Many definitions of sustainable development (often incompatible with each other)have been suggested and debated in literature. What this suggests is that the debate has exposed a range of approaches which differ because they are linked to alternative environmental ideologies. From the ecocentric perspective, the extreme deep ecologists seem to come close to rejecting even a police of modified development based on the sustainable use of nature’s assets. For them only minimalist development strategy is morally supportable. From the opposite technocentric prespective, other analysts argue that the concept of sustainability contributes little new to conventional economics theory and policy. Given this worldview, the maintenance of sustainable economic growth strategy over the long runmerely depends on the adequacy of investment expenditure. Investment in natural capital is not irrelevant but is not overriding importance either. A key assumption of this posisition is that there will continue to be a very high degree of substitubility between all forms of capital (physical, human, and nature capital).
The most publicized definition of sustainability is that of the world commission on environment and development. The commission defined as development the meets the needs of the present without compromising the ability of future generations to meet their own needs.
On the basis of this SD definition both intergenerational equity and intragenerational equity concerns must be met before any society can attain the goal of sustainability. Social and economic development must be undertaken in such a way as to minimize the effects of economic activity (on resource sources and waste assimilation sinks) whenever the cost are borne by future generations. When currently wital impose cost on the future. Full compensation must be paid. (performance or assuance bonds yielding financial aid, or new technologies allowing resource switching say from fossil fuels to solar power.
The commission also highlighted the essential needs of the world’s poor, to which overriding priority should be given. In other words, SD must allow for an increase in people’s standard of living (broadly definied) with particular emphasis on the wellbeing of poor people, while at the same time avoiding uncompensated and significant costs on future people.
The commission also took a fairly optimistic view of the possibilities for decoupling economic activity and environmental impact and in terms of our classification system has put itself into the weak sustainability camp. Recall that the strong sustainability supporters, white not dismissing decoupling, argue that modifications to the scale of the economy (the throughput of matter and energy) will also but required, the amount of scale reduction is debated within the strong sustainability camp.
SD, it is generally agreed, is therefore economic development that endures over the long run. Economic development can be measured in terms of gross national product. (the annual output pf goods and services per capita and imports) per capit, or real consumptions of goods and services per capita. In a latter section we will argue that, in fact, the traditional GNP measure needs to be modified and extended if it is to measure SD, but for the moment SD is definied as at least non-declining consumption, GNP, or some other agreed welfare indicator.
The conditions for sustainable development
A more difficult task is to determine the necessary and sufficient conditions for achieving SD. Fundamentally, how do we compensate the futurefor damage that our activities today might cause? The answers is through the transfer of capital bequests. What this means is that this generation makes sure that it leaves the next generation a stock af capital no less than this generation has now. Capital provides the capability to generate wellbeing through the creation of goods and services upon which human wellbeing depends.
Weak sustainability (WS)
Under this interpretation of SD, it is not thought necessary to single out the environment (natural capital) for special treatment, it is simply another form of capital. Therefore, what is required for SD is the transfer of an aggregate capital slock no less than the one that exists now (this then is the weak sustainability constant capital rule). We can pass on less environment so long as we offset this lose by increasing the stock of roads and machinery, or other man-made (physical) capital. Alternatively, we can have fewer roads and factories so long as we compensate by having more wetlands or mixed woodlands or more education. Perfect substitutability between the different forms of capital.
Strong Sustainability (SS)
Under this interpretation of SD, perfect substitution between different forms of capital is not a valid assumption to make. Some elements of the natural capital stock cannot be substituted for (except on a very limited basis) by man-made capital. Some of the function and services of ecosystems are essential to human survival, they are life support services (biogeochemical cycling) and cannot be replaced. Other ecological assets are at least essential to human wellbeing, if not exactly essential for human survival-landscape, space, and relative peace and quiet. These assets are critical natural capital and since they are not easily substitutable, if at all, the SS rule requires that we protect them.
Measuring sustainable development
Another way of looking at the idea that SD means generating human wellbeing now without impairing the wellbeing of future generations is to think about a sustainable flow income. This is a level on income that the nation can afford to receive without depreciating the overall capital stock of the nation. The danger is that a failure to adequately account for natural capital and the contribution it makes to economic welfare and income will lead to misperceptions about how well an economy is really performing. This danger is real because the current system of national accounts used in many countries fails, in almost all cases, to treat natural capital as assets which play a vital part in providing a flow output/income over time. Extended national accounts (not restricted to market-based outputs, incomes and expenditure, as measured in the gross national product concept) are required in order to improve policy signals relating to SD.
Two adjustments are required, one the depreciation of natural capital (change in quantity) and the other for degradation if the natural capital stock (change in quality). A framework to reflect the use of natural resources at the national level is in the process of being agreed by the united nations statistical office. However, the theory and practice of making those adjustments is complex and they are not discussed further here (we provide some suggested reading at the end of the chapter). Instead we present a simple test for SD which yields data which is at least indicative of national sustainability. The test is, however, far from a definitive sustainability indicator, but it is based on modified national accounting information.
Simple indicator of sustainable development
One SD rule states that an economy must save at least as much as the sum of the depreciation on the value of man-made and natural capital. An analogy with a business is useful in this context. If our business, to replace machinery and buildings as they wear out (depreciate), we might stay afloat for a while but not long term-our business would be unsustainable. The same is true for any economy , its national savings ratio (savings over some measure of income like gross domestic product (GDP)) must be greater than or equal to depreciation in the natural capital and man-made capital stock, if it is to pass our simple sustainability test. Nothing definitive is being claimed since the data available is not always comprehensive and the test itself static and ignores factors such as technological change, population growth and international trade.
Precautionary principle and safe minimum standards
For some analysts supportive of the strong sustainability position, sustainability constraints (such as the critical natural capital protection rule) should be seen as expressions of the so-called precautionary principle and on similar to the notion of safe minimum standard (SMS). The SMS concept is one way of giving shape to the intergenerational social contract idea we discussed. Somehow we have to trade off using resources to produce economic benefits and conservation of resources stocks and flows to guarantee sustainable benefit flows. The trade-off decisions have to be taken within a context of uncertainty and possible irreversibilities (decisions once taken result in changes that are physically impossible to reverse or prohibitively expensive to reverse, loss of tropical forests and complex wetlands). To satisfy the intergenerational social contract (via the constant capital rule and capital bequests), the current generation could rule out in advance, depending on the costs (strictly known as the social opportunity costs, what society has to give up or forgo), development activities that could result in natural capital depreciation beyond a certain threshold of damage cost and irreversibility (loss of critical natural capital, life support service, keystone species and processes). The compatibility between SMS and strong sustainability is not, however, quite complete. SMS says conserve unless the benefits forgone are very large. SS says that, whatever the benefits forgone, loss of critical natural capital is unacceptable.
Any sustainable strategy for the future will have to confront the question of how a much larger total global population can gain least a basic livelihood in a manner which can be sustained. For the people of the south, many of their livelihoods will have to endure in environments which are fragile, marginal and vulnerable. Sustainable livelihoods can only be promoted via policies which reduce vulnerability. Flood protection to guard against sea-level rise induced by climate change due to global warming. Measures to improve food security and offset market and intervention failures such as inappropriate resource pricing and uncoordinated development policies.
Sustainable development: operational principles
A number of rules (which fall some way short of a blueprint) for the sustainable utilization of the natural capital stock can now be outlined (roughly ordered to fit the VSS progression):
- Market and intervention failures related to resources pricing and property rights should be corrected.
- Maintenance of the regenerative capacity of renewable natural capital (RNC) harvesting rates should not exceed regeneration rates and avoidance of excessive pollution which could threaten waste assimilation capacities and life support systems.
- Technological changes should be steered via an indicative planning systems such that, switches from non-renewable (NRNC) to RNC are forested and efficiency-increasing-technical progress should dominate throughput-increasing technology.
- RNC should be exploited, but at a rate equal to the creation of RNC substitutes (including recycling)
- The overall scale of economic activity must be limited so that in remains within the carrying capacity of the remaining natural capital. Given the uncertainties present, a precautionary approach should be adopted with a built-in safety margin.
Summarizes some of the measure and enabling policy instruments that would be involved in any application of an SD strategy.
Although it has been defined in many different, and sometimes contradictory, ways the concept of sustainable development does have both relevance and meaning. Weak and strong versions of the concept can be distinguished, and a rudimentary measure of sustainability can be calibrated. How precisely sustainability principles can be translated into operational practice remains more uncertain. But the framework for general sustainability rules has been set out and will require adaptation to specific economic and environmental circumstances.