The permafrost carbon inventory on the Tibetan Plateau: a new evaluation using deep sediment cores

Jinzhi Ding, Fei Li, Guibiao Yang, Leiyi Chen, Beibei Zhang, Li Liu, Kai Fang, Shuqi Qin, Yongliang Chen, Yunfeng Peng, Chengjun Ji, Honglin He, Pete Smith, Yuanhe Yang

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The permafrost organic carbon (OC) stock is of global significance because of its large pool size, and the potential positive feedback to climate warming. However, due to the lack of systematic field observations and appropriate upscaling methodologies, substantial uncertainties exist in the permafrost OC budget, which limits our understanding of the fate of frozen carbon in a warming world. In particular, the lack of comprehensive estimates of OC stocks across alpine permafrost means that current knowledge on this issue remains incomplete. Here we evaluated the pool size and spatial variations of permafrost OC stock to 3 metres depth on the Tibetan Plateau by combining systematic measurements from a substantial number of pedons (i.e., 342 three-metre-deep cores and 177 50-cm-deep pits) with a machine learning technique (i.e., support vector machine, SVM). We also quantified uncertainties in permafrost carbon budget by conducting a Monte Carlo simulation. Our results revealed that the combination of systematic measurements with the SVM model allowed spatially explicit estimates to be made. The OC density (OC amount per unit area, OCD) exhibited a decreasing trend from the southeastern to the northwestern plateau, with the exception that OCD in the swamp meadow was substantially higher than that in surrounding regions. Our results also demonstrated that Tibetan permafrost stored a large amount of OC in the top 3 metres, with the median OC pool size being 15.31 Pg C (interquartile range: 13.03-17.77 Pg C). 44% of OC occurred in deep layers (i.e., 100-300 cm), close to the proportion observed across the northern circumpolar permafrost region. The large carbon pool size, together with significant permafrost thawing suggests a risk of carbon emissions and positive climate feedback across the Tibetan alpine permafrost region. 

Original languageEnglish
Pages (from-to)2688-2701
Number of pages14
JournalGlobal Change Biology
Issue number8
Early online date31 Mar 2016
Publication statusPublished - Aug 2016

Bibliographical note

We are grateful for Dr. Jens Strauss and the other two anonymous reviewers for their insightful comments on an earlier version of this MS, and appreciate members of the IBCAS Sampling Campaign Teams for their assistance in field investigation. This work was supported by the National Basic Research Program of China on Global Change (2014CB954001 and 2015CB954201), National Natural Science Foundation of China (31322011 and 41371213), and the Thousand Young Talents Program.


  • alpine permafrost
  • carbon-climate feedback
  • deep sediment
  • Soil organic carbon stock
  • support vector machine


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