Environmental Science: The Montreal Protocol

Three out of four Americans believe that the Earth has been gradually warming due primarily or at least partly as the result of human activity and want the government to institute regulations to stop it, according to a new survey by researchers at the Woods Institute for the Environment at Stanford University. The survey was conducted by Woods Institute Senior Fellow Jon Krosnick, a professor of communication and of political science at Stanford, with funding from the National Science Foundation. The results are based on telephone interviews conducted from June 1-7, 2010, with 1,000 randomly selected American adults.

There are several protocols that the government planned to be implemented but only few ones were approved. One of the most successive protocols and said to be lasted for a long term plan is “Montreal Protocol”. This treaty was opened on September 16, 1987 and planned to last till the ozone layer atmospheric concentration be stable. Chemists Frank Sherwood Rowland and Mario Molina studied the impacts of CFCs in the Earth's atmosphere and they found out that CFC molecules were stable enough to remain in the atmosphere until they got up into the middle of the stratosphere where they would finally (after an average of 50–100 years for two common CFCs) be broken down by ultraviolet radiation releasing a chlorine atom. There studies results became basis on how we protect the ozone layer by simply taking precautionary measures to control equitably total global emissions of substances that deplete it, with the ultimate objective of their elimination on the basis of developments in scientific knowledge. 

Depletion of Ozone layer

The ozone layer can be depleted by free radical catalysts, including nitric oxide (NO), nitrous oxide (N2O), hydroxyl (OH), atomic chlorine (Cl), and atomic bromine (Br). While there are natural sources for all of these species, the concentrations of chlorine and bromine have increased markedly in recent years due to the release of large quantities of manmade organohalogen compounds, such as chlorofluorocarbons (CFCs), bromofluorocarbons. These highly stable compounds are capable of surviving the rise to the stratosphere, where Cl and Br radicals are liberated by the action of ultraviolet light. Each radical is then free to initiate and catalyze a chain reaction capable of breaking down over 100,000 ozone molecules. The breakdown of ozone in the stratosphere results in the ozone molecules being unable to absorb ultraviolet radiation. Consequently, unabsorbed and dangerous ultraviolet-B radiation is able to reach the Earth’s surface. Ozone levels over the northern hemisphere have been dropping by 4% per decade. Over approximately 5% of the Earth's surface, around the north and south poles, much larger seasonal declines have been seen, and are described as ozone holes. In 2009, nitrous oxide (N2O) was the largest ozone-depleting substance emitted through human activities.

Regulations

The Montreal Protocol on Substances That Deplete the Ozone Layer is an international treaty designed to protect the ozone layer by phasing out the production of numerous substances believed to be responsible for ozone depletion.

• The treaty was opened for signature on September 16, 1987, and entered into force on January 1, 1989, followed by a first meeting in Helsinki, May 1989. Since then, it has undergone seven revisions, in 1990 (London), 1991 (Nairobi), 1992 (Copenhagen), 1993 (Bangkok), 1995 (Vienna), 1997 (Montreal), and 1999 (Beijing).
• It is believed that if the international agreement is adhered to, the ozone layer is expected to recover by 2050.
• Due to its widespread adoption and implementation it has been hailed as an example of exceptional international co-operation, with Kofi Annan quoted as saying that "perhaps the single most successful international agreement to date has been the Montreal Protocol". It has been ratified by 196 states.

Terms and Purposes

The treaty is structured around several groups of halogenated hydrocarbons that have been shown to play a role in ozone depletion. All of these ozone depleting substances contain either chlorine or bromine (substances containing only fluorine do not harm the ozone layer).

The treaty provides a timetable on which the production of those substances must be phased out and eventually eliminated such as

i. Chlorofluorocarbons (CFCs) Phase-out Management Plan

Various provisions were made which limits the use of CFCs.

ii. Hydrochlorofluorocarbons (HCFCs) Phase-out Management Plan (HPMP)

Various provisions were made which limits the use of HCFCs.

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

There are a few exceptions for "essential uses", where no acceptable substitutes have been found (for example, in the metered dose inhalers commonly used to treat asthma and other respiratory problems) or Halon fire suppression systems used in submarines and aircraft (but not in general industry).


- Young, Liezl 2012

Source: 2006. Ozone layer concern. Retrieved from http://ozonelayerconcern.blogspot.com/2006/12/ozone-layer-is-complex-gossamer-layer.html