What environmental treaty established controls on substances that contribute to ozone depletion?

The Montreal Protocol is an international treaty specifically designed to control and phase out substances that contribute to the depletion of the ozone layer, particularly chlorofluorocarbons (CFCs) and other ozone-depleting substances. Established in 1987, the treaty was significant in bringing together various countries to collectively address the environmental threat posed by these chemicals.

One reason the Montreal Protocol is such a landmark agreement is its focus on specific substances identified as harmful to the ozone layer, promoting alternatives and encouraging sustainable practices. The success of the Montreal Protocol in reducing the use of these harmful substances has contributed to the recovery of the ozone layer, demonstrating effective international cooperation for environmental protection.

The other options, while they address environmental issues, do not specifically focus on ozone depletion. The Kyoto Protocol, for instance, relates primarily to climate change and reducing greenhouse gas emissions. The Rio Declaration outlines principles for sustainable development but does not target ozone-depleting substances. The Clean Air Act is a U.S. environmental law that regulates air emissions but does not specifically focus on the international aspect of ozone depletion or the substances responsible for it.