Worden et al. (2026) Decorrelating carbon and water fluxes in the Amazon Basin

Identification

• Journal: Nature Communications
• Year: 2026
• Date: 2026-08-22
• Authors: Sarah Worden, Nima Madani, Lingcheng Li, Nate McDowell, Yan Yang, Sassan Saatchi
• DOI: 10.1038/s41467-026-75526-3

Research Groups

• Jet Propulsion Laboratory, California Institute of Technology
• UCLA Joint Institute for Regional Earth System Science and Engineering
• Pacific Northwest National Laboratory
• Washington State University
• Ctrees

Short Summary

The study reveals that carbon (GPP) and water (ET) fluxes in the Amazon Basin are frequently decoupled rather than tightly coupled, with this decorrelation increasing over the last 40 years due to rising vapor pressure deficit (VPD).

Objective

• To evaluate the spatial and temporal coupling between gross primary production (GPP) and evapotranspiration (ET) across the Amazon Basin and determine the drivers behind their divergence.

Study Configuration

• Spatial Scale: Amazon Basin
• Temporal Scale: 40 years (since 1982)

Methodology and Data

• Models used: Satellite-based estimation frameworks for GPP and ET.
• Data sources: Satellite-derived estimates of gross primary production (GPP) and evapotranspiration (ET).

Main Results

• 64% of the Amazon Basin exhibits weak positive ($R < 0.3$) or negative correlations between GPP and ET.
• In forests with high baseline water availability, the correlation is nearly absent ($R = -0.03 \pm 0.14$).
• The coupling strength between GPP and ET has declined since 1982, particularly within intact forests.
• The decorrelation is driven by divergent behavior during the dry season, where rising vapor pressure deficit (VPD) suppresses canopy conductance and GPP while simultaneously increasing the atmospheric demand for ET.

Contributions

• Challenges the prevailing assumption that tropical carbon and water fluxes are tightly coupled.
• Identifies rising VPD as a mechanism that decouples carbon gain from water loss, suggesting a potential reduction in the Amazon's capacity to function as a sustained carbon sink.

Funding

• NASA (Contract 80NM0018D0004)
• NASA Postdoctoral Program Fellowship
• U.S. Department of Energy’s Next Generation Ecosystem Experiment-Tropics

Citation

@article{Worden2026Decorrelating,
  author = {Worden, Sarah and Madani, Nima and Li, Lingcheng and McDowell, Nate and Yang, Yan and Saatchi, Sassan},
  title = {Decorrelating carbon and water fluxes in the Amazon Basin},
  journal = {Nature Communications},
  year = {2026},
  doi = {10.1038/s41467-026-75526-3},
  url = {https://doi.org/10.1038/s41467-026-75526-3}
}