Trends in emissions of ozone-depleting substances, ozone layer recovery, and implications for ultraviolet radiation exposure

Also available:
CCSP Synthesis and Assessment Products. Four-page background document (dated September 2007). In addition, it is available as a PDF file and can be ordered in hardcopy from the GCRIO Online Catalog

Reviewers

Ashley D. Williamson
Tel 301 903 3120
Email:

on Behalf of
Jerry Elwood
Tel: 301 903 3281
Email:

General Comments:

The assessment as outlined addresses stratospheric ozone depletion and UV radiative effects; this is a significant environmental issue, and the chapter outline suggests that the significant technical and policy-relevant issues relevant to ozone depleting substances will be addressed. Further, the scientific background and credentials of the team of authors is impressive and clearly suited to this study. However, the prospectus leaves some questions as to the scope and direction of the assessment.

First, the some statements in the prospectus apparently propose to limit focus in some sense to North America /USA (page 1, lines 46-47 state that the analysis “will be carried out within the context of the USA to distill a regional assessment from the global assessments.”). It is not clear what benefit such a limitation of scope would bring or even how it can realistically be done, since most of the important scientific issues are not limited to this region. In fact, the proposed outline does appear to be appropriately global in scope, in spite of statements such as the above.

Second, the relationship between the proposed assessment and the two prior assessments is unclear. The prospectus references the 2006 WHO/UNEP assessment and the 2005 IPCC special report and states the specific intention to rely heavily on these documents, other than the “distilling” process mentioned above. Is any added value is planned in the current product? If there are specific gaps to be filled by this SAP, they should be described so that the reader understands how the document will be more than a rehash of these sources under CCSP covers (as implied in section 5, p 5, lines 8-9). As discussed in the first comment above, it would be even worse to produce a compilation with even less information by deleting information not primarily related to North America.

RESPONSE: We thank Dr. Ashley Williamson for the comments on SAP 2.4.  We appreciate the kind words on the composition of the panel and their expertise.
The strategy of CCSP in this SAP was to actively contribute to and utilize the information from International assessments.  This is a Synthesis and Assessment Product, and there will be a lot of synthesis involved in gelling information from the SROC report of IPCC and the WMO/UNEP ozone assessment.  Some specific information about the contributions of the USA to global emissions of ODSs, how much USA has moved away from CFCs, etc. are important information that will be derived here and of specific use to the policy makers of the country.  As noted in the Prospectus, information such the contributions of the exemptions are of special interest.  So, we can only reassure the commenter that this will not be a “rehash” but provide specific usable information.

Specific Comments:

Page 1, Lines 33-35: Restricting the focus to North America is inappropriate since these items are global in scope or impact. Consider deleting this statement.

RESPONSE: See above, Response to General Comments.

Page 1, Lines 46-47: Restricting the focus to North America is inappropriate since there is little distinctively regional in the topics described here. Consider deleting this statement.

RESPONSE: We do not mean that the SAP will be limited to North America.  We do say that there will be an emphasis on North America.  This was precisely the points noted by the Agencies in their response.  We specifically added this context in response to the comments from the Agencies.  We will indeed cover this issue on a global scale.

Page 2, Lines 10-11: This statement is vague. Does “relate to” mean “affect” or “are affected by”? Does the report really intend to address either of these beyond emissions scenarios?

RESPONSE:  We have changed the sentence to read “Describe how these findings relate to human emissions, with an emphasis on the U.S. emissions.”.

Page 2, Lines 44-45: This statement is vague, and may promise too much. If the report really will describe ozone layer impacts beyond atmospheric and radiation parameters, it is fine as is. If not, I recommend deleting it.

RESPONSE: Dropped this sentence