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Frontmatter -- Contents -- Foreword to the First Edition -- Preface to the First Edition -- Preface to the Enlarged Edition -- Abbreviations -- 1. Lessons from History -- 2. The Science: Models of Uncertainty -- 3. Spray Cans and Europolitics -- 4. Prelude to Consensus -- 5. Forging the U.S. Position -- 6. The Sequence of Negotiations -- 7. Points of Debate -- 8. The Immediate Aftermath -- 9. New Science, New Urgency -- 10. The Road to Helsinki -- 11. The Protocol in Evolution -- 12. The South Claims a Role -- 13. Strong Decisions in. London -- 14. Accelerating the Phaseout -- 15. A New Phase for the Protocol -- 16. "Common but Differentiated Responsibilities" -- 17. Promoting Compliance -- 18. New Controls for North and South -- 19. A New Global Diplomacy: Ozone Lessons and Climate Change -- Chronology -- Appendix A Vienna Convention for the Protection of the Ozone Layer, March 1985 -- Appendix B Montreal Protocol on Substances That Deplete the Ozone Layer, September 1987 -- Appendix C London Revisions to the Montreal Protocol, June 1990 (Excerpts) -- Appendix D Montreal Protocol Phaseout Schedules -- Appendix E Terms of Reference for the Multilateral Fund -- Appendix F Terms of Reference of the Executive Committee -- Appendix G Noncompliance Procedure -- Appendix H The Nearly Universal Treaty: Parties to the 1985 Vienna Convention and 1987 Montreal Protocol, with Ratifications to the 1990 London and 1992 Copenhagen Amendments -- Notes -- Select Ozone Bibliography (cited in chronological order) -- Index

Using the Whole Atmosphere Community Climate Model version 6, stratospheric ozone in the Last Glacial Maximum (LGM) is investigated. It is shown that, compared with preindustrial (PI) times, LGM modeled stratospheric temperatures are increased by up to 8 K, leading to faster ozone destruction rates for gas phase reactions, especially via the Chapman mechanism. On the other hand, stratospheric hydroxyl radical (OH) and nitrogen oxides (NOx) concentrations are decreased by 10?20%, which decreases catalytic ozone destruction, thereby decreasing ozone loss rates. The net effect of these two compensating mechanisms in the upper stratosphere (above 15 hPa) is a vertically integrated 1?3 Dobson unit (DU) decrease during the LGM. In the lower stratosphere (tropopause to 15 hPa), changes in the stratospheric overturning circulation and resulting transport dominate changes in ozone. Consistent with a weakening of the residual circulation in the LGM, lower stratospheric ozone is increased by 2?5 DU in the tropics and decreased by 5?10 DU in the extratropics, but the latter is partly compensated by ozone increases due to a lower tropopause. It is found that tropospheric ozone is decreased by about 5 DU in the LGM versus PI. Combined changes in stratospheric and tropospheric ozone lead to a decrease in total ozone column everywhere except over the northeast North America, equatorial Indian and West Pacific Oceans. Surface ultraviolet radiation in the LGM versus PI is increased over the Northern Hemisphere middle and high latitudes, especially over the ice caps, and over the Southern Hemisphere near 60°S. ; This research was supported by NSF Grant AGS‐1821437 and NASA Grant 80NSSC18K1031. S. S. was supported by NSF AGS project 1848863. R. H. W. was partially funded by the European Union's Horizon 2020 research and innovation program under the Marie Sklodowska‐Curie Grant Agreement No. 797961. We would like to acknowledge high‐performance computing support from Cheyenne (doi:10.5065/D6RX99HX) provided by NCAR's Computational and Information Systems Laboratory, sponsored by the National Science Foundation, for the WACCM6 simulations and analyses presented in this study and for the data management, storage and preservation. The National Center for Atmospheric Research is sponsored by the United States National Science Foundation. We thank the anonymous reviewers for their constructive comments that have helped improve the manuscript. ; Peer Reviewed ; Postprint (published version)