A planetary boundary-based environmental footprint family: From impacts to boundaries

Environmental footprints are of importance for identifying the linkages between human and natural systems. This paper defines a framework for an environmental footprint family that is based on nine major biophysical processes and is linked to the planetary boundaries. Bibliometrics was used to analyze the volume, journals, categories, countries, keywords, priority issues and research prospects of each of the individual footprints. Results show that the total amount of footprint research has been increasing with the United States and China being the regions of highest research intensity based on total publications and frequency of cooperation. Subject category and keyword co-occurrence analyses showed that environmental footprints are widely used as an assessment methodology in relation to the Sustainable Development Goals concerning resource use and pollutant emissions. The most common research topics were energy and supply chain-related carbon footprints, agricultural-related greenhouse gas emissions abatement, volumetric and impact-oriented water footprints, and infrastructure-related environmental footprints. Further research is needed to better align impact-oriented footprints that include regional differentiation with the planetary-scale boundaries. In addition, the earth system is complex and many of the planetary boundaries are inter-related and feedbacks need further definition and quantification. These findings provide an overview of the current state of environmental footprint research which can give direction to future studies.