Threats to cities: hazards of environmental change

The last 250 years have seen an extraordinary acceleration of environmental change. Until recently there was controversy about the degree to which this was natural or human-driven. The conclusion widely reached today is that it is substantially human driven.

In all this a prime factor is climate change. We have had the latest report from the Science Working Group of the Intergovernmental Panel on Climate Change published on 2 February 2007which stated that "warming of the climate system is unequivocal ... Most of the observed increase in globally average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations." In other words we face the challenge of global climate destabilization.

But climate change is only one of the impacts which our small animal species is having on the surface of the Earth and all life within it. Most things have happened in the long history of the Earth, but our current circumstances are unique. The title of a recent book put it well: Something New Under the Sun. To make sense of the scale and character of the impacts, we have to reckon not only with climate change but also with such issues as human population increase, degradation of soils, exploitation of resources, pollution of water both salt and fresh, and destruction of other living species on which we wholly depend.

Perhaps the most conspicuous demonstration of the human impact has been the growth of cities. Seen from space, they look like rapidly growing pimples on the surface of the Earth, a sort of global measles, testifying to favourable conditions and proliferation of the organisms that produce them. At night they become points of light, occasionally animated by flares that come from the extraction of the fossil fuels that make them possible in their current form. In 1900 some 15 percent of the world's 1.5 billion people lived in cities. By 2000 city-dwellers accounted for more than 47 percent of a world population of more than 6 billion, and this year that proportion is likely to exceed 50 percent. What has happened?

The urban phenomenon goes back to that brief patch of time which followed the most recent spasm of the ice ages some 11,000 years ago. Hunter-gatherers began to settle in fixed communities; deforestation and farming followed; communities became villages, and villages became towns; society became more hierarchical with division of functions; and the first cities arose, probably in the river valleys of the Middle East. Such cities were immensely vulnerable to climatic and other environmental change. Some collapsed as they outgrew their resource base, whether in the form of water or food supplies, and their inhabitants were painfully dispersed. In new circumstances and more prosperous times, cities again developed, but eventually had to cope with returning vulnerability. Our situation is not too different today.

Those of us who live in industrial countries have to recognize that the last 250 years have been a bonanza of inventiveness, exploitation and consumption which may not continue. During that time humans have moved more rocks and soil, and lost and poisoned more topsoil and fresh water, than all that their predecessors ever did, and certainly more than all natural climatic variation, volcanoes, glaciers and tectonic plates brought about.

We often reckon ourselves as the most successful species ever known in the history of the Earth. But all successful species, whether bivalves, beetles, swallows, or humans, multiply until they come up against the environmental stops, reach some accommodation with the rest of the environment, and willy nilly restore some balance. That is what we now have to do.

Looking back, cities have so far had three broad characteristics. One has been called 'sacredness of place', or a relationship with divine forces through temples, cathedrals, mosques or pyramids. The second is as a place of refuge from lawlessness: simple self protection. The third is as a focus for commerce, industry, innovation and the generation of wealth.

Today perhaps the third characteristic is most important. But even there change is under way. Whatever the continuing attraction of cities in some parts of the world, their attraction is diminishing elsewhere. Perhaps something of the sacred element remains, but with the growth of shanty towns and sprawling suburbs, security has become worse; and with the development of information technology, commerce, business and industry have sometimes moved out. In short the very reasons for cities are under challenge.

It is not easy to put all this together. Cities are, and have always been, creatures of their environment. Like living organisms, they absorb food, water and materials, and they emit waste of all kinds. The bigger and more complex they become, the more vulnerable they are to bad management from within and environmental change from without. They have sometimes been compared to spinifex grass in Australia that grows in circles outwards from a dying centre.

Let us look particularly at the likely impacts of climate change. Such change, which has so greatly affected cities in the past, is not necessarily slow and linear. It can indeed be relatively sudden. This has led to a new field of study of possible tipping points when one set of circumstances can switch rapidly into another. Here are some examples:

• the state of the Amazonian rainforest
• the direction of the North Atlantic Conveyor current or Gulf Stream
• the release of methane clathrates from beneath the tundra and ocean bed, and release of methane from terrestrial sources, including peat bogs
• the frequency and intensity of the periodical changes of ocean current across the Pacific known as El Niño and La Niña
• the state of the Greenland and West Antarctic ice sheets.

There are two jokers in the pack:

• a sudden cooling effect (such as the Younger Dryas event some 12,500 years ago)
• a runaway greenhouse effect ( such as the Palaeocene / Eocene transition 55 million years ago).

In his recent review of the Economics of Climate Change, Sir Nicholas Stern wrote that current increases in levels of greenhouse gas, now at their highest level for 650,000 years, could lead to a rise of between 2 and 5 degrees C in global mean temperatures between 2030 and 2060. He added that "a warming of 5 degrees C on a global scale would be far outside the experience of human civilization, and comparable to the difference between temperatures between the last ice age and today". He added that some impacts of climate change could themselves amplify warming further by triggering the release of additional greenhouse gases.

Some of his calculations have been challenged, but few have questioned his broad analysis. Later this year the Intergovernmental Panel on Climate Change will publish its complete Fourth Assessment. It will include the science, the social and the economic aspects, and the recommendations for policy. This synthesis paper, together with national and other assessments, should provide the basis for guidance about future policies both short and long term.

Cities should be at the forefront of our preoccupations. I was a member of an Urban Task Force set up by the British government and chaired by Lord Rogers of Riverside in 1999 in which we examined the problems then facing cities in Britain, and made a variety of recommendations for the future. We then returned to the problems on our own initiative six years later, underlining the need for a new approach to urban regeneration. In broad terms our aim should be to restore communities in and out of city centres by rebuilding on old sites, protecting and enlarging green space, limiting specialization of activity (thereby avoiding dormitory versus business ghettoes), insisting on integrated planning, improving public transport, recycling wastes, reducing pollution, and generally taking better account of social as well as environmental considerations.

I cannot pretend that our answers were in any way complete. Others have attempted in different ways to point the way ahead. So far as Britain is concerned, we need to look particularly at the climatic prospects and these impact on our predominantly urban economy. In general terms Britain can be divided by a line running north-west to south-east. There will be warmer summers in both, with more rainfall in the north-west, and much less, even drought conditions, in the south-east. For both winters will be warmer and wetter. Sea level rise will be coupled with isostatic sinking in the south and south-east. Together these changes will have major impacts on the whole economy, including cities. Let us remember that urban areas in England alone account for 90 percent of the population, 91 percent of economic output, and 89 percent of jobs.

I will not pretend that what happens in our small temperate island has much relevance for Arizona or the South West of the United States generally, but the questions we ask ourselves about the future are equally questions for you. Here at least are some of the questions:

Water

• What are the prospects for supply from current sources?
• What will be the effects of any change on reservoirs, storage capacity and sewage systems? Are they in the right place? Can supply match demand?

Energy

• What restrictions should be placed on carbon emissions from cities?
• Should we move to renewable sources of energy (wind, tide, geothermal, solar, biofuels etc), and possibly new nuclear technology?
• How much should we move from macro to micro energy systems?
• How should we best promote energy saving and greater efficiency?
• What new technologies should be applied to transport (cars, aircraft etc)?

Food and materials

• How can we ensure the supply of food if other areas get into difficulty?
• Are other essential commodities going to be in short supply?

Coastlines

(of less direct relevance to you but indirectly of great importance)

• What should governments do to cope with sea level rise? Fortifying sea defences has to be selective. Where should the priorities be, and at whose expense?

Town planning

• Will more controls on urbanization be necessary?
• How should town planning, such as it is, be adapted to take account of
  • urban breakdown of all kinds?
  • buildings, architecture and future design?
  • new configurations of business and industry?
  • disposal of wastes?

Health

• Can we predict changes in the world of the micro-organisms on which we all depend?
• How is human health likely to be affected?
• What new as well as old diseases are likely in the changing circumstances?

In coping with this intimidating range of issues, we should not despair. There are already examples of what can be done. The first goes back to the 1960s when the government of Brazil held a competition for a master plan to expand the town of Curitiba. Particular emphasis was placed on development and control of public transport, and the supply of energy required to run a complex bus system. The result was accompanied by an action plan, labelled eco-feedback, to encourage personal involvement in recycling materials, limitation of air pollution, and use of water. The Curitiba example has already had imitators elsewhere, including the United States.

In China the construction of what has been called the eco-city of Dongtan near Shanghai is already proceeding (as it happens under the direction of a British company Ove Arup).

In Britain there is another example in the town of Woking, south of London. As the result of a public / private partnership, over 12 years there has been a 75 percent reduction of carbon or equivalent emissions; a 50 percent reduction in energy consumption in public buildings; and a 90 percent increase in energy derived from local sustainable sources. Some at least of the lessons from Woking will be applied in London by the Greater London Authority, which has already set a remarkable precedent through the application of a congestion charge on incoming transport. It also has an elaborate programme to cope with the many aspects of climate change, from energy use to building design. The Deputy Mayor has called for a Low Carbon Act to supplement the Clean Air Act on its 50th Anniversary.

In the United States there have also been efforts to green cities, notably in Seattle, Chicago, Los Angeles, Portland and even smoky Pittsburgh. You know what is happening here better than I do. Reading recent predictions of environmental change, there can be little doubt that, as in the long past, the fundamental problem in this area is water, well brought out in a recent report from the US National Academy of Sciences.

I am speaking at a time when awareness of this wide range of environmental issues has now seized the public imagination as never before. The work of Sir Nicholas Stern in crossing the long and rickety bridge between science on the one hand and politics and economics on the other has played a major role. I even heard about the Stern Review from the Chinese when I was in Beijing in November last year.

Britain has a long and honourable record in giving leadership on climate change back to the days of Margaret Thatcher, but here as elsewhere there has so far been more talk than action. This time with all party support, there may be practical results.

Perhaps the most fundamental difficulty is the need for us to think differently across the whole spectrum, and in particular to look at current economics and the way in which we measure wealth, welfare and the human condition in terms of the Earth's good health. Here the Chinese may be in advance of others in applying the principles of what they call "clean green growth" and in working out new methodologies of economics (fitting surprisingly well with the analysis in the Stern Review).

The trouble is that most of us still do not know where our society is going. Should our prime aim be to mitigate change or to adapt to it? The answer is, I suppose, that it should be both for the sake of future generations. Should there be a more coherent action plan for cities of a kind we have not seen so far? Do we have to build grossly inefficient tall glass monsters in our cities? Who is going to bang heads together in time to avoid such catastrophes as building on flood plains or in areas likely to be drowned by sea level rise? How can the public as well as governments be persuaded? Let me quote from Sir Nicholas Stern's most controversial recommendation:

"... if we don't act, the overall costs and risks of climate change will be equivalent to losing at least 5 percent of global GDP each year, now and for ever. If a wider range of risks and impacts is taken into account, the estimates of damage could rise to 20 percent of GDP or more. In contrast the costs of action - reducing greenhouse gas emissions to avoid the worst of climate change - can be limited to around 1 percent of global GDP each year."

In no area of human activity is this more applicable than in cities.

In a recent book The Long Summer about the ups and downs of civilization in the last 10,000 years, Brian Fagan wrote of our current society:

" ... if we've become a super-tanker among human societies, it's an oddly inattentive one. Only a tiny fraction of the people on board are engaged with tending the engines. The rest are buying and selling goods among themselves, entertaining each other, or studying the sky or the hydrodynamics of the hull. Those on the bridge have no charts or weather forecast, and cannot even agree that they are needed; indeed the most powerful among them subscribe to a theory that says storms don't exist, or if they do, their effects are entirely benign, and the steepening swells and albatrosses can only be taken as a sign of divine favour. Few of those in command believe the gathering clouds have any relation to their fate or are concerned that there are lifeboats for only one in ten passengers. And no-one dares to whisper in the helmsman's ear that he might consider turning the wheel."