Page 113 - Materials Chemistry, Second Edition

LIFE CYCLE IMPACT ASSESSMENT 95

their LCA by assessing spatially-specific inventory emissions, if known. The
geographical scope of the majority of these developments, however, remains
restricted within a continental area and ignores transboundary emissions.
Some of them provide a spatially-resolved assessment at the global scale, but
usually by addressing a single impact category that is not available in a ready-
to-use format for the LCA practitioner. More recently IMPACT World+ is being
developed out of the need to offer a regionalized methodology at a global
scale. Spatially-differentiated characterization models and factors have been
developed for respiratory effects, toxic impacts, ionizing radiations, water
use, acidification, eutrophication and land use impact categories, each of them
based on an appropriate spatial scale. This latter was defined around the most
sensitive modeling parameters, such as watersheds for water use impacts,
biomes for land use impacts, or based on an archetype approach built upon the
sensitive parameters. Particular attention has been given to the harmonization
of modeling assumptions between different impact pathways. The uncertainty
associated with the CFs for each of these "fine-scale" models has been deter-
mined. These fine-scale CFs have been aggregated at the country, subconti-
nental, and global scales using the geographical distribution of emissions (or
emission proxis) as weighting factors. This resulted in CFs at different geo-
graphical resolutions, each with its own associated uncertainty and spatial
variability.
The LC-IMPACT project, supported by the European Commission's 7 th
Framework Programme for Research and involving more than a dozen orga-
nizations including a research center and an industry, represents an impor-
tant initiative that demonstrates the growing interest and research activity
around spatially-differentiated LCIA. One of the main objectives of this proj-
ect includes the development of spatially-explicit CFs based on a global scale
for land use, water exploitation, toxicants, priority air pollutants and nutrient
(http://www.lc-impact.eu/about-lc-impact).
The development toward a spatially-differentiated impact assessment is
likely to modify the ISO paradigm. It is foreseeable in the near future that
LCAs will be performed in three separate and successive phases: 1. Goal &
Scope Definition, 2. Life Cycle Inventory, and 3. Impact Assessment, plus the
interpretation step at each phase. In this way, a chemical emission or consump-
tion of a given resource will have a different CF depending on the geographi-
cal location where the environmental intervention occurred. So, instead of
computing an LCI as a sum of chemical emissions over the whole life cycle;
one will first characterize the emissions at each geographical location and then
sum the impact scores among these locations.

4.7.2 Addressing Uncertainty and Variability in Characterization
Factors

Associating uncertainty information with CFs, encompassing both spatial
variability and model uncertainty, is not current practice in LCA. So far,