The Scientific Assessment of Ozone Depletion and Its Impacts on Environmental Policy

The Montreal Protocol on Substances that Deplete the Ozone Layer is perhaps the most successful international treaty for safeguarding our environment. First negotiated in 1987, the Montreal Protocol controls the consumption and production of ozone depleting substances (ODSs) such as chlorofluorocarbons (CFCs) and bromine containing halons. Since 1987, the Protocol has been strengthened with additional amendments, and these major ODSs are now in decline. In 2016, the Protocol evolved when a new amendment was added to the Protocol that controls hydrofluorocarbons (HFCs). HFCs have only a minor impact on the stratosphere, but many are powerful greenhouse gases. A major element of the Protocol is the quadrennial scientific assessment of ozone depletion. These assessments have motivated the strengthening of the Protocol. In this talk, we will review the major elements of the Protocol, show how these elements have been so successful, and discuss the interface of science and policy.