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

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Comments
IPCC WGIII Fourth Assessment Report, Second Order Draft
below the equilibrium level corresponding to 450-ppmv CO2-eq
stabliziation would require policies that lead to peaking of global
emissions within the next few decades. The authors should
potentially clarify the statement of B.5. The key point is that is that
emissions must peak and decline to meet any long-term
concentration level and that the lower the level the more quickly
this peak and decline must occur. The discussion could be
improved to provide greater clarity, more information, more linkage
to the material in Table SPM.1, and more context within which to
interpret the information (e.g., why 450 ppmv, overshoot issues).
U.S. Government
(Government of U.S. Department of State)
B 5 1 5 6 The authors need to clarify the statement of B.5. The key point is
that is that emissions must peak and decline to meet any long-term
concentration level and that the lower the level the more quickly
this peak and decline must occur. The discussion could be
improved to provide greater clarity, more information, more linkage
to the material in Table SPM.1, and more context within which to
interpret the information (e.g., why 450 ppmv, overshoot issues).
U.S. Government
(Government of U.S. Department of State)
A 5 2 5 6 The data in Table SPM1 does not support the assertion that global
emissions need to peak in the next couple of decades. 2080 and
2100 do not connote the next couple of decades. The authors need
to be more careful in making sweeping statements like this. If the
goal here is to do an unbiased survey of the literature, one needs to
be clear that the peak date and therefore what actions need to take
place today is highly dependent upon the stabilization level and key
assumptions about climate sensitivity. If the point is simply to
focus on 450 and 550 cases, then it is true that dramatic change
needs to happen soon. But if that is the goal then the SPM should
drop the pretense of looking at a wide range of stabilization
scenarios.
(James Dooley, Battelle)
Expert Review of Second-Order-Draft
Confidential, Do Not Cite or Quote
Response suggested by cochairs
TIA; heading text to be deleted,
but wording to be used for
merging with para 5
TIA; heading text to be deleted,
but wording to be used for
merging with para 5
Action
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chapter
Considerations
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team
Page 88 of 348