Applying environmental sustainability boundaries for climate change in life cycle assessment: A review of approaches and implications for policymaking

Environmental sustainability boundaries can be used as references in evaluations of the absolute sustainability of activities and for developing policy targets and strategies. Recent literature has applied boundaries for climate change in different ways in life cycle assessment and there is a need for a systematic overview of these approaches, their compatibility with different types of assessments, and their effects on assessment results. This paper addresses that need by identifying and contrasting five approaches to operationalizing the climate change boundary and applying these approaches to a common case of the EU27 + UK consumption footprint in 2019. The identified operationalization approaches are found to be either static or dynamic. Static approaches enable comparison with a boundary which is constant through time, while dynamic approaches interpret the environmental sustainability boundary as a trajectory toward reaching net-zero emissions at the right time. When applying the five operationalization approaches to the 2019 consumption footprint of the EU27 + UK, we find that emissions reduction should be more ambitious than the current European Green Deal targets. For policymaking, the static approaches can offer a highly ambitious ideal reference aiding immediate action but can lack adaptability to evolving conditions. Dynamic approaches better address long-term goals and evolving knowledge but are more complex. This study contributes to the literature on absolute sustainability assessment by unravelling model choices and their implications for assessment results and policymaking.