Scientific Assessment of Ozone Depletion: 1998


1998 Ozone Assessment Executive Summary cover
Executive Summary

The present document contains key summaries from the Scientific Assessment of Ozone Depletion: 1998. 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 stratospheric ozone layer.

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."

Three assessment reports have been prepared during 1998 to be available to the Parties in advance of their meeting in 1999, at which they will consider the need to amend or adjust the Protocol. The two companion reports to the present scientific assessment focus on the environmental and health effects of ozone layer depletion and on the technological feasibilities and economic implications of various mitigation approaches.

The scientific assessment summarized in the present document is the latest in a series of eight 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). The present assessment is the fifth in the set that has been prepared directly as input to the Montreal Protocol process. The chronology of 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.
199911th Meeting of the Parties (China)

The genesis of Scientific Assessment of Ozone Depletion: 1998 occurred at the 7th Meeting of the Conference of the Parties to the Montreal Protocol in Vienna, Austria, in December 1995, at which the scope of the scientific needs of the Parties was defined. The formal planning of the present report was started in January 1997 by an ad hoc international steering group who crafted the outline and suggested scientists from the world community to serve as authors. The first drafts of the chapters were examined at a meeting that occurred on 12 - 14 November 1997 in Washington, D.C., at which the Lead Authors and a small number of international experts focused on the content of the draft chapter and the coordination among the chapters.

The second drafts of the chapters were reviewed by 124 scientists worldwide in a mail peer review. These comments were considered by the authors. At a Panel Review Meeting in Les Diablerets, Switzerland, held on 1 - 5 June 1998, the responses to these mail review comments were proposed by the authors and discussed by the 73 participants. Final changes to the chapters were decided upon there, and the Executive Summary contained herein was prepared by the participants.

The group also focused on updating 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 updated. These questions and answers are included in this report.

As the accompanying list indicates, the Scientific Assessment of Ozone Depletion: 1998 is the product of 304 scientists from the developed and developing world1 who contributed to its preparation and review (218 scientists prepared the report and 148 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. Participating were Argentina, Australia, Austria, Belgium, Brazil, Canada, Chile, Czech Republic, Denmark, Egypt, Finland, France, Germany, Greece, India, Iran, Ireland, Italy, Japan, Kenya, Malaysia, New Zealand, Norway, Poland, Russia, South Africa, Republic of Korea, Sweden, Switzerland, Taiwan, The Netherlands, The People's Republic of China, United Kingdom, United States of America, and Venezuela.