This page summarizes the history of international cooperation on the protection of the ozone layer, including: the Vienna Convention; the Montreal Protocol. The Montreal Protocol on Substances That Deplete the Ozone Layer is an international treaty designed to protect the ozone layerOzone depletion is a global problem and Canada, along with more than 160 other countries, has been pursuing a global problem with a global solution. And ozone depletion. The Keystone XL pipeline has policies, and international agreements related to geologic mat- been added to Case Study 19.