Xu et al. (2026) Divergent latitude-specific urban humid heat risks are regulated by local climate types

Identification

• Journal: Communications Earth & Environment
• Year: 2026
• Date: 2026-03-26
• Authors: Lei Xu, Qing Zhang, Senlin Tang, Xuhui Lee, Hongyu Song, Xinyu Gong
• DOI: 10.1038/s43247-026-03437-8

Research Groups

• School of Technology for Sustainability, Guangdong Provincial Key Laboratory of Wastewater Information Analysis and Early Warning, Beijing Normal University, Zhuhai, China
• School of Remote Sensing Science and Technology, Aerospace Information Technology University, Jinan, China
• School of the Environment, Yale University, New Haven, CT, USA

Short Summary

This study systematically investigates the spatiotemporal evolution and drivers of urban wet-bulb temperature across 56 global cities from 2005-2024, revealing significant increases since 2020 with responses regulated by local climate types.

Objective

• To systematically investigate the spatiotemporal evolution and drivers of urban wet-bulb temperature patterns and their health impacts across 56 globally representative cities, considering the influence of urbanization and local climate types.

Study Configuration

• Spatial Scale: 56 globally representative cities.
• Temporal Scale: 2005-2024.

Methodology and Data

• Models used: Not explicitly mentioned as a primary methodology, but mechanistic analysis was performed to understand the drivers.
• Data sources:
  • ERA5 reanalysis dataset for atmospheric variables.
  • MODIS/Terra Land Surface Temperature daily product (MOD11A1 Version 6.1).
  • Global Station Daily Maximum Wet-bulb Temperature dataset (GSDM-WBT).
  • GlobPOP global population distribution dataset.
  • LandScan global population dataset.
  • Standardized geographic data products from Natural Earth.
  • PKU GIMMS NDVI product from Peking University.
  • Annual VIIRS Nighttime Light product Version 2 from the Earth Observation Group (EOG).
  • Global Summary of the Day (GSOD) dataset from NOAA National Centers for Environmental Information (NCEI).

Main Results

• Pronounced increases in global urban wet-bulb temperature have been observed since 2020.
• Urban wet-bulb temperature responses to urbanization and local climatic conditions are spatially variable.
• Tropical coastal cities (e.g., Jakarta, Bangkok) show relatively stable and high wet-bulb temperatures, where warm humid climates substantially offset the urban heat island effect.
• Inland cities exhibit pronounced spatial gradients in wet-bulb temperature.
• Metropolitan regions at low-to-mid latitudes display higher spatial heterogeneity in wet-bulb temperature than those at high latitudes.
• Mechanistic analysis indicates that variable responses of wet-bulb temperature to air temperature and relative humidity determine the influence of urbanization.
• Extreme heat intensities reached remarkable levels during 2023-2024, posing serious health threats.

Contributions

• Provides a systematic and comprehensive investigation into urban-induced changes in wet-bulb temperature and their health impacts across a global set of cities, addressing a less systematically studied area.
• Identifies a recent and pronounced increase in global urban wet-bulb temperature since 2020.
• Demonstrates that urban humid heat risks are latitude-specific and regulated by local climate types, offering nuanced insights into urban heat island effects.
• Offers a mechanistic understanding of how urbanization influences wet-bulb temperature through its variable responses to air temperature and relative humidity.
• Highlights the critical and escalating health threats posed by extreme heat intensities observed in recent years (2023-2024).

Funding

• Major Science and Technology Special Project of Xinjiang Uygur Autonomous Region (grant no.: 2024A03006-2)
• Major Demonstration Project for Scientific and Technological Innovation in the Inner Mongolia Autonomous Region (grant no. 2025ZDSF0009-04)
• Research Initiation Project for High-Level Talent Team of Arospace Information Technology University (nos. 301010102 and 301010202)

Citation

@article{Xu2026Divergent,
  author = {Xu, Lei and Zhang, Qing and Tang, Senlin and Lee, Xuhui and Song, Hongyu and Gong, Xinyu},
  title = {Divergent latitude-specific urban humid heat risks are regulated by local climate types},
  journal = {Communications Earth & Environment},
  year = {2026},
  doi = {10.1038/s43247-026-03437-8},
  url = {https://doi.org/10.1038/s43247-026-03437-8}
}