How much are nature's services worth?

Abstract

Ecosystem functioning - the flow of materials and energy in biotic communities and the effects of these dynamics on soil and atmosphere - is vital to human welfare. To date, those concerned with quantifying and evaluating benefits of natural ecosystems to man have largely focused on the standing stocks of nature rather than the flows. The quantification of ecosystem functions, here illustrated by absorption of air pollutants, radiation balance, soil binding, and nutrient cycling, is likely to produce evidence on the extent of socially significant damage from pollution. At present, our understanding of ecosystem functioning is limited, but much can be done even now to develop quantitative relationships between pollution levels and damage to ecosystem functions. Evaluating the contribution of ecosystem functioning to human welfare is a complex task. It is a task of weighing human social values and is the quintessential task of politics. In order for citizens to communicate to their representatives their true desires about the maintenance of the natural environment and the pace of development, it is essential for the public to have a clear idea of the benefits they obtain from nature in its undeveloped state. An enumeration of the relationship between the effects of development and physical damage to ecosystems is a helpful first step. A full range of evaluation techniques, including but not limited to the use of economic measures, then awaits the planner in weighing the social value of benefits and costs (32). At the present state in the development of our evaluation methods, it would seem appropriate to seek both expert judgment in the assessment of physical damage and public participation in the assessment of social values. Cost-benefit analysis applied to the development of natural resources will consistently skew estimates of nature's value because of the limited state of our knowledge of ecosystem function and the difficulties in expressing these values in monetary units. Cost-benefit analysis can also be argued to be altogether inappropriate to an assessment of natural values, since there is far from social agreement that monetary units can express the equivalent gains from the loss of nature's services. Although the literature on environmental cost-benefit analysis is becoming increasingly sophisticated, in the eyes of many in our society it has not yet improved upon the poet's summation of nature's worth. This judgment seems to be made both because of the weakness of the assumptions inherent in cost-benefit analysis and because of the inadequacy of our quantitative knowledge of relevant ecological and social factors. It can be expected that as public education on the value of nature's services increases, the estimate of nature's worth on the part of some will increase. Attempts to quantify nature's services have heuristic value in providing perspective on the distance from both present estimates and a full accounting. Yet it is both sobering and important to recognize that, even in the long run, quantitative estimates of the worth of nature to man are likely to remain asymptotic to the value expressed by the poet's phrase.