This article was originally published in Domus 1048, June 2020.

Already more than half of humanity lives in cities, and the urbanisation process advances at so vertiginous a rate that we will soon be able to describe the planet as a built globe, with its population agglomerated in metropolises and the surrounding environment transformed into an artificial landscape. From the city’s mesh of relationships comes its potential and lure, manifested in the territory like a magnetic field that is irresistible to rural populations, a multitude of iron filings dragged beyond remedy towards the metropolitan magnet.

These centripetal forces responsible for the migrations from countryside to city are expressed in the exponential growth of both the urban dimension and the pathologies associated with scale, provoking the contradictory emergence of other centrifugal forces that push large sectors of the population to remote suburban peripheries, where the qualities of civic life are denatured or weakened. At the same time, the dispersal of constructions degrades the natural environment, altering its morphology by modifying its uses, and colonising the landscape by filling it with irreversible works of engineering and architecture. What elsewhere I have called horizontal Babel, formed by sprawl, is thus neither real city nor countryside, and yet the contemporary exuberance of energy has allowed it to spread through the five continents, driven by metropolitan malaise and the nostalgia for nature while undermining civic virtues and pastoral beauty. The tension between the urban gravitation that brings us together and the centrifugal urge that pulls us towards the peripheries produces a vibration of the essential fibre of the debate on territory and landscape, which has its ominous protagonist in that boundless and characterless city, and the most visible cause of our environmental crisis in its planetary metastasis.

In ecological terms, the conventional interpretation of the city is as an organism that feeds on its surroundings. Inscribed in a long tradition of biological metaphors, but equipped in this case with a solid analytical and quantitative base, the description of urban organisms that crystallises in the studies of Howard and Eugene Odum presents these as receivers of a continuous flow of energy and materials that enables them to feed their populations, heat and cool their buildings, and transport people and goods – besides building and repairing their physical fabrics – and also as emitters of waste and heat; in thermodynamic terms, as receivers of negative entropy or negentropy that gives them the capacity to maintain their form or, in Spinoza’s formula, “persevere in being”. This organic view of the city, which in likening it to a living being holds that it must have nourishment – or in physical terms export entropy – requires an exact definition of its limits, something unfortunately less precise in the urban than in the biological sphere, where the skin of an animal or the membrane of a protozoan forms a relatively clear-cut boundary between the individual and the environment that sustains it.

Naturally, it could be argued that living organisms should not be understood exclusively as individuals either, because they are an inextricable part of populations and these in turn subsist in dynamic equilibrium with others of different species in symbiotic or trophic relationships. All told, contemporary sprawl, along with the colonisation of interurban space by huge transport, production and consumption infrastructures – from airport cities, container ports or logistical centres to industrial complexes, commercial centres or theme parks – have turned cities into organisms with blurry edges, not even nodes of communication networks, and can only be described as higher-density zones in a built continuum. The first conurbations have given rise to vast territories that are compactly occupied, fogging the boundaries of cities and making urban ecology give way to territorial ecology in the search for a larger-scale field that allows a better understanding of the material and energy bases of the sustainability of human settlements: a scientific, economic and social endeavour that turns our attention from urban fabrics to the infrastructures that organise the territory.

When we consider the city under the ecological prism, in the current context of energy scarcity and climate change, no parameter is more decisive than density. The compact city, which is not so much the metropolis of skyscrapers as it is the classical Mediterranean town, is the territorial occupation model most readily described as sustainable: that which incurs fewer material and energy expenditures in raising urban infrastructures, which, because they are shared by many, are less costly; that whose buildings consume less non-renewable energy and resources, both in construction and in maintenance during their useful lives, thanks to the advantageous shape coefficient that compactness gives when the relation between the area it encloses and the volume enclosed is reduced; and also that whose density reduces the time and the cost of vehicular commuting by providing the direct contact that is the sign of urban life and the engine of the intellectual, artistic and interpersonal communication that makes cities drivers of social change. The sprawling city, in contrast, which historically arose from the garden city, associated with a return to nature, paradoxically turns out to be less green than the compact one, precisely owing to the greater material and energy costs needed for its vast infrastructures, inefficient constructions and long commuting times.

All this is not to say, of course, that the compact city can do without taking non-renewable resources and energy from the environment, whatever way we set the limits between them, or without dumping residues and emitting carbon dioxide into it. The dream of self-sufficiency, which once nourished so many anti-urban utopias, now comes true in projects for new cities like the well-known Masdar, which the team of Norman Foster is building with the aim of making a town that produces its own energy, recycles all its waste and emits no carbon dioxide into the atmosphere – thus avoiding consumption of non-renewable resources and global warming – but it will take some time before all the objectives are met. While we wait for that day to come, cities will have to continue exporting entropy (or importing negentropy), and the familiar compact town will continue to be our best option for communal life: a solution that is perhaps still suboptimal in the ecological sphere, but probably unsurpassable in the social and cultural, providing spaces for intense and spontaneous interpersonal relations of the kind that make ideas circulate and stimulate innovation, attracting financial capital with its dynamism and human capital with its opportunities and quality of life, all of these being characteristics intimately linked to density.

Beyond its enormous economic and energy cost, as well as its negative impact on the ecology of the planet, sprawl has had the side effect of reducing the public sphere, cutting down on the collective spaces that characterise the compact city. These are the places where shared values are expressed chorally, but also those where individual paths meet and fuse, and this double function enriches cities with a social capital of connections and confidence that is hard to replace with a judicial architecture of laws and contracts. Both the growing privatisation of residual natural spaces and the commercial administration of urban and suburban places dedicated to leisure transform the public domain. This process, which affects the entire territory by fragmenting it and extracting its pieces from the collective sphere, has an even greater impact on the city, whose civic nature requires vertebration through shared spaces. In traditional urbanism, these spaces have always been of a physical nature, and contemporary sprawl has sought to replace them, so far unsuccessfully, with virtual spaces, whether those of the media or those of the emerging social networks, whose penetration in current society brings with it both promises and fears.

Although it seems to have become routine to say that the new generations simultaneously inhabit the immaterial labyrinths of the web and the physical precincts of their biological existence, the truth is that all movements engendered in the digital womb have ended up manifesting themselves, gaining visibility and acquiring legitimacy in the worn public space of the traditional city, whether the fashion trends that scouts look for on the streets of Tokyo and New York, or the political mutations that young Arabs have brought on with their presence in the squares of Tunis or Cairo. No doubt we are faced with a landscape of technical and social changes, but it cannot be ascertained that these mutations will be expressed only, or preferentially, in virtual realms. We inhabit material spaces, consume irreplaceable resources and degrade energy to maintain our social organisation and our own organisms.

In this historic crossroads, the digital revolution will not save the furniture of the physical city, which must progressively abandon the model of the horizontal Babel lest it endanger the future of our species on the planet, and embrace the alternative – density – as something that, freed of its negative associations with pollution and traffic, can effectively offer a more responsible and sustainable way of inhabiting the world: a way of living close together that is more economically efficient, more culturally stimulating, and more gratifying in terms of interpersonal relationships.

Opening image: Egon Schiele, Krumau on the Molde, The Small City, circa 1912. Oil on canvas. Private collection. Photo © Mick Gold / Bridgeman Images  

Luis Fernández-Galiano is an architect, chair professor at Madrid’s school of Architecture (ETSAM) and editor of the journals AV/ Arquitectura Viva.