What is the Montreal Protocol primarily known for?

The Montreal Protocol is primarily recognized for its role in addressing the depletion of the ozone layer by outlining the phase-out of ozone-depleting substances (ODS). The agreement, which was adopted in 1987, was designed to eliminate chemicals such as chlorofluorocarbons (CFCs) and halons that were found to be responsible for the thinning of the ozone layer. The successful implementation of the protocol has led to a significant reduction in the production and consumption of these harmful substances, ultimately contributing to the recovery of the ozone layer.

The protocol is considered one of the most effective international environmental agreements, largely because it involves commitments from over 190 countries to eliminate substances that contribute to ozone depletion. It demonstrates a collaborative approach to environmental issues that transcend national boundaries, showcasing the importance of international cooperation in protecting global resources.

The other options, while related to environmental issues, do not accurately capture the primary focus of the Montreal Protocol. The protocol is not centered on greenhouse gas emissions reductions, carbon trading markets, or the regulation of water pollution, and therefore, it stands distinct in its commitment to protecting the ozone layer specifically.