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Published October 2025 | Version Published
Journal Article Open

Satellite-Constrained Reanalysis Reveals CO₂ Versus Climate Process Compensation Across the Global Land Carbon Sink

Creators

  • 1. ROR icon Jet Propulsion Lab
  • 2. ROR icon Stanford University
  • 3. ROR icon University of California, Santa Barbara
  • 4. ROR icon Australian National University
  • 5. ROR icon University of California, Los Angeles
  • 6. ROR icon California Institute of Technology
  • 7. ROR icon Lawrence Berkeley National Laboratory
  • 8. ROR icon University of Exeter
  • 9. ROR icon Virginia Tech
  • 10. ROR icon University of California, Berkeley
  • 11. ROR icon The Ohio State University

Abstract

Terrestrial ecosystems annually absorb ~30% of anthropogenic C emissions. The degrees to which contemporary CO₂ and climate trends drive this absorption are uncertain, as are the governing mechanisms. To reduce uncertainty, we use Bayesian model-data integration (CARbon DAta MOdel fraMework) to retrieve a terrestrial biosphere reanalysis where Earth Observations optimally inform mechanistic model processes: observations include satellite- and inventory-based constraints on distributions and change in terrestrial C (including live biomass, dead organic C, and land-atmosphere CO₂ exchanges) and underlying mechanisms (including photosynthesis, deforestation, water storage anomalies, and fire). We find that the impact of 2001–2021's atmospheric CO₂ increase on terrestrial C (+39.4 PgC) opposes and far outweighs the impact of climate trends over this period (10.5 PgC). Globally, C gains are mostly attributable to live biomass growth (+31.2 PgC), while CO₂-induced dead organic C gains (+7.8 PgC) are compensated by climate-induced losses (8.8 PgC). The distribution of compensating dead C changes induces an aggregate shift in dead C from high- and mid-latitudes (3.5 PgC) to tropical ecosystems (+2.6 PgC). We additionally find global residence time reductions attributable to CO₂ (2.6%) and climate (1.3%) reflected across latitudes, irrespective of reservoir C changes. In aggregate, these changes reveal an acceleration and redistribution of terrestrial C stores in response to CO₂ and climate trends, which together reflect a gradual but fundamental reorganization of the terrestrial C cycle. Tracking this reorganization—through robust and continual diagnosis of ecosystem function—is essential for accurately resolving the compensating dynamics governing the strength and resilience of the terrestrial C sink.

Copyright and License

© 2025 Jet Propulsion Laboratory, California Institute of Technology and The Author(s). Government sponsorship acknowledged.

This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.

Acknowledgement

The authors acknowledge the Texas Advanced Computing Center (TACC) at The University of Texas at Austin for providing the High Performance Computing resources used in this analysis; these resources were accessed through funding and support from the Jet Propulsion Laboratory Information and Technology Solutions Directorate. We thank the editor, Dr. Sharon Billings, and three anonymous reviewers for their constructive comments, which improved the quality of this work.

Funding

This work was supported by three NASA 2020 Earth Sciences Grants (NNH20ZDA001N-CARBON, NNH22ZDA001N-CMS, NNH20ZDA001N-CMS). MAW was supported by NASA FINESST Grant 80NSSC21K1593. AGK was also supported by the Alfred P. Sloan foundation and by NSF DEB project 1942133. YK acknowledges support from NASA Grant 80NSSC24K1562. RKB acknowledges support from the Resnick Sustainability Institute. Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (80NM0018D0004).

Data Availability

The specific CARDAMOM code version used in this work can be found on the open source CARDAMOM github repository at https://github.com/CARDAMOM-framework/CARDAMOM/tree/b8f1fd648ba9d7b6a42f249af6663fb757daf089. This code has also been placed on a zenodo repository (Bilir, 2025), along with the model output, and files to run both the parameter inversion and the forward model. Additional model documentation and user resources can be found at the CARDAMOM manual page, https://cardamom-framework.github.io/CARDAMOM/ (Levine et al., 2024).

Supplemental Material

Supporting Information S1 (PDF)

Original Version of Manuscript (PDF)

Peer Review History (PDF)

Author Response to Peer Review Comments (PDF)

First Revision of Manuscript (PDF)

Second Revision of Manuscript [Accepted] (PDF)

Files

AGU Advances - 2025 - Bilir - Satellite‐Constrained Reanalysis Reveals CO2 Versus Climate Process Compensation Across the.pdf

Files (11.2 MB)

Additional details

Additional titles

Alternative title
Satellite-constrained reanalysis reveals CO₂ fertilization outweighed climate change impacts on 2001–2021 land carbon sink

Related works

Is supplemented by
Software: https://github.com/CARDAMOM-framework/CARDAMOM/tree/b8f1fd648ba9d7b6a42f249af6663fb757daf089 (URL)
Software: 10.5281/zenodo.15691781 (DOI)
Software: https://cardamom-framework.github.io/CARDAMOM/ (URL)

Funding

National Aeronautics and Space Administration
NNH20ZDA001N‐CARBON
National Aeronautics and Space Administration
NNH22ZDA001N‐CMS
National Aeronautics and Space Administration
NNH20ZDA001N‐CMS
National Aeronautics and Space Administration
80NSSC21K1593
Alfred P. Sloan Foundation
National Science Foundation
1942133
National Aeronautics and Space Administration
80NSSC24K1562
National Aeronautics and Space Administration
80NM0018D0004

Dates

Accepted
2025-08-01
Available
2025-09-04
Version of record online
Available
2025-09-04
Issue online

Caltech Custom Metadata

Caltech groups
Resnick Sustainability Institute, Division of Geological and Planetary Sciences (GPS)
Publication Status
Published