Lu et al. (2025) Atmospheric rivers emerge as future freshwater reserves and heat stocks

Identification

• Journal: Communications Earth & Environment
• Year: 2025
• Date: 2025-10-17
• Authors: Mengqian Lu, Yurong Song, Wen Huang, Lujia Zhang
• DOI: 10.1038/s43247-025-02780-6

Research Groups

• Otto Poon Center for Climate Resilience and Sustainability, World Sustainable Development Institute, Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Hong Kong, China.

Short Summary

This study assesses the evolving roles of global atmospheric rivers (ARs) in moisture and energy transport under climate change, projecting that by 2100, 70% of mid-latitude ARs will exceed Amazon River-scale moisture transport, intensifying flood risks and shifting poleward. It also reveals their crucial role in redistributing heat and energy on subseasonal scales, with distinct heat archetypes influencing regional precipitation and temperature patterns.

Objective

• To quantify the changes in moisture and heat energy transported by atmospheric rivers (ARs) across historical conditions and future climate projections, considering regional differences in AR characteristics.
• To explore the roles of ARs from an energy perspective on synoptic-to-subseasonal timescales.
• To unveil the vital roles of ARs in the future by quantifying their moisture and heat transport.

Study Configuration

• Spatial Scale: Global, mid-latitudes (30° to 60° N/S), specific river basins (Yangtze, Loire, Sacramento), and key AR basins (East Asia: 15–55°N, 110–140°E; North Pacific: 30–60°N, 150–240°E; North Atlantic: 40–65°N, 50°W–15°E).
• Temporal Scale:
  • Historical period: 1980–2009 (CMIP6), 1980–2014 (ERA5).
  • Near-future period: 2025–2054 (CMIP6, SSP585).
  • Far-future period: 2070–2099 (CMIP6, SSP585).
  • Seasonal analysis (December–January–February (DJF), June–July–August (JJA)).
  • Subseasonal timescales (e.g., hourly variations, 15-day AR events).

Methodology and Data

• Models used:
  • Coupled Model Intercomparison Project Phase 6 (CMIP6) models (ensemble of 23 models).
  • Shared Socioeconomic Pathway (SSP) scenarios: SSP245 and SSP585 (high-emission scenario).
• Data sources:
  • ERA5 (fifth generation of the European Centre for Medium-Range Weather Forecasts) reanalysis data (1980–2014): zonal wind, meridional wind, atmospheric temperature, surface temperature (T2m), precipitation, sea surface temperature (SST), integrated water vapor (IWV), integrated water vapor transport (IVT), specific humidity, surface sensible heat flux (sshf), surface latent heat flux (slhf), surface net solar radiation (ssr), and surface net thermal radiation (str).
  • Global atmospheric river (AR) database detected with the PanLu 2.0 algorithm.
  • River discharge data: Sacramento River (Freeport station), Yangtze River (Datong station), and basin-averaged runoff for the Loire River.
  • Attribution analysis using the Fraction of Attributable Risk (FAR).
  • Moisture budget analysis for river basins.
  • Calculation of heat flux (sensible and latent) and moist static energy (MSE) meridional transport.
  • Two-dimensional Kernel Density Estimation (KDE) for AR heat archetypes.

Main Results

• By 2100 under the SSP585 scenario, approximately 70% of mid-latitude ARs are projected to transport moisture exceeding the Amazon River's flow (1.6 × 10⁸ kg s⁻¹), an increase from historical levels of 60%.
• 11% of this intensification of Amazon-scale ARs in mid-latitudes is attributable to future warming.
• The frequency of Amazon River-scale ARs is projected to increase globally, with more substantial increases poleward of 40°S and 40°N.
• Annual peak net AR moisture contribution to river basins is projected to increase under SSP585 (Yangtze: 185%, Loire: 47%, Sacramento: 35%).
• AR moisture contributions are projected to decrease during non-flood seasons in some basins (Yangtze, Loire), potentially exacerbating dry conditions, while increasing substantially during flood seasons.
• Latent heat flux transported by ARs is projected to increase across all regions and seasons under future climate scenarios, becoming the dominant mode of heat transport. Sensible heat flux remains relatively stable during DJF but shows a decreasing trend during JJA in the North Pacific and North Atlantic basins.
• ARs are associated with significant seasonal warming anomalies in near-surface air temperature (T2m) (e.g., exceeding 5 °C in winter) and sea surface temperature (SST) (e.g., exceeding 0.5 °C in winter) across key AR basins.
• ARs consistently correspond to a reduction in climatological upward surface sensible and latent heat fluxes, resulting in positive anomalies (heat transfer from the atmosphere to the surface).
• Poleward transport of sensible heat, latent heat, and moist static energy (MSE) by ARs is projected to increase, with the peak shifting toward higher latitudes under SSP585.
• Distinct AR heat archetypes, defined by sensible and latent heat fluxes, exhibit varying impacts on precipitation and temperature patterns across regions. In the North Atlantic and North Pacific, higher latent and sensible heat fluxes generally lead to stronger rainfall and greater positive SST anomalies. In East Asia (summer), stronger latent heat flux is linked to heavier rainfall, while lower latent heat flux corresponds to warmer land T2m anomalies, suggesting a potential link to humid heat waves.
• On subseasonal timescales, AR events show repeated processes of moisture release and recharge, with MSE, MSE advection, and sensible heat advection closely synchronized with AR-related rainfall intensity.

Contributions

• Quantifies the future role of atmospheric rivers as significant freshwater reserves and heat stocks, using the Amazon River's flow as a benchmark for moisture transport magnitude.
• Provides a comprehensive analysis of projected changes in AR moisture and heat energy transport under climate change, highlighting regional differences and their implications for flood risk and water resource management.
• Explores the role of ARs from an energy perspective, demonstrating their crucial contribution to Earth's energy redistribution on synoptic-to-subseasonal timescales and projecting an intensification and poleward shift of this transport.
• Identifies and characterizes distinct AR heat archetypes, revealing how varying heat flux profiles lead to diverse regional impacts on precipitation and temperature patterns.
• Offers valuable insights for improving future AR predictions and for developing strategies to potentially utilize ARs as future freshwater and heat resources, while also emphasizing the need to mitigate associated hazards like floods and droughts.

Funding

• Collaborative Research Funds (C6032-21G, C5004-23G, and C5002-22Y) of the Hong Kong Research Grants Council.
• General Research Fund (16300424) of the Hong Kong Research Grants Council.
• NSFC/RGC Collaborative Research Scheme (project no. CRS_PolyU503/23).
• Otto Poon Centre for Climate Resilience and Sustainability, HKUST.
• UNESCO International Decade of Sciences for Sustainable Development (IDSSD, 2024–2033).
• Seamless Prediction and Services for Sustainable Natural and Built Environment (SEPRESS) Program (2025–2032).

Citation

@article{Lu2025Atmospheric,
  author = {Lu, Mengqian and Song, Yurong and Huang, Wen and Zhang, Lujia},
  title = {Atmospheric rivers emerge as future freshwater reserves and heat stocks},
  journal = {Communications Earth & Environment},
  year = {2025},
  doi = {10.1038/s43247-025-02780-6},
  url = {https://doi.org/10.1038/s43247-025-02780-6}
}