Abstract
The Paleocene-Eocene Thermal Maximum is a key analog for future climate change. However, how terrestrial ecosystems responded to this extreme warming remains uncertain. We integrate a dynamic global vegetation model with a carbon-isotope mass-balance framework to quantify terrestrial carbon-cycle feedbacks. Our simulations reveal that ancient high-latitude carbon stocks were vast but highly sensitive to extreme warming. We identify a fundamental non-linearity in the terrestrial response: while moderate warming triggers ecosystem shifts, extreme warming drives an abrupt collapse of land carbon, releasing up to ~900 petagrams. This decline stems from a bipolar ecological shift where massive tropical forest loss and accelerated soil heterotrophic respiration overwhelm high-latitude greening and carbon dioxide fertilization. Furthermore, hybrid scenarios combining terrestrial release of sedimentary methane and volcanic carbon dioxide provide the best fit to the geological record. We identify critical thermal thresholds, warning that future terrestrial carbon-climate feedbacks could be more severe than currently projected.
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Acknowledgements
This work was supported by the National Key R&D Program of China (No. 2022YFF0800800), the National Natural Science Foundation of China (NSFC) (No. 42320104005; No. 42372033), the Southeast Asia Biodiversity Research Institute, Chinese Academy of Sciences (Y4ZK111B01), the Young and Middle-aged Academic and Technical Leaders of Yunnan (No. 202305AC160051), the 14th Five-Year Plan of the Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences (No. E3ZKFF7B). The CESM project is supported primarily by the National Science Foundation (NSF). This material is based upon work supported by the National Center for Atmospheric Research (NCAR), a major facility sponsored by the NSF under Cooperative Agreement No.1852977. We acknowledge the Deep-Time Model Intercomparison Project, and thank the respective climate modeling, CRU, and NOAA/CIRES/DOE groups for producing and sharing their model outputs and climate data. We also thank the three anonymous reviewers for their suggestions and constructive comments, which improved the manuscript.
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Fang, X., Izumi, K., Jiang, S. et al. Terrestrial carbon stock vulnerability during the Paleocene-Eocene Thermal Maximum.
Commun Earth Environ (2026). https://doi.org/10.1038/s43247-026-03682-x
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DOI: https://doi.org/10.1038/s43247-026-03682-x
Source: Ecology - nature.com
