Downscaling the Planetary Boundaries in absolute environmental sustainability assessments – a review

Abstract The safe operating space as defined by the Planetary Boundaries framework can be used as an environmental sustainability reference in absolute environmental sustainability assessments (AESAs). In AESAs, the safe operating space must be distributed among human activities so impacts associated with an activity can be related to its assigned share of the safe operating space to assess if the activity can be considered absolute sustainable. To ensure choices concerning sharing principles in AESA are deliberate, there is a need for understanding the distributive justice theory underlying the sharing principles. This study provides a framework for determining and communicating the distributive justice theories that underlie the choice of sharing principles in AESA. To comprehensively describe a sharing principle in relation to distributive justice theories, seven dimensions must be defined, i.e. target, currency, pattern, geographical scope, temporal scope, clauses, and constraints. We conducted a review of sharing principles used in AESAs in relation to contemporary distributive justice theories. 18 studies were identified with 34 sharing principles being applied. The most commonly applied sharing principle is equal per capita sharing of the safe operating space among countries or individuals. This was often combined with utilitarian principles for sharing among industrial units. Based on the review and analysis of the results, we provide recommendations on best practice for defining sharing principles in AESAs systematically based on distributive justice theories and recommendations for further research. The framework developed in this study provide a first step towards a systematic and informed selection of sharing principles used in AESAs.