Metabolic approaches to the urban context

This definition was developed during the first half of the twentieth century by Hans Leo Kornberg2, working in collaboration with his colleague and friend Hans Adolf Krebs3. Such a definition can easily be applied to urban systems when they are considered as living organisms, based on flows of materials and energy exchange, both with the external environment and among their various internal components.

Metabolic approaches to the urban context

In the second half of the twentieth century a metabolic perspective on human settlements led to the definition of several innovative approaches which have allowed us to read cities as open systems characterized by a

He was a contemporary and friend of Frank Lloyd Wright, Clarence Stein, Frederic Osborn, Edmund N. Bacon, and Vannevar Bush. 1 Kornberg, H. L. 1998, Metabolism (Biology), in Britannica. 2 Sir Hans Leo Kornberg, Fellow of the Royal Society, (1928 - 2019) is a German-born British-American biochemist. He was the “Sir William Dunn” Chair of Biochemistry at the University of Cambridge from 1975 to 1995 and Master of Christ’s College, Cambridge from 1982 to 1995. He is co-author of the text Energy Transformations in Living Matter (1957) and author of many papers on cellular metabolism. Krebs H. A., Kornberg L., 1957, Energy, Op. cit. 3 Sir Hans Adolf Krebs (1900 - 1981) was a German-born British biologist, physician, and biochemist who pioneered the study of cellular respiration, a biochemical process in living cells responsible for extracting energy from food and oxygen and making it available to drive life processes. He is best known for his discoveries of two important sequences of chemical reactions that occur in human cells and many other organisms, namely the citric acid cycle and the urea cycle. The former, known as the ‘Krebs cycle’, is the key sequence of metabolic reactions that provide energy to human cells and other oxygen-respiring organisms. His discovery earned Krebs the Nobel Prize in Medicine in 1953. With Hans L. Kornberg he also discovered the glyoxylate cycle, which is a slight variation of the citric acid cycle found in plants, bacteria, protists and fungi. Krebs died in 1981 in Oxford, where he spent 13 years of his career from 1954 until his retirement in 1967 at the University of Oxford.

constant and consistent exchange of flows and energy4 . The relationship between cities and their territory, especially after the first industrial revolution has often been described in terms of conflict. The ecologist Eugene Odum6 in the early ‘60s defined the urban system as “a parasite of the rural environment” because, unlike other ecosystems, it is heterotrophic: it needs materials, resources and energy, and is dependent on neighboring areas. Odum stated that:

As populations and energy use increased, the early cities grew, and surrounding agricultural lands were often converted to urban uses. The recycling of nutrients was discontinued. These are two of the most serious problems associated with urban development; the loss of prime agricultural lands as they are covered by streets, parking lots, and buildings and the pollution of rivers, streams, and lakes as wastes are discarded instead of recycled for productive purposes5 .

As a result of his studies on the exchanges between urban and rural environments, in 1973 Odum introduced a new unit of measurement to evaluate energy flows and stocks: the Emergy (a contraction of the terms ‘embodied’ and ‘energy’), which indicates the total equivalent solar energy used directly and indirectly for the production of goods and services6 .

4 Foster C., Rapoport A., Trucco E. 1957, Some unsolved problems in the Theory of non-isolated systems, in L. von Bertalanffy, General systems, Society for General Systems Research, Washington, vol. 14, pp. 9-14. 5 Odum, E. P. 1963, Ecology, Rinehart and Winston, Holt: New York, p. 201. 6 Odum, H. T. 1973, Energy, Ecology and Economics, Ambio, vol. 2, n. 6, pp. 220-227.

The need for a new model of development in order to reconcile economic growth and the equitable distribution of resources began to emerge in the ‘70s, following the awareness that the concept of classical development, linked exclusively to economic growth and specifically to the increase of the Gross Domestic Product (GDP), would soon cause the collapse of natural systems. In his essay entitled The Economics of the Coming Spaceship Earth (1966), the economist Kenneth Boulding7 stated:

For the sake of picturesqueness, I am tempted to call the open economy the “cowboy economy,” the cowboy being symbolic of the illimitable plains and also associated with reckless, exploitative, romantic, and violent behavior, which is characteristic of open societies. The closed economy of the future might similarly be called the “spaceman” economy, in which the earth has become a single spaceship, without unlimited reservoirs of anything, either for extraction or for pollution, and in which, therefore, man must find his place in a cyclical ecological system which is capable of continuous reproduction of material form even though it cannot escape having inputs of energy8 .

Boulding introduced the idea of the Earth as a closed system; he rejected the myth of the indefinite expansion of consumption, refuting the full validity of GDP9, as

7 Kenneth Ewart Boulding (1910 - 1993) English economist, pacifist and poet naturalized American. A religious mystic, systems scientist, and philosopher, he was a co-founder of general systems theory. 8 Boulding K. E., The Economics of the Coming Spaceship Earth, in H. Jarrett (ed.) 1966. Environmental Quality in a Growing Economy, pp. 3-14, Johns Hopkins University Press, Baltimore. 9 The concept of Gross Domestic Product (GDP), albeit in a sketchy form, was already expressed in a similar way to the current one by economist Adam Smith in his most famous work The Wealth of Nations (“… The annual labour of every nation is the fund which originally supplies it with all the necessaries and conveniencies of life which it annually consumes, and which consist always either in the immediate

developed in its modern form by the economist Simon Kuznets10, who did not include the cost of pollution and limited natural resources among his parameters. Along the same lines, at the end of the sixties, the first essays by the Americans Herman E. Daly11 and Clarence Edwin Ayres12 were published. They stressed the link between the negative effects of economic activities on the environment, the flow of materials through each production process and the entire economy. The 1973 oil crisis, due to the Arab-Israeli war of Yom Kippur13 and the sudden interruption of the supply

produce of that labour, or in what is purchased with that produce from other nations. […]. It is the great multiplication of the productions of all the different art, in consequence of the division of labour, which occasions, in a well-governed society, that universal opulence which extends itself to the lowest ranks of the people”. Smith A. 1776., An Inquiry into the Nature and Causes of the Wealth of Nations, Straman, London). The modern concept of GDP was developed for the first time by Simon Kuznets in a report commissioned by the United States Congress in 1934. In this report, Kuznets warned against using GDP as a measure of wealth. After the Bretton Woods conference in 1944, which established the creation of the International Monetary Fund, GDP became the primary tool for measuring a country’s economy. Simon Kuznets, 1934. “National Income, 1929-1932.” 73rd U.S. Congress, 2nd session, Senate document no. 124, pp. 5-7. 10 Simon Smith Kuznets (1901 - 1985) was an American economist and statesman who received the Nobel Prize in Economics in 1971 for his empirical interpretation of economic growth, which led to a new and deeper understanding of economic and social structure and the process of development. Kuznet made a decisive contribution to the transformation of economics into an empirical science and to the formation of quantitative economic history. 11 Herman Edward Daly (1938) American economist and ecologist, professor at the School of Public Policy at the University of Maryland, College Park in the United States. 12 Clarence Edwin Ayres (1891 - 1972) leading thinker of the Texas school of institutional economics during the mid-20th century. 13 Yom Kippur (in Hebrew רופכ םוי yom kippùr, ‘Day of Atonement’) is the Jewish religious holiday that celebrates the Day of Atonement. Yom Kippur is the Jewish holiday of greatest solemnity and is solemnized by an

of hydrocarbons, was a turning point for the study of financial and energy flows in contemporary socioeconomic systems. For the first time, Western countries became clearly aware of the fragility and precariousness of a production system based on fossil energy sources, evidently exhaustible and above all coming from politically unstable territories. This situation led governments and entrepreneurs to estimate the amount of energy consumed by each process in order to reduce its use, in the first place because of rising monetary costs14 . Various scholars then began to measure not only energy flows but also those of materials that occur in production processes and in urban environments. These measurements were accompanied by a description of the flow of money, taking a further step towards the logical combination of economic and physical-biological phenomena. Thus, we began to talk about energy cost, that is cost in terms of

absolute fast. During the fast it is forbidden to eat and drink, and applies the same requirements for the Sabbath with regard to work and other prohibited activities. So it is clear why the Arab coalition decided to attack, in the day in which the whole state of Israel was in a situation of weakness. 14 The war actually ended after about twenty days with the proclamation of a cease-fire between the two sides. Almost all Arab and anti-American countries, in support of Syria and Egypt, doubled the price of oil, decreasing exports by about 25%, to warn other nations not to support Israel. This process led to a staggering increase in the price of oil, up to three times the price before the Suez crisis. In Italy the government promoted a national plan called ‘economic austerity’ for energy saving that included among other measures: prohibiting driving on Sundays, ending television programs early and a reduction in street and commercial lighting. At the same time the Government rethought its energy policies, promoting the construction of nuclear power plants to limit dependence on fossil fuels. Cinquepalmi F., Analisi delle problematiche ambientali connesse alla filiera dell’energia in Italia in riferimento al traffico marittimo degli Idrocarburi e ai possibili strumenti di gestione del rischio, final doctoral thesis- Doctoral school of Energy Engineering 2008, Sapienza University of Rome (Tutor Prof. Maurizio Cumo)

raw materials and environmental cost of goods, where the latter were defined as the production of waste and scrap, in liquid, solid or gaseous form, related to the production and use of a unit of mass of each commodity. Nicholas Georgescu-Roegen15 in his text Energy and economic myths of 1972, coined the term ‘bioeconomy’ to suggest the need for adaptation of economic activities to natural biogeochemical and energy cycles, stating that our planet could be considered as a closed system whose resources are not infinite. He stated that:

The Second Law of thermodynamics tells us also that the whole universe is subject to a continuous qualitative degradation: entropy increases and the increase is irrevocable. Consequently, natural resources can pass through the economic process only once: waste is irrevocably waste. Man cannot defeat this law, any more than he can stop the law of gravitation from working. The economic process, like biological life itself, is unidirectional16 .

In 1972, the Club of Rome17 published the well-known report “The Limits to Growth”, resulting from the work

15 Nicholas Georgescu-Roegen (1906 - 1994) Romanian mathematician, statistician and economist. He is best known today for his groundbreaking 1971 text, ‘The Entropy Law’ and the Economic Process. 16 Georgescu-Roegen N. 1976, Energy and Economic Myths: Institutional and Analytical Economic Essays, Pergamon, New York p. 98. 17 Founded in 1968 at the Accademia dei Lincei, the Club of Rome is composed of current and former Heads of State, senior United Nations officials, high-level politicians, government officials, diplomats, scientists, economists and business leaders from around the world. The aim of the Club of Rome is to promote a constructive dialogue between business leaders, politicians, and those who lead international agencies, as well as those in universities and schools and in the media. The documents and reports produced by the Club of Rome aim to help decision-makers and the public better understand major global issues, with a particular focus on sustainability issues. They often make specific policy proposals and seek to foster a greater sense of civic responsibility. As of July 1, 2008, the organization is based in Winterthur, Switzerland.