Evaluation of Environmental and Anthropogenic Factors on Urban Heat Island: The Case of Istanbul, Turkey

Abstract

This study aims to evaluate the urban heat island (UHI) phenomenon in Istanbul and the environmental and anthropogenic factors that may contribute to its formation. Air temperature, relative humidity and wind data for the period 1970-2023 provided by the Turkish State Meteorological Service (TSMS) and population, number of motor vehicles and electricity consumption data provided by the Turkish Statistical Institute (Turkstat) are analysed. TSMS data reveals that long-term temperatures in Istanbul show a linear upward trend, especially in January and July. This trend shows that annual average temperatures have increased from 13-14°C to 15-16°C in a period of approximately 50 years, increasing the importance of the urban heat island effect in the context of global climate change. When urban and rural meteorological stations are compared, it is determined that the temperature values differ by approximately 2-4 °C and the UHI is spatially observable in Istanbul. However, no statistically significant relationship was found between annual anthropogenic indicators such as population growth, number of motor vehicles and electricity consumption and air temperature values. This result shows that UHI cannot be explained by annual macro-indicators, but is rather influenced by micro-scale morphological conditions, surface features and settlement pattern. While the study reveals the existence of the UHI effect in Istanbul and the temperature increase spread over many years, it shows that the causal relationship of anthropogenic factors with UHI at the annual level is limited. These findings suggest that enhancement of green areas, protection of wind corridors and micro-scale urban design strategies are critical for mitigating UHI.

Keywords

• Urban heat island
• global warming
• climate change
• Istanbul
• Turkey

Kentsel Isı Adası Üzerinde Etkili Olan Çevresel ve Antropojenik Faktörlerin Değerlendirilmesi: İstanbul – Türkiye Örneği

Abstract

References

1. Akbari, H., & Matthews, H. D. (2020). Global cooling updates: Reflective roofs and pavements. Energy and Buildings, 222, 110022. https://doi.org/10.1016/j.enbuild.2020.110022
2. Alavipanah, S., Weng, Q., & Zhou, Y. (2024). Urban heat vulnerability mapping using multi-variable climate datasets. Remote Sensing of Environment, 305, 114889. https://doi.org/10.1016/j.rse.2024.114889
3. Baş, E., & Partigöç, N. S. (2023). Resilient Cities Against Climate Change: A Review in the Context of Urban Heat Island Effect. Journal of Resilience, 7(1), 183-198. https://doi.org/10.54572/resilience.2023.183
4. Baykara, M. (2023). An assessment of long-term urban heat island impact on Istanbul’s climate. International Journal of Environment and Geoinformatics, 10(2), 40-47.
5. United Nations Framework Convention on Climate Change (UNFCCC). (2015). Paris Climate Agreement. https://unfccc.int/process-and-meetings/the-paris-agreement/the-paris-agreement
6. Bozkurt, D., & Turunç, D. (2020). Regional climate impacts of urban heat islands: A case study of Istanbul. Urban Climate, 34, 100682. https://doi.org/10.1016/j.uclim.2020.100682
7. Canan, M., & Geyikli, H. (2021). Urban morphology and wind corridors: Implications for urban heat islands. Sustainable Cities and Society, 75, 103082. https://doi.org/10.1016/j.scs.2021.103082
8. Chen, L., & Wong, M. S. (2024). Assessing the statistical significance of UHI trends using non-parametric tests in East Asian cities. Urban Climate, 53, 101678. https://doi.org/10.1016/j.uclim.2024.101678

9. Çiçek, İ., & Yılmaz, S. (2020). Urban heat island intensity in Istanbul and its effects on thermal comfort. Urban Climate, 34, 100678. https://doi.org/10.1016/j.uclim.2020.100678
10. Das, S. (2022). A Review of Urban Heat Island formation over changing climate and its impacts on Urban Land Use and Environments and Adaptation Measures. International Journal of Environment and Geoinformatics, 9(1), 64-73.
11. Dogan, E., & Yilmaz, S. (2018). Land use and surface temperature analysis of Istanbul's urban heat island effect. Sustainable Cities and Society, 36, 66-77. https://doi.org/10.1016/j.scs.2017.10.022
12. Duarte, D. H. S., Alves, F., & Moreno, M. (2025). Urban morphology and ventilation pathways as determinants of heat accumulation in compact cities. Building and Environment, 252, 112987. https://doi.org/10.1016/j.buildenv.2025.112987
13. Erdem, Ü., & Kaya, S. (2024). Long-term evolution of the urban heat island in Istanbul using satellite observations (1985-2023). Urban Climate, 56, 101745. https://doi.org/10.1016/j.uclim.2024.101745
14. Gartland, L. (2008). Heat islands: Understanding and mitigating heat in urban areas. Earthscan.
15. Gilbert, R. O. (1987). Statistical methods for environmental pollution monitoring. John Wiley & Sons.
16. Helsel, D. R., & Hirsch, R. M. (2002). Statistical methods in water resources (Vol. 323). U.S. Geological Survey. https://pubs.usgs.gov/twri/twri4a3/
17. Kendall, M. G. (1975). Rank correlation methods (4th ed.). Charles Griffin.
18. Khan, M., Idris, N., & Patel, R. (2025). Urbanisation, anthropogenic pressures and UHI intensity across developing regions. Environmental Pollution, 343, 123654. https://doi.org/10.1016/j.envpol.2025.123654
19. Li, X., Chen, G., Zhang, Y., & Zhou, Q. (2022). Albedo modifications for urban heat island mitigation. Environmental Research, 215, 113048. https://doi.org/10.1016/j.envres.2022.113048
20. Li, X., Zhang, Y., Zhou, D., & Wang, K. (2024). Climate-driven intensification of urban heat islands across global megacities from 1970 to 2020. Nature Communications, 15, 4821. https://doi.org/10.1038/s41467-024-41874-3
21. McMichael, A. J., Woodruff, R. E., & Hales, S. (2006). Climate change and human health: Present and future risks. The Lancet, 367(9513), 859-869. https://doi.org/10.1016/S0140-6736(06)68079-3
22. General Directorate of Meteorology. (2023). Istanbul long-term air temperature, relative humidity and wind data (1970-2023) [Data set]. https://TSMS.gov.tr
23. General Directorate of Meteorology. (2023). Istanbul maximum, minimum and average temperature values [Data set]. https://TSMS.gov.tr
24. Ng, E., Yuan, C., Chen, L., Ren, C., & Fung, J. C. H. (2012). Improving the wind environment in high-density cities by understanding urban morphology and surface roughness: A study in Hong Kong. Landscape and Urban Planning, 101(1), 59-74. https://doi.org/10.1016/j.landurbplan.2011.12.004
25. Oke, T. R. (1982). The energetic basis of the urban heat island. Quarterly Journal of the Royal Meteorological Society, 108(455), 1-24. https://doi.org/10.1002/qj.49710845502
26. Rahman, M., & Sarram, A. (2024). Seasonal variability of urban heat islands and the role of vegetation and built-up intensity. Science of the Total Environment, 921, 171234. https://doi.org/10.1016/j.scitotenv.2024.171234
27. Santamouris, M. (2014). Cooling the cities: A review of reflective and green roof mitigation technologies. Solar Energy, 103, 682-703. https://doi.org/10.1016/j.solener.2012.07.003
28. Santamouris, M. (2015). Environmental design of urban buildings: An integrated approach. Routledge.
29. Santamouris, M. (2020). Recent progress in urban climate mitigation technologies: A review. Renewable and Sustainable Energy Reviews, 130, 109938. https://doi.org/10.1016/j.rser.2020.109938
30. Sen, P. K. (1968). Estimates of the regression coefficient based on Kendall's tau. Journal of the American Statistical Association, 63(324), 1379-1389. https://doi.org/10.1080/01621459.1968.10480934
31. Shochat, E., Warren, P. S., Faeth, S. H., McIntyre, N. E., & Hope, D. (2004). Urbanisation and spider diversity: UHI as an ecological driver. Ecological Applications, 14(1), 268-280. https://doi.org/10.1890/02-5386
32. Stone, B. (2005). Urban heat and air pollution: An emerging role for planners in the climate change debate. Journal of the American Planning Association, 71(1), 13-25. https://doi.org/10.1080/01944360508976434
33. Stewart, I. D., & Oke, T. R. (2012). Local climate zones for urban temperature studies. Bulletin of the American Meteorological Society, 93(12), 1879-1900. https://doi.org/10.1175/BAMS-D-11-00019.1
34. Tozam, M. R. (2016). Urban heat island and cooling strategies: A systematic review. Sustainable Cities and Society, 27, 113-123. https://doi.org/10.1016/j.scs.2016.04.013
35. Turkish Statistical Institute. (2024). Annual electricity consumption and motor vehicle ownership data [Data set]. https://data.tuik.gov.tr
36. Turkish Statistical Institute. (2024). Istanbul district populations [Data set]. https://data.tuik.gov.tr
37. Ünal, Y., Onol, B., & Bozkurt, D. (2021). Impacts of urbanisation on the climate of Istanbul: Long-term trends and future projections. Environmental Research Letters, 16(6), 064015. https://doi.org/10.1088/1748-9326/abf82f
38. Wang, J., He, Q., & Liu, S. (2025). Non-linear urban heat island trend detection under climate variability. Environmental Research Letters, 20(1), 014015. https://doi.org/10.1088/1748-9326/ad7a55
39. Yilmaz, S., & Ozturk, H. (2023). Enhancing urban airflow for thermal comfort: Strategies for mitigating urban heat islands. Building and Environment, 217, 109149. https://doi.org/10.1016/j.buildenv.2022.109149
40. Yue, S., Pilon, P., Phinney, B., & Cavadias, G. (2002). The influence of autocorrelation on the ability to detect trend in hydrological series. Hydrological Processes, 16(9), 1807-1829. https://doi.org/10.1002/hyp.1095
41. Yue, S., & Wang, C. Y. (2004). The Mann-Kendall test modified by effective sample size to detect trend in serially correlated hydrological series. Water Resources Management, 18, 201-218. https://doi.org/10.1023/B:WARM.0000043140.61082.60
42. Zhao, Q., Weng, Q., & Wang, L. (2021). Assessing urban heat island dynamics using time-series thermal remote sensing data. Remote Sensing of Environment, 265, 112678. https://doi.org/10.1016/j.rse.2021.112678