The unrelenting global expansion of the urban heat island over the last century

Yaxue Ren; Raffaele Lafortezza; Vincenzo Giannico; Giovanni Sanesi; Xinna Zhang; Chengyang Xu

doi:10.1016/j.scitotenv.2023.163276

The unrelenting global expansion of the urban heat island over the last century

Sci Total Environ. 2023 Jul 1:880:163276. doi: 10.1016/j.scitotenv.2023.163276. Epub 2023 Apr 4.

Authors

Yaxue Ren¹, Raffaele Lafortezza², Vincenzo Giannico¹, Giovanni Sanesi¹, Xinna Zhang³, Chengyang Xu³

Affiliations

¹ Department of Soil, Plant and Food Sciences, University of Bari Aldo Moro, Via Amendola 165/A, 70126 Bari, Italy.
² Department of Soil, Plant and Food Sciences, University of Bari Aldo Moro, Via Amendola 165/A, 70126 Bari, Italy; The Key Laboratory for Silviculture and Conservation of Ministry of Education, Key Laboratory for Silviculture and Forest Ecosystem of State Forestry Grassland Administration, Research Center for Urban Forestry, Beijing Forestry University, Beijing 100083, China. Electronic address: raffaele.lafortezza@uniba.it.
³ The Key Laboratory for Silviculture and Conservation of Ministry of Education, Key Laboratory for Silviculture and Forest Ecosystem of State Forestry Grassland Administration, Research Center for Urban Forestry, Beijing Forestry University, Beijing 100083, China.

PMID: 37019234
DOI: 10.1016/j.scitotenv.2023.163276

Abstract

The past century has seen dramatic increases in global temperatures and mounting urbanization. As a result of these events, the urban heat island (UHI) effect has received growing attention in scientific research worldwide. A global search was initially conducted using a scientific literature database to collect all available relevant publications to understand how the UHI has been expanding worldwide and affecting more cities across different latitudes and altitudes. Subsequently, a semantic analysis was performed to extract city names. The literature search and analysis combined resulted in 6078 publications in which UHI was investigated in 1726 cities worldwide in the 1901 to 2022 time period. The cities were grouped into 'first appearance' and 'recurrent appearance'. Results show that UHI was studied in only 134 cities during the 90-year period from 1901 to 1992, with a remarkable growth over time in the number of cities where interest in UHI increased. Interestingly, the number of first appearances was always notably higher than the number of recurrent appearances. The Shannon evenness index was employed to identify the spatial locations (hotspots) across the globe where UHI-related research has been concentrated in multiple cities over the last 120 years. Finally, Europe was selected as a testbed for conducting an analysis to shed light on how economic, demographic, and environmental factors can impact UHI. Our study is unique for having demonstrated not only the rapid growth of cities affected by UHI globally but also the increasing and unrelenting expansion of UHI occurrences across different latitudes and altitudes over time. These novel findings will undoubtedly be of interest to scientists investigating the UHI phenomenon and its trends. Stakeholders will acquire a broader perspective and deeper understanding of UHI in order to engage in more effective urban planning to offset and mitigate the phenomenon's adverse effects in the context of increasing climate change and urbanization.

Keywords: Altitude; Climate; Latitude; Literature database; Urban heat island; Vegetation.

Publication types

Review