Giant Footprints
HERBERT GIRARDET
describes how cities trample across the world
environment, and charts some steps away from destruction
Filming at the Brazilian port of Belem a few years ago -
while producing a television documentary on the deforestation of the
Amazon basin and the resulting loss of biodiversity - I saw a huge stack
of mahogany timber with 'London' stamped on it being loaded into a
freighter. As a result, I started to take an interest in the connection
between urban consumption patterns and human impact on the biosphere. It
seemed that the logging of virgin forests, or their conversion into fields
of soya beans for cattle fodder (in Brazil's Mato Grosso region) or of
manioc for pig feed (in the former rainforest regions of Thailand), was
perhaps not the most suitable way to supply urban markets. I began
wondering how the vast appetites of cities for resources, and their huge
discharges of wastes, could be curtailed - and how cities, the main
habitat of one species, could come to live in peace with the global
habitat of millions of others.
The world's major environmental problems can only be solved as part of the
way we run our cities. In just one century, urban populations have
increased ten-fold, to some 2.5 billion people, and they now take centre
stage in the global dramas of pollution,
land degradation and loss of species diversity. Cities occupy only 2 per
cent of the world's land surface, but use some 75 per cent of the world's
resources, and release a similar percentage of wastes. Their concentration
of intense economic processes and high levels of consumption both increase
and stimulate their demands on resources. They profoundly affect rural
economies - and their cultural diversity - far beyond their boundaries. As
better roads are built and access to urban products is assured, rural
people acquire urban standards of living and the mindset to go with them.
Recently the Canadian economist William Rees, started a debate about the
footprint of cities - the area of land required to supply them with food
and timber products, and to absorb their carbon dioxide output through
growing vegetation. I thought it might be useful to examine the impact of
London, the 'mother of megacities', the first - 190 years ago - to exceed
1 million people. Today its footprint, following Rees's definition, is 125
times its surface area; nearly 20 million hectares compared to 159,000.
This means that - although it contains only 12 per cent of Britain's
population - London requires the equivalent of all the country's
productive land, though, of course, this extends to the wheat prairies of
Kansas, the tea gardens of Assam, the copper mines of Zambia and other
far-flung places.
The critical question, as humanity moves to even greater urbanization, is
whether living standards in our cities can be maintained while their
environmental impacts are curbed.
It helps, in answering this question, to draw up balance sheets
quantifying urban resource flows. Similar sized cities supply their needs
with a greatly varying throughput of resources - but most large cities
have been studied in considerable detail and it is often not difficult to
compare them.
Demand for energy defines modern cities more than any other single factor.
All their key activities - transport, electricity supply, heating,
manufacturing and the provision of services - depend on a ready supply of
fossil fuels. London, for instance, currently requires 20 million tonnes
of oil equivalent per year - the equivalent of two supertankers a week -
and discharges some 60 million tonnes of carbon dioxide. Its per capita
energy consumption is amongst the highest in Europe, yet the know-how
exists to bring these figures down by 30 to 50 per cent without affecting
living standards - and creating large numbers of jobs in the process.
Cities need a whole range of new resource-efficient technologies to make
them more sustainable and reduce their impact on the biosphere. These
include combined heat-and-power systems, heat pumps, photovoltaic modules
and low energy road transport. Major steps can also be taken towards urban
sustainability in waste management. Every day London disposes of 6,600
tonnes of household waste - of which only some 4 per cent is recycled.
Meanwhile most cities in Western Europe are developing and adopting
ambitious technologies for recycling and composting waste.
From linear to circular
The metabolism of most 'modern' cities is essentially linear, with
resources flowing through the urban system without much concern either
about their origin, or about the destination of their wastes: inputs and
outputs are considered to be largely unrelated. Nutrients are taken from
the land as food is grown and not returned to it. Trees are felled for
timber or pulp but forests are not replenished. Raw materials are
extracted, combined and processed into consumer goods which end up as
rubbish that cannot beneficially be reabsorbed into living nature. Fossil
fuels are extracted from rock strata, refined and burned; their fumes are
discharged into the atmosphere.
This linear system is profoundly different from nature's own circular
metabolism where every output is also an input which renews, and thus
sustains, life. Cities which take responsibility for their global
environmental impact, and the potential benefits for their own
populations, will adopt circular metabolic systems, assuring a sustainable
relationship with the natural world.
Some cities have made resource efficiency a top priority, installing
sophisticated equipment for resource recovery. Austrian, Swiss and French
cities have taken the lead in installing waste recycling and composting
systems. Twenty seven composting plants, with a combined annual capacity
of 600,000 tonnes, are currently under construction in German towns and
cities. Throughout the developing world, cities have also made it their
business to encourage recycling and composting of wastes. Brazil's
Curitiba is often cited for its energetic efforts towards urban
sustainability, not only in waste management but also in creating a system
of fast, convenient bus routes and persuading drivers to leave their cars
at home.
Cities worthy of a new millennium will be energy and resource efficient,
and culturally rich, with active democracies assuring the best uses of
human energies. In Northern megacities, such as London and New York,
prudent inward investment will contribute significantly to achieving
higher levels of employment. In cities in the South, significant
investment in infrastructure will make a vast difference to health and
living conditions.
Some writers have argued that cities can actually be better for the global
environment than the adjacent rural areas. They emphasize that they often
contain an impressive range of plant and animal species. They suggest that
the very density of human life in cities makes for energy efficiency in
both home heating and transport. Systems for recycling wastes are more
easily organized in densely inhabited areas. And urban agriculture too, if
well developed, could make a significant contribution to feeding cities.
Growing food in urban areas is certainly common enough - a new book
published by the United Nations Development Programme (UNDP) proves the
point. Singapore, it shows, is fully self-reliant in meat and produces a
quarter of the vegetables its people need. Bamako, Mali, is
self-sufficient in vegetables and produces half or more of the chickens it
consumes. Dar-es-Salaam, one of the world's fastest growing large cities,
now has 67 per cent of families engaged in farming compared with 18 per
cent in 1967. Two-thirds of Moscow's families are now involved in food
production compared with a fifth in 1970. There are 80,000 community
gardeners on municipal land in Berlin with a waiting list of 16,000. The
1980 United States census found that urban metropolitan areas produced 30
per cent of the value of United States agricultural production: by 1990,
this figure had increased to 40 per cent, according to UNDP's Urban
agriculture: Food, jobs and sustainable cities.
Cities, particularly those in the North, have yet to prove that they can
be compatible with a healthy biosphere. This is an unaccustomed challenge
for business people, planners, architects, politicians and citizens alike.
Yet central and local governments are increasingly aware that efforts to
improve the living environment must focus on cities. Eco-friendly urban
development could well become the greatest challenge of the 21st century,
not only for human self-interest, but also for the sake of a sustainable
relationship between cities and the biosphere, on which humanity
ultimately depends.
Professor Herbert Girardet of Middlesex University, holder of a Global
500 Award, is a consultant to HABITAT II. A new version of his The
Gaia Atlas of Cities, is being brought out for the Conference, and he
is co-author of Making Cities Work.
