The findings that urban development absorbs only a very small proportion of the available land, that on a macro-scale the loss of agricultural land is modest, and that, if market conditions justified it, the amount of cultivable land could easily be extended, has resulted in extensions of the urban land impact analysis down a broader path. One extension is the concept of the "ecological footprint." The ecological footprint is "the amount of land required from nature to support a typical individual's present consumption " (Wackernagel and Rees 1996, 11). The consumption activities include food, housing, transportation, consumer goods and services, while the land use categories include energy (more specifically, the fossil energy consumed expressed in the land area necessary to absorb the corresponding CO²), degraded land (i.e. the built environment), market gardening, cropland, pasture and forests. If we add up the land use per capita estimates for the national population, we typically find that they exceed the land area of the country. Aggregating across the globe, we find that the land area required to sustain even the current world population is larger than the world's land area, by about 30 percent. If these arguments are accepted, it follows that present consumption patterns are "unsustainable." Thus, by broadening the scope to all consumption (not merely housing, transportation and other directly land-consuming activities) and to all land use, this approach converts the original agricultural land preservation argument from a modest problem into a colossal one.

However, the ecological footprint concept is based on certain unreasonable assumptions. Its accounting approach follows directly from the footprinters' assumptions of "non-substitutability" and "maximum rates of resource harvesting". Rees computes the size of the "personal planetoid" of a typical Vancouverite to be 4.27 hectares. He concludes that all of the countries that he studied, except for Canada and Australia, are "overpopulated in ecological terms" (207). The United States land requirement per capita is 5.1 hectares, the highest in the world, the Netherlands is 3.32, India's is only 0.38, and the world average is 1.8 hectares. The world is "already ecologically full" and "sustainable growth on this scale using present technology would require five to ten additional planets" (211). It is unclear how footprinters view a world in which increasing value added springs from computers on desktops powered by silicon chips made from grains of sand. What kind of a footprint is that?

A related concept to the ecological footprint is the "ecological fair share," i.e. the land requirement per capita that is sustainable in the sense of not using up more land than is available. The presumption of the analysis is that everyone, regardless of location or income, has an equal share. Thus, the ecological fair share concept is based upon the principle of equal allocation of resources to all individuals on the globe. It makes no pragmatic sense unless the rich are so committed to redistribution as to aim for the equalization of income and wealth. This is utopianism gone beserk.

It is interesting that more than one-half of the ecological footprint of Canada (and the same point applies to many other countries) is because of fossil energy consumption and the land requirement (in trees and plants) needed to absorb the excess CO². But the relationship between burning fossil fuel and CO² emissions is a technological one, as is the substitution possibilities between non-fossil sources of energy and fossil fuels. Hence, technological innovation has the potential to break the energy-CO²-land consumption nexus, and significant progress on this front could undermine the unsustainability hypothesis in itself.

Wackernagel and Rees (1996, 97) present a sample of countries comparing their ecological footprints with their actual estimates of ecologically productive land per capita. Where the former exceeds the latter, the country has an "ecological deficit". Almost all the countries on their list are in deficit; the exceptions are Australia (with land per capita about 10 times its footprint) and Canada (3.5 times its footprint). Even India, with its substantial subsistence economy has an ecological footprint 38 percent larger than its productive land. At the other extreme are the Netherlands (with a footprint 19 times its land per capita), Belgium (14 times), South Korea (9.5 times), Germany (7.8 times), the United Kingdom (7.6 times) and Japan (7.3 times). Wackernagel and Rees describe the latter countries as having "a quasi-parasitic relationship," dependent on imports of energy and raw materials from elsewhere. As the authors admit, many of these countries are economic success stories. However, their analysis ends up with attaching a moral stigma to small countries with large populations (which, by definition, will have small amounts of land per capita) while looking favorably at large countries with small populations. However, at the subnational level (when we measure urban ecological footprints; by the way, it is unclear that urban residents consume more resources than rural residents, given the latter's preference for woodburning fires, more vehicle miles traveled in pickups and other fuel-consuming vehicles, etc)), even these countries have areas with ecological deficits; for example, in Canada the Lower Fraser Valley (i.e. Greater Vancouver) makes an ecological footprint 15 times larger than its land mass. The implication of their analysis is that trade is intrinsically bad, because it allows countries to escape the straitjacket of their land limitations. The result is a plea for autarky. But if small, densely populated countries were not allowed to import food, raw materials and fuels, their economies would truly be unsustainable. If the concept of sustainability has any merit at all, it can only be in global not national or subnational terms. Proponents of sustainable development, whether explicitly or implicitly, deny that there are substantial gains from trade. Hong Kong and Singapore are damned as global parasites.

Like all rationing systems that purport to replace markets' accounting of scarcity, this one has problems. (Energy accounting proposals of the 1970s were not very different.) The market is the only system that has the potential to solve the fundamental resource scarcity problem: to simultaneously account for all scarcities and to reveal the possible trade-offs that this implies. Footprint accountants are of a long tradition that sees trade and technology as dehumanizing. Not surprisingly, they see cities are "parasitic" to use Bert Hoselitz's famous epithet. In reality, city residents survive by producing and trading with rural residents, both intranationally and internationally. Once again, if voluntary exchanges are objected to, we are sliding down a very slippery slope. The footprint accountants join the chorus that wants to substitute its own priorities for those of the rest of humanity.

Like their Malthusian antecedents, footprinters emphasize the concept of "general" scarcity which supposedly differs from "relative scarcity" and does not yield to standard market responses, including substitution and innovation. They draw some of the following implications:

• "Carrying capacity" is defined in terms of maximum and fixed populations.

  The ability, indeed the record, of technological change to affect such relationships is dismissed; the suggestion is even made that any such process only makes things worse. In this logic, people are simply a drain. The fewer, the better. This is circular and denies the role of property rights. The great advantage of the modern market economy is that it takes place within legal structures that create a framework within which diverse market participants engage in mutually beneficial exchange. Private energies harnessed in this way have led to astonishing expansions of "carrying capacity".

  Everyone expects there to be problems in the case of common properties. These can be alleviated in a number of ways; the most important antidotes are private ownership and the assignment of property rights in common property resources. Property owners have strong incentives to conserve resources. Only when private property rights are threatened, are we faced with dire prospects, including the cessation of technological advance.

• Everything has an "environmental impact"; all such impacts affect the "global ecosystem" and/or the biosphere.

  The global rather than the local perspective ignores the fact that many environmental impacts occur among neighbors and can be resolved in the civil courts, at least in the cases when transaction costs are not prohibitive. The fundamental importance of institutions that define and enforce property rights is again the cornerstone.

• High standards of environmental purity are taken for granted; trade-offs and marginal considerations are avoided.

  The reasoning that people (footprinters included) use in their everyday economic lives is discarded as they proffer many different prescriptions for resources use. All-or-nothing comparisons and eschewing of trade-offs are equally useless in all walks of life.

• Non-zero-sum possibilities are denied; the developed countries are described as net importers of "carrying capacity"; since the latter is "finite", any more economic development is seen as a threat.

  This is another stunning denial of the historic record, not to mention elementary economic analysis. Malthusian principles ignore the possibility of shifts in technical progress that can dramatically increase the productivity of each unit of natural resources.

• Standard economic analysis rests on varying degrees of substitutability among factors of production; the ecological footprint analysis is based on the assumption of "non-substitutability".

  Elasticities of substitution between any pair of factors vary with technological advance and are usually identifiable empirically. Long-term economic analysis is pointless unless the nature and the role of (changing) substitution possibilities is recognized. Our increasing ability to find substitutes for physical labor has expanded over time, making it less valuable. Our seeming inability to substitute computing power for higher intelligence has made the latter much more valuable.

  Khalil (1997) points out that the distinction is often made between "general" (Malthusian) scarcity vs. "relative" scarcity mediated by scarcity pricing. The former gives rise to "sustainability" concerns. Yet, it is also seen in neo-classical economists' introduction of static aggregate production functions which include the "factors" of production capital, labor, and "environmental resources". Because the latter may be assumed to be limited (forgetting technological advance or even recycling possibilities), substitution possibilities involving the latter input must also have limits. Such static analyses necessarily focus on the "given" resources available now and end up suggesting strict substitution limits.

• The value of price signals is dismissed, focusing on unpriced "life-support services" such as the ozone layer.

  Dismissing all price data and misunderstanding their rationing role surrenders society's most important resource accounting mechanism. Indeed, prices are not simply a scarcity discovery device, they are also the font of entrepreneurial discovery and action. Ad hoc substitute accounting is hopeless. It evokes the consistent failings of centralized economic planning. Also obscured is the importance of extending property rights. Pollution or ozone consumption rights must be made explicit and rationed, rather than being made available at a zero price as most currently are. Making them tradeable is more efficient than allocating them by fiat, as Rees and others suggest.

Footprinters, of course, go far beyond these points. In the presence of "unregulated trade", "the wealthy already consume three times their fair share of sustainable global output" (Rees, 211). "Inter-regional dependency" must be replaced by "intra-regional ecological balance and relative self-reliance". And, "the human economy must be dematerialized in order to fit within global carrying capacity" (Rees, 212). This will all happen, it seems, once individuals surrender their wealth and freedom to the state and its planners.