Khan et al. (2025) Escalating Heat Stress And Outdoor Labor Productivity Loss In The Arabian Peninsula: A Five-Decade Analysis Of Climate Change Impacts

Identification

• Journal: Earth Systems and Environment
• Year: 2025
• Date: 2025-11-03
• Authors: Najeebullah Khan, Zulhilmi Ismail, Mazen Ibrahim Asiri, Farida Behlil, Mohamad Hidayat Jamal, Ilya Khairanis Othman, Mazlin Jumain, Labib Sharrar, Daeng Siti Maimunah Ishak, Shamsuddin Shahid
• DOI: 10.1007/s41748-025-00903-9

Research Groups

• Department of Water & Environmental Engineering, Faculty of Civil Engineering, Universiti Teknologi Malaysia (UTM)
• Centre for River and Coastal Engineering (CRCE), Universiti Teknologi Malaysia (UTM)
• Faculty of Engineering Sciences and Technology, Water and Marine Sciences (LUAWMS), Lasbela University of Agriculture
• Regional Climate Change Center, Kingdom of Saudi Arabia, National Center for Meteorology
• Department of Chemistry, Faculty of Basic Sciences, Sardar Bahadur Khan Womens University
• Department of Electrical, Computer and Energy Engineering, Faculty of Engineering, University of Colorado Boulder

Short Summary

This study analyzes the spatiotemporal trends of Wet Bulb Globe Temperature (WBGT) and its impact on outdoor labor productivity across the Arabian Peninsula over five decades (1974–2023), revealing significant increases in heat stress and substantial productivity losses, particularly for heavy workloads in coastal and urban areas.

Objective

• To assess the spatiotemporal trends of Wet Bulb Globe Temperature (WBGT) across the Arabian Peninsula from 1974 to 2023.
• To evaluate the impacts of WBGT on outdoor labor productivity under light, moderate, and heavy workloads.
• To examine population exposure and key meteorological drivers influencing productivity losses.

Study Configuration

• Spatial Scale: Arabian Peninsula (12°N–32°N latitude and 34°E–60°E longitude, 3,237,500 km²). Data resolution: 0.25° × 0.25° for WBGT, 1 km² for LandScan population data (resampled to 0.25° × 0.25°).
• Temporal Scale: 1974 to 2023 (50 years) for WBGT and productivity analysis, with hourly temporal resolution. LandScan 2022 dataset used for population exposure.

Methodology and Data

• Models used:
  • Wet Bulb Globe Temperature (WBGT) calculated using the Liljegren method, implemented via the Python-based "Thermofeel" package.
  • Outdoor labor productivity assessed following ISO/DIS 7243 guidelines, using metabolic rates of 180 W (light), 297 W (moderate), and 414 W (heavy) workloads.
  • Sen slope estimator for quantifying trend magnitudes.
  • Modified Mann Kendall test for assessing trend significance (95% confidence level).
• Data sources:
  • ERA5 reanalysis data (Copernicus Climate Data Store) for hourly meteorological variables (2 m temperature, dew point temperature, 10-m wind speed, surface pressure, relative humidity, surface solar radiation downwards, surface net solar radiation, surface thermal radiation downwards, direct solar radiation from the sun, total sky direct solar radiation, cosine of the solar zenith angle).
  • LandScan 2022 population data (Oak Ridge National Laboratory) for population exposure analysis.

Main Results

• Annual WBGT levels increased by up to 1.5 °C, and summer levels by 1.0 to 1.5 °C over the past five decades across the Arabian Peninsula.
• Coastal areas exhibited the highest WBGTs, exceeding 28 °C during the summer season.
• Heavy workloads experienced the most severe productivity losses, declining from 94% in 1974 to under 88% in 2023, representing an annual decrease of 0.136%.
• Moderate and light workloads showed smaller annual declines of 0.085% and 0.041%, respectively.
• Coastal and urban regions were identified as hotspots, where midday productivity losses for heavy work could reach 30%.
• Bivariate analyses indicated a strong inverse relationship between productivity and temperature (Pearson correlation coefficient: -0.68), with productivity declining by approximately 2.1% for every 1 °C increase in daytime temperature above 30 °C.
• Specific humidity also showed a negative association with productivity (correlation: -0.53), with a 1.7% productivity decrease for every 2 g/kg increase in specific humidity.
• Higher wind speeds positively correlated with productivity (+0.42), mitigating heat stress effects; a 1 m/s increase in wind speed was associated with a 1.2% increase in productivity under heavy workload conditions.
• Peak heat hours (12:00–16:00) showed the most significant productivity decreases, with annual declines of 0.155% for light, 0.272% for moderate, and 0.5% for heavy workloads.

Contributions

• Provides the first region-wide, long-term (five-decade), high-resolution (0.25° × 0.25° hourly) assessment of heat stress impacts on outdoor labor productivity across the Arabian Peninsula.
• Quantifies WBGT and its differentiated effects on labor productivity for light, moderate, and heavy workloads at an unprecedented granularity for the region.
• Integrates population exposure analysis using LandScan data, offering a unique contextualization of productivity losses in relation to human exposure and regional economic development goals.
• Fills a significant regional research gap by offering a comprehensive perspective on the spatiotemporal evolution of heat stress and WBGT-productivity linkages.

Funding

• The Ministry of Higher Education Malaysia
• Universiti Teknologi Malaysia

Citation

@article{Khan2025Escalating,
  author = {Khan, Najeebullah and Ismail, Zulhilmi and Asiri, Mazen Ibrahim and Behlil, Farida and Jamal, Mohamad Hidayat and Othman, Ilya Khairanis and Jumain, Mazlin and Sharrar, Labib and Ishak, Daeng Siti Maimunah and Shahid, Shamsuddin},
  title = {Escalating Heat Stress And Outdoor Labor Productivity Loss In The Arabian Peninsula: A Five-Decade Analysis Of Climate Change Impacts},
  journal = {Earth Systems and Environment},
  year = {2025},
  doi = {10.1007/s41748-025-00903-9},
  url = {https://doi.org/10.1007/s41748-025-00903-9}
}