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Planning and design for sustainable cities in the MENA region
... -Public health: The implications of environmental degradation and climate change on public health and the state's efforts toward them are not covered in this volume. Air pollution and rising temperatures are adding to existing human health concerns and the increased frequency of certain diseases and health issues (Longlong et al., 2018;Skelhorn, 2019). -Emergency planning: Climate change may not be gradual, but might spike, with climatic tipping points, and so there is the need for climate-related emergency planning. ...
The strategic vision of the State of Qatar seeks to pursue development while aiming for a balanced approach to the social, human, economic, and environmental pillars of the vision. The legal and governance mechanisms supporting this transition are only effective when implemented, and can be hindered by limited access to data for decision-making. In the last decade, significant changes have taken place, catalyzed by commitments made to host the FIFA World Cup 2022 as well as innovations led by the Qatar Foundation. Yet, as a country with heavy reliance on hydrocarbon resources, the transition toward a more sustainable future involves trade-offs, the options for which present different pathways (from pragmatic to transformative). Climate change will present significant challenges for Qatar, including sea level rise and increasing temperatures, but also impacts on terrestrial and marine biodiversity. Domestically, key areas of the economy (energy, water, food, urban development, waste management) require integrated, systems approaches for moving toward greater sustainability. This future needs to be enabled by new ways of teaching and learning as well as new ways of thinking about and doing business. Not all issues could be covered in this collection (most notably, transportation, heating and cooling systems, desalination, health, and air quality, among others). However, this book has provided a wealth of evidence on diverse subjects, and this concluding chapter brings these diverse options and recommendations together.
La productivité de la construction (BTP), y compris le ferroviaire, se trouve en baisse. Pour pallier au problème, nous proposons l’adoption du Railway Information Modeling RIM, adaptation du BIM (Building Information Modeling) qui est une représentation numérique et graphique des caractéristiques physiques et fonctionnelles d'une installation. Nous examinerons le constat de la baisse de productivité, une introduction au BIM, le relevé d’avantages, de risques et de limitations concernant l’utilisation du BIM à travers la revue de la littérature et des expériences. Nous passerons ensuite à étudier le cadre d’adoption du BIM qui permettrait de maximiser ses avantages, de contenir les risques et de dépasser ses limitations. Puis nous considérons des expériences de projets d’envergure conduits avec BIM, avant d’exposer une expérience de deux projets ferroviaires au Maroc, d’en tirer les conclusions, de la comparer aux expériences présentées pour confirmer l’étude de littérature. Enfin, nous proposerons un plan d’actions pour l’adoption du BIM au ferroviaire au Maroc par une analyse multicritère. Ce plan d’action est basé sur une enquête réalisée auprès des professionnels.
BIM est une méthodologie de gestion simultanée des processus, issue de l’industrie 4.0, qui permet des gains de temps, des réductions de budgets et la durabilité. Le plan d’action proposé, construit par une enquête auprès des professionnels marocain, met en lumière la nécessité d’adopter des normes, d’impulser l’adoption par le client final, d’encourager la R&D, d’y adapter la formation professionnelle et d’impulser les changements managériaux.
L’industrie de la construction (ou BTP) est l’une des plus anciennes activités humaines. Néanmoins, sa productivité se trouve en berne, comme témoigne plusieurs index de productivité. Le ferroviaire est un domaine structurant du BTP, nécessaire pour le développement économique et territorial. Au Maroc, le ferroviaire connaît un développement important avec des projets de grande envergure, notamment : LGV, Tram, Lignes régionales.
Pour pallier au problème de productivité, nous proposons l’adoption du BIM : Railway Information Modeling RIM. Le BIM est une représentation numérique et graphique des caractéristiques physiques et fonctionnelles d'une installation.
Nous examinerons dans le premier chapitre de ce mémoire le constat de la baisse de productivité, une introduction au BIM, le relevé d’avantages, de risques et de limitations concernant l’utilisation du BIM (notamment dans le ferroviaire) à travers la revue de la littérature et des expériences. Nous passerons au second chapitre à étudier le cadre d’adoption du BIM qui permettrait de maximiser ses avantages, de contenir les risques et de dépasser ses limitations, notamment sur les plans organisationnel et juridique.
En troisième chapitre, nous passerons en revue des expériences de projets d’envergure conduits en adoptant le BIM, avant de mener une expérience sur deux projets ferroviaires au Maroc utilisant la même méthodologie. Le but étant de tirer les conclusions de l’expérience menée dans le cadre de ce travail de recherche, de la comparer aux expériences présentées pour ainsi confirmer l’étude de littérature. Enfin, le quatrième chapitre proposera un plan d’actions pour l’adoption du BIM au ferroviaire au Maroc par une analyse multicritère. Ce plan d’action est basé sur une enquête réalisée auprès des professionnels.
Le BIM (ou le RIM, son adaptation au ferroviaire) est plus qu’une technologie ou un logiciel 3D. C’est une méthodologie de gestion simultanée des processus, issue des concepts de l’industrie 4.0. Le BIM permet des gains de temps, des réductions de budgets, une meilleure prise en charge de la durabilité, … Ses applications actuelles ont dépassé celles initiales concernant des bâtiments circonscrits. Pour maximiser les chances de réussite de son intégration, il faut définir un cadre d’adoption répondant aux questions organisationnelles, techniques et juridiques. Les expériences ont montré que les avantages cités sont réels et probants.
Le plan d’action proposé, construit autour d’une enquête auprès des professionnels marocain du rail, met en lumière la nécessité d’adopter des normes (techniques, informatiques et managériales), d’impulser l’adoption par le client final et d’encourager la R&D, d’y adapter la formation professionnelle et d’impulser les changements managériaux au sein des entreprises.
The Lancet Countdown tracks progress on health and climate change and provides an independent assessment of the health effects of climate change, the implementation of the Paris Agreement, and the health implications of these actions. It follows on from the work of the 2015 Lancet Commission on Health and Climate Change, which concluded that anthropogenic climate change threatens to undermine the past 50 years of gains in public health, and conversely, that a comprehensive response to climate change could be “the greatest global
health opportunity of the 21st century”. The Lancet Countdown is a collaboration between 24 academic institutions and intergovernmental organisations based in every continent and with representation from a wide range of disciplines. The collaboration includes climate scientists, ecologists, economists, engineers, experts in energy, food, and transport systems, geographers, mathematicians, social and political scientists, public health professionals, and doctors. It reports annual indicators across five sections: climate change impacts, exposures, and vulnerability; adaptation planning and resilience for health; mitigation actions and health co-benefits; economics and finance; and public and political engagement. The key messages from the 40 indicators in the Lancet Countdown’s 2017 report are summarised below.
Evidence that urban green-space promotes health and well-being of urban residents is increasing. The role of biodiversity is unclear: perceived biodiversity may be important, but how accurately it is perceived and the factors influencing this accuracy are poorly understood. We use experimental perennial urban meadows in southern England to investigate the impact of creating biodiverse habitats on green-space users’ i) physical and mental health, psychological well-being, ii) factors moderating health and well-being outcomes (site satisfaction and nature connectedness), and iii) perceived biodiversity. We explore whether ‘nature dose’ (time spent at a site) influences these relationships. We then assess whether green-space users can estimate botanical diversity accurately across meadow treatments differing in plant species richness and vegetation structure, and determine the environmental cues and personal characteristics associated with these estimates. Sites with experimental meadows did not increase respondents’ perceptions of site level biodiversity, their self-rated physical and mental health or psychological well-being relative to control sites lacking meadows. However, there were significant associations between perceived site level biodiversity per se, and site satisfaction and feeling connected to nature. Moreover, we observed a positive association between nature dose and self-estimated mental health. We found that actual and perceived botanical richness in individual meadow plots were strongly positively correlated. Perceived richness was positively associated with vegetation height, evenness, and colourfulness suggesting that these are cues for estimating species richness. The accuracy of estimates varied, but respondents with higher levels of eco-centricity were more accurate than people who were less connected to nature.
Urbanization is one of the most important driving forces of global change. With the quick expansion of the urban environment's size and population, its urban heat island intensity (UHII, expressed as the temperature difference between urban and rural areas) has rapidly increased. The situation is even worse in megacities, whose populations are greater than 10 million. However, very few studies quantitatively reveal the effects of green space and land use/land cover (LULC) on the urban thermal environment because they lack detailed measurements. This study focuses on quantifying the effects of green space on the urban heat island (UHI) in Shenzhen, a subtropical megacity in China. Extensive measurements (air temperature and humidity) were taken using a mobile traverse method in an 8 km long transect, where a variety of LULC types were included. Measurements were conducted at 2-h intervals for 2 years (repeated a total of 7011 times). The relationship between evapotranspiration (ET) and UHII was also studied based on measured data, to understand the mechanism of the cooling effect of vegetation. The main conclusions obtained are as follows: (1) There are obvious differences in the air temperature and UHII among different urban landscapes. The ranking of temperatures from highest to lowest is commercial area > urban village > urban water body > urban green space > suburb. The difference in the UHII is also obvious, especially from 20:00 PM to 06:00 AM, when the UHII is usually greater than 2 °C. (2) Green space and water bodies in the urban environment have obvious effects on reducing the air temperature through evapotranspiration. The cooling effect of urban green spaces is better than that of urban water bodies. Compared to commercial areas, urban water bodies can relieve the UHII up to 0.9 °C, whereas urban green spaces can relieve the UHII up to 1.57 °C. (3) There are obvious linear relationships between air temperature, UHII, and green space in nighttime. Air temperature and the UHII decrease linearly with an increase in urban green space. The correlation is relatively weak in daytime, when the cooling effect of vegetation might be offset by other factors in urban thermal environment. (4) Obvious correlation between ET and UHII was observed and a good positive linear relationship between ET and the decreasing rate of UHII (UHII') was obtained, revealing that the faster ET is, the better UHII mitigating efficiency could be gained. An ET rate of 6.12 mm d⁻¹ could cause a 0.12 °C per hour decrease in UHII under our experimental condition. These results indicate that an increase in urban green space's ET could be a useful way to improve the urban thermal environment and mitigate the UHI.
Cities are embedded within larger‐scale engineered infrastructures (e.g., electric power, water supply, and transportation networks) that convey natural resources over large distances for use by people in cities. The sustainability of city systems therefore depends upon complex, cross‐scale interactions between the natural system, the transboundary engineered infrastructures, and the multiple social actors and institutions that govern these infrastructures. These elements, we argue, are best studied in an integrated manner using a novel social‐ecological‐infrastructural systems (SEIS) framework. In the biophysical subsystem, the SEIS framework integrates urban metabolism with life cycle assessment to articulate transboundary infrastructure supply chain water, energy, and greenhouse gas (GHG) emission footprints of cities. These infrastructure footprints make visible multiple resources (water, energy, materials) used directly or indirectly (embodied) to support human activities in cities. They inform cross‐scale and cross‐infrastructure sector strategies for mitigating environmental pollution, public health risks and supply chain risks posed to cities. In the social subsystem, multiple theories drawn from the social sciences explore interactions between three actor categories - individual resource users, infrastructure designers and operators, and policy actors - who interact with each other and with infrastructures to shape cities toward sustainability outcomes. Linking of the two subsystems occurs by integrating concepts, theories, laws, and models across environmental sciences/climatology, infrastructure engineering, industrial ecology, architecture, urban planning, behavioral sciences, public health, and public affairs. Such integration identifies high‐impact leverage points in the urban SEIS. An interdisciplinary SEIS‐based curriculum on sustainable cities is described and evaluated for its efficacy in promoting systems thinking and interdisciplinary vocabulary development, both of which are measures of effective frameworks.
The potential of trees and other vegetation to reduce building cooling
loads has been recorded in a number of studies but the meso- and
microclimate changes producing such savings are not well understood.
This paper describes a preliminary attempt to model the effects of
landscaping on temperature, humidity, windspeed and solar gain in urban
climates using information from existing agricultural and meteorological
studies, with particular attention placed on quantifying the effects of
plant evapotranspiration. The climate model is then used in conjunction
with the DOE-2.1C building simulation program to calculate the net
reductions in air-conditioning requirements due to trees and other
vegetation.Preliminary results show that an additional 25% increase in
the urban tree cover can save 40% of the annual cooling energy use of an
average house in Sacramento, and 25% in Phoenix and Lake Charles. If
this additional tree cover is located to optimize summer shading, the
savings are further increased to more dun 50% in Sacramento and 33% in
the other two cities. The calculated savings are minimal for Los Angeles
because the base case cooling energy use is small (65 hours) on the
assumption that window venting is used whenever possible in lieu of
mechanical cooling. There are additional benefits in lowering peak power
consumption, where the savings are as much as 34% in Sacramento, 18% in
Phoenix, 22% in Lake Charles, and 44% in Los Angeles. Parametric
analysis reveals that most of the savings can be attributed to the
effects of increased plant evapotranspiration, and only 10% to 30% to
shading. The energy penalties of reduced windspeeds are found to be
small in all four locations.The preliminary results suggest that while
the conservation benefits of planting trees are appreciable at the
individual house level, equally dramatic savings can be realized at the
urban level through modifications of the urban climate by increasing the
total amount of vegetative cover. Such a conservation strategy may be
elective in counteracting the summer heat island evident in cities and
may improve ambient conditions as well as reduce summertime
air-conditioning requirements.
Elevated summertime temperatures in urban ‘heat islands’ increase cooling-energy use and accelerate the formation of urban smog. Except in the city’s core areas, summer heat islands are created mainly by the lack of vegetation and by the high solar radiation absorptance by urban surfaces. Analysis of temperature trends for the last 100 years in several large U.S. cities indicate that, since ∼1940, temperatures in urban areas have increased by about 0.5–3.0°C. Typically, electricity demand in cities increases by 2–4% for each 1°C increase in temperature. Hence, we estimate that 5–10% of the current urban electricity demand is spent to cool buildings just to compensate for the increased 0.5–3.0°C in urban temperatures. Downtown Los Angeles (L.A.), for example, is now 2.5°C warmer than in 1920, leading to an increase in electricity demand of 1500 MW. In L.A., smoggy episodes are absent below about 21°C, but smog becomes unacceptable by 32°C. Because of the heat-island effects, a rise in temperature can have significant impacts. Urban trees and high-albedo surfaces can offset or reverse the heat-island effect. Mitigation of urban heat islands can potentially reduce national energy use in air conditioning by 20% and save over $10B per year in energy use and improvement in urban air quality. The albedo of a city may be increased at minimal cost if high-albedo surfaces are chosen to replace darker materials during routine maintenance of roofs and roads. Incentive programs, product labeling, and standards could promote the use of high-albedo materials for buildings and roads. Similar incentive-based programs need to be developed for urban trees.
Europe is a highly urbanised continent. The consequent loss and degradation of urban and peri-urban green space could adversely affect ecosystems as well as human health and well-being. The aim of this paper is to formulate a conceptual framework of associations between urban green space, and ecosystem and human health. Through an interdisciplinary literature review the concepts of Green Infrastructure, ecosystem health, and human health and well-being are discussed. The possible contributions of urban and peri-urban green space systems, or Green Infrastructure, on both ecosystem and human health are critically reviewed. Finally, based on a synthesis of the literature a conceptual framework is presented. The proposed conceptual framework highlights many dynamic factors, and their complex interactions, affecting ecosystem health and human health in urban areas. This framework forms the context into which extant and new research can be placed. In this way it forms the basis for a new interdisciplinary research agenda.
The growing human population concentrated in urban areas lead to the increase of road traffic and artificial areas, consequently enhancing air pollution and urban heat island effects, among others. These environmental changes affect citizen's health, causing a high number of premature deaths, with considerable social and economic costs. Nature-based solutions are essential to ameliorate those impacts in urban areas. While the mere presence of urban green spaces is pointed as an overarching solution, the relative importance of specific vegetation structure, composition and management to improve the ecosystem services of air purification and climate regulation are overlooked. This avoids the establishment of optimized planning and management procedures for urban green spaces with high spatial resolution and detail. Our aim was to understand the relative contribution of vegetation structure, composition and management for the provision of ecosystem services of air purification and climate regulation in urban green spaces, in particular the case of urban parks. This work was done in a large urban park with different types of vegetation surrounded by urban areas. As indicators of microclimatic effects and of air pollution levels we selected different metrics: lichen diversity and pollutants accumulation in lichens. Among lichen diversity, functional traits related to nutrient and water requirements were used as surrogates of the capacity of vegetation to filter air pollution and to regulate climate, and provide air purification and climate regulation ecosystem services, respectively. This was also obtained with very high spatial resolution which allows detailed spatial planning for optimization of ecosystem services. We found that vegetation type characterized by a more complex structure (trees, shrubs and herbaceous layers) and by the absence of management (pruning, irrigation and fertilization) had a higher capacity to provide the ecosystems services of air purification and climate regulation. By contrast, lawns, which have a less complex structure and are highly managed, were associated to a lower capacity to provide these services. Tree plantations showed an intermediate effect between the other two types of vegetation. Thus, vegetation structure, composition and management are important to optimize green spaces capacity to purify air and regulate climate. Taking this into account green spaces can be managed at high spatial resolutions to optimize these ecosystem services in urban areas and contribute to improve human well-being.
Land use and land cover changes due to urbanization have led to significant modifications in the built environment at both local and regional scales, making adaptation/mitigation strategies imperative for the sustainable development of cities. While urban trees offer great potential for heat mitigation and enhanced environmental quality, most of the existing urban land surface models do not contain adequate representations of trees, particularly the radiative heat exchange in the canyons. In this study, we incorporated the radiative shading effect of urban trees into the state-of-the-art version of the coupled Weather Research and Forecasting-Urban Canopy Model modeling system. This modeling framework, albeit at its infancy, is applied to the Phoenix Metropolitan area to study the regional cooling effect of trees in an arid environment. Simulation results demonstrated the capacity of urban trees in reducing urban surface and air temperature by about 2 ∼ 9 °C and 1 ∼ 5 °C respectively and increasing relative humidity by 10 ∼ 20% during a mean diurnal cycle; the effect is more prominent during nighttime.
The subject of building information modelling (BIM) has become a central topic to the improvement of the AECOO (Architecture, Engineering, Construction, Owner and Operator) industry around the world, to the point where the concept is being expanded into domains it was not originally conceived to address. Transitioning BIM into the domain of infrastructure projects has provided challenges and emphasized the constructor perspective of BIM. Therefore, this study aims to collect the relevant literature regarding BIM within the Infrastructure domain and its use from the constructor perspective to review and analyse the current industry positioning and research state of the art, with regards to the set criteria. The review highlighted a developing base of BIM for infrastructure. From the analysis, the related research gaps were identified regarding information integration, alignment of BIM processes to constructor business processes & the effective governance and value of information. From this a unique research strategy utilising a framework for information governance coupled with a graph based distributed data environment is outlined to further progress the integration and efficiency of AECOO Infrastructure projects.
Climate change is one of the most challenging issues of our time. As key sites in the production and management of emissions of greenhouse gases, cities will be crucial for the implementation of international agreements and national policies on climate change. This book provides a critical analysis of the role of cities in addressing climate change and the prospects for urban sustainability. Cities and Climate Change is the first in-depth analysis of the role of cities in addressing climate change. The book argues that key challenges concerning the resources and powers of local government, as well as conflicts between local goals for economic development and climate change mitigation, have restricted the level of local action on climate change. These findings have significant implications for the prospects of mitigating climate change and achieving urban sustainability. This book provides a valuable interdisciplinary analysis of these issues, and will appeal to students and researchers interested in sustainability at local and global scales. © 2003 Harriet Bulkeley and Michele M. Betsill. All rights reserved.
A human body may be able to adapt to extremes of dry-bulb temperature (commonly referred to as simply temperature) through perspiration and associated evaporative cooling provided that the wet-bulb temperature (a combined measure of temperature and humidity or degree of "mugginess") remains below a threshold of 35 °C. (ref.). This threshold defines a limit of survivability for a fit human under well-ventilated outdoor conditions and is lower for most people. We project using an ensemble of high-resolution regional climate model simulations that extremes of wet-bulb temperature in the region around the Arabian Gulf are likely to approach and exceed this critical threshold under the business-as-usual scenario of future greenhouse gas concentrations. Our results expose a specific regional hotspot where climate change, in the absence of significant mitigation, is likely to severely impact human habitability in the future.
Parametric computer simulations of microclimates and building energy performance were used to investigate the potential of shade trees to save residential heating and cooling energy use in the City of Chicago. Prototypical build-ings included one-, two-, and three-story brick buildings similar to residences in the Chicago area, and one-and two-story wood-frame buildings representing suburban construction. To validate the energy performance of prototypes, building performance indices of reference buildings were calculated, in some cases using whole-house metered data, and com-pared with indices of the prototypes. Increasing tree cover by 10 percent (corresponding to about three trees per building) could reduce total heating and cooling energy use by 5 to 10 percent ($50 to $90). On a per-tree basis, annual heating energy can be reduced by about 1.3 percent ($10, 2 MBtu), cooling energy by about 7 percent ($15, 125 kilowatt-hours), and peak cooling demand by about 6 percent (0.3 kilowatts). Simulation results were used in a 20-year economic analysis of costs and benefits associated with a hypothetical shade-tree program. Benefit-cost ratios of 1.35 for trees planted around typical two-story residential buildings and 1.90 for trees near energy-efficient wood-frame buildings indicate that a utility-sponsored shade-tree program could be cost-effective for both existing and new construction in Chicago.
Discussions leading to the Rio+20 UN conference have emphasised the importance of sustainable development and the protection of the environment for future generations. The Arab world faces large-scale threats to its sustainable development and, most of all, to the viability and existence of the ecological systems for its human settlements. The dynamics of population change, ecological degradation, and resource scarcity, and development policies and practices, all occurring in complex and highly unstable geopolitical and economic environments, are fostering the poor prospects. In this report, we discuss the most pertinent population-environment-development dynamics in the Arab world, and the two-way interactions between these dynamics and health, on the basis of current data. We draw attention to trends that are relevant to health professionals and researchers, but emphasise that the dynamics generating these trends have implications that go well beyond health. We argue that the current discourse on health, population, and development in the Arab world has largely failed to convey a sense of urgency, when the survival of whole communities is at stake. The dismal ecological and development records of Arab countries over the past two decades call for new directions. We suggest that regional ecological integration around exchange of water, energy, food, and labour, though politically difficult to achieve, offers the best hope to improve the adaptive capacity of individual Arab nations. The transformative political changes taking place in the Arab world offer promise, indeed an imperative, for such renewal. We call on policy makers, researchers, practitioners, and international agencies to emphasise the urgency and take action.
Green areas in the urban environment can contribute to the mitigation of the Urban Heat Island. In a context of climate change, with the expected increase in temperature, dryness and intensity of heat waves, green areas assume even higher importance as they can create a cooling effect that extends to the surrounding areas. This study analyses the thermal performance of a small green space (0.24 ha) and its influence in the surrounding atmospheric environment of a densely urbanised area in Lisbon. Measurements of weather parameters (temperature, relative humidity, wind speed, solar and infrared radiation) were carried out along a selected path, starting from inside the green area to surrounding streets with different orientations and solar exposure. It was found that the garden was cooler than the surrounding areas, either in the sun or in the shade. These differences were higher in hotter days and particularly related to the mean radiant temperature (Tmrt). The highest difference found was of 6.9 °C in relation to air temperature and 39.2 °C in relation to Tmrt; in both cases this difference occurred between the shaded site inside the garden and the sunny site in an E–W oriented street in the southern part of the studied area. Besides the local weather conditions, particularly the low wind speed, the sun exposure and the urban geometry are the potential factors that explain these differences. The cooling effect of green areas on the surrounding environment can be enhanced by additional measures related to the urban features of each city.
In this paper, we reflect on the role of cities in responding to climate change over the two decades since the historic agreement of the United Nations Framework Convention on Climate Change. We find a growth in the scale and nature of municipal responses to climate change that has been one of the most significant features of the changing climate governance landscape over the past two decades. We suggest that this has not been a static or uniform process, and reflect on the changing nature of urban responses to climate change over the past two decades, the emergence of new politics of low-carbon urbanism, and challenges that lie ahead for research and policy as this agenda begins to take shape on the ground.
The present paper is a review article aiming to present the actual state of the art on the development and the assessment of cool materials (i.e. materials with high solar reflectance and infrared emittance) for buildings and urban structures. The research in this field is roughly divided in four phases and includes the development and assessment of: (a) highly reflective and emissive light colored materials, (b) cool colored materials, i.e. colored materials with increased near infrared and thus overall solar reflectance compared to similarly colored conventional ones, (c) phase change materials and (d) dynamic cool materials. All major aspects related to each technology are described and the benefits and impacts of these materials at building, city and global scale are reported. The wide use of such materials can significantly contribute to the mitigation of the heat island effect and the improvement of urban environmental quality.
According to projections by the United Nations, 60% of the world’s population will reside in urban areas by 2030. Studies of the ecology of cities and ecology in cities will therefore assume increasing relevance as urban communities seek to protect and/or enhance their ecological resources. Presently, the most serious threats to wildlife include the degradation and/or loss of habitats, the introduction and spread of problem species, water pollution, unsympathetic management, and the encroachment of inappropriate development. Climate change could add to these problems through competition from exotic species, the spread of disease and pests, increased summer drought stress for wetlands and woodland, and sea-level rise threatening rare coastal habitats. Earlier springs, longer frost-free seasons, and reduced snowfall could further affect the dates of egg-laying, as well as the emergence, first flowering and health of leafing or flowering plants. Small birds and naturalized species could thrive in the warmer winters associated with the combined effect of regional climate change and enhanced urban heat island. This article reviews the range of climate-related threats to biodiversity in the aquatic, intertidal and terrestrial habitats of urban areas. London is used as a case study to illustrate potential impacts, and to contend that ‘green spaces’ in cities could be used by planners to counter climate-related threats to biodiversity, as well as to improve flood control and air quality, and reduce urban heat island effects.
Tree canopy cover data from aerial photographs and building energy simulations were applied to estimate energy savings from existing trees and new plantings in California. There are approximately 177.3 million energy-conserving trees in California communities and 241.6 million empty planting sites. Existing trees are projected to reduce annual air conditioning energy use by 2.5% with a wholesale value of $ 485.8 million. Peak load reduction by existing trees saves utilities 10% valued at approximately $778.5 million annually, or $ 4.39/tree. Planting 50 million trees to shade east and west walls of residential buildings is projected to reduce cooling by 1.1% and peak load demand by 4.5% over a 15-year period. The present wholesale value of annual cooling reductions for the 15-year period is $ 3.6 billion ($ 71/tree planted). Assuming total planting and stewardship costs of $ 2.5 billion ($ 50/tree), the cost of peak load reduction is $ 63/kW, considerably less than the $ 150/kW benchmark for cost-effectiveness. Influences of tree location near buildings and regional climate differences on potential energy savings are discussed.
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Heatwaves: number of deadly heat days, ESRI maps: global risk of deadly heat
- Esri
ESRI (2017) Heatwaves: number of deadly heat days, ESRI maps: global risk of deadly heat. Available at:
https://maps.esri.com/globalriskofdeadlyheat/# (Accessed: 13 June 2018).