3.3 Lessons for the Classification and Integration …
47
3.3.2 Lessons for the Classification of Footprints:
A Two-Category Framework
Simply put, environmental footprints are defined as indicators that measure anthropogenic pressure or associated impacts placed on the environment by human actions,
irrespective of their precise units and dimensions. Rather than carrying on the neverending debate over the definition of footprints, we propose shifting the focus to the
classification of footprints which, in our view, is the key to making sense of the
footprint concept. In accordance to the investigation conducted above, two broad
categories of footprints are identified, namely, the IVOFs and IPOFs. This is a rough
dichotomy with respect to the ways in which a growing number of footprints are
shaped. In the following, we elaborate on the two categories of footprints individually,
together with a comparison of their inherent properties.
3.3.2.1 Inventory-Oriented Footprints (IVOFs)
The IVOFs are the footprints that compile and weight the inputs and outputs of
environmental exchange (i.e., hazardous emissions and resource extractions) at the
inventory level. It builds on the belief that physical units (e.g., ha, m
3 , kg) provide an
intuitive and intrinsic understanding of the anthropogenic pressure due to emissions
and extractions, which is probably the original intent of what a footprint is supposed
to convey to the public. This valuable information, however, is found to be lost
when translating into an impact score through characterization modeling (Hoekstra
et al. 2009). Apparently, all the four classical footprints, namely the CF class , WF class ,
LF class , and MF class , fall under the scope of the IVOFs.
3.3.2.2 Impact-Oriented Footprints (IPOFs)
The IPOFs are those which not only comply with an inventory analysis but also
characterize the inventory results through their respective contributions to a given
impact category at the impact assessment level. The rationale behind the IPOFs is that
contributing substances differ in their effects on the same impact category (sometimes
by orders of magnitude), and therefore cannot be compared or aggregated without the
use of characterization factors reflecting the up-to-date scientific knowledge about
the effects of the impact category assessed on the environment and human health.
We classify the CF clim , WF scarc , LF disturb , and MF scarc as members of the IPOFs.
Nevertheless, one should be aware that while some IPOFs use physical look-alikes
units (e.g., the CF clim uses kg CO 2 -eq.), such units differ markedly from the real
measurable footprints in the IVOF category.
47
3.3.2 Lessons for the Classification of Footprints:
A Two-Category Framework
Simply put, environmental footprints are defined as indicators that measure anthropogenic pressure or associated impacts placed on the environment by human actions,
irrespective of their precise units and dimensions. Rather than carrying on the neverending debate over the definition of footprints, we propose shifting the focus to the
classification of footprints which, in our view, is the key to making sense of the
footprint concept. In accordance to the investigation conducted above, two broad
categories of footprints are identified, namely, the IVOFs and IPOFs. This is a rough
dichotomy with respect to the ways in which a growing number of footprints are
shaped. In the following, we elaborate on the two categories of footprints individually,
together with a comparison of their inherent properties.
3.3.2.1 Inventory-Oriented Footprints (IVOFs)
The IVOFs are the footprints that compile and weight the inputs and outputs of
environmental exchange (i.e., hazardous emissions and resource extractions) at the
inventory level. It builds on the belief that physical units (e.g., ha, m
3 , kg) provide an
intuitive and intrinsic understanding of the anthropogenic pressure due to emissions
and extractions, which is probably the original intent of what a footprint is supposed
to convey to the public. This valuable information, however, is found to be lost
when translating into an impact score through characterization modeling (Hoekstra
et al. 2009). Apparently, all the four classical footprints, namely the CF class , WF class ,
LF class , and MF class , fall under the scope of the IVOFs.
3.3.2.2 Impact-Oriented Footprints (IPOFs)
The IPOFs are those which not only comply with an inventory analysis but also
characterize the inventory results through their respective contributions to a given
impact category at the impact assessment level. The rationale behind the IPOFs is that
contributing substances differ in their effects on the same impact category (sometimes
by orders of magnitude), and therefore cannot be compared or aggregated without the
use of characterization factors reflecting the up-to-date scientific knowledge about
the effects of the impact category assessed on the environment and human health.
We classify the CF clim , WF scarc , LF disturb , and MF scarc as members of the IPOFs.
Nevertheless, one should be aware that while some IPOFs use physical look-alikes
units (e.g., the CF clim uses kg CO 2 -eq.), such units differ markedly from the real
measurable footprints in the IVOF category.