SODBatch A&B SPM Comments co-chair response final ... - ipcc-wg3

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IPCC WGIII Fourth Assessment Report, Second Order Draft
scenario. In other words, the overall “reference” technology
pathway can be as, if not more, important in determining the costs
of a given scenario as the stringency of the ultimate climate
stabilization target chosen. (cf. Figure 2.4)” U.S. Government
(Government of U.S. Department of State)
SPM-9 B 0 0 0 0 “optimal” (cost-minimizing) emission scenarios is bimodal,
illustrating that technological lock-in into either high or low
emissions futures respectively that arise from technological
interdependence and spillover effects. U.S. Government
(Government of U.S. Department of State)
SPM-10 B 0 0 0 0 “Differences in the cost of meeting a prescribed CO2 concentration
target across alternative technology development pathways that
could unfold in the absence of climate policies are more important
than cost differences between alternative stabilization levels within
a given technology-reference scenario. In other words, the overall
“reference” technology pathway can be as, if not more, important in
determining the costs of a given scenario as the stringency of the
ultimate climate stabilization target chosen. (cf. Figure 2.4)” U.S.
Government
SPM-
101
(Government of U.S. Department of State)
3 A 0 0 0 0 The issue of PPP, Purchasing Power Parities, is not mentioned in
the SPM. It is a fact that there is uncertainty about the impact of
using MER versus PPP. It is also a fact that there is a data problem
if PPP is used, so most surveys are based on MER. However, there
is no doubt that PPP would be a better option, and MER
underestimates the purchasing power in especially poorer countries,
thereby GDP growth and CO2-emissions are overestimated (as
stated in chapter 3, p. 21-25). The use of MER is therefore likely to
distort the distribution of global emissions and will distort the cost
impact of the mitigation effort. Though facts of how big this
distortionary impact is, cannot be found, it might be significant.
This uncertainty and potential impact is too important to be totally
neglected in the SPM.
Expert Review of Second-Order-Draft
Confidential, Do Not Cite or Quote
Response suggested by cochairs
Identical B-8
Identical B-8
DISCUSS; issue is mentioned in
para 3 but is very weak
conclusion; ch 3 to better
analyse literature to formulate
more meaningful conclusion
Action
for
chapter
Considerations
by the writing
team
3 Noted. Material
in Ch3 being
revised and core
messages will
be brought into
SPM.
(3)
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