The original Montreal Protocol, signed in 1987, was the first step in international efforts to protect stratospheric ozone. This document should be cited as: World Meteorological Organization (WMO).Scientific Assessment of Ozone Depletion: 2022, GAW Report No. 278,. As a result of the Montreal Protocol much more severe ozone depletion in the polar regions has been avoided. This page summarizes the history of international cooperation on the protection of the ozone layer, including: the Vienna Convention; the Montreal Protocol. The characteristics, reasons, causes, and all other asymmetries of ozone resource depletion are mentioned in detail in the later sections of the chapter. Ozone depletion: potential impact on the cetacean environment. The Montreal Protocol on Substances that Deplete the Ozone Layer (the Montreal Protocol) is an international agreement made in 1987.