xix Overexploitation and misuse of resources must be curtailed or prohibited if they cause fundamental harm to environmental processes, but we need indicators of change to guide us along the way (McGlade 2001).

xix It is increasingly important for sustainability policies to be supported by information flows from heterogeneous sources... Indicators represent, at root, an approach designed to meet this challenge... A characteristic of indicators is that they allow an expanding set of sentinel observations to be drawn into policymaking... Perhaps the biggest bottleneck facing us today is our ability to choose the right signal or indicator to make a decision at the right time. What is needed is an indicator framework in which to successfully monitor, learn, decide, and act, to be able to obtain a clear view of where current and proposed policies are taking society.

xix The main purpose of any sustainability indicator framework is to provide a comprehensive and highly scalable information-driven architecture that is policy relevant and understandable to members of society and will help people decide what to do.
 It must contain sentinel indicators, ones that directly reflect changes across significant areas of interest to society and can be communicated easily. In this way we will be able to learn about changes and interpret the various forms of information as clear views of progress to date and possible future decisions. In this way we will be able to achieve balance in our actions.

xxiii Aggregated indicators and indices try to capture a complex reality and propose a single and simple picture of it.

xxv The concept of sustainable development and the ability to measure progress toward its goals have become immensely important for many professions... the community that generates and makes use of indicators is vast... We hope that the considerations raised in this volume will assist in their efforts to ensure a more sustainable society for future generations.

p.1 Indicators are symbolic representations (e.g., numbers, symbols, graphics, colors) designed to communicate a property or trend in a complex system or entity. Traditionally, most indicators for decision makers have been numbers

p.1 Chapter 40 of Agenda 21... states that "indicators of sustainable development need to be developed to provide solid bases for decision-making at all levels and to contribute to a self-regulating sustainability of integrated environment and development systems" (UNCED 1992:paragraph 40.4).

p.2 Assuming that indicators are intended to report on sustainability, the most important and difficult definition is that of sustainability itself. Sustainability is the capacity of any system or process to maintain itself indefinitely. Sustainable development this is the development of a human, social, and economic system able to maintain itself indefinitely in harmony with the biophysical systems of the planet.

p.3 Indicators of sustainability should measure characteristics or processes of the human-environmental system that ensure its continuity and functionality far into the future... effort is needed to apply the techniques of system science to this issue... The resulting understanding can contribute to more adaptive management, with indicators serving as monitoring and signaling mechanisms. The optimal sustainability indicators are those that capture the essential characteristics of the system and show a scientifically verifiable trajectory of maintenance or improvement in system functions.

p.3 Resilience is a more useful aspect of sustainability that can be defined in terms of vulnerability, adaptability, and responsiveness or sensitivity... The goal is to identify irreversible changes beyond which recovery is not possible.

p.4 The packaging of data into indicators is a way of simplifying complex and detailed information... When indicators are combined into indices, they provide a clear picture of the entire system, reveal key relationships between subsystems and between major components, and facilitate analysis of critical strengths and weaknesses.

p.9 A key challenge for sustainability indicators therefore is to reflect time lags, the trade-offs between the short and long term, and the distinction between weak and strong sustainability.

p.11 Where direct indicators do not exist, perhaps because of missing data or insufficient knowledge of interactions, proxy or substitute indicators are widely used. Proxy indicators usually are representations of complex systems and can be useful for communicating complex issues.

p.14 We need to learn by doing. Each [acting agent] should select indicators and approaches suited to its needs, priorities, and means and use them to guide policy and action toward sustainable development.

p.33 Vulnerability and resilience are two terms that are increasingly used in scientific analysis of sustainable development from a system perspective... resilience is the capacity of the coupled human-environment system to cope with internal or external disturbance and its ability to adjust and adapt (Gutierrez-Espeleta 1999)... Vulnerability is a characteristic of the lower end of the resilience spectrum. A system with high resilience has low vulnerability and vice versa. Systems need resilience not only to normal variations but also to extreme events... When a system is not resilient enough to absorb disturbance and is degraded, the changes often are irreversible. It is the irreversible changes that are critical to sustainability.

p.36 Finding the best indicators of sustainability entails breaking away from data availability constraints and determining the appropriate phenomena to monitor and the indicators needed.

p.36 Once development processes and sustainability issues are better understood and modeled with suitable indicators, it should be possible [to] make data collection simpler and more flexible, for example with optimal spatial and temporal sampling, as a guide to institutionalizing long-term monitoring.

p.36 Analyzing complex systems and their properties involves reducing complexity to a degree that we can understand... The process of developing indicators entails simplifying complex and detailed information to provide communication tools for larger audiences.

p.42 A system perspective alerts us to the complex and often nonlinear character of these subsystems, to the existence of thresholds for irreversible switching from one stable system state to another, and to other surprises that are difficult to unravel and even more difficult to predict. Thus, a system perspective implies a more humble approach to governance, recognizing the limits of our ability to fully understand and control the impact of policies and actions. It encourages us to use indicators in a more responsive learning mode, acknowledging the need for wide participation in adaptive management to achieve the dynamic state that is sustainability. [JLJ - wow. I agree.]

p.56 Constructing information on integrated and complex issues is bound by our imperfect understanding of reality... and for issues where reasonable understanding exists, developers of indicators are bound by what is actually measured... and how it is measured

p.65 indicators should guide the decisions made by decision makers

p.69 The three criteria of credibility, legitimacy, and salience are key attributes for characterizing the effectiveness of sustainable development indicators (Cash et al. 2002; Paris and Kates 2003) where credibility refers to the scientific and technical adequacy of the measurement system, legitimacy refers to the process of fair dealing with the divergent values and beliefs of stakeholders, and salience refers to the relevance of the indicator to decision makers.

p.81 The multiple dimensions of sustainability do not lend themselves to a single approach or type of analysis.

p.83 At first sight, indicators seem to be addressed to experts, economists, and statisticians, and yet they are part of our daily life.

p.85 A car driver, an Airbus pilot, and the captain of a cruise ship all have a dashboard in front of them, with an impressive array of instruments that help them make their decisions.

p.94 Sustainable development must become measurable if we want operational... targets

p.97 Indeed, the more complex a research object is, the more indicators are necessary to capture its predicament.

p.125 How do we turn the concept of sustainability into a framework or model and then identify indicators that describe its essential properties in a way that is easily understandable?

p.127 Why do we need frameworks? Applying frameworks to analyze and structure information helps us move from data to information and on to the structured knowledge needed to elucidate environmental and sustainability issues and to design effective responses.

p.135 Indicators always simplify a complex reality, focusing on certain aspects that are regarded as relevant and for which data are available. Indicators are meaningful only as part of a framework or story. Indicators are a necessary part of the stream of information we use to understand the world, make decisions, and plan our actions.

p.141 To be effective, indicators must be selected that come close to answering the policy questions, taking into account the relevant environmental, societal, and economic interactions described in the framework or model for that issue and the relevant policy levers

p.142 Common processes, frameworks, and typologies are guides for the identification and development of indicators.

p.143 Indicators can be powerful tools in the communication of environmental issues to policymakers. They serve a useful function in simplifying complex issues, steering policymaking, and measuring environmental and policy progress.

p.145 To assess sustainable development (SD), new approaches are needed to deal with the issues of system complexity, uncertainty, and ignorance. The necessary information must be condensed and made accessible to... decision makers

p.151 when assessments are designed to address sustainability, guidance is needed to identify the key interfaces on which to focus attention... The way we envisage sustainability must be examined because this will directly affect the features identified as important and the associated assessments and indicators needed.

p.156 We want to maintain and enhance the adaptive capacity of the environmental system (adaptability).

p.157,160 Preventive and precautionary actions must usually be taken on the basis of much less than scientific certainty and well before an understanding of the mechanisms of action has been achieved.

p.160 Measuring sustainable development requires innovative techniques and indicators, rigorous underlying models, and frameworks for interpretation of complex evidence.

p.163 Of all the potential uses of indicators of sustainability, integrated assessment is perhaps the most critical and also the most difficult because such assessments must bring together a wide variety of issues and topics. An assessment is by definition an evaluation, and indicators are one way of expressing the absolute or comparative value of something.

p.164 Sustainability is not a goal to be achieved at some point in time but a characteristic of a dynamic human-environmental system able to maintain a functional productive state indefinitely (Dahl 1996, 1997a). Integrated indicators of sustainability therefore should measure the functional system processes that best represent its capacity to continue far into the future. Defining sustainability in terms of durability over time avoids the problem of specifying the characteristics of the system or entity to be maintained, which can be very subjective and specific, and where political, philosophical, or cultural differences can prevent any wide consensus. The optimal sustainability indicators are those that best show a scientifically verifiable trajectory of maintenance or improvement in system functions... it is... their dynamic change over time that is important for measuring sustainability.

p.170 One approach [JLJ from earlier, to the use of indicators in integrated assessments] will be through complex computerized system models that mathematically reproduce the structure and dynamics of the system.

p.171-172 Care must be taken to select indicators of sustainability that capture all the dimensions of a rich and rewarding human society contributing to social and human sustainability

p.177 In Chapter 10 Arthur Dahl challenges the scientific community to develop sustainability indicators that "measure the functional system processes that best represent its capacity to continue far into the future." According to Dahl, these indicators should "reflect the whole and not just the parts." Indicators should highlight problems rather than symptoms.

p.177 We define an indicator, following Rotmans and de Vries (1997), as "a characteristic of the status and dynamic behaviour of the system concerned. Or equivalently: an indicator is a one-dimensional systems description, which may consist of a single variable or a set of variables." The characteristic of the system that we are most interested in is its ability to sustain itself in the long run in a desired state or on a desired trajectory. A system with that ability is sustainable.

p.178 The target audience could not map these fragmented parts as a system of stocks and flows. Consequently, they could not understand the complex dynamics resulting from these interactions. The target audience was even less able to design and test policy actions for their effects on the sustainability of their region. This results in inefficient actions and counterintuitive surprises.

p.179 the development of any one part of the system toward a desirable state should not occur structurally at the cost of developments elsewhere in the system because this would compromise its continuity and functionality.

p.238 in all situations decision makers... need ready access to accurate information on health hazards associated with the links between development and the environment.

p.239 Indicators can play an important role in turning health and environment data into relevant information for decision makers... Most important, they can help simplify a complex array of information with respect to the health-environment-development nexus. This way, they provide a synthesis view of existing conditions and trends that provides information for decision making

p.239 Briggs et al. (1996) define an environmental health indicator as "an expression of the link between environment and health, targeted at an issue of specific policy or management concern and presented in a form which facilitates interpretation for effective decision-making." Embodied in this definition is the concept of a link between a factor in the environment and a health outcome.

p.311 "Assessment of progress towards sustainable development should be guided by a clear vision of sustainable development and goals that define that vision" (Hardi and Zdan 1997).

p.334 the selection of indicators for the assessment itself is an act of evaluating... Levin (1997) states that "all the important decisions are made with tremendous dependence on embedded values" and that "sustainability is about values..."

p.377 The high statistical significance and usefulness of the index indicate that it is actually measuring something real.