The total of human wealth cannot be measured only by man-made capital but must allow also for natural environmental capital and other aspects of the quality of life. Natural capital consists both of renewable and non-renewable resources. The challenge of sustainable development is to find ways of enhancing total wealth while using common natural resources prudently, so that renewable resources can be conserved and non-renewables used at a rates which considers the needs of future generations.
Environmental economics has an extensive literature on procedures for placing economic values on the environment. Most of these methodologies have been developed and refined in the context of developed countries, where high levels of disposable income allow for a high demand for environmental amenities and a willingness to pay for non-use values. The applicability of these methodologies may be limited in developing countries where the value of environmental amenities is relatively less important than the value of environmental resources in the production process.
Different sectors of society view ecosystems in terms of their own economic, cultural and societal needs. Indigenous peoples and other local communities living on the land are important stakeholders and their rights and interests should be recognized. Both cultural and biological diversity are central components of the ecosystem approach, and management should take this into account. Societal choices should be expressed as clearly as possible. Ecosystems should be managed for their intrinsic values and for the tangible or intangible benefits for humans, in a fair and equitable way.
Usually in current economic thinking, the environment is regarded as a cost factor and not as a kind of capital stock, while resources are considered to be either infinite or smoothly substitutable. There is reason to believe, however that today's economic and political crisis is deeply rooted in the way society values and manages its ecological resources as well as the way it decides about production and consumption.
Too often these days the environmental community finds itself on the sidelines because it has little or no knowledge of economic development, job creation, and control of capital. The corporations have taken hold of environmental policy because they have everyone convinced that environmental quality is primarily an economic issue and environmentalists don't (in general) know much about the economy.
Placing a monetary value on species and ecosystems may be a useful exercise by which to integrate the cost of using and conserving biodiversity, but it will never be possible to comprehend the true value of life in such a system.
Technical descriptions of biodiversity often give the impression that science and economics are adequate tools with which to characterize the qualities of the intricate web of life. In a world increasingly dominated by mega-modelling, global commerce and consumerism, it is easy to forget that the values of plants, animals, ecosystems and landscapes cannot be adequately measured in statistical or monetary terms. These values can certainly not be adequately described using the conceptual languages of a handful of academic disciplines.