Montreal Protocol

The Montreal Protocol, full name Montreal Protocol on Substances that Deplete the Ozone Layer, is an agreement between countries that limits and controls the of chemical compounds that cause ozone depletion.

The Montreal Protocol has been ratified by all 193 members of the United Nations, four non-UN member states (Cook Islands, Niue, Palestine, and Vatican City), and the European Union, for a total of 198 parties. This is every party capable of ratifying a treaty in the current UN system.

Between its universal ratification and the gradual recovery of the ozone layer since it went into force, the Montreal Protocol is often used as an example of successful international collaboration.