Showing papers on "Urban climate published in 2023"

Mapping and evaluating global urban entities (2000–2020): A novel perspective to delineate urban entities based on consistent nighttime light data

Abstract: The differences in the definition of urban areas lead to our contrasting or inconsistent understanding of global urban development and their corresponding socioeconomic and environmental impacts. The existing urban areas were widely identified by the boundaries of built-environment or social-connections, rather than urban entities that are essentially the spatial extents of human activity agglomerations. Thus, this study has attempted to map and evaluate global urban entities (2000–2020) from a perspective of an updated urban concept of urban entities based on the consistent remotely sensed nighttime light data. First, a K-means algorithm was developed to cluster urban and non-urban pixels automatically in consideration of global region division. Then, a post-processing was conducted to enhance the temporal and logical consistency of urban entities during the study period. Rationality assessment indicates that urban entities derived from remotely sensed nighttime light data more effectively reflect the spatial agglomeration extents of human activities than those of physical urban areas. Global urban entities increased from 157,733 km2 in 2000 to 470,632 km2 in 2020 accompanied by a differentiated urban expansion at global, continental, and national levels. Our study provides long-time series and fine-resolution datasets (500 m) and new research avenues for spatiotemporal analysis of global urban entity expansion with the improvement of the understanding of urbanization and the emergence of effective urban mapping theories and approaches.

Mapping urban morphology changes in the last two decades based on local climate zone scheme: A case study of three major urban agglomerations in China

Abstract: Urbanization has been bringing extensive land use and land cover change over the last several decades, which has an impact on the urban climate and also further affects public health and energy consumption, due to human activities. The local climate zone (LCZ) classification system was proposed in 2012 to depict the complexity of urban morphology. However, until the present, LCZ long-time series product was rarely seen for its mapping difficulty. This study proposed a framework for mapping annual LCZ time series with spatial-temporal consistency in the three major urban agglomerations in China and the temporal and spatial pattern of LCZ time series was also revealed. The result showed that the high-rise and open urban LCZ types tended to occupy higher proportion in the urban area in the past two decades and urban morphology varied much in urban expansion areas and urban renewal areas. From 2000 to 2020, the differences in urban morphology between the three urban agglomerations and urban areas of different urban sizes narrowed, but the differences between urban areas with different land uses widened.

Mitigating urban heat island effects in urban environments: strategies and tools

Abstract: In the twenty-first century, urban heat islands (UHIs) have become a major problem for humanity as a consequence of urbanization and industrialization. The main causes of UHI are the vast amounts of heat generated by urban structures as they consume and re-radiate solar energy and anthropogenic heat sources. The two heat sources cause an urban area’s temperature to rise above its surroundings, a phenomenon known as Urban Heat Island (UHI). Many approaches, methods, models, and investigative tools have been implemented to study and analysis this phenomenon. In general, green areas in cities are thought to be an effective approach to mitigate urban heat island effects and bring comfort to residents. The improvement of microclimatic conditions in urban environments is mostly influenced by evapotranspiration. Most of the studies show a rising trend in the UHI, which is linked to decreased plant cover and land-use changes. The main objectives of this paper were to explain the concept, formation factors, and influential factors of UHI. In addition, the most common strategies and tools that are applied in mitigating rising temperatures in urban areas were reviewed and summarized. The finding of several studies showed that increasing urban vegetation areas in addition to optimizing their spatial distribution and configuration is an effective strategy to reduce the impact of UHI.

Micro-scale UHI risk assessment on the heat-health nexus within cities by looking at socio-economic factors and built environment characteristics: The Turin case study (Italy)

Abstract: Today the most substantial threats facing cities relate to the impacts of climate change. Extreme temperature such as heat waves and the occurrence of Urban Heat Island (UHI) phenomena, present the main challenges for urban planning and design. Climate deterioration exacerbates the already existing weaknesses in social systems, which have been created by changes such as population increases and urban sprawl. Despite numerous attempts by researchers to assess the risks associated with the heat-health nexus in urban areas, no common metrics have yet been defined yet. The objective of this study, therefore, is to provide an empirical example of a flexible and replicable methodology to estimate the micro-scale UHI risks within an urban context which takes into account all the relevant elements regarding the heat-health nexus. For this purpose, the city of Turin has been used as a case study. The methodological approach adopted is based on risk assessment guidelines suggested and approved by the most recent scientific literature. The risk framework presented here used a quantitative estimate per each census tract within the city based on the interaction of three main factors: hazard, exposure, and vulnerability. Corresponding georeferenced maps for each indicator have been provided to increase the local knowledge on the spatial distribution of vulnerability drivers. The proposed methodology and the related findings represent an initial stage of the urban risk investigation within the case study. This will include participatory processes with local policymakers and health-stakeholders with a view to guiding the local planning agenda of climate change adaptation and resilience strategies in the City of Turin.

Urban Greening as a Response to Climate-Related Heat Risk: A Social–Geographical Review

Abstract: With the increasing intensity, frequency and duration of heat waves, adaptation measures are becoming increasingly relevant and are moving up the agenda of decision-makers. In particular, urban areas require effective solutions due to the urban heat island effect and the increasing number of urban dwellers, including highly vulnerable social groups, such as people with low income or who lack access to public areas. However, despite there being strong agreement about the relevance of urban greening as an adaptation measure, there is still a limited understanding of where such measures should be implemented and for whom they are potentially accessible and beneficial. Through a systematic scoping review of the academic literature, this paper shows critical regional and methodological research gaps in mainstream adaptation research, including a bias towards Asian and European cities, and a lack of assessments of the socio-economic context and the accessibility of urban greening structures. Addressing the spatial issues of urban greening is of great importance for achieving the Sustainable Development Goals, given the ongoing urbanisation trends and projected increase in heat risk.

A Machine Learning Framework for Assessing Urban Growth of Cities and Suitability Analysis

Abstract: Rural–urban immigration, regional wars, refugees, and natural disasters all bring to prominence the importance of studying urban growth. Increased urban growth rates are becoming a global phenomenon creating stress on agricultural land, spreading pollution, accelerating global warming, and increasing water run-off, which adds exponentially to pressure on natural resources and impacts climate change. Based on the integration of machine learning (ML) and geographic information system (GIS), we employed a framework to delineate future urban boundaries for future expansion and urban agglomerations. We developed it based on a Time Delay Neural Network (TDNN) that depends on equal time intervals of urban growth. Such an approach is used for the first time in urban growth as a predictive tool and is coupled with Land Suitability Analysis, which incorporates both qualitative and quantitative data to propose evaluated urban growth in the Greater Irbid Municipality, Jordan. The results show the recommended future spatial expansion and proposed results for the year 2025. The results show that urban growth is more prevalent in the eastern, northern, and southern areas and less in the west. The urban growth boundary map illustrates that the continuation of urban growth in these areas will slowly further encroach upon and diminish agricultural land. By means of suitability analysis, the results showed that 51% of the region is unsuitable for growth, 43% is moderately suitable and only 6% is suitable for growth. Based on TDNN methodology, which is an ML framework that is dependent on the growth of urban boundaries, we can track and predict the trend of urban spatial expansion and thus develop policies for protecting ecological and agricultural lands and optimizing and directing urban growth.

Multi-scale climate-sensitive planning framework to mitigate urban heat island effect: A case study in Singapore

Abstract: This study developed a climate-sensitive planning framework to assess Urban Heat Island (UHI) intensity and wind potential, and apply assessment results into urban planning practice. Multi-scale environmental assessments and mitigation were interlinked from the urban design perspective. Three steps are conducted: (1) UHI intensity assessment to identify hot spots, (2) urban wind assessment to evaluate mitigation potential, and (3) urban design implications. A case study in Singapore was conducted to demonstrate the application of the framework. Geographic Information System-based tools that are accessible to designers and planners were used to conduct a coherent assessment-mitigation planning workflow. The empirical model between sky view factor and air temperature increment was modified by local data to be applied in Singapore. East Singapore, with a UHI intensity of 3 °C to 4 °C, was identified as the hot spot of UHI. Natural ventilation potential of the identified area was evaluated, and air paths were identified through urban permeability map based on frontal area density calculation. Climate-sensitive urban design prototypes were thus proposed by balancing climate considerations and urban planning complex (i.e., site structure, density distribution, land use pattern). Research outputs from this study increase the engagement of climate considerations in the decision-making of urban design process.

Integration of Remote Sensing and Big Data to Study Spatial Distribution of Urban Heat Island for Cities with Different Terrain

Abstract: Urban microclimate has posed a detrimental effect on the life of the urban population. This research drives with an aim of identifying environmentally conscious factor vis-a-vis urban planning which leads to the vicious cycle of urban climate change. The vicious cycle is inclusive of many urban dynamics’ parameters, which are complicated to understand. This research emphasizes on using Remote Sensing Big Data on Google Earth Engine as an advancement to study Climate Vulnerability leading to Urban Climate Gentrification. Temporal data of Landsat for the past 30 years has been taken into consideration for the study. Three cities with diverse geographical and terrain characteristics have been selected for the study, to understand the modern decisive planning is in coherence with the Sustainable Development Goals. Understanding spatial and temporal information of Urban hotspots using High-Resolution Satellite data is just not enough to suffice the need to decrease the temperature by 2- 3°C. The present study is a toll on how the reasons for microclimate change vary along with the terrain, spatial location, and urban growth pattern of the city.

Urban Heat Mitigation towards Climate Change Adaptation: An Eco-Sustainable Design Strategy to Improve Environmental Performance under Rapid Urbanization

Abstract: Rapid urbanization has led to drastic land-use/cover changes (LUCCs) and urban heat islands (UHIs), negatively altering the urban climate and air quality. LUCC’s significant impacts on human health and energy consumption have inspired researchers to develop nature-based solutions to mitigate UHIs and improve air quality. However, integrating GIS-CFD modeling for urban heat mitigation towards climate change adaptation was largely neglected for eco-sustainable urban design in rapidly urbanizing areas. In this study, (1) long-term LUCC and meteorological analyzes were conducted in the Wuhan metropolitan area from 1980 to 2016; (2) to mitigate the adverse effects of LUCC under a speedy development process, the role and relevance of optimizing building morphology and urban block configuration were discussed; (3) and particular design attention in strategy towards climate change adaptation for environmental performance improvement was paid in Wuhan’s fast-growing zones. The results show that UHII in 1980 was less severe than in 2016. Air temperature (Ta) increased by 0.4 °C on average per decade in developing areas. This increases the severity of UHII in urban fringes. It is found obligatory for a nature-based design to adopt urban morphology indicators (UMIs) such as average building height (μBH), sky view factors (ψSVF), and building density (BD/λp = % of built area) towards these changes. Further, on-site measurement revealed that λp is the most effective indicator for increasing urban heat around the buildings and boosting UHII. Using UMIs and a combined three-in-one regulation strategy based on μBH of common building types of high-rise (BHA), mid-rise (BHB), and low-rise (BHC) buildings can effectively contribute to regulating Ta and air movement within block configuration. As a result of this study’s strategy, urban heat is mitigated via reinforcing wind in order to adapt to climate change, which impacts the quality of life directly in developing areas.

Urban gardening for mitigating heat island effect

Abstract: Excess anthropogenic CO2 in the atmosphere above urban areas can create an isolated heat island closely related to dense cities. Adding more green spaces may be strenuous because of the lack of public spaces. The upgrowth of the human population, along with anthropogenic activities, is the critical factor that escalates the effect of the urban heat island. However, they could be the most prominent resources to decrease it by utilizing community gardens or their private land as a functional green space. This paper is a literature study to determine the importance of urban gardening for heat island mitigation. We also conducted a spatial analysis to measure land surface temperature to understand the benefit of urban gardens for dense cities. Based on the previous studies, promoting urban gardening to the citizens can be an effective strategy to increase the green space proportion to meet the requirement for a healthy urban environment. Urban gardens help reduce the heat island effect by creating thermal comfort, reducing flood risk and water runoff, and conserving energy for building architects. This paper also recommends strategic plans for policymakers to achieve practical urban gardening as an urban heat island mitigation strategy.

For an Urban Politics of Looking Elsewhere: Climate Action in Rapidly Growing Chinese Cities

Abstract: Urban areas mediate climate transformations and generate new forms of climate urbanism. Looking at climate action in the twelve fastest-growing cities in China with under one million people, this paper proposes a perspective on urban climate politics ‘from elsewhere' that foregrounds the potential role of smaller urban areas in mediating climate transformations. The analysis reveals three climate action strategies that reflect practical, institutional, and personal spheres of climate transformations. Planning action in the personal sphere provides opportunities for urban transformations. A perspective ‘from elsewhere’ calls for greater attention to planning for diverse change strategies for climate transformation.

Large humidity effects on urban heat exposure and cooling challenges under climate change

Abstract: Many urban climates are characterized by increased temperature and decreased relative humidity, under climate change and compared to surrounding rural landscapes. The two trends have contrasting effects on human-perceived heat stress. However, their combined impact on urban humid heat and adaptation has remained largely unclear. Here, we use simulations from an earth system model to investigate how urbanization coupled with climate change affects urban humid heat stress, exposure, and adaptation. Our results show that urban humid heat will increase substantially across the globe by 3.1 °C by the end of the century under a high emission scenario. This projected trend is largely attributed to climate change-driven increases in specific humidity (1.8 °C), followed by air temperature (1.4 °C)—with urbanization impacts varying by location and of a smaller magnitude. Urban humid heat stress is projected to be concentrated in coastal, equatorial areas. At least 44% of the projected urban population in 2100, the equivalent of over 3 billion people worldwide, is projected to be living in an urban area with high humid heat stress. We show a critical, climate-driven dilemma between cooling efficacy and water limitation of urban greenery-based heat adaptation. Insights from our study emphasize the importance of using urban-explicit humid heat measures for more accurate assessments of urban heat exposure and invite careful evaluation of the feasibility of green infrastructure as a long-term cooling strategy.

Urban growth in peri-urban, rural and urban areas: Mexico City

Abstract: This remote sensing study compares growth occurring in three urban types between 2005 and 2014: peri-urban, rural and urban, in a fast-growing metropolitan region west of Mexico City. Future urban growth for the period 2014–24 is modelled using the land-use/cover change (LUCC) model Geomod. Urban expansion is correlated with some socio-territorial factors and the impacts are assessed for the loss of biomass. In both periods, the urban zone differed the most from the other two in terms of urban expansion. The Geomod predictions overestimate the urban expansion in the urban zone and underestimate it in the peri-urban and rural zones. Significant differences exist in the average urban expansion between zones. The main urban growth drivers were elevation, population density, distance to previous urban land and distance to roads. A substantial loss of biomass is due to urban growth, including expansion and infill. The research reveals significant differences in growth between peri-urban, rural and urban areas, and contributes spatial information for designing focused land-use policies in dynamic urban contexts. Policy relevance This article contributes to understanding the differentiated urban growth of urban, peri-urban and rural areas, which can translate into more precise and effective public policies. Urban expansion and infill patterns differ. For peri-urban and rural areas, the main growth is infill, so actions should be implemented to sustainably manage the vacant or undeveloped land within an existing human settlement to prevent further expansion, but also to avoid the loss of priority areas for the provision of ecosystem services. In urban areas where the main urban increment is expansion, sensible consolidation decisions need to be taken to avoid further urban expansion and the incorporation of urban green space.

A New Phase of Just Urban Climate Action in the Rocky Mountain West

Abstract: The imperative of climate change has inspired hundreds of cities across the United States to act to reduce greenhouse gas emissions. Yet in some contexts, urban greening and climate action have exacerbated social injustices, spawning green gentrification or increasing the cost of living. In response, cities are beginning to shift their governing institutions to foster collaboration between departments and build local capacities while leaning into the interconnected nature of climate change mitigation, housing affordability, and social justice. Through a cross-case comparison of Denver, Colorado and Salt Lake City, Utah, two cities committed to climate action while facing severe housing crises, this study argues that cities are entering a new phase of urban climate action, one that can build a more sustainable and equitable urban environment for all.