Government Comments on the Final Draft of the SPM IPCC Working ...

<strong>Government</strong> <strong>Comments</strong> on the Final Draft of the SPM
IPCC Working Group I Fourth Assessment Report
Batch
Page:line
No.
From To Comment
SPM-886 A 14:8 14:8 It would be helpful to add some examples of important "dynamical processes not included in current models".
[Govt. of United Kingdom (Reviewer’s comment ID #: 2022-45)]
SPM-887 A 14:8 14:8 Explain “dynamical process”. Vector displacement of ice sheets?
[Govt. of United States of America (Reviewer’s comment ID #: 2023-92)]
SPM-888 A 14:11 14:11 The problem with models is much bigger than just the recent observations. Antarctic models can't even reproduce the ice
streams that control the mass balance of WAIS. The SPM needs to underscore the profound shortcoming of models, ie, we
have no credible tool for projecting the ice sheet contribution to SLR. We need to communicate very clearly on the reasons
why the SLR range in this assessment is smaller than in the TAR.
[Govt. of Belgium (Reviewer’s comment ID #: 2003-65)]
SPM-889 A 14:12 14:12 The authors need to include a dot point explaining the uncertainties about the feedback caused by ice albedo effect in the
Arctic
[Govt. of Australia (Reviewer’s comment ID #: 2002-133)]
SPM-890 A 14:13 14:15 The two sentences on Antarctica and sea level rise needs to be expanded as they give no indication of the uncertainty in
present continental ice sheet models. Suggest change to something like: "Present continental ice sheet models have projected
that the Antarctic ice sheet will remain too cold for widespread surface melting and there would be a gain in mass due to
increased snowfall. Dynamical processes not included in these models would likely change this assessment as a net loss of ice
mass could occur if dynamical ice discharge dominates the ice sheet mass balance. In the recent decade 1993-2003 for
Antarctica these models estimated a take of ice with a sea level fall of -0.2±0.4 mm/yr whilst observations indicated a loss due
likely to the kinds of fast ice dynamics not included in the models of 0.21 ± 0.35 mm/yr. At the present time little confidence
can be placed in the sign or magnitude of the projections by continental ice sheet models of the response of Antarctica to
global warming.”
[Govt. of Germany (Reviewer’s comment ID #: 2011-54)]
SPM-891 A 14:13 14:15 See point 10 above. (SPM page 8, lines 42-45. - TSU Edit)
[Govt. of Italy (Reviewer’s comment ID #: 2012-50)]
SPM-892 A 14:13 14:15 Please rephrase the first sentence as follows: "Current global model studies project that the Antarctic ice sheet will remain too
cold for widespread surface melting and increased snowfall will represent a positive input to the mass balance." The current
wording could be misinterpreted to suggest confidence that there will be a net mass gain.
[Govt. of New Zealand (Reviewer’s comment ID #: 2015-12)]
SPM-893 A 14:13 14:15 We would suggest the second sentence in this paragraph include a reference to observations, as follows: "However, net loss of
icemass will occur if dynamical ice discharge dominates the ice sheet mass balance, as recent observations suggest.
[Govt. of New Zealand (Reviewer’s comment ID #: 2015-13)]
SPM-894 A 14:13 14:15 What confidence levels are attached to the statements in this bullet? How likely is it that the Antarctic ice sheet will remain
too cold for widespread melting? How likely is it that Antarctica will make a net positive contribution to sea level rise over
the 21st century?
[Govt. of United Kingdom (Reviewer’s comment ID #: 2022-46)]
SPM-895 A 14:13 14:15 Model projections of mass gain over Antarctica remains a concern. The statement is unclear with respect to time scale, but
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