period

Donglin Guo*, Huijun Wang, Vladimir E. Romanovsky, Alan M. Haywood, Nick Pepin, Ulrich Salzmann, Jianqi Sun, Qing Yan, Zhongshi Zhang, Xiangyu Li, Bette L. Otto-Bliesner, Ran Feng, Gerrit Lohmann, Christian Stepanek, Ayako Abe-Ouchi, Wing-Le Chan, W. Richard Peltier, Deepak Chandan, Anna S. von der Heydt, Camille ContouxMark A. Chandler, Ning Tan, Qiong Zhang, Stephen J. Hunter, Youichi Kamae

*Corresponding author for this work

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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.

Original languageEnglish
Article numbere2301954120
Number of pages10
JournalProceedings of the National Academy of Sciences
Issue number36
Early online date28 Aug 2023
Publication statusPublished - 5 Sept 2023

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