Wang et al. (2025) Climate drives observational changes in hydrological extremes across most global regions

Identification

• Journal: The Innovation
• Year: 2025
• Date: 2025-10-01
• Authors: Ning Wang, Fubao Sun, Wenbin Liu, Siquan Yang, Hong Wang, Feng Yao, Qi Huang
• DOI: 10.1016/j.xinn.2025.101171

Research Groups

• National Institute of Natural Hazards, Ministry of Emergency Management of China, Beijing 100085, China
• Key Laboratory of Water Cycle and Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
• College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China

Short Summary

This study analyzes changes in drought and flood flows and their dominant drivers across 9,531 global hydrological stations from 1980 to 2014, revealing that most regions experience simultaneous increases (28.14%) or decreases (33.36%) in both extremes, with climate primarily influencing the Southern Hemisphere and human activities dominating specific Northern Hemisphere regions.

Objective

• To identify the common dominant drivers of simultaneous changes in drought and flood flows across global regions, addressing a gap in current global assessments.

Study Configuration

• Spatial Scale: Global, across 9,531 hydrological stations, covering Earth’s sub-regions as defined by the IPCC. Basin areas exceed 100 square kilometers, with drivers resampled to a 1 kilometer spatial resolution.
• Temporal Scale: 1980–2014, using annual streamflow indices and daily streamflow data.

Methodology and Data

• Models used: Theil-Sen slope estimator for trend quantification, quadrant classification for joint analysis of extreme flow changes, and panel regression methodology for quantitative attribution analysis.
• Data sources:
  • Annual streamflow indices: Global Streamflow Indices and Metadata Archive (GSIM), Global Streamflow Indices Time Series Dataset (GSITSD).
  • Daily observed streamflow data: Global Runoff Data Centre (GRDC).
  • Daily precipitation data: Multi-Source Weighted-Ensemble Precipitation dataset (MSWEP).
  • Evapotranspiration data: Global Land Evaporation Amsterdam Model (GLEAM).
  • Air temperature data: National Centers for Environmental Prediction-Department of Energy (NCEP-DOE) Reanalysis II.
  • Water withdrawal (WW) data: Yan et al. (2022).
  • Native vegetation cover (VC) data: ESA/CCI Land Cover v.2.0.8 (European Space Agency/Climate Change Initiative).
  • Catchment boundaries: Lehner and Grill (2013).

Main Results

• A significant majority of global regions (61.50% of stations) exhibit simultaneous changes in hydrological extremes, with 28.14% showing concurrent increases (wetting) and 33.36% showing concurrent decreases (drying) in both drought and flood flows.
• Anthropogenic activities, including water withdrawal and changes in vegetation cover, primarily influence regions such as Alaska, Central America, the Amazon region, and Northern and Central Europe.
• Climatic factors, including atmospheric water balance and its seasonal variability, predominantly influence other regions, particularly in the Southern Hemisphere.
• Mean spring temperature increased by 3.31% per decade and water withdrawal by 3.29% per decade, while the annual minimum 30-day precipitation minus evapotranspiration (P-Etmin) showed the most pronounced decline at -10.26% per decade.
• Panel regression analysis demonstrated strong explanatory power (average R² = 0.51), identifying the top three contributing factors to extreme flow variability across 21 IPCC sub-regions.
• Wetting trends in East Asia are strongly associated with reduced water withdrawal (81.07% for drought flows, 85.09% for flood flows), while the Amazon region shows high sensitivity to vegetation cover (average contribution of approximately 22.58%).
• Northern Europe and Northern Asia exhibit high sensitivity to spring temperature, with mean absolute trends of 26.55% and 33.93% per decade, respectively, indicating a significant response to snow and glacier melt.

Contributions

• Provides a comprehensive global analysis of simultaneous changes in drought and flood flows and their common dominant drivers, addressing a critical gap in existing literature.
• Challenges the conventional "dry gets drier, wet gets wetter" paradigm by demonstrating that wet regions can experience drying trends and arid regions can experience wetting trends when focusing on extreme streamflow indices.
• Reveals that in 39% of basins, patterns emerge where both enhanced flooding and enhanced drought, or mitigated flooding and mitigated drought, occur, diverging from assumptions of uniform corresponding changes.
• Highlights the differential influence of anthropogenic activities on hydrological extremes between the Northern and Southern Hemispheres, emphasizing the need for tailored water resource management and adaptation strategies.
• Offers critical insights for developing targeted adaptive strategies to mitigate the impacts of hydrological extremes by identifying region-specific dominant drivers.

Funding

• National Natural Science Foundation of China, China (42025104)
• National Key R&D Program of China, China (2024YFC3013304 and 2024YFC3013401)
• National Institute of Natural Hazards, Ministry of Emergency Management, China (2023-JBKY-58, ZDJ2024-29, and 2024-JBKY-34)

Citation

@article{Wang2025Climate,
  author = {Wang, Ning and Sun, Fubao and Liu, Wenbin and Yang, Siquan and Wang, Hong and Yao, Feng and Huang, Qi},
  title = {Climate drives observational changes in hydrological extremes across most global regions},
  journal = {The Innovation},
  year = {2025},
  doi = {10.1016/j.xinn.2025.101171},
  url = {https://doi.org/10.1016/j.xinn.2025.101171}
}