ix This book examines the ways in which sustainable development can be measured and modelled.

p.11 First, what system or subsystems do we want to sustain? For how long do we intend these systems or parts thereof to continue? What do we assess to determine whether or not the system is actually on a sustainable development path? What policies can we introduce to ensure that the path we develop is in fact sustainable?

p.35-36 Common to all research into sustainable development indicators, are the problems of identifying what to measure and how to measure it. Obviously, the information on which the indicators are based must be available. Similarly, the indicators must be both informative (revealing whether sustainable development is being achieved) and act as an effective guide to policy makers.

p.43 Even if data were freely available and/or easily accessible, the problems of obtaining good quality data to create a set of sustainable development indicators still remain.

p.45 it is clear that maintaining and improving environmental and ecological quality is essential as a necessary condition for development to be sustainable.
 In an attempt to measure environmental indicators of sustainable development, it is obvious that many single measures could be used... Such individual measures simply record the factual observations of an environmental system. Single measures do not necessarily say anything about whether or not the entire ecological system is sustainable.... but, in most cases, individual variables have to be related to the effect that these have upon the organisms (including people).

p.46 Sustainable development indicators need to connect with the ways in which the environment is being altered so that its ability to support human and other forms of life might not be compromised.

p.47 single environmental indicators need to examine, at least, the minimum conditions for human survival. [JLJ - the business world uses the term 'critical success factors']

p.49 An early attempt to measure sustainability was the carrying capacity concept, developed in biological and ecological science... Generally, the carrying capacity is restricted by Leibig's law of the minimum which implies that the overall development of a system is dependent upon the lowest constraint being reached.

p.75 Sustainable development... a consensus as to its general implications is that sustainable development requires a non-declining level of wellbeing for future people.

p.90-91 Resilience is potentially a very useful concept in the sustainability debate. It refers to the ability of a system's parameters to stay within defined boundaries following an exogenous shock, so retaining the self-organising capacity of the system.

p.91 sustainable development is essentially concerned with maintaining a sufficient capacity to generate non-declining welfare over time

p.132 Indicators ought to be useful at a number of different levels: for research purposes, for policy makers, and as a source of information for the general public.

p.137 The Genuine Progress Indicator proposed by Cobb et al. (1995)... 'to provide a new economic scorecard that more accurately reflects the health of the economy in a common sense fashion'.

p.148 In a sense it is unsurprising that the different indicators give different messages about the sustainability of an economy... this possibly is inevitable given the multifaceted nature of the concept of 'sustainable development'

p.153 Sustainable development is a broad, multidisciplinary topic that incorporates ethical, economic, social and environmental/ecological aspects of the real world.

p.175 there is a need to develop a sound theoretical base for the concept of sustainable development... It is therefore essential to develop a theory of sustainable development which would satisfy the global constraints of living well within the confines of the carrying capacity of the ecosphere and ensuring that economic activity remains within the bounds of these sustainable limits.

p.178 Whilst sustainable corridors are conceptually simple to define they are very difficult to measure in such a way that they can help decision makers ensure that human activities are sustainable.

p.185 Model building is an activity whereby we seek to simplify the structure of a real world system in order to understand it; and, perhaps, to improve the operation of the real world system by managing it... Models of real world systems can be classified in many different ways such as iconic, analogue and mathematical. Iconic models represent an aspect of the real world by means of a symbol or icon.

p.198 It may be that in further research a single measure can be used to evaluate whether development is sustainable, but at present no single measure exists which would satisfy all participants on theoretical or pragmatic grounds. [JLJ - yet, human beings do this with ease, almost by instinct, by intuitive thinking.]

p.198 Dynamic models stress the ways in which a system of interest changes through time and therefore have great relevance to the sustainable development debate. Dynamic models are, however, difficult to deal with when they contain nonlinearities.

p.199 One of the major advantages of dynamic modelling is that it allows the development of medium- to long-range forecasting.

p.226 In brief, the base run of the model... The total population continues to rise from 2.5 billion in 1950 to 14.1 billion before becoming extinct in 2150... The main cause of collapse of the human population is due to starvation caused by food shortage