In 1987, the United Nations identified sustainable development as a critical priority. This concentrated the world’s attention on a set of related issues and problems, which had been recognised earlier, but in sporadic and specialised fashion. Put simply, the problem was that existing patterns of growth and development, while driven by rational behaviour at the individual, enterprise and even national level, produced aggregate effects that jeopardise not only the collective aspiration for adequate, equitable and fulfilling life for all but even the very continuation of life on the planet. In order to deal with such a problem, it is necessary to recognise it at a collective level, to understand its dimensions and uncertainties, to identify the important actors and their motivations and powers, and to develop collective institutions (of whatever degree of formality) capable of supporting solutions.

The UN report identified three dimensions along which sustainability could be assessed: environmental (comprising resource use and ecological impact); economic (combining the provision and distribution of the means of sustaining life) and societal (including the institutions through which we interact with one another). Subsequent work has expanded this view (recognising in particular an additional, cultural dimension to sustainability), greatly improved our scientific understanding of the mechanisms and processes involved, generated masses of new data about the state and trajectory of world systems, and produced a host of policy and institutional suggestions. Some have been tried out, and many more have been discussed. But the challenges of sustainability, far from receding, have sharpened and drawn closer. Moreover, despite the early and largely uncontested recognition that these problems (as a whole) are global in scope and require collective solution, increased awareness and knowledge have largely served to exacerbate division and suspicion.

In addition to recognising the importance of the environmental, economic, societal and cultural dimensions of sustainability, it is increasingly recognised that these dimensions are important as a means of measuring sustainability and as a domain within which human institutions operate. The assessment of sustainability has also advanced; in the beginning, it was measured in terms of stocks of scarce resources, income, social capital, cultural products, etc. Despite early indications, we have not run out of these things. From this, we have learnt two lessons. First, human ingenuity can identify substitutes for scarce resources. Second, from the human welfare perspective the ownership and distribution of resources matters as much as their absolute levels. This suggests that we should be concerned with the capability of world systems to support life – this is a more general and technology-friendly concept than a stock-based definition. Moreover, the past three decades have thrown up a number of shocks to the system. Some reflect unforeseen events, though most are the result of unanticipated spillovers from one sustainability domain to another or from responses to past changes. The conclusion here is that sustainability concepts and analyses based on capabilities need to be bolstered by considerations of resilience to shocks, and that policies and plans need to be both robust and adaptive.

Overall, we are led to focus on what can be sustained, and what is needed to sustain it. To usefully implement such a definition, it is necessary to consider multi-dimensional outcome surfaces , develop interlinked representations of world systems, deal sensibly with risk and uncertainty, develop indicators that are connected to relevant decisions and consider ranges of preferences in a balanced, transparent and neutral way.