Review of the U.S. Climate Change Science Program's Draft Synthesis and Assessment Product 2.4: Trends in Emissions of Ozone Depleting Substances, Ozone Layer Recovery, and Implications for Ultraviolet Radiation Exposure (2007)

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1 Introduction The U.S. Climate Change Science Program (CCSP) was established in 2002 to coordinate climate and global change research conducted in the United States. Building upon and incorporating the U.S. Global Change Research Program of the previous decade, the program integrates federal research on climate and global change, as sponsored by 13 federal agencies and overseen by the Office of Science and Technology Policy, the Council on Environmental Quality, the National Economic Council, and the Office of Management and Budget. A primary objective of the CCSP is to provide the best possible scientific information to support public discussion and government and private sector decision making on key climate-related issues. To help meet this objective, the CCSP is producing a series of Synthesis and Assessment Products (SAPs) that address its highest priority research, observation, and decision-support issues. The CCSP is conducting 21 such activities, covering topics such as the North American carbon budget and implications for the global carbon cycle, coastal elevation and sensitivity to sea-level rise, and use of observational and model data in decision support and decision making. Each of these documents will be written by a team of authors selected on the basis of their past record of interest and accomplishment in the given topic. A list of the CCSP SAPs is provided in Appendix A. The purpose of SAP 2.4, the subject of this report, is to address key issues related to the stratospheric ozone layer, including its changes in the past and expected abundance in the future. Also, this SAP will address current abundances and emissions of ozone- depleting substances. Further, it will synthesize the best available information on the past and future levels of ultraviolet radiation at the Earth’s surface. Lastly, it will explore the interactions between climate change and stratospheric ozone changes. The SAP will address all of these issues within a U.S. context to distill a national assessment from two global assessments: the World Meteorological Organization 2006 assessment on the ozone layer (WMO 2007) and the 2005 Special Report of the Intergovernmental Panel on Climate Change, Safeguarding the Ozone Layer and the Global Climate System – Issues Related to Hydrofluorocarbons and Perfluorocarbons (IPCC/TEAP 2005). A prospectus for SAP 2.4 was developed to describe the goals and the questions to be addressed (see (CCSP 2007). In a review of the CCSP Strategic Plan, the National Research Council (NRC) recommended that SAPs should be produced with independent oversight and review from the wider scientific and stakeholder communities (NRC 2004). As part of its efforts to meet this goal, the National Oceanic and Atmospheric Administration (NOAA) requested that the NRC provide an independent review of SAP 2.4. The NRC appointed an ad hoc committee composed of nine members to provide this review (see Appendix B). The committee’s Statement of Task is in Box 1.1. The committee conducted its work by reading the draft SAP 2.4 document, Trends in Emissions of Ozone Depleting Substances, 3 

4 Review of CCSP SAP 2.4 Ozone Layer Recovery, and Implications for Ultraviolet Radiation Exposure (draft dated August 20, 2007). Next, the committee met with the SAP authoring team, who provided in-depth presentations of their research and material used to formulate the draft document. The committee met in closed session to discuss the draft SAP in detail. This present report constitutes the committee’s peer review of SAP 2.4 and results from the committee’s careful study of the draft and its interactions with those present at the meeting. This report includes the committee’s findings, recommendations, suggestions, and options for the authors to consider in finalizing SAP 2.4. BOX 1.1 The Statement of Task for the NRC Committee The committee will address the following review criteria (which are based on the NRC's own review criteria): 1. Are the goals, objectives and intended audience of the product clearly described in the document? Does the product address all questions outlined in the prospectus? 2. Are any findings and/or recommendations adequately supported by evidence and analysis? In cases where recommendations might be based on expert value judgments or the collective opinions of the authors, is this acknowledged and supported by sound reasoning? 3. Are the data and analyses handled in a competent manner? Are statistical methods applied appropriately? 4. Are the document's presentation, level of technicality, and organization effective? Are the questions outlined in the prospectus addressed and communicated in a manner that is appropriate and accessible for the intended audience? 5. Is the document scientifically objective and policy neutral? Is it consistent with the scientific literature? 6. Is there a summary that effectively, concisely and accurately describes the key findings and recommendations? Is it consistent with other sections of the document? 7. What other significant improvements, if any, might be made in the document? The following two chapters provide detailed comments for improving SAP 2.4. Chapter 2 of this report presents the committee’s overarching comments, which span more than one section of the SAP. Chapter 3 of this report provides both major and specific comments for the individual sections of the SAP. REFERENCES CCSP (U.S. Climate Change Science Program). 2007. CCSP Synthesis and Assessment Product 2.4: Prospectus for Trends in Emissions of Ozone-Depleting Substances, Ozone Layer Recovery, and Implications for Ultraviolet Radiation Exposure. Washington, DC: U.S. Climate Change Science Program. Available online: http://www.climatescience.gov/Library/sap/sap2-4/sap2-4prospectus-final.pdf. 

Introduction 5 IPCC/TEAP (Intergovernmental Panel on Climate Change/Montreal Protocol’s Technology and Economic Assessment Panel). 2005. Safeguarding the Ozone Layer and the Global Climate System: Issues Related to Hydrofluorocarbons and Perfluorocarbons. IPCC/TEAP Special Report. Geneva: IPCC. Available online: http://arch.rivm.nl/env/int/ipcc/pages_media/SROC- final/SpecialReportSROC.html. NRC (National Research Council). 2004. Implementing Climate and Global Change Research: A Review of the Final U.S. Climate Change Science Program Strategic Plan. Washington, DC: National Academies Press. Available online: http://www.nap.edu/catalog/10635.html. WMO (World Meteorological Organization). 2007. Scientific Assessment of Ozone Depletion: 2006. Global Ozone Research and Monitoring Project - Report No. 50. Geneva. Available online: http://ozone.unep.org/Assessment_Panels/SAP/Scientific_Assessment_2006/inde x.shtml.