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The Montreal Protocol on Substances that Deplete the Ozone Layer

" Perhaps the single most successful international agreement to date has been the Montreal Protocol.  "-Kofi Annan, Former Secretary General of the United Nations

In 1985 the Vienna Convention established mechanisms for international co-operation in research into the ozone layer and the effects of ozone depleting chemicals (ODCs). 1985 also marked the first discovery of the Antarctic ozone hole. On the basis of the Vienna Convention, the Montreal Protocol on Substances that Deplete the Ozone Layer was negotiated and signed by 24 countries and by the European Economic Community in September 1987. The Protocol called for the Parties to phase down the use of CFCs, halons and other man-made ODCs.

After a series of rigorous meetings and negotiations, the Montreal Protocol on Substances that Deplete the Ozone Layer was finally agreed upon on 16 september 1987 at the Headquarters of the International Civil Aviation Organization in Montreal. The Montreal Protocol stipulates that the production and consumption of compounds that deplete ozone in the stratosphere--chlorofluorocarbons (CFCs), halons, carbon tetrachloride, and methyl chloroform--are to be phased out by 2000 (2005 for methyl chloroform). Scientific theory and evidence suggest that, once emitted to the atmosphere, these compounds could significantly deplete the stratospheric ozone layer that shields the planet from damaging UV-B radiation.

Man-made chlorines, primarily chloroflourobcarbons (CFCs), contribute to the thinning of the ozone layer and allow larger quantities of harmful ultraviolet rays to reach the earth.

The Montreal Protocol on Substances that Deplete the Ozone Layer is one of the first international environmental agreements that includes trade sanctions to achieve the stated goals of a treaty. It also offers major incentives for non-signatory nations to sign the agreement. The treaty negotiators justified the sanctions because depletion of the ozone layer is an environmental problem most effectively addressed on the global level. Furthermore, without the trade sanctions, there would be economic incentives for non-signatories to increase production, damaging the competitiveness of the industries in the signatory nations as well as decreasing the search for less damaging CFC alternatives.

NASA/NOAA satellite data showing the rise in stratospheric chlorine and corresponding decline in ozone layer thickness from 1979 to 1997. As stratospheric chlorine declined in response to enactment of the Montreal Protocol, the first stage of ozone recovery began.

At meetings in London (1990), Copenhagen (1992), Vienna (1995), Montreal (1997) and Beijing (1999) amendments were adopted that were designed to speed up the phasing out of ozone-depleting substances.

Montreal Protocol Full Text

Ratification of:

  Vienna Convention Montreal Protocol London Amendment Copenhagen Amendment Montreal Amendment Beijing Amendment
Total number of countries 191 191 185 176 152 124

The table below shows the status of Ratification, Accession, or Approval of the agreements on the protection of the stratospheric ozone layer as provided by the Depositary, the United Nations Office of Legal Affairs, New York

Summary of Montreal Protocol Control Measures
Ozone Depleting Substances Developed Countries Developing Countries
Chlorofluorocarbons (CFCs) Phased out end of 1995 a Total phase out by 2010
Halons Phased out end of 1993 Total phase out by 2010
Carbon tetrachloride Phased out end of 1995 a Total phase out by 2010
Methyl chloroform Phased out end of 1995 a Total phase out by 2015
Hydrochlorofluorocarbons (HCFCs) Freeze from beginning of 1996 b  
  35% reduction by 2004  
  65% reduction by 2010 Freeze in 2016
  90% reduction by 2015 at 2015 base level
  Total phase out by 2020 c Total phase out by 2040
Hydrobromofluorocarbons (HBFCs) Phased out end of 1995 Phased out end of 1995
Methyl bromide Freeze in 1995 at 1991 base level d Freeze in 2002 at average
  25% reduction by 1999 1995-1998 base level
  50% reduction by 2001 20% reduction by 2005 e
  70% reduction by 2000 Total phase out by 2015
  Total phase out by 2005  

a With the exception of a very small number of internationally agreed essential uses that are considered critical to human health and/or laboratory and analytical procedures.
b Based on 1989 HCFC consumption with an extra allowance (ODP weighted) equal to 2.8% of 1989 CFC consumption.
c Up to 0.5% of base level consumption can be used until 2030 for servicing existing equipment.
d All reductions include an exemption for pre-shipment and quarantine uses.
e Review in 2003 to decide on interim further reductions beyond 2005.