Which international agreement marked a significant step towards protecting the ozone layer?

The Montreal Protocol is recognized as a landmark international agreement that specifically addresses the depletion of the ozone layer through the phase-out of substances responsible for ozone depletion, particularly chlorofluorocarbons (CFCs) and other halogenated compounds. It was adopted in 1987 and has been ratified by nearly every country in the world, making it one of the most successful environmental agreements in history.

The protocol established specific targets and timetables for the reduction and elimination of ozone-depleting substances, and it has been effective in significantly reducing the concentrations of these harmful chemicals in the atmosphere. This effort has led to a measurable recovery of the ozone layer, showcasing how coordinated global action can yield positive environmental outcomes.

In contrast, while other agreements like Agenda 21, the Paris Agreement, and the Cairo Declaration address various aspects of environmental protection and sustainable development, they do not specifically target the protection of the ozone layer to the same extent as the Montreal Protocol.