Preface

2014 Ozone Assessment cover

Scientific Assessment of Ozone Depletion: 2014

World Meteorological Organization Global Ozone Research and Monitoring Project - Report No. 55

National Oceanic and Atmospheric Administration

National Aeronautics and Space Administration

United Nations Environment Programme

World Meteorological Organization

European Commission



This document is part of the information upon which the Parties to the United Nations Montreal Protocol will base their future decisions regarding ozone-depleting substances, their alternatives, and protection of the ozone layer. It is the latest in a long series of scientific assessments that have informed the Parties.

The Charge to the Assessment Panels

Specifically, the Montreal Protocol on Substances that Deplete the Ozone Layer[1] states (Article 6): ". . . the Parties shall assess the control measures . . . on the basis of available scientific, environmental, technical, and economic information." To provide the mechanisms whereby these assessments are conducted, the Protocol further states: ". . . the Parties shall convene appropriate panels of experts" and "the panels will report their conclusions . . . to the Parties."

To meet this request, the Scientific Assessment Panel (SAP), the Environmental Effects Assessment Panel (EEAP), and the Technology and Economic Assessment Panel (TEAP) have each prepared, about every 3-4 years, major assessment reports that updated the state of understanding in their purviews. These reports have been scheduled so as to be available to the Parties in advance of their meetings at which they will consider the need to amend or adjust the Protocol.

The Sequence of Scientific Assessments

The present 2014 report is the latest in a series of 12 scientific Assessments prepared by the world's leading experts in the atmospheric sciences and under the international auspices of the World Meteorological Organization (WMO) and/or the United Nations Environment Programme (UNEP). This report is the eighth in the set of major assessments that have been prepared by the Scientific Assessment Panel directly as input to the Montreal Protocol process. The chronology of all the scientific assessments on the understanding of ozone depletion and their relation to the international policy process is summarized as follows:

Year Policy Process Scientific Assessment
1981 The Stratosphere 1981 Theory and Measurements. WMO No. 11.
1985 Vienna Convention Atmospheric Ozone 1985. Three volumes. WMO No. 16.
1987 Montreal Protocol
1988 International Ozone Trends Panel Report 1988. Two volumes. WMO No. 18.
1989 Scientific Assessment of Stratospheric Ozone: 1989. Two volumes. WMO No. 20.
1990 London Adjustments and Amendment
1991 Scientific Assessment of Ozone Depletion: 1991. WMO No. 25.
1992 Methyl Bromide: Its Atmospheric Science, Technology, and Economics (Assessment Supplement). UNEP (1992).
1992 Copenhagen Adjustments and Amendment
1994 Scientific Assessment of Ozone Depletion: 1994. WMO No. 37.
1995 Vienna Adjustment
1997 Montreal Adjustments and Amendment
1998 Scientific Assessment of Ozone Depletion: 1998. WMO No. 44.
1999 Beijing Amendment
2002 Scientific Assessment of Ozone Depletion: 2002. WMO No. 47
2006 Scientific Assessment of Ozone Depletion: 2006. WMO No. 50
2007 Montreal Adjustment
2010 Scientific Assessment of Ozone Depletion: 2010. WMO No. 52
2014 Scientific Assessment of Ozone Depletion: 2014. WMO No. 55

The Current Information Needs of the Parties

The genesis of Scientific Assessment of Ozone Depletion: 2014 was the 23rd Meeting of the Parties to the Montreal Protocol held during 21–25 November 2011 in Bali, Indonesia, at which the scope of the scientific needs of the Parties was defined in their Decision XXIII/13 (4), which stated that: "...for the 2014 report, the Scientific Assessment Panel should consider issues including:

  • Assessment of the state of the ozone layer and its future evolution, including in respect of atmospheric changes from, for example, sudden stratospheric warming or accelerated Brewer-Dobson circulation;
  • Evaluation of the Antarctic ozone hole and Arctic winter/spring ozone depletion and the predicted changes in these phenomena, with a particular focus on temperatures in the polar stratosphere;
  • Evaluation of trends in the concentration in the atmosphere of ozone-depleting substances and their consistency with reported production and consumption of those substances and the likely implications for the state of the ozone layer and the atmosphere;
  • Assessment of the interaction between the ozone layer and the atmosphere; including: (i) The effect of polar ozone depletion on tropospheric climate and (ii) The effects of atmosphere-ocean coupling;
  • Description and interpretation of observed ozone changes and ultraviolet radiation, along with future projections and scenarios for those variables, taking into account among other things the expected impacts to the atmosphere;
  • Assessment of the effects of ozone-depleting substances and other ozone-relevant substances, if any, with stratospheric influences, and their degradation products, the identification of such substances, their ozone-depletion potential and other properties;
  • Identification of any other threats to the ozone layer."

The 2014 SAP Assessment has addressed all the issues that were feasible to address to the best possible extent. Further, given the change in the structure of the report and the evolution of science, the UV changes are addressed by the Environmental Effects Assessment Panel (EEAP) of the Montreal Protocol. The SAP has provided the necessary information on ozone levels, now and in the future, to EEAP as input to their assessments.

The 2014 Assessment Process

The formal planning of the current Assessment was started early in 2013. The Cochairs considered suggestions from the Parties regarding experts from their countries who could participate in the process. Two key changes were incorporated for the 2014 Assessment: (1) creation of a Scientific Steering Committee consisting of the Cochairs and four other prominent scientists; and (2) instituting Chapter Editors for each chapter to ensure that the reviews were adequately and appropriately handled by the authors and key messages were clearly enunciated to take them to the next level. For this reason, the Chapter Editors are also Coauthors of the Assessment for Decision Makers (ADM) of the Scientific Assessment of Ozone Depletion: 2014. The plan for this Assessment was vetted by an ad hoc international scientific advisory group. This group also suggested participants from the world scientific community to serve as authors of the science chapters, reviewers, and other roles. In addition, this advisory group contributed to crafting the outline of this Assessment report. As in previous Assessments, the participants represented experts from the developed and developing world. The developing country experts bring a special perspective to the process, and their involvement in the process has also contributed to capacity building in those regions and countries.

The 2014 Scientific Assessment Panel (SAP) Report

The 2014 report of the Scientific Assessment Panel differs from the past seven reports in its structure and mode of publication. However, as in the past, it is a thorough examination and assessment of the science. The process by which this report was generated, as in the past, was also thorough; the documents underwent multiple reviews by international experts.

The Structure of the 2014 Report

The previous SAP reports have served well the Parties to the Montreal Protocol, the scientific community, and the managers who deal with the research activities. However, the Montreal Protocol process has matured significantly and its needs have evolved. It was clear from the discussions between the Cochairs and both the Party representatives and the people involved in decision making that the previous very lengthy assessment reports would not meet the current needs of the Parties for a short, pithy, document that is written for them and not for the scientific community. Yet, it was also clear that the integrity of and the trust in the SAP reports come from the very thorough assessment of the science. Therefore, this 2014 Assessment was restructured to serve both purposes. The new structure is shown schematically below.

structure schematic

First, as in the past, a major scientific assessment process was carried out and the findings from these discussions and reviews constitute the five major chapters of the assessment foundation from the scientific community. This is shown on the left hand side of the diagram. The five scientific chapters are published only on the web but are an integral part of the 2014 SAP report to the Parties. Also, as discussed earlier, the assessment of the surface UV changes due to past ozone depletion or to projected future ozone levels are not included in this document. Readers are referred to the 2014 Environmental Effects Assessment Panel report for the UV discussion.

Second, the findings from the SAP’s five scientific chapters were then synthesized and written in a language that is accessible to the Parties to the Protocol. The contents of the Assessment for Decision- Makers document—an Executive Summary and three sections—are shown on the right hand side. This short document, which contains all the major scientific summary points written in a clear and accessible language, is available in print and on the web. It is hoped that this new document will be useful to and usable by the Parties to the Protocol, countries, and high-level policymakers and managers. If more scientific details are needed, the complete document can be accessed via the web.

Third, for this Assessment, the Twenty Questions and Answers About the Ozone Layer has been only updated. This is because the overarching scientific understanding has not changed significantly from the previous Assessment. The update will ensure that the answers include the most current data and are consistent with the 2014 Assessment. These updated questions and answers are published separately (both in print and on the web) in a companion booklet to this report.

It is hoped that these steps will enhance the usefulness of the document to the Parties, meet the needs of the multiple user communities for the information, minimize the workload of the scientific community, and reduce costs.

The Process of Preparing the 2014 Assessment

The initial plans for the scientific chapters of the 2014 Scientific Assessment Panel's report were examined at a meeting that occurred on 10–11 June 2013 in Cambridge, UK. The Lead Authors, the Scientific Steering Committee, and Chapter Editors – along with a few representatives of other assessment panels and organizations – focused on the planned content of the chapters and on the need for coordination among the chapters.

The first drafts of the scientific chapters were mailed to 213 experts for written reviews. The chapters were revised to take into account the comments of the reviewers. The revised drafts were subsequently sent to 65 reviewers who either attended a review meeting in Boulder or communicated their comments back to the group. These second drafts were reviewed by 63 experts in person in Boulder, CO, USA during 8–10 April 2014. Final changes to the chapters were decided upon at this meeting, and the final chapter summary points were agreed. Subsequently, the chapters were revised for clarity and to address specific points that were agreed to at the Boulder meeting. Final drafts of the scientific chapters were completed in May 2014.

Subsequent to the finalization of the five chapters, an author team consisting of the Scientific Steering Committee, Chapter Lead Authors, and Chapter Editors wrote a draft of the Assessment for Decision-Makers. This document was based on the science findings of the five chapters. The draft ADM was made available on June 13 to the attendees of a Panel Review Meeting that took place in Les Diablerets, Switzerland, on 23–27 June 2014. The overall ADM was reviewed, discussed, and agreed to by the 59 participants. The Executive Summary of the ADM, contained herein (and posted on the UNEP and WMO websites on 10 September 2014), was prepared and completed by the attendees of the Les Diablerets meeting.

The final result of this two-year endeavor is the present assessment report. As the accompanying list indicates (Appendix A) PDF file, the Scientific Assessment of Ozone Depletion: 2014 is the product of 285 scientists from 36 countries[2] of the developed and developing world who contributed to its preparation and review (133 scientists prepared the report and 220 scientists participated in the peer review process).


[1] In this report, ozone-depleting substances (ODSs) refer to the gases listed in the Annexes to the Montreal Protocol. In addition to these gases, other chemicals also influence the ozone layer, and they are referred to as ozone-relevant gases.

[2] Argentina, Australia, Austria, Belgium, Botswana, Brazil, Canada, People's Republic of China, Comoros, Costa Rica, Cuba, Czech Republic, Denmark, Finland, France, Germany, Greece, India, Israel, Italy, Japan, Korea, Malaysia, New Zealand, Norway, Poland, Russia, South Africa, Spain, Sweden, Switzerland, The Netherlands, Togo, United Kingdom, United States of America, Zimbabwe.