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Showing papers on "Urban climate published in 2014"


Journal ArticleDOI
10 Jul 2014-Nature
TL;DR: For cities across North America, geographic variations in daytime ΔT are largely explained by variations in the efficiency with which urban and rural areas convect heat to the lower atmosphere, if urban areas are aerodynamically smoother than surrounding rural areas, urban heat dissipation is relatively less efficient and urban warming occurs (and vice versa).
Abstract: Climate modelling is used to show that for cities across North America, geographic variations in daytime urban heat islands—that is, the temperature differences between urban and adjacent rural areas—are largely explained by variations in the efficiency with which those areas convect heat to the lower atmosphere. It is often warmer in a city than in the surrounding rural areas, sometimes by up to a few degrees. This urban heat island effect is commonly explained as a consequence of a lower rate of evaporative cooling in urban areas. But here Xuhui Lee and colleagues use climate modelling to show that for cities across North America, the daytime urban heat island effect varies with the efficiency of heat convection between the land surface and the lower atmosphere. The convection effect varies with climate regime, causing significant urban warming in wet climates but cooling in dry climates. Aerodynamics also play a part, and if urban areas are aerodynamically smoother than surrounding rural areas, urban heat dissipation is less efficient and warming occurs. The health impact of heatwaves means that mitigation of the heat island effect may be beneficial. The authors suggest that aerodynamic spoilers — a city-wide increase in building height for instance — may be impractical. But efforts to increase urban albedo, by installing reflective roofs for instance, might be worth pursuing. The urban heat island (UHI), a common phenomenon in which surface temperatures are higher in urban areas than in surrounding rural areas, represents one of the most significant human-induced changes to Earth’s surface climate1,2. Even though they are localized hotspots in the landscape, UHIs have a profound impact on the lives of urban residents, who comprise more than half of the world’s population3. A barrier to UHI mitigation is the lack of quantitative attribution of the various contributions to UHI intensity4 (expressed as the temperature difference between urban and rural areas, ΔT). A common perception is that reduction in evaporative cooling in urban land is the dominant driver of ΔT (ref. 5). Here we use a climate model to show that, for cities across North America, geographic variations in daytime ΔT are largely explained by variations in the efficiency with which urban and rural areas convect heat to the lower atmosphere. If urban areas are aerodynamically smoother than surrounding rural areas, urban heat dissipation is relatively less efficient and urban warming occurs (and vice versa). This convection effect depends on the local background climate, increasing daytime ΔT by 3.0 ± 0.3 kelvin (mean and standard error) in humid climates but decreasing ΔT by 1.5 ± 0.2 kelvin in dry climates. In the humid eastern United States, there is evidence of higher ΔT in drier years. These relationships imply that UHIs will exacerbate heatwave stress on human health in wet climates where high temperature effects are already compounded by high air humidity6,7 and in drier years when positive temperature anomalies may be reinforced by a precipitation–temperature feedback8. Our results support albedo management as a viable means of reducing ΔT on large scales9,10.

844 citations


Journal ArticleDOI
TL;DR: It is shown that, in the absence of any adaptive urban design, urban expansion across the United States imparts warming over large regional swaths of the country that is a significant fraction of anticipated temperature increases resulting from greenhouse gas-induced warming.
Abstract: Modeling results incorporating several distinct urban expansion futures for the United States in 2100 show that, in the absence of any adaptive urban design, megapolitan expansion, alone and separate from greenhouse gas-induced forcing, can be expected to raise near-surface temperatures 1–2 °C not just at the scale of individual cities but over large regional swaths of the country. This warming is a significant fraction of the 21st century greenhouse gas-induced climate change simulated by global climate models. Using a suite of regional climate simulations, we assessed the efficacy of commonly proposed urban adaptation strategies, such as green, cool roof, and hybrid approaches, to ameliorate the warming. Our results quantify how judicious choices in urban planning and design cannot only counteract the climatological impacts of the urban expansion itself but also, can, in fact, even offset a significant percentage of future greenhouse warming over large scales. Our results also reveal tradeoffs among different adaptation options for some regions, showing the need for geographically appropriate strategies rather than one size fits all solutions.

409 citations


Journal ArticleDOI
TL;DR: It is concluded that in order to be effective, green infrastructure-based efforts to offset urban pollution at the municipal level have to be coordinated with territorial policies at broader spatial scales.
Abstract: Mounting research highlights the contribution of ecosystem services provided by urban forests to quality of life in cities, yet these services are rarely explicitly considered in environmental policy targets. We quantify regulating services provided by urban forests and evaluate their contribution to comply with policy targets of air quality and climate change mitigation in the municipality of Barcelona, Spain. We apply the i-Tree Eco model to quantify in biophysical and monetary terms the ecosystem services “air purification,” “global climate regulation,” and the ecosystem disservice “air pollution” associated with biogenic emissions. Our results show that the contribution of urban forests regulating services to abate pollution is substantial in absolute terms, yet modest when compared to overall city levels of air pollution and GHG emissions. We conclude that in order to be effective, green infrastructure-based efforts to offset urban pollution at the municipal level have to be coordinated with territorial policies at broader spatial scales.

312 citations


Journal ArticleDOI
TL;DR: In this article, the authors performed a detailed analysis of 200 large and medium-sized cities across 11 European countries and analyzed the cities' climate change adaptation and mitigation plans, finding that 35% of European cities studied have no dedicated mitigation plan and 72% have no adaptation plan.
Abstract: Urban areas are pivotal to global adaptation and mitigation efforts. But how do cities actually perform in terms of climate change response? This study sheds light on the state of urban climate change adaptation and mitigation planning across Europe. Europe is an excellent test case given its advanced environmental policies and high urbanization. We performed a detailed analysis of 200 large and medium-sized cities across 11 European countries and analysed the cities’ climate change adaptation and mitigation plans. We investigate the regional distribution of plans, adaptation and mitigation foci and the extent to which planned greenhouse gas (GHG) reductions contribute to national and international climate objectives. To our knowledge, it is the first study of its kind as it does not rely on self-assessment (questionnaires or social surveys). Our results show that 35 % of European cities studied have no dedicated mitigation plan and 72 % have no adaptation plan. No city has an adaptation plan without a mitigation plan. One quarter of the cities have both an adaptation and a mitigation plan and set quantitative GHG reduction targets, but those vary extensively in scope and ambition. Furthermore, we show that if the planned actions within cities are nationally representative the 11 countries investigated would achieve a 37 % reduction in GHG emissions by 2050, translating into a 27 % reduction in GHG emissions for the EU as a whole. However, the actions would often be insufficient to reach national targets and fall short of the 80 % reduction in GHG emissions recommended to avoid global mean temperature rising by 2 °C above pre-industrial levels.

302 citations


Journal ArticleDOI
TL;DR: In this paper, a hierarchical framework for representing and communicating the spatial extent of the world's urbanized land at the global, regional, and more local levels is proposed, which consists of three spatially nested definitions: urban area, built-up area, and impervious surface area.
Abstract: Urbanization has transformed the world’s landscapes, resulting in a series of ecological and environmental problems. To assess urbanization impacts and improve sustainability, one of the first questions that we must address is: how much of the world’s land has been urbanized? Unfortunately, the estimates of the global urban land reported in the literature vary widely from less than 1–3 % primarily because different definitions of urban land were used. To evade confusion, here we propose a hierarchical framework for representing and communicating the spatial extent of the world’s urbanized land at the global, regional, and more local levels. The hierarchical framework consists of three spatially nested definitions: “urban area” that is delineated by administrative boundaries, “built-up area” that is dominated by artificial surfaces, and “impervious surface area” that is devoid of life. These are really three different measures of urbanization. In 2010, the global urban land was close to 3 %, the global built-up area was about 0.65 %, and the global impervious surface area was merely 0.45 %, of the word’s total land area (excluding Antarctica and Greenland). We argue that this hierarchy of urban land measures, in particular the ratios between them, can also facilitate better understanding the biophysical and socioeconomic processes and impacts of urbanization.

269 citations


Journal ArticleDOI
TL;DR: In this paper, the authors collected air temperature measurements within an urban block in each neighborhood during the summer of 2010 and found that the urban block's percentages of impervious surface and tree canopy explained 91% of the variation in air temperature.

244 citations


Journal ArticleDOI
TL;DR: Based on weather observations by Dutch hobby meteorologists and a station network in Rotterdam (Netherlands), this article showed that water bodies increase rather than decrease the 95 percentile of the daily maximum UHI.

227 citations


Book
13 Feb 2014
TL;DR: Urban ecology: Science of Cities as mentioned in this paper explores the entire urban area: from streets, lawns, and parks to riversides, sewer systems, and industrial sites, and presents models, patterns, and examples from hundreds of cities worldwide.
Abstract: How does nature work in our human-created city, suburb, and exurb/peri-urb? Indeed how is ecology - including its urban water, soil, air, plant, and animal foundations - spatially entwined with this great human enterprise? And how can we improve urban areas for both nature and people? Urban Ecology: Science of Cities explores the entire urban area: from streets, lawns, and parks to riversides, sewer systems, and industrial sites. The book presents models, patterns, and examples from hundreds of cities worldwide. Numerous illustrations enrich the presentation. Cities are analyzed, not as ecologically bad or good, but as places with concentrated rather than dispersed people. Urban ecology principles, traditionally adapted from natural-area ecology, now increasingly emerge from the distinctive features of cities. Spatial patterns and flows, linking organisms, built structures, and the physical environment highlight a treasure chest of useful principles. This pioneering interdisciplinary book opens up frontiers of insight, as a valuable source and text for undergraduates, graduates, researchers, professionals, and others with a thirst for solutions to growing urban problems.

225 citations


Journal ArticleDOI
TL;DR: In this paper, the authors examined the impact of future urban expansion on local near-surface temperature for Sydney (Australia) using a future climate scenario (A2) and found that the changes were mostly due to increased heat capacity of urban structures and reduced evaporation in the city environment.
Abstract: This study examines the impact of future urban expansion on local near-surface temperature for Sydney (Australia) using a future climate scenario (A2). The Weather Research and Forecasting model was used to simulate the present (1990–2009) and future (2040–2059) climates of the region at 2-km spatial resolution. The standard land use of the model was replaced with a more accurate dataset that covers the Sydney area. The future simulation incorporates the projected changes in the urban area of Sydney to account for the expected urban expansion. A comparison between areas with projected land use changes and their surroundings was conducted to evaluate how urbanization and global warming will act together and to ascertain their combined effect on the local climate. The analysis of the temperature changes revealed that future urbanization will strongly affect minimum temperature, whereas little impact was detected for maximum temperature. The minimum temperature changes will be noticeable throughout the year. However, during winter and spring these differences will be particularly large and the increases could be double the increase due to global warming alone at 2050. Results indicated that the changes were mostly due to increased heat capacity of urban structures and reduced evaporation in the city environment.

220 citations


Journal ArticleDOI
TL;DR: In this article, the authors investigated the effect of air conditioning (AC) systems on air temperature and examined their electricity consumption for a semi-arid urban environment and showed that releasing waste heat into the ambient environment exacerbates the nocturnal urban heat island and increases cooling demands.
Abstract: This article investigates the effect of air conditioning (AC) systems on air temperature and examines their electricity consumption for a semiarid urban environment We simulate a 10 day extreme heat period over the Phoenix metropolitan area (US) with the Weather Research and Forecasting model coupled to a multilayer building energy scheme The performance of the modeling system is evaluated against 10 Arizona Meteorological Network weather stations and one weather station maintained by the National Weather Service for air temperature, wind speed, and wind direction We show that explicit representation of waste heat from air conditioning systems improved the 2 m air temperature correspondence to observations Waste heat release from AC systems was maximum during the day, but the mean effect was negligible near the surface However, during the night, heat emitted from AC systems increased the mean 2 m air temperature by more than 1°C for some urban locations The AC systems modified the thermal stratification of the urban boundary layer, promoting vertical mixing during nighttime hours The anthropogenic processes examined here (ie, explicit representation of urban energy consumption processes due to AC systems) require incorporation in future meteorological and climate investigations to improve weather and climate predictability Our results demonstrate that releasing waste heat into the ambient environment exacerbates the nocturnal urban heat island and increases cooling demands

210 citations


Journal ArticleDOI
23 Jul 2014-PLOS ONE
TL;DR: This work develops simulations using the SLEUTH urban growth model that complement population-driven models but focus on spatial pattern and extent, and extends the capabilities of SLEuth by incorporating street-network information.
Abstract: The future health of ecosystems is arguably as dependent on urban sprawl as it is on human-caused climatic warming Urban sprawl strongly impacts the urban ecosystems it creates and the natural and agro-ecosystems that it displaces and fragments Here, we project urban sprawl changes for the next 50 years for the fast-growing Southeast US Previous studies have focused on modeling population density, but the urban extent is arguably as important as population density per se in terms of its ecological and conservation impacts We develop simulations using the SLEUTH urban growth model that complement population-driven models but focus on spatial pattern and extent To better capture the reach of low-density suburban development, we extend the capabilities of SLEUTH by incorporating street-network information Our simulations point to a future in which the extent of urbanization in the Southeast is projected to increase by 101% to 192% Our results highlight areas where ecosystem fragmentation is likely, and serve as a benchmark to explore the challenging tradeoffs between ecosystem health, economic growth and cultural desires

Journal ArticleDOI
TL;DR: In this paper, the authors identify a range of research needs: (1) the roles of design and location of urban ponds in influencing biodiversity, (2) the function of urban wetlands for stormwater and pollution management, and (3) public perceptions of urban ecosystems and how those perceptions are influenced by interactions with natural systems.
Abstract: Recent research has demonstrated that ponds contribute a great deal to biodiversity at a regional level as networks of habitat patches that also act as ‘stepping stones’ to facilitate the movement of species through the landscape. Similarly, a great deal of biodiversity persists in urban environments where synanthropic communities are supplemented by species that thrive in disturbed environments. Aquatic urban biodiversity appears to persist despite anthropogenic stressors: an array of anthropogenic pollutants (road salt and heavy metals), invasive species, and active mismanagement—particularly the removal of riparian vegetation. Optimizing urban ponds for different ecosystem services results in conflicting priorities over hydrological, geochemical, ecological, aesthetic, and cultural functions. The socio-ecosystem approach to environmental management opens a path to greater incorporation of biodiversity into town planning and sustainability, while accounting for cultural attitudes to urban ecosystems. I identify a range of research needs: (1) the roles of design and location of urban ponds in influencing biodiversity, (2) the function of urban wetlands for stormwater and pollution management, and (3) public perceptions of urban ecosystems and how those perceptions are influenced by interactions with natural systems. Urban wetlands offer an important opportunity to educate the general public on natural systems and science in general using a resource that is located on their doorstep. In the face of increasing pressures on natural systems and increasing extent and intensity of urbanization, a more comprehensive appreciation of the challenges and opportunities provided by urban ponds could play a substantial role in driving sustainable urban development.

Journal ArticleDOI
TL;DR: In this paper, meteorological measurements in various local climate zones were performed to demonstrate the influence of evaporation surfaces and other factors on thermal comfort, as determined by the physiologically equivalent temperature (PET).
Abstract: Cities represent thermal load areas compared with their surrounding environments. Due to climate change, summer heat events will increase. Therefore, mitigation and adaptation are needed. In this study, meteorological measurements in various local climate zones were performed to demonstrate the influence of evaporation surfaces and other factors on thermal comfort, as determined by the physiologically equivalent temperature (PET). Furthermore, a quantification of the thermal effects of several adaptation measures and varying meteorological parameters was made using model simulations (ENVI-met) in an inner-city neighborhood (Oberhausen, Germany). The results show that the most effective adaptation measure was increased wind speed (maximal 15 K PET reduction). Moreover, vegetation areas show greater PET reductions by the combination of shading and evapotranspiration than water surfaces. The creation of park areas with sufficient water supply and tall, isolated, shade-providing trees that allow for adequate ventilation can be recommended for planning.

Journal ArticleDOI
TL;DR: Weighted urban proliferation (WUP) as discussed by the authors is based on the following definition of urban sprawl: the more area built over in a given landscape and the more dispersed this built-up area in the landscape (spatial configuration), and the higher the uptake of builtup area per inhabitant or job (lower utilization intensity in the built up area).

Journal ArticleDOI
TL;DR: In this paper, the authors examine three climate adaptation planning approaches in the cities of Quito (Ecuador), Surat (India), and Durban (South Africa) and analyze the trade-offs associated with different planning pathways and different forms of stakeholder involvement.
Abstract: In recent years, an increasing number of local governments are recognizing the impact of climate change on different urban sectors. This has led many to pursue climate adaptation planning, seeking to achieve preparedness through reducing vulnerability and enhancing resilience of populations, assets, and municipal operations. Although cities typically share these common goals, many are electing to pursue different planning approaches. In this paper, we examine three climate adaptation planning approaches in the cities of Quito (Ecuador), Surat (India), and Durban (South Africa) and analyze the trade-offs associated with different planning pathways and different forms of stakeholder involvement. We assess the potentials and limitations of these different approaches, including their implications for enhancing government integration and coordination, promoting participation and adaptive capacity of vulnerable groups, and facilitating overall urban resilience. We find that, in order to gain widespread commitment on adaptation, sustained political leadership from the top, departmental engagement, and continued involvement from a variety of stakeholders are integral to effective decision-making and institutionalization of programs in the long run. When climate adaptation is advanced with a focus on learning, awareness, and capacity building, the process will likely lead to more sustained, legitimate, and comprehensive adaptation plans and policies that enhance the resilience of the most affected urban areas and residents.

Journal ArticleDOI
TL;DR: In this article, the authors introduce a systemic modelling approach to the problem of how best to adapt cities is especially challenging as urban areas will evolve as the climate changes, and examine adaptation strategies for cities requires a strong interdisciplinary approach involving urban planners, architects, meteorologists, building engineers, economists, and social scientists.
Abstract: Societies have to both reduce their greenhouse gas emissions and undertake adaptation measures to limit the negative impacts of global warming on the population, the economy and the environment. Examining how best to adapt cities is especially challenging as urban areas will evolve as the climate changes. Thus, examining adaptation strategies for cities requires a strong interdisciplinary approach involving urban planners, architects, meteorologists, building engineers, economists, and social scientists. Here we introduce a systemic modelling approach to the problem. Our four-step methodology consists of: first, defining interdisciplinary scenarios; second, simulating the long-term evolution of cities on the basis of socio-economic and land-use models; third, calculating impacts with physical models (such as TEB), and; finally, calculating the indicators that quantify the effect of different adaptation policies. In the examples presented here, urban planning strategies are shown to have unexpected influence on city expansion in the long term. Moreover, the Urban Heat Island should be taken into account in operational estimations of building energy demands. Citizens’ practices seem to be an efficient lever for reducing energy consumption in buildings. Interdisciplinary systemic modelling appears well suited to the evaluation of several adaptation strategies for a very broad range of topics.

Journal ArticleDOI
TL;DR: In this article, the authors used a simple approach, based on different global-scale datasets, to assess to what extent urban agriculture is constrained by the existing amount of urban space.
Abstract: Urban agriculture (UA) has been drawing a lot of attention recently for several reasons: the majority of the world population has shifted from living in rural to urban areas; the environmental impact of agriculture is a matter of rising concern; and food insecurity, especially the accessibility of food, remains a major challenge. UA has often been proposed as a solution to some of these issues, for example by producing food in places where population density is highest, reducing transportation costs, connecting people directly to food systems and using urban areas efficiently. However, to date no study has examined how much food could actually be produced in urban areas at the global scale. Here we use a simple approach, based on different global-scale datasets, to assess to what extent UA is constrained by the existing amount of urban space. Our results suggest that UA would require roughly one third of the total global urban area to meet the global vegetable consumption of urban dwellers. This estimate does not consider how much urban area may actually be suitable and available for UA, which likely varies substantially around the world and according to the type of UA performed. Further, this global average value masks variations of more than two orders of magnitude among individual countries. The variations in the space required across countries derive mostly from variations in urban population density, and much less from variations in yields or per capita consumption. Overall, the space required is regrettably the highest where UA is most needed, i.e., in more food insecure countries. We also show that smaller urban clusters (i.e., <100 km2 each) together represent about two thirds of the global urban extent; thus UA discourse and policies should not focus on large cities exclusively, but should also target smaller urban areas that offer the greatest potential in terms of physical space.

Journal ArticleDOI
TL;DR: The Local Climate Zones (LCZ) classification system was initially designed for mapping, but to classify temperature observation sites as mentioned in this paper, and as a need arose to characaine...
Abstract: The recently developed Local Climate Zones (LCZ) classification system was initially not designed for mapping, but to classify temperature observation sites. Nevertheless, as a need arose to charac ...

Journal ArticleDOI
TL;DR: In this article, an approach based on the mapping of urban biotope types as well as an analysis of terrestrial and aerial photographs is proposed to identify urban vegetation structure types (UVSTs).

Journal ArticleDOI
TL;DR: In this article, the authors synthesize empirical data and review existing literature, including papers in this special issue, and propose the concept of "urban evolution" to study the evolution of urban biogeochemical cycles across time.
Abstract: This overview and synthesis paper focuses on the evolution of urban biogeochemical cycles across time. We synthesize empirical data and review existing literature, including papers in this special issue, and we propose the concept of “urban evolution.” The built environment often changes quickly in response to human activities, thus contributing to an urban evolution that affects structure, function, and ecosystem services of human settlements over time. Depending upon management, these changes can result in rapid losses of ecosystem functions/services or progress towards restoration. We explore urban evolution through empirical examples such as: (1) land development and nitrogen inputs within a metropolitan region over half a century; (2) watershed drainage by different forms of stormwater management over decades; (3) human-accelerated weathering in urbanized watersheds over decades; and (4) global salinization of freshwater across urbanizing landscapes over a century. We also synthesize concepts relevant to studying urban evolution of infrastructure and ecosystems including: (1) urban watersheds have challenged our whole notion of the “watershed approach” due to complex hydrologic boundaries and flow paths over time; (2) the urban hydrologic cycle evolves due to changing infrastructure and human water use over time; (3) the importance of extending research beyond individual sites using an urban watershed approach over space and time; (4) salinization as a universal tracer of watershed urbanization over time; (5) human-accelerated weathering of concrete and construction materials contributing to an “urban karst” over time; (6) human alteration of the carbon cycle in urban watersheds over time; and (7) detecting distinct biogeochemical signatures across cities globally over time. Our synthesis and this special issue suggest that urban biogeochemical cycles have exerted a major influence on the elemental composition of the Earth’s surface from local to global scales. A new global research agenda is needed to track the evolution of urban biogeochemical cycles as land development proceeds and infrastructure/management changes so we can better evaluate potential losses in ecosystem services, set realistic watershed and river restoration goals, and formulate effective environmental policy for Earth’s growing urban population.

Journal ArticleDOI
TL;DR: In this paper, a neighbourhood-scale multi-layer urban canopy model of shortwave and longwave radiation exchange that explicitly includes the radiative effects of tall vegetation (trees) is presented.
Abstract: A neighbourhood-scale multi-layer urban canopy model of shortwave and longwave radiation exchange that explicitly includes the radiative effects of tall vegetation (trees) is presented. Tree foliage is permitted both between and above buildings, and mutual shading, emission and reflection between buildings and trees are included. The basic geometry is a two-dimensional canyon with leaf area density profiles and probabilistic variation of building height. Furthermore, the model accounts for three-dimensional path lengths through the foliage. Ray tracing determines the receipt of direct shortwave irradiance by building and foliage elements. View factors for longwave and shortwave diffuse radiation exchange are computed once at the start of the simulation using a Monte Carlo ray tracing approach; for subsequent model timesteps, matrix inversion rapidly solves infinite reflections and interception of emitted longwave between all elements. The model is designed to simulate any combination of shortwave and longwave radiation frequency bands, and to be portable to any neighbourhood-scale urban canopy geometry based on the urban canyon. Additionally, the model is sufficiently flexible to represent forest and forest-clearing scenarios. Model sensitivity tests demonstrate the model is robust and computationally feasible, and highlight the importance of vertical resolution to the performance of urban canopy radiation models. Full model evaluation is limited by the paucity of within-canyon radiation measurements in urban neighbourhoods with trees. Where appropriate model components are tested against analytic relations and results from an independent urban radiation transfer model. Furthermore, system response tests demonstrate the ability of the model to realistically distribute shortwave radiation among urban elements as a function of built form, solar angle and tree foliage height, density and clumping. Separate modelling of photosynthetically-active and near-infrared shortwave bands is shown to be important in some cases. Increased canyon height-to-width ratio and/or tree cover diminishes the net longwave radiation loss of individual canyon elements (e.g., floor, walls), but, notably, has little effect on the net longwave loss of the whole urban canopy. When combined with parametrizations for the impacts of trees on airflow and hydrological processes in the urban surface layer, the new radiation model extends the applicability of urban canopy models and permits more robust assessment of trees as tools to manage urban climate, air quality, human comfort and building energy loads.

Journal ArticleDOI
TL;DR: For example, Nguyen et al. as discussed by the authors analyzed the urbanization and peri-urbanization in the greater Ho Chi Minh City metropolitan area from 1990 to 2012 and found that 660.2 km 2 of cropland was converted to urban uses, while 3.5 million persons moved into the region, bringing the total population to nearly 12 million by 2012.

Journal ArticleDOI
TL;DR: In this paper, the authors propose a coproduced, integrated framework for understanding urbanization, urban areas, and their relationships to carbon, and explore options, barriers, and limits to transitioning cities to low-carbon trajectories.
Abstract: Independent lines of research on urbanization, urban areas, and carbon have advanced our understanding of some of the processes through which energy and land uses affect carbon. This synthesis integrates some of these diverse viewpoints as a first step toward a coproduced, integrated framework for understanding urbanization, urban areas, and their relationships to carbon. It suggests the need for approaches that complement and combine the plethora of existing insights into interdisciplinary explorations of how different urbanization processes, and socio-ecological and technological components of urban areas, affect the spatial and temporal patterns of carbon emissions, differentially over time and within and across cities. It also calls for a more holistic approach to examining the carbon implications of urbanization and urban areas, based not only on demographics or income but also on other interconnected features of urban development pathways such as urban form, economic function, economic-growth policies, and other governance arrangements. It points to a wide array of uncertainties around the urbanization processes, their interactions with urban socio-institutional and built environment systems, and how these impact the exchange of carbon flows within and outside urban areas. We must also understand in turn how carbon feedbacks, including carbon impacts and potential impacts of climate change, can affect urbanization processes. Finally, the paper explores options, barriers, and limits to transitioning cities to low-carbon trajectories, and suggests the development of an end-to-end, coproduced and integrated scientific understanding that can more effectively inform the navigation of transitional journeys and the avoidance of obstacles along the way.

Journal ArticleDOI
TL;DR: In this paper, a research framework including content analysis, brainstorming and semi-structured interviews was used to identify the risk factors of urban-rural conflict, which indicated that the main risk factors between urban and rural areas comprise conflicts in property, resources and development.

Journal ArticleDOI
Ronghui Tan1, Yaolin Liu1, Yanfang Liu1, Qingsong He1, Licai Ming1, Shuohua Tang1 
TL;DR: Wu et al. as discussed by the authors examined the features and spatial determinants of urban growth in the Wuhan urban agglomeration (WUA) from 1988 to 2011, with an annual growth rate of 46.75% over the past two decades.

Journal ArticleDOI
TL;DR: Around 5-28% and 37-99% reduction in heat related mortality rate have been estimated by doubling the city's vegetation coverage and transforming the city into parklands respectively with the limited buildings and local meso-climates investigated in this study.

Journal ArticleDOI
TL;DR: In this article, a new high-resolution dynamical downscaling strategy to examine how rural and urban areas respond to change in future climate is presented, where a new version of the limited-area model of the ARPEGE-IFS system running at 4 km resolution coupled with the Town Energy Balance (TEB) scheme is presented.
Abstract: A new high-resolution dynamical downscaling strategy to examine how rural and urban areas respond to change in future climate, is presented. The regional climate simulations have been performed with a new version of the limited-area model of the ARPEGE-IFS system running at 4 km resolution coupled with the Town Energy Balance (TEB) scheme. To downscale further the regional climate projections to a urban scale, at 1-km resolution, a stand-alone surface scheme is employed in offline mode. We performed downscaling simulations according to three model set-ups: (1) reference run, where TEB is not activated neither in 4 km simulations nor in 1 km urban simulation, (2) offline run, where TEB is activated only for 1 km urban simulation and (3) inline run, where TEB is activated both for regional and urban simulations. The applicability of this method is demonstrated for Brussels Capital Region, Belgium. For present climate conditions, another set of simulations were performed using European Center for Medium-Range Weather Forecasts global reanalysis ERA40 data. Results from our simulations indicate that the reference and offline runs have comparable values of daytime and nocturnal urban heat island (UHI) and lower values than the inline run. The inline values are closer to observations. In the future climate, under and A1B emission scenario, the three downscaling methods project a decrease of daytime UHI between −0.24 and −0.20 °C, however, their responses are different for nocturnal UHI: (1) reference run values remains unaltered, (2) for the offline runs, the frequency of present climate weak nocturnal UHI decreases to the benefit of negative UHIs leading to a significant decrease in the nocturnal UHI over the city and (3) for the inline run, nocturnal UHIs stays always positive but the frequency of the strong UHI decreases significantly in the future by 1 °C. The physical explanation is put forth. Copyright © 2013 Royal Meteorological Society

Journal ArticleDOI
TL;DR: A multi-method approach for estimating summer waste heat emissions from anthropogenic activities (QF ) was applied for a major subtropical city (Phoenix, AZ).

Journal ArticleDOI
TL;DR: In this article, the authors examined the effect of green roof drainage area on system performance in an urban climate and found that green roof flooding area has the greatest impact on peak runoff reduction, whereas rainfall retention and the time to peak runoff are not greatly influenced by drainage area.

Journal ArticleDOI
TL;DR: The Urban Weather Generator (UWG) is a simple and computationally efficient model that predicts canopy level urban air temperature using meteorological information measured at a reference weather station.
Abstract: The Urban Weather Generator (UWG) is a simple and computationally efficient model that predicts canopy level urban air temperature using meteorological information measured at a reference weather station. An evaluation of an improved version of the model, which accounts for different urban morphologies and building usage distributions within a city, is presented in this paper. Calculated urban air temperatures are compared with measurements from a network of weather stations in Singapore, representing a range of land uses, morphological parameters and building usages. The comparison shows a satisfactorily performance of the model for all weather conditions and for different reference weather stations. Singapore is located in a hot and humid climate where vegetation plays a critical role in climate regulation, the urban morphology is very heterogeneous and air-conditioning systems are generally used throughout the year. This makes Singapore an interesting case study in order to analyse the potential and limitations of the model. The study shows that the model can be applied to different climates and urban configurations to obtain an estimation of the Urban Heat Island (UHI) effect. However, the simplifications and assumptions of the model prevent it from capturing very site-specific microclimate effects.