Global agreement in specific control strategies to reduce the release of ozone depleting substances was adopted by

The Montreal Protocol was signed at Montreal (Canada) in 1987 and became effective in 1989.
It laid down definite control strategies and time-bound road maps, separately for developed and developing countries, for reducing the emission of CFCs and other ozone-depleting chemicals.
The Vienna Convention (1985) only provided a general framework for protecting the ozone layer, without specific control measures.
The Rio de Janeiro conference (1992) dealt with biodiversity and sustainable development, and the Kyoto Protocol (1997) with greenhouse gases.
Hence the specific control strategies were adopted by the Montreal Protocol.