TITLE:
Policies and Consumption-Based Carbon Emissions from a Top-Down and a Bottom-Up Perspective
AUTHORS:
Kirsten S. Wiebe, Simon Gandy, Christian Lutz
KEYWORDS:
Carbon Emissions, Life Cycle Assessment, Multi-Regional Input-Output Analysis, Car Industry, Renewable Energy
JOURNAL NAME:
Low Carbon Economy,
Vol.7 No.1,
March
16,
2016
ABSTRACT: Two major approaches for calculating consumption-based carbon emissions
can be distinguished: top-down approaches, in the form of multi-regional
input-output (MRIO) models, and bottom-up approaches, in the form of life cycle
assessment (LCA). Both approaches have pros and cons and are very data-intensive.
Several MRIO databases have been developed and published over the past years.
These databases, which have been refined and validated, will be used for policy
analysis. As LCA is usually only applied to very specific products and product
groups, analysis is limited and many products have not yet been looked at. This
paper makes use of both a top-down and bottom-up approach to calculate the
impacts of different policy measures on the development of consumption-based
carbon emissions in the EU28 and on emissions elsewhere in the world. The policy
examples used are the EU’s CO2 in Cars Regulations and the South
African renewable energy initiative. The results from the top-down approach are
then compared with those from the bottom-up approach. Both bottom-up and
top-down approaches use the same underlying assumptions regarding the impacts,
but due to the very different nature of the methodologies, differences in the
results are observed, though sign and scope of the results are the same for the
two cases. Part of the deviations can be explained by differences in
methodology and scenario design due to these differences. It can be concluded
that bottom-up and top-down approaches can and need to be applied to different
policies and are generally complementary.