Indicators of sustainable development

Chemosphere, Vol. 33, No. 9, Pp. 1739-1748, 1996 Copyright 8 1996 Elsevier Science Ltd Printed in Great Britain. All tights reserved 0045-6535/96 $15.C~?+O.o0 Pergamon PII: zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLK S0@45-6535(96)00190-7 CRITERIA FOR SUSTAINABILITY IN THE DEVELOPMENT INDICATORS FOR SUSTAINABLE DEVELOPMENT OF Alison Gilbert Institute for Environmental Studies, Free University, Provisorium De Boelelaa~~I1 15,108 1 Amsterdam, The Netherlands ABSTRACT Opschoor and Reijnders (1991) propose a simple structure for the development of physical indicators of sustainabie development. It begins with the development of two types of environmental indicators: one describing the pressure being placed on the environment, and one describing the effects of this pressure. The sustainability indicator then measures the distance between current or predicted conditions, as described in these simple ‘state’ indicators, and a reference condition. The reference condition is equated to sustainability. Specification of this reference requires the making of explicit choices as to the types of environmental change. It implies setting standards which make the criteria for sustainability explicit. The power of this simple construct is demonstrated using three examples. The first Sustainability indicator comprises a pressure indicator describing acid deposition in the Netherlands and a reference condition based on ecosystem sensitivity to this deposition. The second comprises an effect indicator describing species composition in the Dutch North Sea and a reference condition based on past species composition before this ecosystem was adversely affected by pollution, overlishing, etc. The third indicator deals with cadmium accumulation in Dutch soil. It identifies two criteria for sustainability, one constraining additions of cadmium to soil and one spedjing soil quality. Copyright 0 1996 Elsevier Science Ltd 1. INTRODUCTION Opschoor and Reijnders (1991) propose a simple structure for the development indicators of sustainable development. Two types of environmental pressure and impact. 1739 of physical indicators are identified - 1740 Environmental of environmental volumes pressure indicators are intended to express (changes in) the levels of use functions; for example, amounts of emissions, of raw materials and species extracted, discharges levels of recreational and depositions, use, habitat loss and landscape modification. These pressures can be regarded as structural or incidental shocks to the environment which are transformed and transported in a variety of natural processes to manifest themselves as changes in quantity and quality of environmental receptors. human beings and their artefacts as well as ecosystems, natural resources Impact quantity plant and animal populations, other and landscapes. indicators are intended to express the consequent changes in environmental and quality over time. Examples could include repercussions health, on populations (e.g. McCarthy These receptors include on human welfare and of commercial species and bio-markers of environmental and Shugart, 1990) on bio-diversity, and on descriptors contamination of ecosystem function such as integrity, health or vitality (e.g. Schaeffer et al., 1988; Braat, 1992). The development of sustainability indicators requires the making of explicit choices as to the types of environmental change. These are not simple ‘state indicators’ reflecting environmental conditions or pressures (as are the pressure and impact indicators), but normative measures of the gap(s) between current’or predicated states and some reference situation which is equated to ’ sustainability’. This reference condition could be some past environmental state or a firture on regarded as more desirable than the present. It implies the setting of standards which make criteria for sustainability explicit. The purpose of this paper is to provide examples of such reference conditions subsequent development and the of sustainability indicator. 2. EXAMPLES 2.1 Example 1 The first example shows the upgrading indicator for acid deposition as reported of a pressure in Van Dijk et al. (1991). Selection of a reference condition (or sustainability criterion) required consideration acid deposition. indicator into a sustainability of spatial differences in sensitivity to It was proposed that the most sensitive receptor area should determine the reference condition. 1741 The approach distinguishes between primary and secondary sustainability indicators. Primary indicators present the situation in a given year relative to a base year; the indicator takes the value of 100 in the base year. Secondary indicators present development over time. Relevant formulae are as follows: &I = ((PD - DN) /(GDP, - DN)) * 100 (Eq. 1) Where: $1 = the primary sustainability indicator in a given year; PD = potential acid deposition for the given year; DN = reference condition or sustainabiity criterion; and W.mc= mean acid deposition per hectare in the base year. For the Netherlands, Van Dijk et al. (1991) recommended 500 acid equivalents/ha/year as the reference condition. 1980 as the base year when estimated mean acid deposition was 6700 acid equivalents/ha. Equation 1 then condenses to the following: $1 = ((PD - 500) / 6200) * 100 (Eq. 2) The secondary indicator is calculated as: ,$I = DI,, - DI, Where: _JI, = the secondary sustainability indicator in year t; DL, = the primary sustainability indicator for year t-l; and, DI, = the primary sustainability indicator for year t. (Eq.3) 1742 2.2 Example 2 The second is the AMOEBA developed by Ben Ten Brink (Ten Brink, 1991) and shows the upgrading ecosystem Dutch of a ‘state’ or ‘impact’. The acronym may be translated to “ general method for description and assessment” . coastal zone ecosystems. compared with a reference abundances correspond The AMOEBA addresses the issue of bio-diversity It comprises the abundance condition of 32 plant and animal species (see Figure I). The reference in 1930, taken to represent the undisturbed in condition is species state of the ecosystem and so to to a sustainable condition. An index, which Ten Brink refers to as an ecological Dow Jones, can be constructed by summing the percentage difference between the actual situation and the reference condition over the 32 species. Reservations have been expressed with regards to this indicator and its index. The focus of discussion lies on: 1. criteria interdependencies 2. for selection between of the 32 species and possibility of (some of) them; the implication that the closer to the reference guarantee the for ecological condition, the larger the sustainability, raising issues of multiple sustainable states and reversibility; 3. good equal weighting of all species first visualization decision-making Further information in constructing of a multi criteria the index which, while a situation, is a poor basis for or ecological economic analysis. and comments on this indicator may be found in Ten Brink and Hosper (1989). Verbuggen and Kuik (1991) Ten Brink et al. (1991) RIVM (1991) and Janssen (1992). 2.3 Example 3 The third example is an indicator developed within the environmental diffusion - the movement of toxic micro pollutants into and throughout focusing on cadmium’s accumulation in soil (Gilbert and Feenstra, policy theme the environment - and 1994). Both pressure and impact variables, combined with sustainability criteria, are used to construct the indicator. These criteria, both of which must be satisfied for sustainability, are : 1743 Figure I An AMOEBA, comparing the present ecological situation and the reference cot&ion for the Dutch marine environment zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPO Common s SOURCE: Ten Brink zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA (1991) 1744 1. additions of deposition, cadmium to the soil from all sources (atmospheric fertilizer use, sewage sludge disposal) should not exceed losses from the soil due to leaching, runoff and uptake by crops; and, 2. the total volume or concentration of cadmium in the soil should not exceed soil quality standards. The indicator is presented as a ‘state space’ in which the two criteria define the axes of a graph (see Figure 2). The horizontal axis reflects the pressure which economic activity, in its deliberate and incidental use of cadmium, places on the soil. This pressure is calculated as the net deficit of cadmium additions to and losses from the soil. Sustainability is indicated by a zero or positive net deficit; a negative net deficit corresponds to an unsustainable condition. Figure 2 Inferpretation of values from the two sustainability criteria positive soil quality index (clean soil) . trend towar negative net deficit (net accumulation) ::betterthan : : sustainable :I. ::: . L positive net deficit (net loss) trend towards susrainable neua,i!e soil quxlity index (pollured soil) 1745 The vertical axis reflects the impact of cadmium use on soil quality. It compares the concentration of cadmium in the soil with a standard, yielding an index of soil quality. When the concentration second of cadmium in the soil equals the standard, implying correspondence sustainability standard, the concentrations criterion, the value of this index is 0. At concentration index is negative suggesting contaminated soils with the greater than the and unsustainability; less than the standard, the index is positive suggesting conditions at better than srlstainability. Sustainability condition is represented represented by two deficit is negative (accumulation) trend towards unsustainability by the origin and the top right quadrant of Figure 2. A negative values is quite clearly unsustainable. When the net but soil quality is positive, clean soil is being polluted and so a can be implied. While the origin is the target, it can also be seen that coordinates in the right-hand half of this figure indicate a more desirable condition than those in the left-hand half Selection of the soil quality standard is obviously an issue for the implementation of this indicator. A standard of 0.8 mg Cd/kg dry soil, aggregated over the whole of the Netherlands, was used to demonstrate the indicator. It was selected on the basis of proposed in the Netherlands for different types of soils and uses (Stoop and Rennen, 1991) and to ensure the multi fimctionality of soils, in particular options permitting soils under agricultural uses to revert back to natural cover. This approach is essentially the same as that taken by Van Dijk et al. (1991) in the first example. Figure 3 demonstrates the indicator. The results of dynamic material balance incorporating three policy scenarios is presented in the state space format. All three trajectories are located in the top left quadrant - ‘trend towards unsustainability’ - of the indicator and so only this quadrant is shown. Materials balances 6om 1980 and 1985 provide the basic data for the model, and so all three scenarios share the same trajectory between these years. No new policies are initiated in the moderate and strict policy scenarios after 2005. For the strict policy scenario, almost half of the cadmium additions to the soil after 2005 derives from transboundary transport of air-borne cadmium. None of the three scenarios sustainability. achieves a trajectory which is incontrovertibly towards The base scenario leads to exceeding of the soil quality standard in 2020 and the trajectory’s moving into the ‘unsustainability’ quadrant. The moderate and strict policy scenarios achieve a slowing of the rate of cadmium accumulation, but extrapolation eventually to overshooting the x-axis and entering the unsustainability for this would be longer with the strict policy scenario. from 2020 would lead quadrant. The time taken 1746 Figure 3 Trajectories for the three scenarios from the dynamic materials balance 0.3 0.2 g _. & g r: G _. 0.1 $ X 2020 -0.0 -10 -8 Net deficit ?? - -4 -6 (tonnes 5 year time step .+ Base scenario ‘...*__* Strict policy scenario -2 Cd/year) Moderate policy scenario 3. SOME FINAL COMMENTS In gaining experience with indicator development, it is natural to begin with very narrowly defined or bounded issues. However, these boundaries are artificial and deliberate choices will have to be made regarding them. To illustrate, Example 3 deals with cadmium accumulation in the soil. If consideration was extended to cadmium accumulation in environmental media, the first sustainability criterion would need to be altered, say to ‘additions should not exceed uptake by commercial species’. Losses Corn soil via drainage and runoff are merely inter-media transfers. The shift in consideration to include groundwater and aquatic sediments criterion, making it stricter. from soil removes these losses from the sustainability 1747 Consider the ‘trend towards sustainability’ quadrant in Figure 3, where cadmium is draining out of polluted soil. This trend is interpreted positively, as something desired, even though it may occur at the cost of groundwater quality or of the suitability of agricultural products for animal consumption. Sustainability, as defined by an indicator, may be achieved at a cost to elements or actors outside the indicator’s boundaries. Fiiy, it should be quite clear that selection and specification of the reference condition is crucial to an indicator’s development. Boundaries are not the only stumbling block here. Each of the examples above raises issues with regards to specification of sustainability, for example: the most sensitive receptor in Example 1; selection of species, the possibility of multiple sustainable states, of irreversibility or of discontinuities between present and desired conditions in Example 2; the requirement for multi fimctionality in selecting the soil quality standard in Example 2; the requirement for complicated the issue, or broader its boundaries, the more questions will probably be raised over sustainability criteria. REFERENCES Braat.L.C. (1992) Sustainable Multiple Use of Forest Ecosystems: an economic ecological analysis for forest management in the Netherlands, Ph.D. dissertation, Free University, Amsterdam. Brink B. 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