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Creating Sustainable Cities
By Herbert Girardet
UIT Cambridge LtdCopyright © 2011 Herbert Girardet
All rights reserved.
Urban Sustainability: a contradiction in terms?
City growth is changing the condition of humanity and the face of the earth. In one century, global urban populations have expanded from 15 to nearly 50 per cent of the total, and this figure is likely to increase to 60 or even 70 per cent in the next century. By 2000, half of humanity will live and work in urban areas, while the other half will increasingly depend on them for their economic survival. The size of modern cities, too, in terms of their numbers as well their physical scale, is unprecedented: in 1800 there were only two cities with a million people — London and Peking. At that time the largest 100 cities in the world had 20 million inhabitants, with each city usually extending to just a few thousand hectares. In 1990 the world's 100 largest cities accommodated 540 million people and 220 million people lived in the 20 largest cities: mega-cities of over 10 million people, some extending to hundreds of thousands of hectares. In addition, there were 35 cities of over 5 million people and hundreds of over one million.
It is evident that there has been a profound change in the size of cities, their use of land and resources, and their environmental impact. Contemporary cities are very different places from their historical predecessors. They are wide open to the outside world, with road and rail systems and sea and air transport routes stretching beyond their local horizons, often for thousands of miles. A major variable is their dependence on fossil fuel (and nuclear energy) technologies to power their buildings, their factories and their transport systems.
City people have changed, too. Our evolution into 'amplified human beings' — people amplified by ever more numerous, more varied and more powerful technologies — occurred primarily in cities. We have changed profoundly as a result, with technologies now merged into our very being, and the experience of nature becoming ever more distant.
The physiology of traditional towns and cities was very different from that of modern conurbations. It was defined by production and transport systems based on muscle, water and wind power, which inevitably limited their outward and upward growth. Until the 18th century, densely populated towns ringed by defensive walls were the norm. Their historical development is also the story of the emergence of complex forms of human interaction, developing highly formalised political, economic, spiritual and military hierarchies.
The emergence of settled or sedentary urban living, with thousands of people sharing one urban space, was only possible through the concentration of food production on closely defined areas of land, a dramatic departure from hunting and gathering. Urban living, to be viable in the long term, presupposes a clear understanding of conditions for sustainable human interactions with nature — an understanding that was not required before urbanisation started. Above all else, it requires the management of soil fertility and crops for the assured supply of foodstuffs to urban populations over sustained periods of time.
Early cities, such as Ur in Mesopotamia (today's Iraq) some 3,500 years ago, were themselves centres of food production. One author conjures up an image of Ur: "Most of the people we pass in the streets would be farmers, market gardeners, herdsmen and fishermen and correspondingly many of the goods transported in carts would be food products. However, some of the farmers could have had other roles as well: carpenters, smiths, potters, stone-cutters, basket-makers, leatherworkers, wool-spinners, baker and brewers are all recorded, as are merchants and what we might call the 'civil service' of the temple community — the priests and the scribes."
But early towns such as Ur did not acquire their prosperity purely on the basis of urban agriculture. They also drew in resources from territories beyond, most importantly forest products. Deforestation certainly occurred on a massive scale on the hills around the cities of Mesopotamia, both for the acquisition of timber and firewood as well as for the expansion of farmland. In the case of Ur, this eventually had dramatic consequences. When Sir Leonard Wooley excavated Ur in the 1880s, he found a three-foot layer of mud that had inundated the city in around 2500 BC, and other cities in Mesopotamia suffered similar fates. The eventual decline of that civilisation is linked to a further environmental factor: the salinisation of farmland as a consequence of the injudicious use of irrigation water, with catastrophic consequences for the productivity of farmland feeding these cities. The yields of wheat and then barley declined; eventually the only food plants that would still grow were date palms. When Europeans first travelled extensively in Mesopotamia in the 19th century they found few traces of the ancient cities: only mounds of sand and rubble in a salt-encrusted desert landscape. Are we in danger of repeating these impacts — except on a global scale?
The mode of adaptation of cities to their hinterland ultimately defines their sustainability, or the lack of it. This is strikingly illustrated in the case of ancient Rome. As it grew into a city of up to a million people, its supplies of timber and food were brought in from ever more distant territories. It was Julius Caesar who decided that North Africa would be a suitable region for supplying Rome with grain, having exhausted the fertility of farmland in Italy itself, as well as that of territories elsewhere in the Mediterranean basin. Caesar's armies conquered much of the African territory north of the Sahara. It was a largely wooded landscape and one Roman writer, Pliny, marvelled at the abundance of fruits in the forests on the slopes of the Atlas mountains and the great variety of animals. The night, Pliny wrote, was filled with the sounds of drums, cymbals, flutes — the sounds of people dancing.
Roman veterans who were settled in North Africa got on with the tasks of appropriating land from nomadic tribes and converting forests into farmland. Forest timber was made into ships or houses or exported across the Mediterranean to Rome itself. Thousands of animals — lions, elephants, zebras, and gorillas — were captured and shipped to Rome to be put up against gladiators in the Colosseum. Some 500 towns were built in North Africa to act as epicentres of Rome's economy. Their construction and their food and fuel supplies had a huge impact on the local landscape. For some 200 years, North Africa also supplied some 500,000 tonnes of grain to 300,000 Romans who were eligible for free grain, some two-thirds of Rome's total grain supply.
Over the years, climate change as a result of deforestation, salinisation as a result of irrigation, and the continued export of soil fertility took their toll. Around 250 AD St Cyprian, Bishop of Carthage, wrote that the "world has grown old and does not remain in its former vigour. It bears witness to its own decline. The rainfall and the sun's warmth are both diminishing; the metals are nearly exhausted; the husbandman is failing in his fields. Springs which once gushed forth liberally ... now barely give a trickle of water."
Rome's collapse occurred for a variety of reasons. Internal dissension was certainly a major factor; a lack of sustainable relationships with the environments from which it drew its resources was certainly another critical feature. At the height of its decline, between 400 and 1000 AD, Rome contracted to a town of only 30,000 people.
The German scientist Justus Liebig, a pioneer of modern chemistry in the mid-nineteenth century, was an eager student of the environmental history of Rome, and tried to understand its impact on the land supplying its food. He was particularly concerned about the way Rome had removed plant nutrients in North African soil as grain was exported from there. The minerals contained in the grain — nitrogen, potash, phosphate, magnesium and calcium — were removed from the farmland and flushed into the Mediterranean via Rome's Cloaca Maxima, never to be returned to the land. Liebig was observing the unprecedented growth of cities in the 19th century and tried to asses its impact on Europe's farmland. Would cities permanently deplete the fertility of Europe's farmland in the way Rome had done to North Africa 1800 years before? In the 1840s Liebig tried to persuade the London authorities to build a sewage recycling system for the city. When they decided in the 1850s to build a sewage disposal system instead, Liebig and others set to work on the development of artificial fertilisers, to replenish the fertility of soil feeding cities by artificial means. This scientific departure contributed to the current unsustainability of both agriculture and of urban systems.
A major difference between 19th century Europe and ancient Rome was the scale of urban growth and its associated environmental impact. Rome, as already stated, had grown to around one million people; only a few other cities in history — Constantinople (Istanbul), Edo (Tokyo) and Peking (Beijing) — reached a similar size. London's growth in the 19th century was of a new order of magnitude: in 1800 it had nearly one million people, by 1850 it reached an unprecedented population of four million. (It peaked in 1939 at 8.65 million people, with a peripheral urban region accommodating a further four million.) Cities of such vast size represented a completely new scale of urbanisation and, in addition, of human impact on the environment.
This impact is not confined to urban land use. The most pronounced difference between ancient Rome and much larger modern cities such as London is their vast use of energy. Contemporary London, with 7 million people, uses around 20 million tonnes of oil equivalent per year, or two supertankers a week, discharging some 60 million tonnes of CO2 into the atmosphere. The critical issue is whether, and how, these figures can be reduced in the process of assuring greater sustainability. Can modern cities reduce their impact on the biosphere by processes of enlightened self-regulation and self-limitation?CHAPTER 2
Urbanisation and its Impacts
Many people have deplored the growth of large cities all over the world. At the 1976 Habitat Conference, the first UN city summit, for instance, a major concern was with preventing outright urbanisation from occurring worldwide. Policies were initiated to try to counter these trends and to help improve living conditions in rural areas — by supporting rural education and health programmes, improved water supplies and sanitation, village electrification and investment in rural economies. But more often than not, these sorts of policies ultimately contribute to rural-urban migration by importing urban concepts and culture into rural areas. The spread of western media to the remotest communities has further added to the process. Since the late seventies, urbanisation in the South has accelerated rather than slowed down. Only major economic crises, such as the recent slump in Asia, seem at times to dampen down further urban growth.
The global economy has grown many times over in the last 50 years and it is becoming ever more integrated. "In 1950, most of the world's workforce was employed in agriculture; by 1990 most worked in services." It is clear that urbanisation is driven above all else by economic factors, and in discussing sustainable development we have to deal with the reality of a planet that is urbanising, industrialising and globalising — at least for the time being.
Today, the world's largest and fastest growing cities are emerging in the South, because of unprecedented industrial growth there, and as a consequence of rapid changes in rural areas. Migration to cities is commonplace, particularly in places where traditional rural lifestyles are changing rapidly, and where population growth, changes in land tenure and the mechanisation of farming pushes people off the land. Development also pulls people into cities. As they grow, their impact on adjacent rural communities increases as new urban employment opportunities and the expansion of transport and communications systems attract people from outlying areas.
Whilst the migration to cities can increase peoples' standards of living, it can also be a health threat for people, particularly in squatter communities, as they become exposed to high concentrations of disease vectors and pollutants. Tackling urban environmental problems, and particularly the conditions suffered by low income people, is one of the great challenges in the age of the city. Many poor Third World urban neighbourhoods don't have effective infrastructures to cope with the accumulation and disposal of wastes and sewage. Rats and other vermin proliferate. Infectious diseases such as cholera, typhoid and TB, well known in cities such as London 150 years ago, are commonplace in developing cities, sometimes reaching epidemic proportions.
Urban growth is most rampant in countries undergoing rapid industrial growth. Throughout the '80s and '90s Asia, in particular, has been catching up with the per capita resource use of cities in developed countries. Until recently a few developing countries, such as China, deliberately prevented rural-urban migration by issuing local passports to stop people from moving away, but this policy is now being abandoned. Today China is probably urbanising faster than any other country in history. Like elsewhere, its urbanisation is closely linked to industrialisation. With economic growth of around 10 per cent per year, China is in the process of building some 600 new cities, doubling their current number to over 1200 by 2010. Some 300 million people — a quarter of China's population, will be moving to cities, converting from peasant farming and craft-based living to urbanindustrial lifestyles. But what are the likely environmental impacts of urban development in China? Increased purchasing power is already leading to greatly increased demand for consumer goods and a more meat-based diet. Can soil, water and air contamination be avoided in these new cities, or will they undergo the same old 'dirty' development so familiar from Europe and North America?
The growth of modern urban economies, then, usually means two things: increased demands on the natural capital supplying cities, as well as increased discharges of wastes into the local and global environment. The global environmental impact of urban resource use is becoming a critical issue in the future of urbanisation and the dominant feature of the human presence on earth. As humanity urbanises, it also changes its very relationship to its host planet: global urbanisation has greatly increased humanity's use of natural resources. This can be witnessed today in developing countries, where urban people typically have much higher standards of living than rural dwellers, depending on massively increased throughput of fossil fuels, metals, meat and manufactured products. A recent study shows that a doubling of the proportion of India's and China's populations that live in cities could increase per capita energy consumption by 45 per cent — even if industrialisation and income per capita were to remain unchanged. Only in countries that are 'fully' developed, such as the UK or USA, where rural lifestyles have been effectively urbanised, are levels of consumption in urban and rural areas broadly similar.
All in all, then, the growth of modern urban economies usually means two things: increased demands on natural capital and increased discharges of wastes into the local and global environment. Proposals for sustainable development have to be made in this context. The global environmental impact of urban resource use could well become the dominant feature of the human presence on earth and, given the reality of ever larger numbers of cities, one of humanity's greatest challenges for the new millennium.CHAPTER 3
Cities as Superorganisms
Urban systems with millions of inhabitants are unique to the current age and they are the most complex products of shared human creativity. They are both organisms dependent on biological re-production, as well as mechanisms utilising mechanical production processes. Cities, and particularly large modern cities, are uniquely 'multi-layered' systems, developing extraordinary degrees of economic and social interaction. The larger a city, the more complex its system of commerce and services and the huge variety of professions associated with these.
Excerpted from Creating Sustainable Cities by Herbert Girardet. Copyright © 2011 Herbert Girardet. Excerpted by permission of UIT Cambridge Ltd.
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