Download What is a Wedges Analysis? - Department of Premier and Cabinet

What is a Wedges Analysis?
A Wedges Analysis is a means of comparing the Business As Usual (BAU) greenhouse gas
emissions scenario with the potential reductions available over time through various
abatement methods.
The Wedges Analysis concept was first developed by the Carbon Mitigation Initiative,
Princeton University, in the scientific paper Stabilization Wedges: Solving the Climate Problem
for the Next 50 Years with Current Technologies1 (Pacala and Socolow, 2004).
Figure 1 shows an example of a Wedges Analysis graph. The broken black line shows the
green house gas emissions growth under the BAU scenario. The orange line shows the
emissions reduction target, or the maximum greenhouse gases that can be produced in
order to stay below a given concentration of CO2 in the atmosphere and therefore to limit
global warming.
Figure1. An example of a Wedges Analysis graph, courtesy of the Carbon Mitigation
Initiative, Princeton University, http://cmi.princeton.edu/wedges/
1
Pacala, S. & Socolow, R. 2004. Stabilization Wedges: Solving the Climate Problem for the Next 50 Years with
Current Technologies. Science, 305 (5686): 968-972.
Tasmanian Climate Change Office
Department of Premier and Cabinet
We d ge s An alys is
Each of the “wedges” between these two paths represents the potential for a particular
abatement technology or activity to reduce greenhouse gas emissions over time. Some
examples of “wedges” could be improved fuel economy, substituting natural gas for coal, or
wind energy generation.
In the Stabilization Wedges paper, each wedge was equal in size, starting at zero emissions
reduction today and increasing in a linear fashion to one gigatonne per year of carbon
emissions reduction in 50 years’ time. This is a total of 25 gigatonnes of reduced emissions
over the full 50 year period. The authors then identified numerous existing activities which
could be scaled up to produce the required result for each wedge.
A more recently developed approach models the abatement potential of variety of potential
abatement activities or technologies to shape realistic wedges for a particular jurisdiction.
The advantage of this method is that a wedges model can be developed that shows how
reductions may be achieved more quickly or economically and allows realistic, jurisdictionspecific targets to be identified.
The capacity for emissions reductions from a particular technology depends on how much it
is used and how it relates to other factors. For example, if coal is not widely used for energy
generation, the substitution of natural gas will have a less significant effect on overall
emissions. Similarly, if emissions reductions have already been achieved through uptake of
hybrid or electric vehicles, the widespread adoption of biofuels will have less impact than on
a fleet of petrol driven cars, and vice versa.
The original Wedges Analysis considered only those options which were already being
deployed on an industrial scale, regardless of their costs and benefits. The newer approach,
used in the Tasmanian Wedges Project, ensures that the assessment of each abatement
option takes into account the relative benefits and costs of that option.
The aim of a Wedges Analysis is to provide a basis for the setting of interim emission
reduction targets and the formulation of Government policy required to meet these targets.
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Tasmanian Climate Change Office
Level 5, 15 Murray Street, Hobart TAS 7000
Tel: 03 6270 5485 Email: [email protected]