International Environmental Agreements

The Montreal Protocol (1987) is widely regarded as the most successful international environmental agreement. It phased out production of chlorofluorocarbons (CFCs) and other ozone-depleting substances that were creating a 'hole' in the stratospheric ozone layer over Antarctica, increasing UV radiation that causes skin cancer and cataracts. All 198 UN member states ratified the treaty. By 2023, atmospheric concentrations of ozone-depleting substances had fallen by 99%, and the ozone layer is projected to recover to 1980 levels by 2066. The Protocol succeeded because the science was clear, alternatives existed (HFCs replaced CFCs), a multilateral fund helped developing countries transition, and the treaty included trade sanctions against non-parties.