Concrete Jungle

Richard Black recently wrote a very informative article for BBC News on the need for green space in urban environments and the paradoxical nature of cities. "Apart from a few lower members of the animal kingdom, no-one other than human beings build cities." Here are some excerpts from 'Finding green In the concrete jungle'

They are totally artificial constructs and in them we live artificial lives. We travel differently, eat different food, receive water and energy through pipes and wires, live in different kinds of buildings, do different jobs.

All of these things come with an environmental price-tag. Given that the world's urban population is expanding at such a rate, it is worth asking what are the numbers on that price-tag, and whether they are higher or lower than the environmental cost of living a rural life.

Does a person produce more or less carbon dioxide on moving from the countryside to the city? If the answer is "less", how should that be offset against a bigger contribution to urban smog? Is trash piling up on a street corner better or worse than excess fertiliser running from farmland into the water supply? How far does a city's environmental footprint extend beyond its boundaries - to the natural resources which feed it with water and food, or to the other side of the planet which feels its greenhouse gas emissions?

There is no simple answer.

"What is needed is research that focuses on the large-scale, long-term environmental changes, not just on the immediate impact of cities," concludes the International Human Dimensions Programme on Global Environmental Change (IHDP), a global research alliance.

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In 2002, the United Nations Development Programme (UNDP) focused much of its Human Development Report on China. "Rural residents consume less than 40% of the commercial energy used by their urban counterparts," it concluded. "However, if biomass [principally wood-burning] is included, the average person in the countryside uses nearly one-third more energy than a city dweller." So the rural resident apparently contributes more to global climate change than the urban citizen - but the equation hinges on how the energy is produced.

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In any case, talk of a "city environment" brings a basic question - which city? In London and Tokyo, air quality has improved over the last 50 years. In Shanghai and Kuala Lumpur, it has gone down, though there are signs of improvement elsewhere in the developing world.

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"But there's a paradigm question here - whether cities are being urged to move away from the traditional 'grow first and clean up later paradigm' to a 'sustainable growth paradigm'." The "sustainable city" is a concept which has received a lot of academic attention in recent times. An Australian group, the Halifax EcoCity Project, has developed what it calls an "ecological measuring stick". Essential elements of sustainable urban development include, it says:

-- extensive use of vegetation to filter pollution, prevent the "heat island" effect and capture carbon dioxide
-- purification and recycling of all water and waste
-- 100% supply of renewable energy
-- a sustainable food supply which does not deplete nearby lands and grow as much as possible with city limits

The EcoCity concept, says Bert Metz, would have a major impact on greenhouse gas emissions. "How cities are planned definitely has an impact. Are there many trees planted, which reduces the need for cooling? How are houses built - that has a huge effect on greenhouse gas emissions." But by the Halifax yardstick, virtually every city in the developed as well as the developing world would fail the sustainability test. Planning cities to allow for green spaces, wildlife, trees and watercourses can have a huge benefit on people as well as on the natural environment, says David Goode, a visiting professor at University College London and former director of the London Ecology Centre.

There's a lot of evidence that both physical and mental wellbeing increases with access to nature and green spaces
David Goode, University College London. "When you've got more than half the world's population living in urban areas, it's crucial they have access to some kind of ecological area within a stone's throw of where they live," he argues. "There's a lot of evidence that both physical and mental wellbeing increases with access to nature and green spaces."

Since the big clean-up began half a century ago, many British cities have become home to the fox, while birds such as the black redstart have become "urban specialists". But is it real nature, or just a designed and planned imitation? "It is different," says Dr Goode, "but you can encapsulate a lot of the features of natural habitat within a city environment."

In any case, much of the world's countryside is far from "natural", shaped as it has been by centuries of human agriculture, in some cases producing vast prairies of monoculture monotony where hardly a bird is heard. But fundamentally people are not flocking to the vast cities of Asia and South America with nature and green spaces in mind. They are coming for jobs, to improve their economic and social prospects. It may be sobering then to consider the UNDP's judgement on China's urbanisation and its concomitant rising toll of pollution and waste: "Environmental factors are likely to constrain, or even reverse, social and economic progress." It is the same old message: societies neglect environmental progress at their economic peril.