International conventions
Protecting the Ozone Layer
Vienna Convention / Montreal Protocol
After the depletion of the ozone layer was discovered in the early 1970s, two international treaties to protect the ozone layer, the Vienna Convention and the Montreal Protocol, negotiated and signed in 1985 and 1987, respectively. These treaties have been ratified by all member states of the United Nations. In addition, the 2016 expansion of the Montreal Protocol, known as the "Kigali Amendment," also regulates hydrofluorocarbons, which are potent greenhouse gases.