A large global soil carbon sink informed by repeated soil samplings

Abstract Partitioning the terrestrial carbon sink between vegetation and soil is crucial for predicting future climate change, but the role of soils remains poorly quantified. Here, we compiled 3,099 soil organic carbon time series spanning five decades. We found a global soil organic carbon sink of 1.83 ± 0.9 (mean ± SE) petagrams per year from 1992 to 2020, driven by extratropical young forests, boreal old forests, and grasslands, while trends in tropical ecosystems remain uncertain. Our findings suggest the net land sink resides almost exclusively belowground as soil carbon, emphasizing the global opportunity of soil conservation and restoration for climate mitigation. Competing Interest Statement The authors have declared no competing interest. Funder Information Declared This material is based upon work supported by the National Science Foundation under Grant No. DEB-2339051. This research was supported by a seed award from the MIT Climate and Sustainability Consortium. This is a contribution of the MIT Terrer Lab. AM was supported by a Laboratory Directed Research and Development Program at PNNL. This work was generated using data from the Nutrient Network (This material is based upon work supported by the National Science Foundation under Grant No. DEB-2339051. This research was supported by a seed award from the MIT Climate and Sustainability Consortium. This is a contribution of the MIT Terrer Lab. AM was supported by a Laboratory Directed Research and Development Program at PNNL. This work was generated using data from the Nutrient Network (http://www.nutnet.org) experiment, funded at the site-scale by individual researchers. Coordination and data management have been supported by funding to E. Borer and E. Seabloom from the National Science Foundation Research Coordination Network (NSF-DEB-1042132) and Long Term Ecological Research (NSF-DEB-1234162 and NSF-DEB-1831944 to Cedar Creek LTER) programs, and the Institute on the Environment (DG-0001-13). We also thank the Minnesota Supercomputer Institute for hosting project data and the Institute on the Environment for hosting Network meetings. Soil analyses were supported, in part, by USDA-ARS grant 58-3098-7-007 to ETB. The evaluation was based on data that was collected by partners of the official UNECE ICP Forests Network (http://icp-forests.net/contributors). Part of the data was co-financed by the European Commission (Data achieved at 10/12/2023)., , Copyright The copyright holder for this preprint is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY-NC 4.0 International license.