Laura McBride, Ph.D.

This document, Twenty Questions and Answers About the Ozone Layer: 2022 Update, is a component of the Scientific Assessment of Ozone Depletion: 2022 report. The report is prepared quadrennially by the Scientific Assessment Panel (SAP) of the Montreal Protocol on Substances that Deplete the Ozone Layer*. The 2022 edition of the Twenty Questions document is the fifth update of the original edition that appeared in the 2002 Assessment Report. The motivation behind this scientific publication is to tell the story of ozone depletion, ozone-depleting substances and the success of the Montreal Protocol. The questions and answers format divides the narrative into topics that can be read and studied individually by the intended audience of specialists and non-specialists. The topics range from the most basic (e.g., What is ozone?) to more recent developments (e.g., the Kigali Amendment to the Montreal Protocol). Each question begins with a short answer followed by a longer, more comprehensive answer. Figures enhance the narrative by illustrating key concepts and results. This document is principally based on scientific results presented in the 2022 and earlier Assessment Reports and has been extensively reviewed by scientists and non-specialists to ensure quality and readability.

The 2022 WMO/UNEP Ozone Assessment contains the most up-to-date understanding of ozone depletion, reflecting the thinking of hundreds of international scientific experts who contribute to its preparation and review. This assessment includes an update on trends in ODSs, HFCs, global and polar ozone and the link between stratospheric ozone changes and climate, as well as a new chapter on the impacts of stratospheric aerosol injection on the stratosphere and ozone. Co-Chairs of the Scientific Assessment Panel (SAP) of the Montreal Protocol on Substances that Deplete the Ozone Layer and Assessment Co-Chairs are Dr. David W. Fahey of the NOAA Chemical Sciences Laboratory, USA, Dr. Paul A. Newman of the NASA Goddard Space Flight Center, USA, Dr. John A. Pyle of the University of Cambridge, UK, and Dr. Bonfils Safari of the National University of Rwanda, Butare. Sarah Doherty of CIRES, University of Colorado, USA is the Assessment Coordinator. Other members of the NOAA Earth System Research Laboratories (ESRL) are making substantial contributions to the report, serving as coauthors, contributors, reviewers, and editorial and support staff. The Scientific Assessment of Ozone Depletion: 2022 contains the 2022 core assessment report PDF file, the Executive Summary of the assessment report, and an update to Twenty Questions and Answers About the Ozone Layer (expected release early 2023).