Concerns the Earth’s stratospheric ozone layer could be at risk from chlorofluorocarbons (CFCs) and other anthropogenic substances first arose in the early 1970s. By 1985, scientific understanding of ozone depletion and its impacts on human health and the environment had advanced. In response, governments adopted the Vienna Convention for the Protection of the Ozone Layer—a framework convention that lays out agreed principles to combat this ozone depletion. It does not, however, require countries to take control actions to protect the ozone layer.
In September 1987, efforts to negotiate binding obligations to reduce use of ozone depleting substances led to the adoption of the Montreal Protocol on Substances that Deplete the Ozone Layer. The Montreal Protocol phases out both the production and consumption of ozone-depleting substances. The Protocol has been adjusted or amended six times since its creation, most recently by the Kigali Amendment in 2016.