Scientific Assessment of Ozone Depletion: 1998

Executive Summary

1998 Ozone Assessment Executive Summary cover
Executive Summary

The 1987 Montreal Protocol on Substances that Deplete the Ozone Layer commemorated its 10th anniversary in September 1997. Among the provisions of the Protocol was the requirement that the Parties to the Protocol base their future decisions on the available scientific, environmental, technical, and economic information as assessed by the worldwide expert communities. The advances of the understanding in ozone science over this decade were assessed in 1988, 1989, 1991, and 1994. This information was input to the subsequent Amendments and Adjustments of the 1987 Protocol. The Assessment summarized here is the fifth in that series.

Recent Major Scientific Findings and Observations

Since the Scientific Assessment of Ozone Depletion: 1994, significant advances have continued to be made in the understanding of the impact of human activities on the ozone layer, the influence of changes in chemical composition on the radiative balance of the Earth's climate, and, indeed, the coupling of the ozone layer and the climate system. Numerous laboratory investigations, atmospheric observations, and theoretical and modeling studies have produced several key ozone- and climate-related findings:

Supporting Scientific Evidence and Related Issues

Recent Halogen and Methane Changes

Stratospheric Particles

Ozone in the Midlatitudes and Tropics

Ozone in High-Latitude Polar Regions

Stratospheric Temperatures

Tropospheric Ozone

Changes in UV Radiation

Changes in Climate Parameters

Future Halogen Changes

Recovery of the Ozone Layer

Implications for Policy Formulation

The results from more than two decades of research have provided a progressively better understanding of the interaction of human activities and the chemistry and physics of the global atmosphere. New policy-relevant insights to the roles of trace atmospheric constituents have been conveyed to decision-makers through the international state-of-the-understanding assessment process. This information has served as a key input to policy decisions by governments, industry, and other organizations worldwide to limit the anthropogenic emissions of gases that cause environmental degradation: (1) the 1987 Montreal Protocol on ozone-depleting substances, and its subsequent Amendments and Adjustments, and (2) the 1997 Kyoto Protocol on substances that alter the radiative forcing of the climate system.

The research findings that are summarized above are of direct interest and significance as scientific input to governmental, industrial, and other policy decisions associated with the Montreal Protocol (ozone layer) and the Kyoto Protocol (climate change):