GCRA
OVERVIEW
FAQ
NEWS
ARTICLES
PHOTOS
REEF ISSUES
RESTORATION
PAPERS
LINKS
|
|
|
|
Environmentally
Sound Technology for Sustainable Development Department of Economic and Social Development United Nations New York Issue 7, 1992 Thomas J. Goreau Technology assessment methodologies: An analytical framework for environmentally sound technology assessment This paper critically examines the concept of sustainability and concludes that it is widely used in ways that are meaningless unless a quantitative measure of sustainability is used. Many forms of sustainability are neither optimal nor desirable. Introduction To assess the effects of technology on the environment requires objective and quantitative measures; only then can the real costs of remedying human damage to the environment be efficiently paid. Energy and environmental transactions exchange carbon dioxide, just as economic transactions exchange monetary value. If accounting of global carbon exchanges is linked to global financial accounting, changes in biomass and biological productivity could provide quantitative criteria for evaluating the environmental costs and benefits of technological choices. When combined with "the polluter pays" principle, they provide criteria for efficiently internalizing the environmental costs of technology or for assessing action targets designed to halt climate change. The costs of global environmental sustainability will be minimized if sustainability is achieved rapidly, and if the total benefits are maximized through intelligent use of science and technology in building sustainable endogenous research and development capacity in environmentally sound technologies, especially in the tropics. Components of sustainability The concept of sustainable development has come to be widely accepted as development that docs not compromise the future for the sake of the present (1), yet there is uncertainty as to how environmental sustainability can be identified or measured. Assessment of various science and technology policy options in terms of environmental sustainability requires tools to evaluate the effects of our actions on natural as wel1 as social milieu (2). Sustainability is often considered in terms of several components--environmental, ecological, economic, social and cultural. Social, cultural and political structures can change much more rapidly than environmental and ecological patterns. The cultural and social effects of technology are not easily predicted, and are usually evaluated post hoc in terms of how technology use fits into or changes existing sociocultural structures. The metaphysical criteria that influence any valuation of social and cultural structures are not easily amenable to objective analysis. Sustainability of socio-cultural practices may not even be desirable if existing ones are inequitable towards currently living individuals or future generations. In contrast to social and cultural components, the economic, ecological and environmental components can in principle be evaluated by quantitative tools such as systems theory, economic input-output accounting (3), and appropriate models. To quantify economic sustainability, our health, wealth and quality of life are assessed by considering population life spans, per capita income, savings, costs of goods and services, and quality parameters including non-monetarized social services and equitable access to resources. This paper argues that environmental and ecological sustainability, in an analogy to economic sustainability, can be assessed by analogous analytical tools if sufficient data are available on carbon input to and output from the atmosphere. Environmental and ecological sustainability Economic sustainability is a concept with clear quantitative implications; it can only be realized if one spends less than the interest on one's accumulated capital (4). Sustainability can also be achieved by spending all the interest, but this allows for no growth, and the most prudent course in the long run is to delay consumption and invest as much as possible to increase future income. If one discounts the interests of future generations, one can spend more than the interest and deplete the capital, but this is unsustainable, and the wealth will steadily vanish. Sustainable development means that renewable resources can be managed in the same way as money, thereby preventing a decrease in resources, and preferably an increase for future generations. Environmental sustainability implies avoiding degradation of biomass and bio-productivity—major components of our "natural capital". Ecological sustainability is harder to evaluate than environmental sustainability. It depends on the complexity and quality of the biological productivity of each species in a particular habitat, not just on the total quantity, because each species has a unique role and value. A potential criterion for ecological sustainability could be the total diversity of hereditary information genetically encoded in the nucleic acid of species and individuals. Organisms are not fixed in an unvarying habitat, and in an ever-changing world they must constantly adapt to deal with environmental change and keep up with their competitors—running just to stay in place. Variety is the key to the ecological survival of organisms and species in a changing and unpredictable world; it is literally the spice of life. Having a few of each species subsisting in a zoo, botanical garden or deep freeze is not enough; we should seek to maintain the widest potential range of new combinations of genetic and species diversity. Preservation of germ plasma allows a small fraction of each species to be sustained, but most of the adaptation and evolutionary requirements for adapting to new conditions is lost. If conservation of genetic information is an adequate criterion for ecological sustainability, this would require a greatly expanded taxonomic, genetic and biochemical study of the species around us Sustainable and unsustainable resources In the long run, the welfare of the human species depends on how profitably it manages its resources. Resources can be classified according to whether they are renewable, that is capable of being recycled, resupplied endlessly, or grown continually—or non-renewable, that is incapable of being replaced naturally or through human action (see figure 1). Of course, renewable resources such as trees or fish may be unreliably managed, managed to grow, or be maintained at a steady state. For non-renewable resources such as gold or iron, every unit ruined depletes future stocks, so the wealth generated should be invested in such a way that it provides adequate future returns and increases in total value. Renewable resources should be managed so that their productivity grows, or at least does not decline. Figure 1. Resource sustainability index Note: These relative natural resource sustainability indexes are defined as the proportion of resource potentially used per unit of time by current technologies. Positive values indicate increase, negative values indicate depletion, and zero indicates no change. Uranium refers to conventional nuclear reactors, and plutonium to production from uranium in breeder reactors. Of these natural resources, only biomass can be easily managed to increase, decrease, or be held at some constant value. Sustainability indexes shown are relative, and apply only to the quantity of available resource supplies. Additional financial and quality criteria are needed to evaluate the sustainability of each resource with regard to cost and the effects on the environment and the biosphere. These criteria place more stringent limits on overall resource sustainability than quantity alone. The sustainability of a resource can be defined as the fraction consumed or produced each year, or the inverse of the time it will take to exhaust or double that resource at current consumption rates. Resources that are being depleted will have a negative sustainability index, so a resource that is completely consumed in a year would have an index value of minus one. A strictly sustainable resource-—solar energy for example, does not change with use; such a resource would have an index value of zero. A resource that increased over time would have a positive sustainability index. Sustainability as defined in this index takes into account only the quantity of a resource, not its cost. Economic sustainability may therefore result in more stringent constraints on the use of a resource than availability alone. Most non-fuel mineral resources are sufficiently large to have fairly small negative sustainability indexes. The world's largest iron mine, Serra do Carajas, in Para, Brazil, would have a life-span of 400 years at the current rate of use. Fossil fuels are less sustainable. Oil and coal are sufficient to last roughly 100 and 300 years, respectively, at current consumption rates; producing sustainability indexes of approximately -0.01 and -0.003. Oil and coal are not strictly speaking non-renewable as they are being slowly formed from the deep burial of organic material in sediment. As the average age of oil and coal is about 100 and 300 million years, respectively, sustainable use would amount to about one millionth of current consumption. Alternative energy sources can a]so be considered in terms of sustainability. If nuclear power is obtained from enriched uranium nuclear reactors, the total amount of energy available is roughly comparable to that of oil, and it could be a major energy source for about a century. If uranium is converted by breeder reactors into plutonium nuclear fuel, hundreds of times more energy can be obtained. This would be a more sustainable energy supply than uranium or fossil fuels. Since sustainability as defined here refers only to resource quantity, it does not take into account factors such as nuclear waste disposal, reactor decommissioning, accidents or nuclear terrorism, factors that could limit plutonium energy use more than its availability or technical feasibility. In comparison, direct solar energy conversion is completely renewable and will continue to be available regardless of how much is used. Its sustainability index is zero. It can be tapped sustainable through photovoltaic cell conversion to electricity and the use of non-imaging optics to generate sunlight intensities greater than at the surface of the sun (5). Both techniques can be applied to less-polluting industrial processes in the sunny tropics. Photovoltaic energy can also be used for electrolysis of seawater. The mineral precipitate from this process can be used for prefabricated construction, shoreline protection, and artificial reef frameworks, using techniques developed by W. Hilbertz (6). It may be necessary to apply such techniques on a large scale in tropical countries if coral reefs are to be protected from elevated ocean temperatures. Biomass-derived energies are a special case, in that their degree of sustainability is the direct result of human actions. Biomass can be managed unsustainably by cutting, burning and not replanting; or managed sustainability by cutting and burning only as much as is planted and grown; or reforested in a way that enables the resource to continue to increase in magnitude. The index of sustainability can be positive, zero, or negative. The wisest course for such a resource, as with money, is to allow it to meet current needs and to grow to provide more wealth for future generations. Sadly, the biological resources around us have rarely been treated in that fashion. But the potential rewards are very great if biodiversity is conserved and modern biological techniques are employed to enhance the magnitude and value of such resources. Biomass and productivity as quantitative criteria If all technological processes were evaluated according to their quantitative influences on biomass and bio-productivity, a common criteria would be available by which to evaluate and manage those processes' environmental effects. Carbon dioxide serves as a common exchange medium that links the biosphere, the climate system, and global energy use. By quantifying these carbon tlows, carbon dioxide can serve as an environmental currency. Most anthropogenic contributions to greenhouse gas emissions consist of carbon dioxide; therefore, stabilizing the concentration of CO2 in the atmosphere will be central to containing global warming. This can be achieved at relatively low cost if biomass and biological activity are increased and then stabilized (7) concurrent with an improvement in energy efficiency and a switch to less-polluting energy sources (8). Increasing biomass by halting deforestation and replanting only a modest part of areas already cleared, degraded or abandoned, on a scale adequate to absorb the current atmospheric increase, could stabilize carbon dioxide in the atmosphere for several decades (9) until fossil fuels can be replaced by non-carbon-dioxide-producing energy sources. Only photovoltaic and plutonium breeder reactors have the total potential capacity to supply required future energy levels. Both nuclear and photovoltaic energy sources are now too expensive to compete with fossil fuels. It is likely that the costs of photovoltaic cells will sharply decrease with mass production but the costs of containing radioactive waste and decommissioning old reactors have steadily escalated. Nuclear energy produces long-lived radioactive pollution, and is unlikely to be a widespread energy source in third world countries for economic and political reasons. Solar energy would appear to be the most sustainable long-term option for tropical areas if solar cells can be mass-produced and if the production of renewable biological materials is expanded. Total biomass and biological productivity are measures of the wealth and health of earth's natural resources, and they can be readily measured quantitatively if the resources are made available. Each needs to be conserved or increased for different reasons. Biomass is a major carbon store, and if it could be increased world wide, carbon dioxide would be removed from the atmosphere. If the rate of biomass build-up were increased to a level equal to the current net build-up of carbon dioxide in the atmosphere, the concentration of the gas in the atmosphere would be stabilized. Numerous estimates suggest that this is technically feasible and could be accomplished at a cost of a few dollars a ton of carbon converted into biomass (10). If that cost were to be divided by per capita fossil fuel carbon emissions, it might amount to around 15 dollars a person a year at United States emission rates (the highest), 2 dollars at Jamaican rates (close to the world-wide mean), and less than 1 dollar at Indian, Chinese, or African rates. The carbon removal costs would be far less than some taxes now being proposed to increase the price of fossil fuels and thereby reduce demand (11). The rate at which the biosphere exchanges carbon dioxide with the atmosphere must also be protected as biomass is increased. Most carbon dioxide taken up by plants during photosynthesis is not accumulated in biomass but is fairly quickly reconverted to carbon dioxide and returned to the atmosphere by respiration and decomposition. These biological carbon flows through the atmosphere are very large compared to fossil fuel combustion. Their global magnitude—the sum of the metabolism of all ecosystems—is the major control on the lifetime of new carbon dioxide added to the atmosphere by fossil fuel combustion. When biological productivity is degraded, fossil fuel carbon will remain in the atmosphere longer, and absorb more heat (12). On the other hand, an increase in biological productivity would reduce carbon dioxide's atmospheric lifetime and total thermal effect. A comparison of the forests of the tropics and those of the boreal zone is helpful. Both need to be preserved and enhanced, but for different reasons. Siberian and Canadian trees grow very slowly, but are very efficient at converting most of the carbon they remove from the atmosphere into long-lasting woody biomass. Because of their high biomass carbon, rich soil, and the huge areas they cover, these trees are one of the largest long term carbon stores of any ecosystem. Amazonian forests, by comparison, take up more carbon dioxide from the atmosphere per unit area per unit of time, but most of it is promptly returned to the atmosphere through respiration during the hot humid nights. The fraction that becomes biomass is not taken up by long-lasting wood biomass but by short-lived leaf, flower and fruit biomass that is recycled by birds, animals, insects (especially ants and termites) and decomposing organisms, thus returning more carbon to the atmosphere within days or weeks. Amazonian and other tropical rain forests are therefore the most important in terms of their productivity and role in recycling the atmosphere. The stabilization of atmospheric composition and the halting of climate change are major components of global environmental sustainability. They require that any reduction in biomass and biological productivity caused by technological activities be balanced by increases elsewhere. To halt climate change we must ensure that quantitative restoration of ecosystem biomass and productivity damaged by our actions takes place in affected areas or elsewhere. The "not in kind" type of restitution for environmental damage is not an acceptable alternative to restoration because it does not remove the resulting increase of carbon dioxide. Both conservation of global biomass and productivity, as indexes of environmental sustainability, require much more extensive conservation of the biosphere than ecological, species or genetic sustainability. To assess the quantitative effects of technological practices on environmental sustainability, the quantity of all environmentally active waste products produced, their lifetimes and effects on the biosphere, and the cost of removing them or paying for the damages caused by their excess must be taken into account. The necessary technology and analytical tools already exist, but they have never been applied on the scale required. If carbon storage and exchange were monitored in the same way as monetary reserves and financial exchanges, the biospheric costs and benefits of different energy options affecting carbon dioxide could be evaluated. It would then be straightforward to determine and allocate the costs of carbon dioxide removal, internalize those costs and other real costs in the prices of environmentally damaging fuels, and control carbon recycling to a longterm advantage. Sustainability and optimal sustainability Sustainability alone is not an adequate criterion for satisfactory development. There are many possible scenarios that are sustainable, but because they provide different levels of resources per capita, not all of them are equally desirable. A doomsday scenario in which population and pollution increase, leading to a population crash, could ultimately become sustainable at a very low level of population or standard of living. Many sustainable paths are highly sub-optimal, and analytical tools must allow them to be quantified and compared. The optimal approach to sustainability would be one in which a rapid growth of renewable resources maximizes return to future generations, though some deferral in initial return may be required. Environmental efficiency would need to be maximized, that is, the rate at which the natural environment recycles and retains carbon dioxide, and the economic value of the products sustainably produced by that biomass would need to be increased. Forestalling climate change by maximizing biomass and bio-productivity is prudent for many reasons, and it is the least costly option. Anticipation and prevention are always less costly than hindsight, clean up, environmental restoration or financial compensation, as evidenced by the Alaskan oil spill and the disasters at Chernobyl, Bhopal, Seveso, Minamata, and Cubatao. Stabilizing atmospheric composition, containing global climate change, conserving our natural heritage, promoting truly renewable energy sources and enhancing our renewable resource base are technically feasible at a modest cost, one that is far less than the costs of unabated greenhouse warming and a rise in sea levels. Global photosynthetic rates need be increased only a few percent in order to accommodate the current carbon dioxide build-up, and this could be accomplished at a cost well under 1 percent of global gross national product (GNP). This is hardly inflationary compared to the astonishing fraction of GNP that must be used to pay national and foreign debt—up to 50 per cent in many countries—which promotes increased environmental destruction for shortsighted and unsustainable profits. As soon as analytical tools adequately evaluate the costs of human actions on environmental sustainability in terms of biological carbon, the costs of action to stabilize climate change and promote sustainable development could be minor compared to those of financial sustainability. The sooner a sustainable environment is achieved, the lower the cost and the greater the rewards. 1. World Commission on Environment and Development, Our Common Future (Oxford, England, Oxford University Press. 1987). United Nations Environment Programme (UNEP), The Environmental Impact of Production and Use of Energy, Part IV Comparative Assessment of the Environmental Impacts of Energy Sources, Phase 1: Comparative data on the Emissions, Residuals, and Health Hazards of Energy Sources, Energy Report Series 14-85 (Nairobi, Kenya, UNEP, May 1985); Phase 11: Cost-benefit Analysis of the Environmental lmpact of Commercial Energy Sources and Its Use in Emission Control of Energy Systems, Energy Report Series 15-85 (Nairobi, Kenya, May 1985); Phase 111: Assessment of Tools and Methods for Incorporating the Environmental Factor into Energy Planning and Decision-making, Energy Report Series 17-86 (Nairobi, Kenya, UNEP, 1986). 3. W. Leontief, A. Carter and P. Petri, Future of the World Economy (New York, Oxford University Press, 1977). 4. D. Pearce, A. Markandya and E.B. Barbier, Blueprint for a Green Economy (London, Earthscan Publications, 1989). 5. D. Cooke and others, "Sunlight brighter than the sun", Vature, vol. 346 (1990), p. 802. 6. W.H. Hilbertz, "Electrodeposition of minerals in sea water: experiments and applications", Institute of Electrical and Electronics Engineering, IEEE Journal on Oceanic Engineering, vol. OE-4, No. 3 (1979), pp. 94-112; and "Solar-generated building materials from seawater as a sink for carbon", Amblo (forthcoming). 7. T. J. Goreau, "The other half of the global carbon dioxide problem", Nature, vol. 328 (1987), pp. 581-582. 8. J. Goldemberg, and others, Energy for Development and Energy for a Sustainable World (Washington, D.C., World Resources Institute, 1987). 9. T.J. Goreau, "Balancing atmospheric carbon dioxide", Ambio, vol. 19 (1990), pp. 230-236; R. Grantham, "Approaches to correcting the global greenhouse drift by managing tropical ecosystems", Tropical Ecology vol. 30 (1989), pp. 157-174; G. Maryland, The Prospect of Solving the CO2 Problem through Global Reforestation (Washington, D.C., United States Department of Energy, 1988); and S. Postel and L. Heise, Reforesting the Earth (Washington, D.C., Worldwatch Institute. 1988). 10. N. Myers and T.1. Goreau, "Tropical forests and the Greenhouse effect: a management response", Climate Change, vol. 19 (1991), pp.215-225. 11. J.M. Epstein and R. Gupta, Controlling the greenhouse effect. Occasional Paper Series Washington D.C.. The Brookings Institution (1991), 12. T.J. Goreau and W. de Mello, "Tropical deforestation: some effects on atmospheric chemistry", Ambio 17 (1988). pp. 275-281. 13. H. Rodhe, "A comparison of the contribution of various gases to the greenhouse effect", Science, vol. 36 (1990), pp. 1217-1219. |
|