Nguyen‐Duy et al. (2025) Increasing compound heat and precipitation extremes and population exposure in a warming Vietnam

Identification

• Journal: Natural Hazards
• Year: 2025
• Date: 2025-10-04
• Authors: Tung Nguyen‐Duy, Thanh Ngo‐Duc, Dzung Nguyen‐Le, Thanh Nguyen‐Xuan, Quan Tran-Anh
• DOI: 10.1007/s11069-025-07696-0

Research Groups

• REMOSAT Laboratory, University of Science and Technology of Hanoi (USTH), Vietnam Academy of Science and Technology (VAST), Hanoi, Vietnam
• Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam
• Faculty of Environment, Hanoi University of Mining and Geology (HUMG), Hanoi, Vietnam

Short Summary

This study projects future changes in compound heat and precipitation extremes (CHPEs) and associated population exposure across Vietnam using high-resolution climate data and population scenarios. It finds a significant increase in CHPEs and population exposure under warmer scenarios, primarily driven by climate change.

Objective

• To investigate future changes in compound heat and precipitation extremes (CHPEs) across seven climatic regions of Vietnam and the corresponding population exposure under various Shared Socioeconomic Pathway (SSP) scenarios.

Study Configuration

• Spatial Scale: Vietnam, covering seven climatic regions, utilizing a high-resolution dataset with approximately 10 km grid spacing.
• Temporal Scale: Historical period (1980–2014) for baseline and model validation; future projections extending to the end of the twenty-first century under SSP1-2.6, SSP2-4.5, and SSP5-8.5 scenarios.

Methodology and Data

• Models used: High-resolution CMIP6-VN dataset (dynamically downscaled CMIP6 climate models).
• Data sources:
  • Extreme events identified using the 95th percentile of historical data (1980–2014).
  • A compound event is defined as at least three consecutive days of extreme temperature coinciding with an extreme precipitation event within a 7-day window.
  • Future population projections (specific source not detailed, but mentioned as "future population projections").

Main Results

• The CMIP6-VN dataset accurately reproduces the spatial and seasonal variability of historical CHPEs (1980–2014), demonstrating high reliability for future projections.
• Future changes in CHPE events vary significantly by SSP scenario:
  • Under SSP1-2.6, most regions show a slight, statistically insignificant increase in CHPEs.
  • Under SSP2-4.5, a significant increase in CHPEs is projected across all regions.
  • Under SSP5-8.5, the most pronounced rise is observed, with some areas potentially experiencing up to 15 CHPEs per year by the end of the twenty-first century.
• The increase in future CHPEs is primarily driven by rising temperatures, as the number of days with extreme temperatures increases substantially, while precipitation hazard days remain relatively stable.
• Seasonal distributions of CHPEs are projected to shift, with a notable increase towards the later months of the year. Specifically, under SSP5-8.5, northern regions are projected to experience CHPEs more than once per month from May to September.
• Despite a projected decline in population after mid-century, population exposure to CHPEs increases significantly under warmer scenarios, indicating climate change as the dominant driver of future risk.
• Quantifying contributions, climate change is found to be the dominant driver of future population exposure across all regions and scenarios, outweighing the influence of population change, which is notable only in some regions during the early to mid-century.

Contributions

• Provides the first comprehensive assessment of future changes in compound heat and precipitation extremes (CHPEs) and associated population exposure across Vietnam using a high-resolution (approximately 10 km) CMIP6-VN dataset.
• Quantifies the distinct contributions of climate change and population change to future population exposure to CHPEs, highlighting the dominant role of climate change.
• Offers reliable projections and insights into the spatial and seasonal shifts of CHPEs, crucial for climate change adaptation and disaster risk reduction strategies in Vietnam.

Funding

• Vietnam National Foundation for Science and Technology Development (NAFOSTED) under Grant 105.06-2021.14.

Citation

@article{NguyenDuy2025Increasing,
  author = {Nguyen‐Duy, Tung and Ngo‐Duc, Thanh and Nguyen‐Le, Dzung and Nguyen‐Xuan, Thanh and Tran-Anh, Quan},
  title = {Increasing compound heat and precipitation extremes and population exposure in a warming Vietnam},
  journal = {Natural Hazards},
  year = {2025},
  doi = {10.1007/s11069-025-07696-0},
  url = {https://doi.org/10.1007/s11069-025-07696-0}
}