Rateb et al. (2026) Structural deficits in large ensembles limit detection and attribution of terrestrial water storage

Identification

• Journal: Communications Earth & Environment
• Year: 2026
• Date: 2026-07-01
• Authors: Ashraf Rateb, Bridget R. Scanlon, Brett Buzzanga
• DOI: 10.1038/s43247-026-03772-w

Research Groups

• Bureau of Economic Geology, Jackson School of Geosciences, The University of Texas at Austin (Ashraf Rateb & Bridget R. Scanlon)
• Jet Propulsion Laboratory, California Institute of Technology (Brett Buzzanga)

Short Summary

This study investigates the ability of two large ensemble archives to provide a credible counterfactual baseline for detecting and attributing terrestrial water storage trends and extremes.

Objective

• Determine whether widely used single-model large-ensemble archives can reproduce observed basin-scale variability in terrestrial water storage.

Study Configuration

• Spatial Scale: Global river basins (184)
• Temporal Scale: 23 years (2002-2024)

Methodology and Data

• Models used: CESM2-LENS2, IPSL-CM6A-LR
• Data sources: GRACE and GRACE-FO terrestrial water storage record

Main Results

• Both ensembles frequently fail to reproduce observed amplitude, dispersion, persistence, and severity of extremes in terrestrial water storage.
• A four-metric benchmark classifies 78 to 82% of basins as incompatible with the model distributions.

Contributions

• The study highlights that null hypotheses for internal climate variability should be tested against observations before being used in detection and attribution to avoid biased inference about emergence and external forcing.
• The main limitation is not ensemble size but model structure, implying that progress depends more on improving the representation of hydrologic storage, transport, and memory in Earth system models.

Funding

• This work was supported by the Bureau of Economic Geology, Jackson School of Geosciences, The University of Texas at Austin.

Citation

@article{Rateb2026Structural,
  author = {Rateb, Ashraf and Scanlon, Bridget R. and Buzzanga, Brett},
  title = {Structural deficits in large ensembles limit detection and attribution of terrestrial water storage},
  journal = {Communications Earth & Environment},
  year = {2026},
  doi = {10.1038/s43247-026-03772-w},
  url = {https://doi.org/10.1038/s43247-026-03772-w}
}