Montreal Protocol

Introduction

The Montreal Protocol on Substances That Deplete the Ozone Layer is a treaty that was negotiated in 1987 and was signed by 191 nations. The treaty, which took effect at the beginning of 1989, has been revised seven times (most recently in 1999), and provides a timetable for the phasing-out of the use of several types of compounds called halogenated hydro-carbons that are known to destroy atmospheric ozone.

Protection of ozone in the atmosphere is very important, since the compound absorbs ultraviolet radiation entering the atmosphere from the sun. Ultraviolet light can damage skin cells and can break apart genetic material inside cells, which can lead to harmful cell changes (mutations) including cancer.

The Montreal Protocol and its regularly scheduled revisions, which have provided achievable targets for nations to meet in reducing the manufacture and use of ozone-depleting chemicals, has been cited as an example of how nations can successfully

agree to and implement meaningful climate protective measures.

Historical Background and Scientific Foundations

Beginning in the 1930s, chlorofluorocarbons (CFCs) beganto bewidelyused inanvariety of manufactured products including refrigerators and spray cans. Also known as Freon, the five main formulations of CFCs were a safe, non-poisonous, and non-flammable replacement for harmful compounds such as ammonia.

Over the intervening decades, CFCs that were given off by the various products dissipated into the atmosphere. In 1973, scientists at the University of California, Irvine, discovered that CFCs persist for 20–100 years in the region of the atmosphere known as the stratosphere, and that the CFCs are broken apart by incoming ultra-violet light.

The destruction of the CFCs releases chlorine. It was proposed and later proven that the freed chlorine destroys another compound in the atmosphere called ozone. Bromine-containing halogenated hydrocarbons also destroy ozone.

Ozone is made up of three oxygen atoms. When intact, an ozone molecule is able to absorb the ultra-violet portion of incoming sunlight, reducing the amount of the radiation that reaches Earth. However, as ozone is depleted from the stratosphere, more ultra-violet radiation reaches Earth's surface.

Ultraviolet light possesses sufficient energy to break one or both of the strands of the genetic material (usually deoxyribonucleic acid; DNA) that is present inside plant, animal, and human cells. When this happens, the result can be a change (mutation) in the cells that survive. Although some changes are not serious, others are. For example, mutations that affect the controls on cell division can lead to the runaway growth and division of cells that is the hallmark of cancer. Indeed, ozone depletion and the resulting increased exposure to ultraviolet light has been linked to increasing rates of several types of cancer.

The longevity of CFCs means that even a single molecule can be very destructive over its lifetime. Indeed, a CFC molecule is approximately 10,000 times more potent as a greenhouse gas than carbon dioxide.

Concern over ozone depletion and the link between this depletion and an increased threat to health was heightened in the early 1980s by the discovery of the virtual absence of ozone in the atmosphere over Antarctica. Dubbed the ozone hole, this dramatic evidence of ozone depletion spurred the global community into action. The result was the Montreal Protocol.

The protocol imposes strict time deadlines for the phasing out of nearly 100 compounds that contain ozone depleting chlorine and bromine. The list includes CFCs and hydrochlorofluorocarbons (HCFCs). Through the 1990s, HCFCs were popular as replacements for CFCs since they are not as ozone-destructive. However, they are also scheduled to be phased out according to the protocol by 2030 in developed countries and by 2040 in developing countries.

The effect will be a nearly 50% reduction in the emissions of ozone-depleting chemicals.

Impacts and Issues

The Montreal Protocol is an evolving agreement. The protocol timetable includes regularly scheduled revisions, which allow new scientific discoveries and advances to be incorporated into the agreement. The latest meeting of the 191 participating nations took place in Montreal on September 12–21, 2007.

WORDS TO KNOW

CHLOROFLUOROCARBONS: Members of the larger group of compounds termed halocarbons. All halocarbons contain carbon and halons (chlorine, fluorine, or bromine). When released into the atmosphere, CFCs and other halocarbons deplete the ozone layer and have high global warming potential.

OZONE: An almost colorless, gaseous form of oxygen with an odor similar to weak chlorine. A relatively unstable compound of three atoms of oxygen, ozone constitutes, on average, less than one part per million (ppm) of the gases in the atmosphere. (Peak ozone concentration in the stratosphere can get as high as 10 ppm.) Yet ozone in the stratosphere absorbs nearly all of the biologically damaging solar ultraviolet radiation before it reaches Earth's surface, where it can cause skin cancer, cataracts, and immune deficiencies, and can harm crops and aquatic ecosystems.

STRATOSPHERE: The region of Earth's atmosphere ranging between about 9 and 30 mi (15 and 50 km) above Earth's surface.

ULTRAVIOLET RADIATION: The energy range just beyond the violet end of the visible spectrum. Although ultraviolet radiation constitutes only about 5% of the total energy emitted from the sun, it is the major energy source for the stratosphere and mesosphere, playing a dominant role in both energy balance and chemical composition.

The Montreal Protocol has been very successful in curbing the use of CFCs. Although the global production of CFCs exceeded 1.2 million tons in 1983, by 2004 global production had declined to 70,000 tons.

An aspect of the protocol that has been cited as a model for other environmental agreements is the built-in financial support for developing countries, courtesy of money contributed by participating nations and agencies including the United Nations Environmental Programme, U.N. Development Programme, U.N. Industrial Development Organization, and the World Bank. The monetary assist given by the developed world to developing countries makes it easier for poorer nations to meet the protocol's reduction targets.

Emissions from developed nations have largely stopped, since products containing CFCs can no longer be sold. Still, production of CFCs does continue, and CFC-containing products continue to be sold and used in the developing and under-developed world.

This, combined with the longevity of CFCs in the stratosphere, continues to produce ozone destruction. The damage will continue until late in the twenty-first century.

As effective as the Montreal Protocol has been, it is not a complete solution, since the agreement is concerned with HCFCs and not with another potent ozone destructive type known as hydrofluorocarbons (HFCs). The protocol mandates a complete phase-out of HCFCs by 2030, but no targets have yet been set for HFCs.

See Also Berlin Mandate; Bonn Conference (2001); Delhi Declaration; Intergovernmental Panel on Climate Change (IPCC); Kyoto Protocol; Ozone Depletion; United Nations Framework Convention on Climate Change (UNFCCC).

BIBLIOGRAPHY

Books

Anderson, Stephen, K., and Madhava Sarma. Protecting the Ozone Layer: The United Nations History. London: Earthscan Publications, 2005.

Kaniaru, Donald. The Montreal Protocol: Celebrating 20 Years of Environmental Progress. London: Cameron, May 2007.

Web Sites

“NOAA Observes 20th Anniversary of the Montreal Protocol.” National Oceanographic and Atmospheric Administration, September 16, 2007. <http://www.noaamews.noaa.gov/stories2007/s2918.htm> (accessed November 23, 2007).

“Montreal Protocol Could Be Model for Addressing Climate Change.” U.S. Department of State,October 18, 2007. <http://usinfo.state.gov/gi/> (accessed November 23, 2007).

Brian D Hoyle