WHAT SHOULD BE SUSTAINED?

Even if it is agreed that we have an obligation to future generations, the nature of that obligation is controversial. Do we need to do more than simply protect those aspects of the environment necessary for survival and health, such as ensuring a minimal standard of clean air and water? And what standard would that be? Which risks from hazardous and radioactive substances do we need to prevent?

The problem is that protecting the interests of the future may conflict with the interests of current generations.

At the other extreme is the opulence model, where present generations consume all they want and assume that future generations will be able to cope with the impoverished environment that remains because they will be technologically better off. Alternatively, advocates of this model assume that future generations will have the technological expertise to find new sources or substitutes for exhausted resources and extinct species (Weiss 1992). This model seems overly optimistic about the ability of wealth and technology to deal with environmental catastrophe and losses.

Weak sustainability

Many economists and businesspeople argue that communities can use up natural resources and degrade the natural environment as long as they compensate for the loss with 'human capital' (skills, knowledge and technology) and 'human-made capital' (buildings, machinery, etc).

Economists often think of the environment in terms of 'natural capital', that is, aspects of nature that are of use to humans including min­erals, biological yield potential, and pollution absorption capacity. There is also 'cultivated capital', which includes natural capital that has been transformed or adapted by humans. Examples include domesticated animals and plant varieties (Holland 1999: 50). These economists argue that what needs to be maintained for future generations is 'total capital':

Total Capital = Natural Capital + Cultivated Capital + Human Capital + Human-made Capital

In this formula the actual mix or proportions is not important. The Business Council of Australia (BCA1991: 4), for example, has argued that:

The principle of sustainable development does not require that the physical configuration of the environment or the economy's capital stock remains constant. The current generation does not owe future generations a share of particular resources. Rather, it requires that the capacity to generate resources from the total stock of environmental, physical and human capital resources not be diminished.

Advocates of weak sustainability point out that the loss of income from a depleted resource could be compensated for by other investments which generate the same income. If the money obtained from exploiting an exhaustible resource, such as oil, is invested so that it yields a contin­uous flow of income, this is equivalent to holding the stock of oil con­stant. They argue that not only is some substitution inevitable when it comes to the commercial exploitation of minerals, but that this is consis­tent with intergenerational equity, 'provided that the community returns from that exploitation are reinvested to give an equivalent income indef­initely' (ESD Working Group Chairs 1992: 37).

Economist David Pearce (1991: 2-3) says that this means that the Amazon forest can be removed so long as the proceeds from removing it 'are reinvested to build up some other form of capital'.

Weak sustainability provides a rationale for continuing to use non- renewable resources at ever-increasing rates. 'Inevitably, as we deplete the stock of resources, there are less resources for future generations. While this can cause temporary shortages it is not regarded as a matter of longer-term concern' (ESD Working Groups 1991: 78-9). This is because during times of shortage the prices will go up and new reserves will be found, substitutes discovered and more efficient use encouraged. It is for this reason that Pearce and his colleagues (1989) suggest that what should remain constant is not the stocks of non-renewable resources but the economic value of the stock.

Natural limits

While the economic value of natural resources can be easily replaced, their functions are less easily replaced. Most people, even economists, agree that there are limits on the extent to which natural resources can be replaced without changing some biological processes and putting eco­logical sustainability at risk. Pearce and his colleagues (1989), for example, argue that the requirement to keep the total amount of capital constant 'is consistent with "running down" natural capital - i.e. with environmental degradation', as long as human-made capital can be sub­stituted for natural capital. He recognises that some environmental assets could not be 'traded-off' because they are essential for life-support systems and as yet they cannot be replaced. In this view, the proportion of natural to human-made capital does matter, as economist David James (1999: 156) notes:

Community welfare, in the widest sense, is derived from a combina­tion of natural and man-made capital. In achieving an acceptable balance of economic development and resource protection, and in ensuring that excessive risks of damage are minimised, the practical policy issue to be addressed is how to define and achieve an optimal or acceptable mix of both kinds of capital.

Others advise caution with respect to declining natural capital. 'As an economist I would say that loss of natural capital can be compensated for by human made capital but in practice I would advise policy-makers to avoid depletion of natural resources unless there was a good reason' (Harris 1991). In fact, the precautionary principle would prevent us from assuming that natural resources can be replaced without good evidence that they can.

Despite holding that stocks of non-renewable resources need not remain constant, Pearce and his colleagues (1989: ch 2) give the following reasons for maintaining a minimal level of natural capital:

Non-substitutability

There are many types of environmental assets for which there are no sub­stitutes: for example, the ozone layer, the climate-regulating functions of ocean phytoplankton, the watershed protection functions of tropical forests, the pollution-cleaning and nutrient-trap functions of wetlands. For those people who believe that animals and plants have an intrinsic value, there can be no substitute.

Uncertainty

We cannot be certain whether or not we will be able to substitute for other environmental assets in the future and what the consequences of continually degrading nature will be. Scientists do not know enough about the functions of natural ecosystems and the possible consequences of depleting and degrading natural capital. And 'if we do not know an outcome it is hardly consistent with rational behaviour to act as if the outcome will be a good one'.

Irreversibility

The depletion of natural capital can lead to irreversible losses such as the loss of species and habitats, which once lost cannot be recreated through man-made capital. Other losses are not irreversible but repair may take centuries - for example, damage to the ozone layer and soil degradation.

Equity

There is an equity issue involved in replacing natural resources and envi­ronmental assets - that are currently freely available to everyone - with human-made resources that have to be bought and may only be acces­sible to some people in the future.

Resilience

Human-made capital often lacks an important feature of natural capital - diversity. Diverse ecological systems are more resilient to shocks and stress. Biological diversity ensures that ecosystems are robust and more likely to survive disruption, disease and natural disasters. Even in eco­nomic systems, diversity helps to spread risks and maintain options.

Strong sustainability

Understandably, environmentalists generally reject the concept of weak sustainability even if it incorporates the idea of maintaining minimal environmental functions. They argue that the environment should not be degraded for future generations, even if the future generations are com­pensated with greater human-made capital. They claim that human welfare can only be maintained over generations if the environment is not degraded; in economists' terms, if natural capital is not declining. They point out that we do not know what the safe limits of environ­mental degradation are; if those as yet unknown safe limits are crossed, the options for future generations will be severely limited.

Secondly, many environmentalists do not agree that human and natural capital are interchangeable. They believe that a loss of environ­mental quality cannot be substituted with a gain in human or human- made capital without loss of welfare. Therefore, they argue, future generations should not inherit a degraded environment, no matter how many extra sources of wealth might be available to them. This is referred to as 'strong sustainability'.

The production and consumption values and absorption capacity provided by natural capital may be able to be replaced or extended, par­ticularly through technological innovation.

If an old growth forest is cut down, a commercial tree plantation may replace much of its economic value, but a plantation is unlikely to recreate the original ecosystem and support the biodiversity provided by the natural forest. Nor will it have the beauty or spiritual value of the original forest. The plantation will be an impoverished version of the original forest, with many of the values associated with forests gone (Humphreys 1999: 113).

Should we preserve these non-economic values of the environment for future generations? How can we know what sorts of environmental values future generations will appreciate? Visser 't Hooft (1999: 22) asks: 'If a majority is convinced that a worthwhile life depends on being able to walk in parks and forests, must it anticipate a possible fading out of that conviction in the minds of posterity?' Similarly, Bryan Norton (1999: 132) asks:

... suppose that our generation converts all wilderness areas and natural communities into productive mines, farmland, production forests, or shopping centres, and suppose we do so efficiently, and that we are careful to save a portion of the profits, and invest them wisely leaving the future far more wealthy than we are. Does it not make sense to claim that, in doing so, we harmed future people, not economically, but in the sense that we seriously and irreversibly nar­rowed their range of choices and experiences? A whole range of human experience would have been obliterated.

Future people who have never experienced wilderness would not miss it and would make do with human-made landscapes. They would not know they were worse off. However, current generations would clearly have diminished the range of future choices and opportunities and impoverished future lives.

A professor of international and environmental law, Edith Brown Weiss (1990), argues that intergenerational equity consists of preserving options, environmental quality and access for future generations. Overdevelopment reduces options and reduces diversity. The principle of 'conservation of access' implies that current generations should ensure that future generations can also enjoy this access. Equity and fairness would seem to require that future generations not only be able to subsist but that they have the same level of opportunities to thrive and be happy as current generations.

Further Reading

Partridge, Ernest (2006) 'The Gadfly Papers',

Principles of environmental justice, Environmental Justice Net, October 1991,

Shrader-Frechette, Kristin (2002) Environmental Justice: Creating Equality, Reclaiming Democracy, Oxford University Press, Oxford.

Smith, Mark J (ed.) (1999) Thinking Through the Environment, The Open University, London & New York.

UNESCO Declaration on the Responsibilities of the Present Generations Towards Future Generations, 1997,

Visser 't Hooft, Hendrik Ph (1999) Justice to Future Generations and the Environment, Kluwer Academic, Dordrecht.

Weiss, Edith Brown (1990) Intergenerational fairness and the rights of future gener­ations, Foundation for the Rights of Future Generations, April,