CFCs and Stratospheric Ozone Loss

From Science Online

Chlorofluorocarbons

The uses of CFCs in various products before the Montreal Protocol

Chlorofluorocarbons (CFCs) are the main cause of depletion of the ozone layer. Humans produce CFCs by using air conditioning, refrigerators, cleaning solvents, aerosols, etc. They were invented in 1928 by Thomas Midgley and are useful because they are nontoxic, nonflammable, and can be easily converted from a liquid to a gas and from a gas to a liquid. (Walker, 2007) These chemicals are in the atmosphere almost completely because of humans. One of the main elements of CFCs is chlorine, and very little chlorine exists naturally in the atmosphere; as it turns out, the chlorine is deleterious to the ozone layer. (The Ozone Hole) Once CFCs reach the stratosphere, they are dissociated by ultraviolet light to release the chlorine atoms. These chlorine atoms proceed to break down tens of thousands of ozone molecules before they leave, 20 to 100 years later.

Where is this problem happening, and who discovered it?

The most distinct decrease in ozone has occurred in the lower stratosphere, about 50 kilometers above the surface of the earth, which protects the earth from UV-B radiation that comes from the sun. (Sarma, 1998) Sherry Rowland and Mario Molina were the first to discover the damage caused by CFCs, and published a paper about it in 1974. However, the CFC industry was worth billions of dollars at this time, and no one wanted to deal with the danger. Then, a hole in the ozone layer that had formed over Antarctica, caused mainly by CFCs, was discovered in 1985 by Joe Farman and his colleagues. They had been taking continuous O₃ column-density measurements at Halley Bay in Antarctica and they realized that there was significant O₃ loss occurring in that region. The knowledge of this shocked the world into action, creating the Montreal Protocol. In the four years after their discovery, O₃ levels continued to drop such that in 1989, 70% of the total O₃ content over Antarctica was lost during September and October. (Anderson, 1991) Thankfully, the hole has shrunk since then largely because of the ban of CFCs.

What laws/treaties/protocols exist to deal with the problem?

The Montreal Protocol is an international treaty, created in 1987, to initiate a change in the quantity and use of fluorocarbons and move towards more environmentally friendly compounds and technologies. It set target dates for replacing the products that had become an integral part of our daily lives and monitors over 100 chemicals. (Benedick, 1998) 150 countries had ratified the treaty by 1996, with about a third of them developed and two thirds developing. (Climate Institute) Developing countries that ratify the Montreal Protocol are given ten years longer than developed countries to implement the provisions of the treaty and are also given financial assistance to develop the country's individual ozone protection program.

In addition, the Kyoto Protocol, entered into force on February 16, 2005, aims for the "stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system." (UNFCCC) More specifically, it aims to reduce the emissions of six greenhouse gases (CO₂, CH₄, N₂O, HFCs, PFCs, and SF₆) referenced to a 1990 baseline. (Velders, 2007) This treaty has been ratified by over 130 countries, excluding the United States and Australia. (Gore , 2006)

World Production of CFCs

The effort put forth by all these countries has drastically reduced the atmospheric concentrations of the most significant CFCs and shrunken the hole in the ozone layer. In fact, the Montreal Protocol has been called the most successful international environmental agreement so far. (, 2002) However, in late 2006, scientists discovered that the ozone hole had once again expanded. Experts attribute this to the fact that, in places like India and southern China, the demand for air conditioners has exploded. India and China have the fastest growing economies and the living standards have risen substantially. These two countries are still considered developing countries, giving them exemptions from global environmental standards that the Kyoto Protocol instilled. China's Environmental Protection Agency has promised to stop all consumption and production of the most damaging chlorofluorocarbons by July 2007, and hopefully progress will be seen in the ozone hole. (Bradsher, 2007)

An alternative has also been sought to replace CFCs- hydrochlorofluorocarbons (HCFCs). They are much more reactive than CFCs are, and therefore a large percentage of them are broken down in the troposphere. However, some HCFCs do make it to the stratosphere, and do inflict damage, but they are only 5% as harmful to the ozone layer as the CFCs.

Are there emerging threats related to this topic?

Depletion of the ozone layer affects all living things on Earth- stratospheric ozone protects organisms from the damaging effects of the Sun's ultraviolet radiation. Decreases in ozone can lead to increases in skin cancer, weakening of the immune system, increased risk of eye disorders, and genetic damage. (Climate Institute) Also, stratospheric ozone affects the temperature distribution in the atmosphere. CFCs are considered a greenhouse gas, and definitely contribute to global warming. (Solomon, 1999)

Is this a local, state, regional, federal, or international problem?

Stratospheric ozone loss is an international problem because it affects everyone- this is why international treaties like the Montreal and Kyoto Protocol have been created. It is in everyone's best interests to combat ozone loss.

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