No abstract

Sustainability assessment is a recent framing of impact assessment that places emphasis on delivering positive net sustainability gains now and into the future. It can be directed to any type of decision-making, can take many forms and is fundamentally pluralistic. Drawing mainly on theoretical papers along with the few case study examples published to date (from England, Western Australia, South Africa and Canada), this paper outlines what might be considered state-ofthe-art sustainability assessment. Such processes must: (i) address sustainability imperatives with positive progress towards sustainability; (ii) establish a workable concept of sustainability in the context of individual decisions/assessments; (iii) adopt formal mechanisms for managing unavoidable trade-offs in an open, participative and accountable manner; (iv) embrace the pluralistic inevitabilities of sustainability assessment, and (v) engender learning throughout. We postulate that sustainability assessment may be at the beginning of a phase of expansion not seen since environmental impact assessment was adopted worldwide.

Impact assessment has been in place for over 40 years and is now practised in some form in all but two of the world's nations. In this paper we reflect on the state of the art of impact assessment theory and practice, focusing on six well-established forms: EIA, SEA, policy assessment, SIA, HIA and sustainability assessment. We note that although the fundamentals of impact assessment have their roots in the US National Environmental Policy Act 1969 (NEPA) each branch of the field is distinct in also drawing on other theoretical and conceptual bases that in turn shape the prevailing discourse in each case, generating increasing degrees of specialisation within each sub-field. Against this backdrop, we consider the strengths and weaknesses of collective impact assessment practice, concluding that although there are substantial strengths, the plethora of specialist branches is generating a somewhat confusing picture and lack of clarity regarding how the pieces of the impact assessment jigsaw puzzle fit together. We use this 2 review to suggest an overarching research agenda that will enable impact assessment to evolve in line with changing expectations for what it should deliver.

We suggest that the impact assessment community has lost its way based on our observation that impact assessment is under attack because of a perceived lack of efficiency. Specifically, we contend that the proliferation of different impact assessment types creates separate silos of expertise and feeds arguments for not only a lack of efficiency but also a lack of effectiveness of the process through excessive specialisation and a lack of interdisciplinary practice. We propose that the solution is a return to the basics of impact assessment with a call for increased integration around the goal of sustainable development and focus through better scoping. We rehearse and rebut counter arguments covering silo-based expertise, advocacy, democracy, sustainability understanding and communication. We call on the impact assessment community to rise to the challenge of increasing integration and focus, and to engage in the debate about the means of strengthening impact assessment.