Liu et al. (2026) A snow-fire bridge mechanism for the 2025 Southern California winter wildfire

Identification

• Journal: Nature Communications
• Year: 2026
• Date: 2026-03-19
• Authors: Shizuo Liu, Shineng Hu, Richard Seager
• DOI: 10.1038/s41467-026-70827-z

Research Groups

• Division of Earth and Climate Sciences, Nicholas School of the Environment, Duke University, Durham, NC, USA
• Department of Civil and Environmental Engineering, Duke University, Durham, NC, USA
• Lamont Doherty Earth Observatory of Columbia University, Palisades, NY, USA

Short Summary

This study identifies a "snow-fire bridge" mechanism where reduced western Eurasian snow cover triggers an atmospheric teleconnection, leading to weather conditions favorable for winter wildfires in Southern California, as observed during the January 2025 event.

Objective

• To identify remote, large-scale climatic precursors for the rare and highly destructive January 2025 Southern California winter wildfire, differing from those of previous wildfires.

Study Configuration

• Spatial Scale: Western Eurasia, North Pacific, North America (specifically Southern California).
• Temporal Scale: December-January (wintertime), interannual variability, focusing on the January 2025 event.

Methodology and Data

• Models used:
  • Community Earth System Model version 2.1 (CESM2.1) for large-ensemble numerical simulations.
• Data sources:
  • Observational analysis.
  • gridMET (gridded surface meteorological data).
  • WUMI burned area (Western United States MTBS-Interagency database of large wildfires).
  • ERA5-based Fire Weather Index (FWI).
  • ERA5 reanalysis data (single levels monthly means, pressure levels monthly means).
  • NOAA Snow Cover Extent (SCE).
  • IMS SCE (Interactive Multisensor Snow and Ice Mapping System).
  • MODIS SCE.
  • GISTEMP (GISS Surface Temperature Analysis).
  • CMIP6 (Coupled Model Intercomparison Project Phase 6) data, including FWI.
  • Snow cover forcing experiments data.

Main Results

• Reduced snow cover over western Eurasia is associated with weather conditions conducive to wildfires in Southern California during December-January.
• This association occurs via an atmospheric teleconnection from western Eurasia, across the North Pacific, and into North America.
• The reduced western Eurasian snow cover contributes to a typical wintertime western warming-eastern cooling dipole pattern in North America.
• The underlying dynamical mechanisms involve downstream propagating Rossby wave trains, triggered by the snow cover reduction, and wave-mean flow interaction over the North Pacific.

Contributions

• Identifies a novel "snow-fire bridge" mechanism linking Eurasian cryosphere variability to remote climate extremes and wildfire risk in Southern California.
• Establishes a predictive link between Eurasian snow cover anomalies and subsequent wildfire risk in California, as well as the wintertime North American zonal dipole temperature pattern.
• Provides insights into the large-scale climatic precursors for unusual winter wildfire events, such as the January 2025 Southern California wildfire.

Funding

• NASA grants: 80NSSC22K1025, 80NSSC23K0988
• DOE grant: DE-SC0024186
• NSF grant: AGS-2127684

Citation

@article{Liu2026snowfire,
  author = {Liu, Shizuo and Hu, Shineng and Seager, Richard},
  title = {A snow-fire bridge mechanism for the 2025 Southern California winter wildfire},
  journal = {Nature Communications},
  year = {2026},
  doi = {10.1038/s41467-026-70827-z},
  url = {https://doi.org/10.1038/s41467-026-70827-z}
}