Research

Position of existing footprints in the environmental sustainability landscape

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Abstract

To address the sustainability challenges, an increasing number of footprints have been developed. Their relative simplicity has contributed to make some of them, like ecological footprint and carbon footprint, widely used and broadly accepted by stakeholders in industry and authorities. But how do these different footprints relate to the overall context of environmental sustainability, and where are they positioned compared to other tools and framework such as life cycle assessment (LCA) and planetary boundaries (PB)? In this study, we performed a review of existing footprints, evaluated their roles and limitations in relation to more broadly-encompassing assessment tools like LCA, and discussed the need and approaches to set up footprint thresholds that can indicate levels, above which the analysed system reaches environmentally-unsustainable states, and help benchmark footprint results. Our results showed that the role of footprints should be detached from that of LCA, which aims to comprehensively assess environmental impacts while footprints are directed to addressing specific area of concern defined by the interest of society. Studies have showed that stand-alone footprints do not comprehensively capture all environmental problems, hence emphasising the need for researchers and stakeholders to be careful not to overstate the conclusions of their footprint results, e.g. claiming environmental sustainability when only performing a carbon footprint. To complement footprint results and facilitate interpretation and communication of the results to stakeholders, footprint thresholds are required. Global thresholds have been proposed in earlier studies. However, only in the case of blue water scarcity footprint did we find a good match between the PB framework and existing footprint thresholds. For carbon footprint, thresholds based on the 2-degree target were not found to completely match with the planetary boundaries for climate change, defined at the level preventing the Earth System from moving out of its stable, Holocene-like state. For other footprints, weak or irrelevant linkages between the footprint indicators and the PB were observed, e.g. ecological footprints. In this setting, we therefore recommend that science-based sustainability targets be consistently developed as footprint thresholds, also addressing the need to define these at scales corresponding to the assessed entities, e.g. individuals, products, organisations, industrial sectors.