Climate and Urban Development

World Meteorological Organization WMO - No. 844 Climate and Urban Development

WMO-No. 844

Geneva, Switzerland 1996 For more information contact: The World Meteorological Organization World Climate Programme 41 Avenue Ciuseppe-Motta CH-1211 Geneva 2, Switzerland ©: (41-22)730 83 14/730 83 15 FflX: (41-22) 734 23 26 E-mail: ipa @www.wmo.ch

Cover. Urban design is determined by climate. (Photos: Anne Duhamel von Moos, Swiss Federal Institute of Technology/1 Morimoto)

WMO-No. 844 © 1996, World Meteorological Organization

ISBN 92-63-1 0844-7 NOTE The designations employed and the presentation of material in this publication do not imply the expression of any opinion whatsoever on the part of the Secretariat of the World Meteorological Organization concerning the legal status of any country, territory, city or area, or of its authorities, or concerning the delimitation of its frontiers or boundaries. FOREWORD

Urban populations are growing very rapidly with issues that relate to urban weather and throughout the world and by the turn of the climate. The Twelfth World Meteorological century almost half of the world's popula­ Congress, which met in June 1995, recognized tion will live in urban areas. The rate of «that a broad new thrust to which WMO urbanization, particularly in developing should attach special attention was ... the countries, necessitates new ways of gover­ urban environment in which most people live, nance. For example, a city of one million most energy is consumed, and many disas­ inhabitants generates 25 000 tons of carbon ters, including pollution, took place». dioxide and 300 000 tons of waste water This brochure relates to some of the every day. activities of WMO with regard to urban The temperature is normally higher in a environment and was one of the WMO city. In some cases, especially in the tropics, contributions to the Second United it leads to excessive heat stress. The pollu­ Nations Conference on Human Set­ tion in the urban air blocks solar radiation tlements (HABITAT II), held in Istanbul, and can be a health hazard itself. By design­ Turkey from 3-14 June 1996. I should like to ing and building urban areas in harmony express my gratitude to Mrs Anne Duhamel with climate and the environment, it is von Moos of the Swiss Federal Institute of possible to mitigate many of the negative Technology, who prepared this brochure in impacts related to urbanization. As most of cooperation with staff of the WMO the energy is used in urban areas, energy Secretariat. Thanks are also due to efficient urban planning and design can Professors Ernest Jauregui and Tim Oke for contribute to the decrease of greenhouse their advice on the development of WMO gas emissions and, thus, lessen the threat programmes in the area of urban climatol­ of global climate change. By arranging for ogy and in reviewing this brochure. appropriate warning systems and related preparedness schemes, the impacts of severe storms and flooding can be mini­ mized. The World Meteorological Organization G. O. P. Obasi (WMO) has for a long time been engaged Secretary-General through several programmes and projects World Meteorological Organization Human settlement The Intergovernmental Panel on Climate interacts with the Change (IPCC) has stated that "during environment in a complex the past few decades, two important fashion involving many different scales. factors regarding the relationship between humans and the Earth's climate have become apparent. First, human activities, including the burning of fossil fuels, land-use change and agriculture, are increasing the atmospheric concentrations of greenhouse gases {which tend to warm the atmosphere) and, in some regions, aerosols {microscopic airborne particles, which tend to cool the atmosphere). These changes in greenhouse gases and aerosols, taken together, are projected to change regional and global climate and climate-related parameters such as temperature, precipitation, soil moisture and sea level. Second, some human communities have become more In its second assessment vulnerable to hazards, such as storms, report IPCC concludes that floods and droughts, as a result of "the balance of evidence, increasing population density in sensitive from changes in global areas, such as river basins and coastal mean surface air tempera­ plains. Potentially serious changes have ture and from changes in been identified, including an increase in geographical, seasonal, and some regions in the incidence of extreme vertical patterns of atmos­ high-temperature events, floods and pheric temperature, droughts, with resultant consequences for suggests a discernible fires, pest outbreaks, and ecosystem human influence on global composition, structure and functioning, climate". including primary productivity". INTRODUCTION

Human life and socio-economic activities populations are forced to use more and have always been subject to many chal­ more marginal land, thereby augmenting lenges, among which climate variations and the potential impacts of climate change, change are the most important. Many including sea-level rise, and the possible regions are particularly sensitive to short- increase in severe weather events and term climate variations, leading on occasion flooding. to societal transformations, migrations The objective of this brochure is to and/or upheavals. These consequences can outline the relationship between urbaniza­ be, and have been, dramatic with profound tion and climate. The influence of various effects on human activities and social struc­ characteristics of an urban structure, such tures. Urbanization is one phenomenon that as surface roughness and cover, urban may cause changes in local and even design, and "green space area" benefits regional climate. At the same time, climate will be discussed. In this context, an over­ changes may lead to socio-economic riding goal is to convey the message that changes, including migration patterns to urban planners should carefully consider cities. Urban populations are growing very environmental conditions in order to rapidly throughout the world. achieve and enhance the quality of life in The potential for anthropogenic inter­ different geographical areas, while keeping ference with the climate system has been the environmental capital unchanged. assessed by the Intergovernmental Panel on Special attention is directed towards Climate Change (IPCC). the implementation of Agenda 21 and the Determined to protect the climate global plan of action, "The HABITAT system for present and future generations, Agenda", resulting from the HABITAT II Governments have agreed to a United Conference in Istanbul (June 1996). The Nations Framework Convention on Climate HABITAT Agenda deals with a range of Change (UN/FCCC). issues that concern builders, operators, Urbanization is related to the climate regulators, and users of human settle­ change issue in at least two ways. Firstly, a ments. Their related activities are affected significant amount of energy is used in to a greater or lesser extent by local and urban areas which it is, indirectly, a major regional climate, which, in turn, affect local source of greenhouse gases. By designing, climate. Although each impact is minimal, building, and operating urban areas in an the cumulative effect may be considerable. energy efficient way, significant decreases in All deliberations on the HABITAT issues greenhouse gas emissions can be achieved. must, therefore, take account of the climate Secondly, the rapidly increasing urban factor. Excerpt from a INTERACTION BETWEEN URBANIZATION AND CLIMATE declaration of municipal leaders-. Global "The abatement of The urban environment issue has become one of the most important within the overall The ultimate objective of the UN/FCCC, fossil fuel emissions context of global change and development of as expressed in Article 2 is-. sufficient to response strategies. Urban activities are "...stabilization of greenhouse gas stabilize major contributors to the increasing emis­ concentrations in the atmosphere at a concentrations of sions of greenhouse gases due to their greenhouse gases in relatively intense use of energy. The rapidly level that would prevent dangerous the atmosphere will growing populations in many urban areas are anthropogenic interference with the also the most vulnerable to the impact of climate system. Such a level should be require policies and climate and climate change. These conclu­ achieved within a time-frame sufficient initiatives based on sions were noted during the Twelfth World to allow ecosystems to adapt naturally a thorough Meteorological Congress (1995), which to climate change, to ensure that food understanding of decided that an enhanced effort should be the urban made by WMO, in cooperation with other production is not threatened and to environment as an organizations concerned, to address the enable economic development to proceed meteorological and hydrological aspects of in a sustainable manner." energy system". urbanization.

Annual global mean temperature anomalies as departures from the 1961-1990 base-period means. Local — urban

The urbanization process is influenced by introduced by urbanization may also have a local climatic conditions. At the same time, negative influence on structures and mate­ urban development has introduced changes rials. A most direct impact relates to the in land surface characteristics which, in turn, local ability to withstand the forces in has changed the local climate into what can connection with natural disasters. The be defined as "urban climate". hard, often paved, surfaces in urban areas The natural environment found in the influence the runoff patterns and may, if countryside, favoured by an equable poorly designed and maintained, be climate blessed with clean air and ample the direct reason for the disastrous effects pure water, is indeed a wondrous and a of flooding. High structures and buildings most precious resource for mankind. Urban often cause damaging and uncomfort­ climates are mostly inferior in quality to able wind gusts and the warm air over rural climates, especially in relation to a city may trigger severe local thunder­ human health and well being. The changes storms.

Meteorological processes and climate develop on many different time- and space-scales which are linked to each other and depend on geography as well as on topography. 8

THE URBAN CLIMATE Upper limit of inversion

Temperature: The urban heat island (UHI)

The temperature in an urban area is usually higher than in the surrounding countryside. The magnitude or intensity of this so-called urban heat island (UHl) depends on various factors, such as the size and morphology of the city. The primary factors are the increased absorption of heat caused by changes in land cover, the trapping of heat by buildings due to S Very weak synoptic wind their mass and canyon-like geometry, and the reduction in vegetation. Heating and other increased energy uses no doubt contribute to increased outdoor city temperatures espe­ cially during winter at high latitudes. At lower latitudes, air conditioning increases outdoor temperatures while providing a pleasant indoor climate. The change in water balance in the urban area contributes to the forma­ tion of the UHl as a result of reduced evaporational cooling from vegetation and forced drainage of rain-water. Moderate synoptic wind

Mitigation strategies for the reduction of The urban heal island over a city lakes on a urban heat islands could save US$ 5 to Ihree-dimensional dome-like shape and is 10 billion in energy costs in the United affecled by the synoptic/large-scale winds. States. The nature of urban climate effects (approxi­ mate effects of a mid-latitude city of one million inhabitants) (after Oke, 1994) Ai VARIABLE CHANGE MAGNITUDE temperature • UV radiation Much less (25-90%) • Solar radiation Less (1-25%) • IR input More (5-40%) • Visibility Reduced • Evaporation Less [50%) • Heat flux More [50%) • Turbulence Greater ; 10-50%) • Wind speed Decreased [5-30% at 10 m) • Wind direction Altered [1-10°) • Temperature Warmer 11-3°C annual mean, 5 up to 12°C on indi­ ^S^lîlmT^" ! vidual occasions) Humidity Day - less; night - more Rural Suburb Downtown Cloud More moist urban haze, more cloud in lee of city Fog Either more or less, depends on city Generalized cross-section of Precipitation Less snow (converted to rain), a typical urban heat probably more total precipitation in In large inland cities in the tropics, island. lee of city mean monthly urban heat island intensities may reach 10°C at the end of the night, especially during the dry Daily summer mortality There is a general relationship between heat island season. rate during a heat wave in intensities and the population, even if the slope New York in 1966. varies between different parts of the world.

40 50 60 70 80 90 Days from May to August Population 10

URBAN WATER BALANCE

Water, in its various forms, deeply affects Urban areas may cause considerable the life of a city. Great quantities are piped intensification of rain, hail, and thunder­ around for industrial and domestic use. storms, especially «downwind» from the Rain-water must be drained away in a major sources of rain triggering nuclei. Icing controlled manner in order to avoid flood­ on structures, such as masts and power ing, erosion, and landslides. Snow and ice lines, may pose a safety threat to people have to be cleared and the potential and property. The peak runoff is reached impact of hail and thunderstorms should more rapidly and is higher than if the city be minimized. were not there.

The urban area, the production of dust and other pollutants, coupled with the effect of the urban heat island may trigger cloud formation and even precipitation. 11 boundary layer to be both deeper and more turbulent. When large-scale winds are strong, both a decrease in wind speed and changes in wind direction are experienced as air crosses the city. SOLAR RADIATION

Due to pollution and, in some cases, increased cloudiness, the amount of short­ wave solar radiation which reaches the surface in an urban area is normally less than that in the surrounding countryside. Photochemical reactions contribute to the formation of secondary pollutants and haze.

The rougher urban area URBAN WINDS POLLUTION causes the wind to change both in speed and When the large-scale winds are light or Urbanization is associated with pollution of direction. calm, the UHI can generate its own wind both water and air in many different ways. In system. What is sometimes called the "city addition to the direct effects that the vari­ wind" develops in a fashion that is similar to ous pollutants have on health, they also that of the sea breeze; in coastal areas, the have an impact on climate. Aerosols, espe­ two wind systems may combine into intense cially, affect the incoming solar radiation and complex circulations. The surface in an and may also play an important role in trig­ urban area is normally rougher than in the gering precipitation, thus having an impact surrounding countryside causing the urban on the precipitation pattern. The evolution of urban air pollution in and around large cities results in a new mixture of contami­ nants which do not only pose serious health hazards and deteriorate in the quality of life, but can also destabilize the urban atmos­ pheric chemistry, thus creating different end products that have a long life-span and can spread well beyond the boundaries of the Urban pollution under normal sphere of influence. inversion conditions. (Photo. T. Kuenzle, Swiss Federal Institute of Technology) 12

DEVELOPING SUSTAINABLE HUMAN SETTLEMENTS

Solar radiation

Raw materials

Heat island

Plume of polluted air

Évapotranspiration

Export of materials

Surface water

Solid waste Waste fluids

Sewage 13 Land-use planning The United Nations launched the The location of a town within a given region International Decade for Natural may affect the urban climate and the Disaster Reduction (IDNDR, comfort of the inhabitants. Land uses may 1990-2000) in order to promote change with time; buildings and even neigh­ bourhoods may be demolished and rebuilt, disaster prevention and preparedness but the geographical location of the town through concerted international action, may exist for many centuries. especially in developing countries, and to Variations in topography should be reduce the loss of life, property damage, carefully considered when deciding on the and social and economic disruption location of new towns, or in the expansion caused by natural disasters. IDNDR of existing towns. In a cold climate, the criteria for the focuses on natural disasters, such as location of a town may include protection earthquakes, tsunamis, volcanic from the winds, while in a hot climate, and eruptions, landslides, avalanches, especially in a hot humid one, the prefer­ cyclones, floods, drought, and locust ence would be for locations with maximum infestations, many of which are directly wind exposure. related to weather and climate.

At the United Nations Conference on In regions where mountain ranges are Environment and Development perpendicular to the prevailing winds, espe­ (UNCED) (Rio de Janeiro, June 1992), cially where the winds come from the ocean the international community agreed upon or great lakes, a marked difference in a set of objectives and actions aimed at cloudiness is usually experienced on the promoting sustainable human settlement two slopes of the range. When humid air rises over the windward slopes, it cools development. In Chapter 7 of Agenda 21, down and its moisture condenses into the concept of «enabling approach» in the clouds, promoting precipitation. However, human settlement sector was introduced, as the air stream passes over the top of the whereby a partnership among the public, mountain range, it sinks down and heats up. private and community sectors seeks to The water droplets in the clouds evaporate improve the social, economic, and environ- and result in less precipitation on the leeward slope. mental quality of human settlements and The siting of urban areas is an important decision in the living and working environment of urban planning and people. design. 14

Natural hazards in cities Noise is part of urban pollution that needs to be Prevention, mitigation, and preparedness by very heavy precipitation and, along the screened out. are the basic principles associated with coast, by marked sea-level rise resulting (Photo: Anne Duhamel von urban planning. The urban design should from the strong storm surges. The floods Moos. Swiss Federal aim firstly at preventing natural hazards and resulting from heavy precipitation often Institute of Technology) then at mitigating their impact once they cause widespread loss of life and property. occur. Many coastal areas, especially in the Valley bottoms, even shallow ones, can be tropical and subtropical latitudes, are prone used for runoff water discharge; land uses to tropical storms (hurricanes and should take into consideration their typhoons). These storms are accompanied usefulness. 15 Various urban designs. (Photos: I. Morimoto) URBAN DESIGN The density and size of the built urban area affect the degree by which a regional climate is modified to create a specific urban climate. It is possible to modify the urban climate through design: (a) To improve the comfort for the inhabi­ tants outdoors and indoors; (b) To reduce the energy demand of build­ ings for heating in winter and for cooling in summer; (c) To reduce the quantity and increase the quality of surface water runoff. The urban climate may be improved by the deliberate design of city structures, for example: {a) By opening urban corridors and benefit­ ing from nocturnal downslope winds; [b] By varying the heights of building to increase urban ventilation; and (c) By orienting and grouping buildings.

Maximize the amenity of the environment and make useful connections to public facilities. 16

ARCHITECTURE IN HARMONY WITH CLIMATE

Adapting buildings to regional climate is an constructed from very different materials. important feature in improving comfort. Financial resources are usually too scarce to Bioclimatology is the name given to the build high quality housing that take into increasing trend towards integrating account climatic constraints. Persistent climatic parameters into urban planning. temperatures above 30°C and heavy rains This concern has, in fact, been known represent the two major threats to the for ages. The Roman architect Marcus solidity, foundation, and durability of Vitruvius Pollio, who lived during the first buildings. century B.C., wrote a treatise on architecture in which climate was well taken into Cold/dry climate In alpine regions, the account. typical chalet is built of At high latitudes, temperatures can plunge stout timber, with good Hot/dry climatic zones to as low as -60°C. Strong winds may insulation, storm windows enhance the wind chill and make any and roofs having a Urban civilizations developed early in hot outdoor life difficult. Most building materi­ pronounced overhang to and dry regions characterized by intensive als do not resist temperatures below -45°C. cope with snow. solar radiation in the summer, often Plastic hardens and breaks easily. However, (Photo: Anne Duhamel von exposed to strong winds and, from time to steel which is specially conceived for cold Moos, Swiss Federal time, to heavy rains, provoking floods. The climate can be used. The soil is usually Institute of Technology) main concern in designing buildings in these zones is to minimize heat penetration into the house. Walls are painted white, thus allowing a good reflection of sun rays and limiting heat absorption. Shady zones are planned for comfort. Openings are narrow and often equipped with fixed elements like shutters, which let the light in, but not the heat or strong winds. Hot/humid climatic zones Many cities in the hot, humid tropics are developing rapidly with massive immi­ gration from rural zones. The structures of homes are often very precarious and 17

Large, flat roof Thick wall for insulation '0Qr~ Well insulated and S * H 1

Im vis Narrow One of the best examples of shaded £* Shuttering street Small shuttered adaptation to a hot and humid or mesh windows HOT DRY ZONE HOUSE climate is the Palace of Justice in Crass, mud, branches Klungkung, chief city of Bali \ Small {Indonesia), built in 1710. The opening pavilion is surrounded by a ditch filled with water, the evaporation of which causes fresh air to circulate. The rooms on the first floor are totally open to the outdoors in order to allow WP Be.'li optimal ventilation. The ceiling,

MEDITERRANEAN ZONE COURTYARD HOUSE supported by 24 pillars, has the shape of a tent. Heat accumulates and Steep gables HOT DESERT ZONE TENT forms a dome that serves as an Vent insulating layer which protects the jHS Lamp platform inside from the heat of the Sun. The Windows roof juts out in order to prevent set high T damage that rain could cause to the base of the walls.

COLD ZONE HOUSE ESKIMO IGLOO

Housing in different deeply frozen and when it melts on the Kitchens and auxiliary rooms face north climatic zones. surface during the summer, it turns into while bedrooms and living rooms face mud and destabilizes the foundations of south. The temperature contrast between the buildings. In cities located in indoors and outdoors can reach 80°C. This permafrost areas, buildings are often built requires the use of one to three locks, for on concrete pillars which are rammed passage out and in. deeply into the earth down to a level that never defreezes and they are laid out after taking into account the wind conditions. 18

ENERGY

The main human influence on global improved through suitable vegetation and climate is due to changes in carbon dioxide better urban design. This involves and other greenhouse gases in the atmos­ consideration of appropriate exposure to phere caused mainly by the burning of fossil wind and solar radiation. The benefits of fuels (coal, gas and oil). This has led to a energy efficient siting and design of significant climate in radiative forcing. buildings are economic, social, and Radiative forcing plays a major role in the ecological. Since 1970, total energy use per climate change mechanism due to the year has actually declined in the domesic perturbation of the energy balance of the sector. The use of locally available Earth-Atmosphere system. renewable energy sources, for example for Energy production is also a major water heating, should also be considered. contributor to local and regional air pollu­ Energy efficient transport is a key to tion which, in turn, generates acidification sustainable human settlement design and of water and soil. The reduction of energy operation. Besides reducing energy-related use through more efficient urban design and emissions of greenhouse gases, an efficient \ndoor comfort needs operations will, in general, lead to the transport system will have a beneficial influ- depend also on climate. reduced emissions of greenhouse gases as well as of other pollutants. The Intergovernmental Panel on Climate Change (1996) estimates that about COLD CLIMATE WARM HUMID CLIMATE half of the carbon dioxide emissions glob­ ally can be attributed to activities normally related to urbanization, i.e. the residen­ HEATING tial/commercial sector (29 per cent) and transport (21 per cent). Projected energy use for the year 2025 in these sectors could be reduced by 25-35 per cent without compro­ mising comfort, services, and performance. Technical changes include the use of better adapted building materials and GOOD insulation, more efficient space INSULATION heating/cooling, effective sanitation, including adequate water supply, energy efficient lighting, and appliances. Ambient conditions around buildings can be 19 Housing density may be used as one urban indicator. (Photo: Anne Duhamel von Moos, Swiss Federal Institute of Technology)

In the United Kingdom road traffic accounts for: A first major step to be taken by local 21 per cent of total United Kingdom production of carbon authorities is to incorporate energy dioxide; policies within the plan of action as a part 52 per cent of nitrogen oxides; of the local Agenda 21. This should 46 per cent of hydrocarbons and; include identification of a set of relevant 89 per cent of carbon monoxide.lt may also be noted that indicators in support of the 75 per cent of all journeys are less than eight kilometers, an ideal distance to cycle; implementation of the plan. 25 per cent of carbon dioxide emissions are transport related. It is observed the since 1952, car travel has increased 10-fold and air travel 30-fold. In 1932, the average distance people trav­ elled per day was six miles; it has now reached 25 miles. Since ence on reducing noise pollution. Land-use 1976, there are an extra 6.9 million cars and two to three billion planning should centre around the princi­ fewer journeys by bus. This leads to the slogan "Travel by bus ples of reducing the need to travel and or rail — no need to worry about parking" or "Consider sharing maximizing the accessibility to public cars — the more passengers, the better." services within an overall objective of envi­ ronmental sustainability. 20

URBAN HYDROLOGY: DRAINAGE

Many human settlements are located near Flooded streets in water bodies. Aside from their aesthetic Bangkok. (Photo: League attractions, streams, lakes, and rivers can of Red Cross and Red also become the site for villages, towns, and Crescent Societies) cities because they are a source of water supply. Rivers offered an early means of transportation and their valleys made construction of highways and railroads easier. Unfortunately, running water is also used, in many cases, as an inexpensive means of sewage disposal. Cities are particularly prone to floods, especially cities in the developing world; as urban populations in the developing world are growing at a rate of about four per cent per year, more and more people are at risk. Important changes are observed in the urban hydrological cycle, especially the apparent increases in rainfall. Radical changes in surface characteris­ tics and water management in urban areas have led to: (a) Rapid precipitation runoff; [b] Flooding; (c) Erosion; [d] Earth sinkage. On natural soil, water is In order to alleviate floods in cities and allowed to permeate and towns, research, planning, and operation of reach the groundwater projects have been aimed at: sources. \n cities, the (a) The installation of new systems for increased volume of runoff drainage; water and the speed of \b) The rehabilitation of existing systems; response lead to urban (c) Renewal of underground water sources flooding. through selective infiltration. Time 21

Landscaping primarily to one side, to facilitate maintenance and reduce Holding tank overshadowing upstream serving of water irrigation channels

Reducing the quantity and improving the water quality is a goal of surface water runoff. 22

CARBON FIXATION

"Urban greening" through more parks, vege­ Finally, urban greenery absorbs carbon tation, and lakes in cities relates to a dioxide from the atmosphere and converts commitment under the United Nations it to leafy stems, branches, and tree trunks. Framework Convention on Climate Change The expansion of urban greenery, therefore, Urban greening (UN/FCCC) to maintain or increase the serves to enhance the terrestrial carbon contributes to a better capacity of carbon sinks. It is estimated that sink and, thereby, reduce the atmospheric environment. an urban tree is 1 5 times more useful than a concentration of carbon dioxide. (Photo: I. Morimoto) rural tree because in addition to absorbing an equal amount of carbon dioxide it can be used to shade and cool buildings and, hence, reduce the need for energy for cool­ ing and comfort. The presence and distribution of urban greenery, including parks, trees, shrubs, and grass, can be used to influence the microcli­ mates of cities. Trees, for instance, have a cooling effect. They shelter the ground from solar radiation by providing shade for streets and houses. In addition, as their leaves tran­ spire, the resulting evaporation of water has a general cooling effect on the surrounding atmosphere. One of the key strategies that local authorities can pursue to adapt to climate change is to promote urban greening in order to cool off the city and to ameliorate the local effects of warmer seasons. In addition to beautifying the city and providing amenities like parks for its citizens, an urban greening strategy can also help to reduce the energy required to heat and cool buildings. Trees and shrubs planted strategically around buildings, for instance, wind breakers help to reduce the conductive heating and cooling losses that wind inflicts on buildings. 23 SECOND UNITED NATIONS CONFERENCE ON HUMAN Examples of best SETTLEMENTS (HABITAT II): THE MILESTONE CONFERENCE practices

\n Los Angeles, an From 3-14 )une 1996, the United Nations growth, of production and consumption, and organization called organized the Second United Nations of land use and mobility, as well as degrada­ Tree People mobilizes Conference on Human Settlements tion of their physical structure. Such citizens to plant and (HABITAT II) in Istanbul, Turkey, 20 years problems are often synonymous with soil, air, maintain trees that after HABITAT I, which was held in and water pollution, waste of resources, and cool and beautify the Vancouver, Canada. HABITAT II, which has the destruction of natural resources. been called «The City Summit» by United Therefore, a largely urbanized world implies city, conserve energy, Nations Secretary-General Dr Boutros that sustainable development will depend and prevent erosion. Boutros-Ghali contributed to respond to an very largely on the capacity of urban and ever-increasing concern on urbanization metropolitan areas to manage production issues. The overall goal of HABITAT II was to and consumption patterns. The so-called S1RDO make the world's cities, towns, and villages system in Mexico City healthy, safe, equitable, and sustainable. collects sewage and The two overall themes of the Conference Global Plan of Action were: waste water, filters it, (a) Adequate shelter for all; National delegations, which included local and creates water for [b] Sustainable human settlements devel­ government and private sector representa­ gardening and opment in an urbanizing world. tives, as well as representatives of non­ fertilizer for local use Rapid urbanization, the concentration of governmental organizations, agreed to a and sale. urban population in large cities, the sprawl of Global Plan of Action for human settle­ cities into wider geographical areas, and the ments development. This Plan addresses rapid growth of megacities are among the the issues facing us during the next two New York City is most significant transformations of human decades, with a focus on immediate actions adapting Sâo Paulo's settlements. The sustainability of the global in the first five years. environment and human life will not be Alert II programme, achieved unless, among other things, human Best practice which uses publicly settlements in both urban and rural areas are displayed air pollution made economically viable, socially vibrant, Best practice refers to successfully identified monitors to restrict and environmentally sound. Urban settle­ local initiatives. The dissemination of expe­ automobile traffic in ments hold a promise for human develop­ rience will be achieved through both the centre of the city ment and protection of the world's natural publications and the organization of resources through their ability to support regional and interregional conferences on when pollution levels large numbers of people while limiting their specific issues and problems of metropoli­ are too high. impact on the natural environment. Yet many tan governance development. This will help cities are witnessing harmful patterns of build a network of leaders and experts. 24

FURTHER READING Baker, N. V., 1987: Passive and Low Energy Building Design for Lowry, W. P., 1988: Atmospheric Ecology for Designers and Planners. Tropical Island Climates. Commonwealth Science Council, Peavine Press, McMinnville, Oregon. London. Oke, T R.. 1994: Global Change and Urban Climate. Proceedings of Barton, H., Davis, G. and Guise, R., 1995: Sustainable Settlements-. the Thirteenth International Congress of Biometeorology. A Guide for Planners, Designers and Developers. The Local Calgary, Canada, 12-18 September 1993, Part II, Volume 1. Government Management Board, London. Papers presented at the International Workshop on Solar Boillat, I.-L., 1995: Gestion des eaux dans les zones habitées. Architecture and Planning. Calcutta, India, 8-10 Hydraulic Construction Laboratory, Swiss Federal September 1995. Institute of Technology, Lausanne, Switzerland. Thurow, C, 1983: Improving Street Climate Through Urban Design Changnon, S. A., 1996: The Great Flood of 1993: Causes, Impacts Planning. Advisory Service Report No. 376, American and Responses. Westview Press, Oxford. Planning Association, Chicago, Cities on Water, 1991 : Impact of Sea Level Rise on Cities and United Nations Centre for Human Settlements (HABITAT), Regions. Proceedings of the First International Meeting 1994: Sustainable Human Settlements Development: of Cities on Water (R. Frassetto, éd.). Venice, 1 1-13 \mplementing Agenda 21. Nairobi. December 1989. United Nations Centre for Human Settlements (HABITAT), Deelstra, T., Galjaard, )., Jongman. R. H. G., 1989: Possible 1996: The Habitat Agenda. United Nations Conference on \mpacts of Climatic Change on European Cities-. A ReconnaissanceHuma n Settlements, Istanbul, Turkey, 3-14 (une 1996. of A New Problem. The International Institute for Urban World Meteorological Organization, 1986: Proceedings of the Environment, The Netherlands. Technical Conference on Urban Climatology and its Applications, Hardoy, |. E., Mitlin, D., Satterthwaite, D., 1992: Environmental With Special Regard to Tropical Areas (T. R. Oke). Mexico City, Problems in Third florid Cities. Earthscan Publications Ltd., 26-30 November 1984, WMO-No. 652, Geneva. London. World Meteorological Organization, 1989: Urban Design in Hertig, |.-A., 1986: La physique de l'atmosphère et les îlots de chaleur Different Climates (B. Givoni). World Climate Applications au-dessus des villes. Possibilités et limites de la modélisation. Programme Report No. 10, WMO/TD-No. 346, Geneva. Société de physique et d'histoire naturelle de Genève. World Meteorological Organization, 1990: Bibliography of Urban Climate Intergovernmental Panel on Climate Change, 1996: Second 1981-1988 (T. R. Oke). World Climate Applications Programme Assessment Report: Climate Change 1995. Geneva. Report No. 15, WMO/TD-No. 397, Geneva. International Federation for Housing and Planning/ World Meteorological Organization, 1991: Climate Change-. Science, International Council for Building, Research, Studies and \mpacts and Policy. Proceedings of the Second World Climate Documentation/World Meteorological Organization/ Conference. Geneva, 29 October-7 November 1990, International Geophysical Union/Kyoto University, 1991: Geneva. Urban Climate, Planning and Building. Proceedings of the World Meteorological Organization, 1993: Bibliography of Urban Fourth International Conference on Urban Climate, Climate in Tropical/Subtropical Areas 1981-1991 (E. Jauregui). Planning and Building (A. Bitan, éd.), Kyoto, lapan, World Climate Applications and Services Programme 6-1 1 November 1989, Volumes. 1 and 2. Report No. 25, WMO/TD-No. 552, Geneva. International Institute for Environment and Development, World Meteorological Organization, 1994: Report of the Technical 1992: Environment and Urbanization. Volume 4, Number 2, Conference on Tropical Urban Climates. Dhaka, Bangladesh, 28 London. March-2 April 1993, World Climate Applications and Landsberg, H. E., 1981: The Urban Climate. Academic Press, Services Programme Report No. 30, WMO/TD-No. 647, New York. Geneva.