Hadei et al. (2025) Three Decades of Climate Change in Iran: Spatiotemporal Evidence from National-Scale Meteorological Indicators

Identification

• Journal: Earth Systems and Environment
• Year: 2025
• Date: 2025-11-13
• Authors: Mostafa Hadei, Philip K. Hopke, Fatemeh Chaparinia, Yasaman Oshidari, Abbas Ostadtaghizadeh, Mohammad Sadegh Hassanvand, Fatemeh Momeniha, Hanieh Aliakbar, Kazem Naddafi
• DOI: 10.1007/s41748-025-00930-6

Research Groups

• Center for Air Pollution Research (CAPR), Institute for Environmental Research (IER), Tehran University of Medical Sciences, Tehran, Iran
• Department of Environmental Health Engineering, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
• Departments of Public Health Sciences and Environmental Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
• Institute for a Sustainable Environment, Clarkson University, Potsdam, NY, USA
• Department of Environmental Health Engineering, School of Public Health, Iran University of Medical Sciences, Tehran, Iran
• Department of Health in Emergencies and Disasters, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
• Climate Change and Health Research Center (CCHRC), Institute for Environmental Research (IER), Tehran University of Medical Sciences, Tehran, Iran
• Center for Solid Waste Research (CSWR), Institute for Environmental Research (IER), Tehran University of Medical Sciences, Tehran, Iran
• Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran

Short Summary

This study assessed climate trends in Iran over three decades (1993–2022) using national meteorological data, revealing widespread warming, heterogeneous precipitation changes, and complex wind and dew point patterns with significant regional variability. These observed shifts indicate a transition towards a warmer, drier, and more hydrologically variable climate, necessitating targeted adaptation strategies.

Objective

• To evaluate the spatiotemporal trends in key meteorological variables (mean, maximum, and minimum air temperature, precipitation, dew point temperature, mean wind speed, and maximum sustained wind speed) across major Iranian cities over the past three decades (1993–2022) to understand regional climate dynamics and inform adaptation strategies.

Study Configuration

• Spatial Scale: National-scale for Iran, covering 29 provincial capitals for trend analysis and an expanded network of 69 cities for spatial mapping.
• Temporal Scale: Three decades (1993–2022).

Methodology and Data

• Models used: Linear regression, Thiel-Sen slope analysis, Inverse Distance Weighting (IDW) interpolation.
• Data sources: Daily observational meteorological data measured by the Iranian Meteorological Organization (IRIMO), retrieved from the Global Surface Summary of the Day (GSOD) database managed by the United States National Oceanic and Atmospheric Administration (NOAA). Only stations with greater than 90% data completeness were included.

Main Results

• Mean Temperature: Most cities experienced significant increasing trends, with the highest increase in Zanjan and the lowest in Bandar Abbas. Western, northwestern, and northeastern regions showed more pronounced warming.
• Maximum Temperature: All cities, except Kermanshah and Sari, showed significant increasing trends. Zanjan had the highest increase (0.147 °C per year), while Sari had the lowest (0.072 °C per year). Central, southern, northwestern, and western regions experienced more remarkable increases.
• Minimum Temperature: Displayed mixed patterns; predominantly increasing in eastern and northern regions (e.g., Ilam: 0.154 °C per year, Rasht: 0.035 °C per year), but decreasing in specific areas such as Isfahan (-0.106 °C per year), Shiraz, Gorgan, Birjand, and Tehran.
• Precipitation: Exhibited spatially heterogeneous trends, with significant decreases in southern and central regions (e.g., Isfahan, Ahvaz) and increases in parts of the northeast (e.g., Mashhad, Yazd). Overall, no clear national trend, but localized heavy rainfall was noted.
• Dew Point Temperature: Generally decreased in central and southern areas (e.g., Kerman: -0.151 °C per year, Birjand: -0.149 °C per year, Tehran: -0.141 °C per year), indicating drier atmospheric conditions. Northern regions saw slight increases (e.g., Ilam: 0.073 °C per year, Zanjan: 0.073 °C per year, Qazvin: 0.061 °C per year, Rasht: 0.053 °C per year).
• Wind Speeds (Mean and Maximum Sustained): Increased significantly in central, northeastern, and some northern cities (e.g., Birjand mean wind: 0.066 m/s per year; Zanjan maximum sustained wind: 0.096 m/s per year). Declines were observed predominantly in southern and western locations (e.g., Shiraz mean wind: -0.016 m/s per year; Semnan maximum sustained wind: -0.112 m/s per year).
• Decadal Averages: Spatial mapping of decadal averages (2013–2022 vs. 1993–2002 and 2003–2012) showed substantial warming and drying trends in several regions, indicating a shift toward a warmer, drier, and more hydrologically variable climate.

Contributions

• Provides a comprehensive, national-scale spatiotemporal assessment of multiple key meteorological indicators (temperature, precipitation, dew point, wind speed) over three decades in Iran, addressing a gap in existing literature which often focused on limited areas or shorter periods.
• Offers detailed, localized observational evidence of climate change impacts across Iran's diverse geography, highlighting regional variability that is crucial for targeted adaptation strategies.
• Utilizes a robust methodology (linear regression, Thiel-Sen slope, IDW interpolation) on quality-controlled daily observational data from a broad network of stations, enhancing the reliability and detail of the findings.
• Identifies atypical behaviors, such as weakly positive or negative minimum temperature trends despite overall warming, and provides potential explanations related to Iran's arid climate and regional dynamics.

Funding

• Tehran University of Medical Sciences, Tehran, Iran (Project No.: 1402-3-462-65769).

Citation

@article{Hadei2025Three,
  author = {Hadei, Mostafa and Hopke, Philip K. and Chaparinia, Fatemeh and Oshidari, Yasaman and Ostadtaghizadeh, Abbas and Hassanvand, Mohammad Sadegh and Momeniha, Fatemeh and Aliakbar, Hanieh and Naddafi, Kazem},
  title = {Three Decades of Climate Change in Iran: Spatiotemporal Evidence from National-Scale Meteorological Indicators},
  journal = {Earth Systems and Environment},
  year = {2025},
  doi = {10.1007/s41748-025-00930-6},
  url = {https://doi.org/10.1007/s41748-025-00930-6}
}