Montreal Protocol

What is the Montreal Protocol?
The Montreal Protocol on Substances that Deplete the Ozone Layer is an international treaty designed to protect the ozone layer by phasing out a number of substances believed to be responsible for ozone depletion.

The Montreal Protocol was adopted on 16 September 1987. The Montreal Protocol has been revised five times to tighten the control over the subtstances that are believed to be responsible for ozone depletion and their phase-out schedules.

Terms and Purposes of the Montreal Protocol

The treaty is structured around several groups of halogenated hydrocarbons that have been shown to play a role in ozone depletion. All of these substances contain either chlorine or bromine.

For each group, the treaty provides a timetable on which the production of these substances must be phased out and eventually eliminated.

Chloroflurocarbons (CFCs) Phase-out Management Plan

The stated purpose of the treaty is that the signatory states recognizes that worldwide emissions of certain substances can significantly deplete and otherwise modify the ozone layer in a manner that is likely to result in adverse effects on human health and the environment, are determined to protect the ozone layer by taking precautionary measures to control total global emissions of substances that deplete it, with the ultimate objective of their elimination on the basis of developments in scientific knowledge and acknowledges that special provision is required to meet the needs of developing countries.

The signatory states accept a series of stepped limits on CFC use and production, including the following.

The levels of consumption and production of the controlled substances in Group I of Annex A from 1991 to 1992 do not exceed 150% of its calculated level of consumption of those substances in 1986.

The calculated levels of consumption and production of the controlled substances in Group I of Annex A from 1994 onwards does not exceed 25% of its calculated level of consumption and production in 1986.

The calculated levels of consumption and production of the controlled substances in Group I of Annex A from 1996 onwards does not exceed zero.

The substances in Group I of Annex A are:

• CFCl₃ (CFC-11)
• CF₂Cl₂ (CFC-12)
• C₂F₃Cl₃ (CFC-113)
• C₂F₄Cl₂ (CFC-114)
• C₂F₅Cl (CFC-115)
  

There is a slower phase out of substances such as halon 1211, 1301, 2402 and CFCs 13, 111, 112 etc and some chemicals that get individual attention such as carbon tetrachloride and trichloroethane. They are to be phased out to zero by 2010. The phasing out of the less active HCFCs started out in 1996 and will go on until 2030.

Hydrochloroflurocarbons (CFCs) Phase-out Management Plan

Parties to the Protocol agreed to set the year 2013 as the time to freeze the consumption and production of HCFCs. They also agreed to start reducing its consumption and production in 2015.

The HCFCs are transitional CFCs replacements, used as refrigerants, solvents, blowing agents for plastic foam manufacture and fire extinguishers. In comparison to CFCs that have Ozone Depleting Potential (ODP) of 0.6 – 1.0, HCFCs have a lesser ODP of 0.01 – 0.5. In comparison to CFCs in terms of Global Warming Potential(GWP) that has a GWP of 4,680 – 10,720, HCFCs have a lesser GWP of 76 – 2,270.

There are a few exceptions for uses where no acceptable substitutes have been found. For example, in the metered dose inhalers that are commonly use to treat asthma and other respiratory problems or in Halon fire suppression systems used in submarines and aircraft.

Parties to the Protocol must base their future decisions on the current scientific, environmental, technical, and economic information that is assessed through panels drawn from worldwide expert committees. To provide the input to the decision making process, advances in understanding of these topics were assessed in 1989, 1991, 1994, 1998 and 2002.

Several reports have been published by various governmental and non-governmental organizations to present alternatives to the ozone depleting substances, since the substances have been used in various technical sectors such as refrigerating, agriculture, energy production and laboratory measurements.

Impact of the Montreal Protocol
Since the implementation of the Montreal Protocol, the atmospheric concentrations of the most important chlorofluorocarbons and related chlorinated hydrocarbons have either been levelled off or reduced. Halon concentrations have increased, as the halons present in fire extinguishers are released. Their rate of increase, however, has slowed down and their abundances are expected to decline by 2020. The concentration of HCFCs has also increased drastically partly due to the replacement of CFCs by HCFCs. Recent scientific evaluation in 2006 have shown that there is a clear decrease in the atmospheric burden of ozone depleting substances and there are some early signs of stratospheric ozone recovery.

But HCFCs are now thought to contribute to global warming. These compounds are much more potent greenhouse gases than carbon dioxide. Although the Montreal Protocol calls for a phase-out of HCFCs by 2030, there is no restriction placed on its use. Over time, a steady increase in the use of HCFCs could change the climate.

source: http://en.wikipedia.org/wiki/Montreal_Protocol
http://app.mewr.gov.sg/web/contents/Contents.aspx?Contld=939
http://ozone.unep.org