1.2 The Development of Environmental Footprints
3
In keeping with the ongoing expansion of the footprint family (Fang et al. 2014;
Galli et al. 2012), the underlying methodologies are currently undergoing rapid development. In addition to the NFA, life cycle assessment (LCA) (Weidema et al. 2008),
input–output analysis (IOA) (Hertwich and Peters 2009), material flow analysis
(MFA) (Schoer et al. 2012), and emergy-based (Zhao et al. 2005) and exergy-based
methods (Chen and Chen 2007) have proved useful in calculating different environmental footprints at scales ranging from single products, processes, organizations,
industries, nations, even to the whole human economy. Recently emerging hybrid
approaches that take advantage of both LCA and IOA have shown great potential for
meso-level footprint accounting for which well-established methods are lacking. As
a whole, the choices of appropriate methods are playing a central role in quantitative
footprint studies.
The footprint family concept has attracted considerable interest as it offers the
scientific community an opportunity to achieve simultaneous measurement of various
environmental footprints with implications for trade-off issues (e.g., De Meester et al.
2011; Ridoutt et al. 2014). By structuring a specified footprint family based on LCA
(De Benedetto and Klemeš 2009) or on multi-regional input–output (MRIO) models
(Ewing et al. 2012), for instance, current accounts for selected footprints have been
conceptually integrated into single unified frameworks that would allow for greater
transparency and consistency. A further step towards policy-relevant research is to
develop an integrated footprint family that is supposed to encompass the complexity
of some highly heterogeneous environmental issues, such as climate change (carbon
footprint), water use (water footprint), land use (land footprint), and material use
(material footprint).
1.3 Debates on Environmental Footprints
Since the first emergence of the ecological footprint, the term “footprint” has stimulated scientific debates, representing important steps in the ongoing discourse on
sustainability (e.g., Hoekstra and Wiedmann 2014; Kitzes et al. 2009). Of particular concern is what actually counts as a footprint. Efforts have been made to lay the
foundation for a widely accepted footprint definition (e.g., Hammond 2007; Pelletier
et al. 2014). At least five competing criteria are evidently available in the literature
for definition of footprints:
1. Footprints are indicators that express their results in an area-based metric unit.
Clearly the ecological footprint represents the most obvious example of this.
Many other well-known indicators, like the carbon footprint and the water
footprint, would fall outside the scope by this definition.
2. Footprints are indicators that are intended for easy communication of results to
the general public, policy makers, or other decision-makers. Indicators that aim to
inform scientists and engineers, for instance, would in that case not be considered
as a footprint. An example of such indicators is eutrophication potential.
3
In keeping with the ongoing expansion of the footprint family (Fang et al. 2014;
Galli et al. 2012), the underlying methodologies are currently undergoing rapid development. In addition to the NFA, life cycle assessment (LCA) (Weidema et al. 2008),
input–output analysis (IOA) (Hertwich and Peters 2009), material flow analysis
(MFA) (Schoer et al. 2012), and emergy-based (Zhao et al. 2005) and exergy-based
methods (Chen and Chen 2007) have proved useful in calculating different environmental footprints at scales ranging from single products, processes, organizations,
industries, nations, even to the whole human economy. Recently emerging hybrid
approaches that take advantage of both LCA and IOA have shown great potential for
meso-level footprint accounting for which well-established methods are lacking. As
a whole, the choices of appropriate methods are playing a central role in quantitative
footprint studies.
The footprint family concept has attracted considerable interest as it offers the
scientific community an opportunity to achieve simultaneous measurement of various
environmental footprints with implications for trade-off issues (e.g., De Meester et al.
2011; Ridoutt et al. 2014). By structuring a specified footprint family based on LCA
(De Benedetto and Klemeš 2009) or on multi-regional input–output (MRIO) models
(Ewing et al. 2012), for instance, current accounts for selected footprints have been
conceptually integrated into single unified frameworks that would allow for greater
transparency and consistency. A further step towards policy-relevant research is to
develop an integrated footprint family that is supposed to encompass the complexity
of some highly heterogeneous environmental issues, such as climate change (carbon
footprint), water use (water footprint), land use (land footprint), and material use
(material footprint).
1.3 Debates on Environmental Footprints
Since the first emergence of the ecological footprint, the term “footprint” has stimulated scientific debates, representing important steps in the ongoing discourse on
sustainability (e.g., Hoekstra and Wiedmann 2014; Kitzes et al. 2009). Of particular concern is what actually counts as a footprint. Efforts have been made to lay the
foundation for a widely accepted footprint definition (e.g., Hammond 2007; Pelletier
et al. 2014). At least five competing criteria are evidently available in the literature
for definition of footprints:
1. Footprints are indicators that express their results in an area-based metric unit.
Clearly the ecological footprint represents the most obvious example of this.
Many other well-known indicators, like the carbon footprint and the water
footprint, would fall outside the scope by this definition.
2. Footprints are indicators that are intended for easy communication of results to
the general public, policy makers, or other decision-makers. Indicators that aim to
inform scientists and engineers, for instance, would in that case not be considered
as a footprint. An example of such indicators is eutrophication potential.