Earth’s ozone layer acts as a protective shield, absorbing and blocking harmful radiation from the Sun. In the 1970s, scientists began to worry that the ozone layer was being depleted by manufactured chemicals like chlorofluorocarbons, or CFCs, commonly used as a refrigerant and in aerosols.

Soon pressure grew for global action. In 1987, a United Nations summit in Montreal brought global leaders, scientists, and industry representatives together to address the problem.The treaty they ratified, known as the Montreal Protocol, was ultimately a success, pushing chemical companies to invest in profitable alternatives to help save the ozone. Earlier this year, scientists announced that Earth’s ozone layer was starting to recover.

The Montreal Protocol has been recognized as a template for encouraging science-based policy and global cooperation to address environmental challenges. Today, as global warming caused by burning fossil fuels has become the most pressing climate problem, will the world be able to duplicate the Montreal Protocol's success?

This documentary was created in partnership with Scientific American. You can view past collaborations here.

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