P. 22, Figure 1.1: Discussion of this figure could be expanded to include much more about the role of ozone in the climate system and vice versa. Figure 1.1 lacks methane and N2O components.
P. 24, L. 483: Not all CFC substitutes are “climate friendly.”
P. 24, L. 491: After “Perfluorocarbons”, add “and referenced therein.”
Chapter 2 of the draft SAP is comprehensive in its discussion of the production, consumption, emissions, and atmospheric abundances of ODSs and total equivalent chlorine. Although the committee was impressed with the completeness of this review of ODSs, which includes all the information required, it is not presented in an understandable way. Chapter 2 is a long chapter, and its organization was difficult to follow. To aid other readers, the authoring team should consider including an introduction to the chapter and a brief discussion about the organization of the chapter. Chapter 2 should include more thorough explanations throughout, should synthesize information on production, consumption, emissions, and banks, and should explain the various measures of ozone before presenting the key findings. Making the detailed suggestions in the following comments will improve the readability and the accuracy of the synthesis presented in Chapter 2. Chapter 2 of the draft is written at level only understood by halocarbon experts rather than a level accessible for professionals who work at the interface between science and policy.
Background information should be presented at the beginning of the draft SAP Chapter 2, perhaps defining concepts and incorporating parts of the key issues section, before presenting the key findings. As part of this background information, the authoring team should add a box in either SAP Chapter 1 or the introduction to SAP Chapter 2 to explain the life cycle of fluorochemicals, define consumption, and explain the relationship between production, consumption, emission, atmospheric concentrations, and EESC or radiative forcing. Elements of that box should include the following:
A cartoon similar to Figure SPM-1 of the IPCC/TEAP Special Report on Ozone and Climate (IPCC/TEAP 2005).
A definition of consumption, in agreement with the Clean Air Act and the Montreal Protocol: Consumption = Production + Imports − Exports. Include a statement that consumption equals production at the global level. Under the Montreal Protocol, the primary control is on consumption and not emissions. This means that there is no control of “banks under the Protocol.” Probably not to be stated in the SAP, an issue of note is the growing movement in the United States to control HFCs through control of consumption. The justification and implication of this definition are the basis for focusing on consumption in Chapter 2.