Scientific Assessment of Ozone Depletion: 2006


2006 Ozone Assessment Executive Summary cover
Executive Summary

The present document contains key summaries from the Scientific Assessment of Ozone Depletion: 2006. The full assessment report will be part of the information upon which the Parties to the United Nations Montreal Protocol will base their future decisions regarding protection of the Earth's stratospheric ozone layer.

The Charge to the Assessment Panels

Specifically, the Montreal Protocol on Substances that Deplete the Ozone Layer 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, the Environmental Effects Panel, and the Technology and Economic Assessment Panel have each periodically prepared major assessment reports that updated the state of understanding in their purviews. These reports have been scheduled 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 scientific assessment summarized in the present document is the latest in a series of ten 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 the United Nations Environment Programme (UNEP). The 2006 report is the sixth 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:

YearPolicy ProcessScientific Assessment
1981The Stratosphere 1981 Theory and Measurements. WMO No. 11.
1985Vienna ConventionAtmospheric Ozone 1985. Three volumes. WMO No. 16.
1987Montreal Protocol
1988International Ozone Trends Panel Report 1988. Two volumes. WMO No. 18.
1989Scientific Assessment of Stratospheric Ozone: 1989. Two volumes. WMO No. 20.
1990London Adjustments and Amendment
1991Scientific Assessment of Ozone Depletion: 1991. WMO No. 25.
1992Methyl Bromide: Its Atmospheric Science, Technology, and Economics (Assessment Supplement). UNEP (1992).
1992Copenhagen Adjustments and Amendment
1994Scientific Assessment of Ozone Depletion: 1994. WMO No. 37.
1995Vienna Adjustment
1997Montreal Adjustments and Amendment
1998Scientific Assessment of Ozone Depletion: 1998. WMO No. 44.
1999Beijing Amendment
2002Scientific Assessment of Ozone Depletion: 2002. WMO No. 47
2006Scientific Assessment of Ozone Depletion: 2006. WMO No. 50
200719th Meeting of the Parties

The Current Information Needs of the Parties

The genesis of Scientific Assessment of Ozone Depletion: 2006 occurred at the 15th Meeting of the Parties to the Montreal Protocol in Naoirobi, Kenya, at which the scope of the scientific needs of the Parties was defined in their Decision XV/53 (4), which stated that "....for the 2006 report, the Scientific Assessment Panel should consider issues including:

  1. Assessment of the state of the ozone layer and its expected recovery;
  2. Evaluation of specific aspects of recent annual Antarctic ozone holes, in particular the hole that occurred in 2002;
  3. Evaluation of the trends in the concentration of ozone-depleting substances in the atmosphere and their consistency with reported production and consumption of ozone-depleting substances;
  4. Assessment of the impacts of climate change on ozone-layer recovery;
  5. Analysis of atmospheric concentrations of bromine and the likely quantitative implications of the results on the state of the ozone layer;
  6. Description and interpretation of the observed changes in global and polar ozone and in ultraviolet radiation, as well as set future projections and scenarios for those variables, taking also into account the expected impacts of climate change...".

The Assessment Process

The formal planning of the current assessment was started early in 2005. A Scientific Steering Committee consisting of five scientists from various countries assisted the Scientific Assessment Panel's Cochairs throughout the planning, preparation, review, and finalization of the 2006 assessment. The Cochairs and Scientific Steering Committee considered suggestions from the Parties regarding experts from their countries who could participate in the process. Furthermore, an ad hoc international scientific group also suggested participants from the world scientific community. In addition, this group contributed to crafting the outline of the assessment report. As in previous assessments, the participants represented experts from the developed and developing world. In addition to the scientific expertise, the developing country experts bring a special perspective to the process, and their involvement in the process has also contributed to capacity building.

The information of the 2006 assessment is contained in eight chapters associated with ozone-layer topics:

    Chapter 1. Long-Lived Compounds (Cathy Clerbaux and Derek Cunnold)
    Chapter 2. Halogenated Very Short-Lived Substances (Katherine S. Law and William T. Sturges)
    Chapter 3. Global Ozone: Past and Present (Martyn P. Chipperfield and Vitali E. Fioletov)
    Chapter 4. Polar Ozone: Past and Present (Paul A. Newman and Markus Rex)
    Chapter 5. Climate-Ozone Connections (Mark P. Baldwin and Martin Dameris)
    Chapter 6. The Ozone Layer in the 21st Century (Greg Bodeker and Darryn W. Waugh)
    Chapter 7. Surface Ultraviolet Radiation: Past, Present, and Future (Alkiviadis F. Bais and Dan Lubin)
    Chapter 8. Halocarbon Scenarios, Ozone Depletion Potentials, and Global Warming Potentials (John S. Daniel and Guus J.M. Velders)

A special resource for the Panel's work was the 2005 Special Report of the Intergovernmental Panel on Climate Change (IPCC) and the Technology and Economics Assessment Panel (TEAP) of the Montreal Protocol, Safeguarding the Ozone Layer and the Global Climate System: Issues Related to Hydrofluorocarbons and Perfluorocarbons. This report was used as a basis for many scenarios for modeling runs and hypothetical cases that are included here.

The initial plans for the chapters of the 2006 Scientific Assessment Panel's report were examined at a meeting that occurred on 26-27 July 2005 in Paris, France. The Lead Authors, Steering Committee, and Cochairs focused on the content of the draft chapters and on the need for coordination among the chapters.

The first drafts of the chapters were examined at a meeting that occurred on 30 November-2 December 2005 in Herndon, Virginia, United States, at which the Lead Authors, Steering Committee, Cochairs, and a small group of international experts focused on the scientific content of the draft chapters.

The second drafts of the chapters were reviewed by 125 scientists worldwide in a mail peer review. Those comments were considered by the authors. At a Panel Review Meeting in Les Diablerets, Switzerland, held on 19-23 June 2006, the responses to these mail review comments were proposed by the authors and discussed by the 77 participants. Final changes to the chapters were decided upon at this meeting. The Executive Summary contained herein (and posted on the UNEP web site on 18 August 2006) was prepared and completed by the attendees of the Les Diablerets meeting.

The 2006 State-of-Understanding Report

In addition to the scientific chapters and the Executive Summary, the assessment also updates the 2002 assessment report's answers to a set of questions that are frequently asked about the ozone layer. Based upon the scientific understanding represented by the assessments, answers to these frequently asked questions were prepared, with different readerships in mind, e.g., students and the general public. These updated questions and answers are included in the full report and are available also as a separate publication.

As the accompanying list indicates, the Scientific Assessment of Ozone Depletion: 2006 is the product of 310 scientists from 34 countries who contributed to its preparation and review1 (205 scientists prepared the report and 183 scientists participated in the peer review process).

What follows is a summary of their current understanding of the stratospheric ozone layer and its relation to humankind.

1. Participants were from Argentina, Armenia, Australia, Austria, Belgium, Bolivia, Canada, Czech Republic, Denmark, Egypt, Estonia, Finland, France, Germany, Greece, India, Israel, Italy, Japan, Kenya, Malaysia, New Zealand, Norway, Poland, Russia, South Africa, Spain, Sweden, Switzerland, The Netherlands, The People's Republic of China, Togo, United Kingdom, and United States of America.