Search Results (388)

Under the dual pressure of rapid urbanization and global warming, the urban heat island (UHI) effect has been intensifying, accompanied by a continuous increase in heat exposure. As a typical example of rapid urbanization in China, Xi’an is facing severe challenges. However, previous research on diurnal variations in long-term UHI effects and heat risks is insufficient. So, this study utilized the temperature level threshold method and the heat exposure risk assessment model to investigate the spatiotemporal evolution characteristics of diurnal variations in the UHI and population heat exposure risks in Xi’an from 2003 to 2023. The results indicate that (1) over the past two decades, both the summer UHI intensity and the population heat exposure risks in Xi’an exhibited an overall intensifying trend, (2) spatial expansion followed a radial diffusion pattern centered on the urban core, with heat risk levels decreasing outward, (3) the nighttime expansion of high-level UHI zones and risk areas was slightly less than during the daytime, and (4) changes in the thermal environment often preceded population aggregation, indicating a lag effect in the evolution of heat exposure risks. This study deepened the understanding of the UHI and heat exposure for governments and planners and can help propose scientific UHI mitigation measures. Full article

Taiwan, located in a subtropical region, has experienced continuous warming in recent years, making the Urban Heat Island (UHI) effect one of its most pressing environmental challenges. Importantly, UHI is not confined to Taipei, the most populous city, but is also present in other metropolitan areas. This study investigates UHI effects in the five largest cities in Taiwan and examines climate-related news attention using web crawling. Cross-city comparisons are further conducted through Urban Heat Island Intensity (UHII) and correlation analysis. The results reveal that Taipei records the highest number of UHI-related news reports, particularly during summer, and its UHII is about 1.5 °C to 3 °C higher than in the other four cities. In addition, UHII in Taipei shows a marked increase between 2021 and 2023, suggesting a worsening impact on citizens’ living conditions. Meanwhile, news coverage in Taipei dominates nationwide attention, creating a spatially uneven distribution of media focus. This imbalance may undermine efforts to promote UHI mitigation and adaptation strategies in cities outside Taipei. Overall, this study highlights that UHI is not solely a problem of Taipei but a widespread issue across Taiwan’s urban areas. The findings provide useful references for policymakers and government agencies, emphasizing the need for equitable attention and broader public engagement through media channels to raise awareness and foster comprehensive climate adaptation actions. Full article

The urban heat island (UHI) significantly compromises outdoor thermal comfort and public health in hot climates. While urban vegetation is a recognized mitigation strategy, its performance variability across different urban fabrics remains a critical knowledge gap. This research quantitatively evaluates the microclimatic impact of vegetation strategies by comparing two districts with distinct urban morphologies: low-density and high-density. Using the Envi-met software, we simulated a reference case and four vegetation scenarios with constant 50% grass coverage and incrementally increasing tree percentages (0% to 75%). Thermal performance was assessed through key metrics, including air temperature (T_a), relative humidity (RH), mean radiant temperature (T_mrt), and Physiologically Equivalent Temperature (PET). The results reveal that vegetation’s effectiveness is directly correlated with urban density. The most comprehensive strategy (Scenario-D: 50% grass, 75% trees) reduced peak PET by up to 7.5 °C in the low-density El Khazzan, a reduction nearly three times greater than the 2.7 °C achieved in the high-density El Akkad. Similarly, this scenario achieved a maximum daytime T_a reduction of 0.92 K in El Khazzan, compared to only 0.4 K in the high-density district. The study also identifies a critical trade-off: high-density tree scenarios increased nighttime temperatures by up to 0.4 K due to disrupted airflow, whereas the grass-only scenario maintained thermal stability. These findings underscore that a one-size-fits-all approach to urban greening is insufficient. For practical implications, urban planners must abandon generic strategies and integrate a nuanced understanding of local morphology to maximize the thermal benefits of vegetation, particularly in hot, arid environments. Full article

Urban microclimates depend on the city’s features, geographical position, climatic conditions, solar irradiance, and building materials. Many urban elements delay heat dissipation, giving rise to the urban heat island (UHI) phenomenon. (1) In Mexico City, UHIs occur mainly during the dry season (April–May) and likely increase in energy consumption in buildings. (2) Computational fluid dynamics models such as Ansys Fluent provide detailed flow field data related to atmospheric parameters and building surface fluctuations. With the data generated, a mitigation technique is proposed that displaces heat away from buildings, using air turbulence to actively cool them by examining the performance of w. (3) An experimental analysis was carried out to simulate thermal and aerodynamic scenarios throughout the day around three modules of different sizes, configurations, and albedo values. All modules showed a decrease in the difference between the building temperature and the air temperature, becoming colder with differences from −0.46 to −0.76 °C, while w presented values from −1.3 to 0.59 m·s⁻¹, indicating some turbulence. (4) Therefore, it is necessary to consider mitigating UHIs in urban planning through efficient use of the properties and construction materials of each building and their arrangement in each block. Full article

With accelerating urbanization and global climate warming, Urban Heat Islands (UHIs) pose serious threats to urban development. Existing UHI research mainly focuses on inland regions, lacking systematic understanding of coastal city heat island mechanisms. We selected eight Chinese coastal cities with different backgrounds, quantitatively assessed urban heat island intensity based on summer 2023 Landsat 8 remote sensing data, established block-LCZ spatial analysis units, and employed a combination of machine learning models and causal inference methods to systematically analyze the regional differentiation characteristics of Urban Heat Island Intensity (UHII) and the influence mechanisms of multi-dimensional driving factors within land–sea interaction contexts. The results revealed the following: (1) UHII in the study area presents obvious spatial differentiation, with the highest value occurring in Hong Kong (2.63 °C). Northern cities generally had higher values than southern ones. (2) Different Local Climate Zone (LCZ) types show significant differences in thermal contributions, with LCZ2 (compact midrise) blocks presenting the highest UHII values in most cities, while LCZ G (water) and LCZ A (dense trees) blocks exhibit stable cooling effects. Nighttime light (NTL) and distance to sea (DS) are dominant factors affecting UHII, with NTL marginal effect curves generally presenting hump-shaped characteristics, while DS shows different response patterns across cities. (3) Causal inference reveals true causal driving mechanisms beyond correlations, finding that causal effects of key factors exhibit significant spatial heterogeneity. The research findings provide a new cognitive framework for understanding the formation mechanisms of thermal environments in Chinese coastal cities and offer a quantitative basis for formulating regionalized UHI mitigation strategies. Full article

The global rapid urbanization intensifies environmental challenges related to climate change, such as air pollution and the urban heat island (UHI) effect in built environments. The need to optimize nature-based solutions (NBSs) is imperative to mitigate climate change and adapt to extreme weather phenomena. Against this background, this review offers an analysis regarding the integration of vertical greenery systems (VGSs) into urban environments so as to capitalize on their environmental, social, and economic benefits. Key aspects of the review include the positive role of VGSs in UHI mitigation, air quality improvement, stormwater management, and biodiversity enhancement, while examining social aspects (i.e., improved well-being and mental health, noise reduction, and urban built aesthetics). Finally, parameters related to economic benefits and energy efficiency are assessed. The submission further analyses the significant challenges that VGSs face, such as high maintenance costs, structural risks, plant health issues, fire hazards, and other limitations (legislative and technical). The crucial need for interdisciplinary collaborations among urban planners, architects, environmental engineers, and stakeholders is highlighted, in order to successfully integrate VGSs into urban buildings. Thus, this paper aims to identify key strategies for optimizing VGSs’ implementation and provide valuable insights for policymakers and researchers aiming to enhance urban sustainability through vertical greening. Full article

This paper evaluates Urban Heat Island (UHI) mitigation strategies in Florence’s historical centre, characterized by relevant cultural heritage value and significant tourist fluxes but increasingly susceptible to heatwaves. The research work focused on the evaluation of both current microclimate conditions and mitigation solutions for UHI-related issues, using ENVI-met microclimate modelling software as a simulation tool. Different models, featuring a 2 m grid resolution and detailed material properties, were produced to assess outdoor air temperature (Ta), mean radiant temperature (MRT), and Universal Thermal Climate Index (UTCI), chosen as reference parameters for human thermal sensation. Diversified conditions induced by the peculiarities of the urban layout were highlighted, with current Ta up to 32 °C and MRT exceeding 55 °C in paved open areas. Site-specific measures and their expected effectiveness were hence analyzed. De-paving and greening yield modest local cooling (Ta reduction up to −0.25 °C, MRT up to −1.75 °C), while tree installation ensures that MRT decreases by −7.50 °C to −12.00 °C. Most effectively, suspended shading fabrics preventing direct radiation can act on Ta (−0.09 °C to −0.25 °C) and provide substantial MRT reductions (−7.50 °C to −17.00 °C), significantly improving thermal comfort. The findings emphasize the potentialities of site-specific, reversible interventions in historic centres to combine climate adaptation and heritage preservation. Full article

Urban growth in hot, arid regions intensifies the urban heat island effect, making green spaces vital for climate mitigation. This research investigates the impact of public gardens on the surrounding urban thermal environment and on the mitigation of the urban heat island (UHI) in a hot arid region. This study selects an important public garden in Biskra, the “5 July 1962” Garden, as a case study of significance at the urban scale. To achieve research objectives, onsite measurement using a digital measurement device (5-in-1 Environmental Meter “Extech EN300”) and satellite remote sensing data from LANDSAT8 are employed, capturing summer measurements of key parameters and indices: Land Surface Temperature (LST), Air Temperature (AT), Relative Humidity (RH), Normalized Difference Vegetation Index (NDVI), Normalized Difference Water Index (NDWI) and Normalized Difference Moisture Index (NDMI). The analysis and correlation of these indices with the LST values allow us to evaluate the zoning and distance impacts of the garden studied. Land surface temperature rises gradually from the garden outward, peaking in the North-East with the strongest heat island effect and remaining lower in the cooler, vegetation-rich South-West. The results reveal that air temperature is the primary driver of land surface temperature (72% impact), while relative humidity (17.3%), vegetation index (7.8%), moisture index (2.9%), and water index (1.7%) contribute to cooling, with vegetation and moisture reducing surface temperatures through shading, transpiration, and latent heat exchange. Full article

Urbanization and intensified human activity have significantly impacted city climates, amplifying the urban heat island effect and increasing thermal stress on residents. This study focuses on the design of a pocket park in the Municipality of Kallithea as a targeted bioclimatic intervention. Through the integration of on-site microclimate measurements, GIS mapping, and 2D design tools, the research evaluates key bioclimatic indicators to inform climate-responsive design strategies. Proposed solutions include the use of cool materials, reflective surfaces, permeable pavements, and water features to enhance natural ventilation and mitigate surface temperatures. The project demonstrates how small-scale green infrastructure can improve thermal comfort in dense urban areas while supporting sustainability goals. By highlighting the potential of localized interventions, the study contributes to the broader discourse on urban resilience and the role of bioclimatic planning in creating healthier, more livable cities. Full article

The rapid urbanization process has exacerbated the urban heat island (UHI) effect in megacities like Shanghai. Urban green infrastructure (UGI) plays a crucial role in mitigating the UHI effect; however, its cooling capacity is subject to various urban land development patterns. This study examined 39 typical locations in downtown Shanghai to measure how urban land development patterns affect the UGI’s cooling capacity. Using a data-driven framework, we identified 12 key influencing factors and explored 4 interactions for building three regression models: multiple linear regression (MLR), partial least squares regression (PLSR), and support vector regression (SVR). For each of these models, we considered two variations: a basic model neglecting interactions and an enhanced model including interactions. Results showed that all enhanced models outperformed their basic counterparts. On average, the enhanced models increased their predictive power by 14.59% for training data and 32.15% for testing data. Additionally, among the three enhanced models, the SVR-enhanced models show the best performance, followed by the PLSR-enhanced models. Their mean predictive power increased by 8.33−37.43% for training data and 31.77−43.558% for testing data vs. the MLR-enhanced models. Overall, our findings revealed that impervious surfaces contribute positively to urban warming, while UGI acts as a negative contributor. Moreover, we highlighted how urban land development metrics, particularly the UGI’s percentage and spatial arrangements in relation to adjacent buildings, significantly affect the thermal environment. The findings can offer valuable insights for urban planners and decision-makers involved in managing UGI and developing strategies for UHI mitigation and urban climate adaptation. Full article

In the context of global climate change and rapid urbanization, the urban heat island (UHI) effect has emerged as a critical issue impacting urban sustainability. This study analyzes 945 publications retrieved from the Web of Science Core Collection (2000–2025) and employs VOSviewer and Scimago Graphica to construct and visualize a knowledge map. The findings indicate that, since 2013, there has been a significant increase in research interest in utilizing green infrastructure (GI) to mitigate UHI, with China, the United States, and Europe leading international collaboration efforts. Keyword analysis reveals that early studies primarily focused on thermodynamic manifestations. Recent research has shifted toward more diverse topics, including artificial neural networks (ANNs), environmental justice, and public participation. By constructing a knowledge framework, this study clarifies how GI mitigates UHI while simultaneously promoting carbon reduction, enhancing health benefits, and supporting resilient governance. This research provides a comprehensive overview of the role of GI in mitigating UHI, offering theoretical insights and practical solutions for achieving integrated governance that combines climate resilience, biodiversity conservation, and social equity. These findings have significant theoretical and practical implications for advancing both UHI mitigation and sustainable development. Full article

The urban heat island (UHI) effect, intensified by urbanisation and climate change, leads to increased urban temperatures and poses a serious environmental challenge. Understanding its causes, impacts, and mitigation strategies is essential for sustainable urban planning. The aim of this study is to systematically analyse how the Urban Heat Island (UHI) effect has been addressed in the scientific literature, to identify key research themes and their temporal evolution, and to critically highlight knowledge gaps in order to provide guidance for future research and urban planning policies. Using BERTopic, an advanced natural language processing (NLP) tool, the study extracts dominant themes from a large corpus of academic literature and tracks their evolution over time. A total of 9061 research articles from the Web of Science database were collected, pre-processed, and analysed. BERTopic clustered semantically related topics and revealed their temporal dynamics, offering insights into emerging and declining research areas. The results show that pavement materials and urban vegetation are among the most studied themes, highlighting the importance of surface materials and green infrastructure in mitigating UHI. In line with this aim, the study identifies a rising interest in urban cooling strategies, particularly reflective surfaces and ventilation corridors. Consistent with its aim, the study provides a comprehensive overview of UHI literature, critically identifies existing gaps, and proposes clear directions for future research. It provides supports for urban planners, policymakers, and researchers in developing data-driven strategies to mitigate UHI impacts and strengthen enhance urban climate resilience. Full article

The urban heat island (UHI) effect has become a critical environmental issue affecting urban livability and public health, attracting widespread attention from both academia and society. Although numerous studies have examined the influence of urban characteristics on land surface temperature (LST), most have been restricted to single variables or single time points, and the traditional “urban–rural dichotomy” approach fails to capture intra-urban thermal heterogeneity. To address this limitation, this study integrates the Local Climate Zone (LCZ) framework with machine learning techniques to systematically analyze the diurnal variation patterns of LST across different LCZ types in Beijing and explore the interactive effects of urban characteristic variables on LST. The results show the following: (1) Compact building zones (LCZ 1–3) exhibit significantly higher daytime LST than open building zones (LCZ 4–6), with reduced differences at night; high-rise buildings cool daytime surfaces through shading but increase nighttime LST due to heat storage. (2) Blue–green space variables, such as NDVI and tree coverage (T_PLAND), substantially lower daytime LST through evapotranspiration, but their nighttime cooling effect is weak; cropland coverage (C_PLAND) plays a particularly important role in lowering nighttime LST. (3) Blue–green space and urban form variables exhibit significant interaction effects on LST, with contrasting impacts between day and night. (4) Population activity variables are strongly correlated with increased LST, especially at night, when their warming effects are more prominent. This study reveals the relative importance and nonlinear relationships of different variables across diurnal cycles, providing a scientific basis for optimizing blue–green space configuration, improving urban morphology, regulating human activity, and formulating effective UHI mitigation strategies to support the development of more sustainable urban environments. Full article

The intensified exposure to high temperature in urban areas, resulting from the combination of heat waves and the urban heat island (UHI) effect, necessitates a deeper understanding of the climate–health relationship. This knowledge directly influences the strategies employed by policy makers and urban planners in their efforts to regenerate cities and protect their population. Nature-based solutions and the widely accepted 15 min city model, characterized by a polycentric structure, should drive the implementation of effective adaptation policies, especially given the persistent delay in mitigation efforts. However, it is less clear whether current or future policies are adequately structured to broadly address the complex forms of social vulnerability. A prime example of this complexity is the demographic shift observed since the mid-20th century, characterized by a relative increase in the elderly population, and a shrinking youth demographic. While extensive literature addresses the physiological impacts of heat wave on human health, evidence regarding the neuro-psychological and cognitive implications for elderly individuals, who frequently suffer from chronic diseases, remains less comprehensive and more fragmented. The purpose of this concise review is to emphasize that crucial findings on the climate–health relationship, particularly concerning the elderly, have often been developed within disciplinary silos. The lack of comprehensive interdisciplinary integration coupled with an incomplete understanding of the full spectrum of vulnerabilities (encompassing both physiological and cognitive) may lead to urban policies that are egalitarian in principle but fail to achieve true equity in practice. This review aims to bridge this gap by highlighting the need for a more integrated approach to urban policy and regeneration. Full article

This study applies the Integrated Modification Methodology (IMM) to assess how morphology-driven, nature-based solutions reduce urban heat island (UHI) effects and flooding in Rio de Janeiro’s Cidade Nova. Multi-scale GIS diagnostics identify green continuity and vertical permeability as critical weaknesses. Simulations (Ladybug/Dragonfly) and hydrological modelling (rational method) quantify the intervention’s impact, including greening, material retrofits, and drainage upgrades. Results show a 38% increase in albedo, a 13% reduction in volumetric heat capacity, and a 30% drop in thermal conductivity. These changes reduce the peak UHI by 0.2 °C hourly, narrowing the urban–rural temperature gap to 3.5 °C (summer) and 4.3 °C (winter). Hydrologically, impervious cover decreases from 22% to 15%, permeable surfaces rise from 9% to 29%, and peak runoff volume drops by 27% (16,062 to 11,753 m³/h), mitigating flood risks. Green space expands from 7.8% to 21%, improving connectivity by 50% and improving park access. These findings demonstrate that IMM-guided interventions effectively enhance thermal and hydrological resilience in dense tropical cities, aligning with climate adaptation and the Sustainable Development Goals. Full article