CFC Essay, Research Paper

Discovery of the hole in the ozone layer showed that human activity has a major impact on Earth. The destruction of ozone in the stratosphere high above the planet’s surface has been brought about as the result of the widespread use of chemicals, which under normal conditions are chemically inert and harmless.

Ozone occurs at all levels in the atmosphere, but most of it is found in the stratosphere, between about 15-50 kilometres above the Earth’s surface. Even there it occurs in minute concentrations, but it plays a very important role. Ozone absorbs harmful ultraviolet radiation which is produced by the Sun. Ultraviolet radiation can damage cells of living things – plants, animals and people. Whereas small doses result in nothing worse than sunburn, larger amounts may cause cataracts or skin cancer, and can affect the growth of plants.

The hole in the ozone layer is formed over the Antarctic continent each spring. During the dark Antarctic winter, the atmosphere becomes colder than anywhere else on Earth. Strong winds enclose the cold air above the Antarctic, allowing ice clouds to form. The ice crystals provide the sites where chlorine reacts with ozone when sunlight returns in the spring, and results in the ozone hole. In early summer, the ozone hole mixes with the rest of the stratosphere. Over the past years, the concentrations of chlorine in the atmosphere have been steadily increasing, and more ozone has been destroyed.

Ozone itself is a useful protective layer high above our heads, but in the cities is an irritating pollutant. The CFCs have other effects too. As well as contributing to the breakdown of ozone, CFCs are also very effective ‘greenhouse gases’, contributing to a gradual warming of the atmosphere. However, the possible change in climate resulting from increases in various greenhouse gases might actually make the stratosphere colder, not warmer. Even if we were able to reduce CFC emissions effectively, these lower temperatures could mean that ozone destruction would continue.

Governments of many countries agreed in 1987 to the Montreal Protocol in an effort to reduce the amount of CFCs being produced, and so protect the ozone layer. Since then, this agreement has been strengthened; more countries have signed it, and more substances included for control. As a result, the amount of chlorine and bromine in the atmosphere seems to be decreasing. With less chlorine in the atmosphere the ozone hole should become smaller, and eventually close up, but it is likely to take 20-30 years for this to happen.