The earth's ozone layer, located high above the ground in the stratosphere, filters out harmful burning ultraviolet rays from the sun. For about a billion years, the natural ozone system worked smoothly, allowing life to flourish on earth.
In the 1920's, however, scientists developed a class of chemicals known as chlorofluorocarbons (CFCs) which were most commonly used as propellants in spray cans and which continue to be used as coolants and insulation in refrigerators and car air conditioners. CFCs are highly stable compounds that drift slowly upwards, carrying millions of tons of extra chlorine into the stratosphere. Many of the CFCs and related HCFCs have atmospheric lifetimes of 50-100 years or longer.
The manufacturers of CFCs and other ozone depleting chemicals include: DuPont, Elf-Atochem, ICI, LaRouche, Akzo Chemie, Rhone-Poulenc, Nippon Halon and Allied Signal. The total value of sales of ozone depleting chemicals since 1986 has exceeded $30.6 billion USD with the USA responsible for 30 percent of the total production.
In the 1974, two scientists Drs. Sherwood Rowland and Mario Molina hypothesized that chlorine from CFCs could destroy the earth's ozone layer. According to their predictions, each chlorine atom could destroy 100,000 ozone molecules, meaning that decades of CFC use would cause a substantial decline in the ozone layer. By 1979, the US and some other governments responded by banning the sale of CFC based aerosol cans, this slowed the growth of CFC production. However, worldwide production of the chemicals continued to grow, reaching 3 percent annual growth rate by 1985.
In 1985, many of the world's governments signed the Vienna Convention that called on participants to draw up a plan for action on the issues. As of May 1985, the British Antarctic Survey reported dramatic declines in ozone values over Antarctica each spring- defining the so-called ozone hole.
In September 1987, negotiators from around the world met in Montreal to sign a treaty setting limits on the use of CFCs and Halons (another class of ozone depleting chemicals). Scientific evidence that emerged throughout the late 1980s prompted further strengthening of the Montreal Protocol, first in London, then in Copenhagen.
Although concentrations of ozone-depleting chemicals may already have peaked, due to the measures taken under the Protocol, destruction of the earth's ozone layer continues at a rapid rate. In fact, ozone depletion over the Arctic has continued to be worse than predicted--approximately 40% worse than forecast on average.
Scientists attribute some of this unprecedented ozone depletion to worsening global climate change. Warming in the lower atmosphere is causing cooling in the upper atmosphere according to the National Air and Space Agency (NASA). Cooling in the stratosphere, according to NASA, supercharges ozone depletion.
The result of such ozone destruction is an increase in the amount of ultraviolet-B (UV-B) radiation striking the earth's surface. Scientists estimate that, depending upon weather conditions, for every 1 percent of ozone depletion, approximately 2 percent more UV-B
radiation strikes the earth's surface. The impacts of increased UV-B radiation exposure includes increased risk of skin cancer and cataracts as well as immune suppression.
A recent evaluation of UV-B radiation striking the Pt. Barrow station demonstrated increases ranging between 3 and 10 percent per year between 1991 and 1996. The paper, published in Geophysical Research Letters in March 1998, continued to say that the combination of "a high-albedo surface [reflective] due to persistent snow cover and rising UV-B irradiance levels may have particularly serious implications for facial erythema [sunburn] and eye injury in this part of the world.
Governments still could take numerous steps to reduce the amount of ozone depleting chemicals in the earth's stratosphere, in particular, strengthening controls on methyl bromide (a toxic pesticide) and HCFCs (a coolant).
To demonstrate the availability of solutions, Greenpeace not only has campaigned and lobbied governments to strengthen controls on ozone depleting substances, but also has developed a refrigerator which is entirely ozone safe. The Greenfreeze refrigerator, now a dominant force in the European Union, already has been introduced in other parts of the world including China and Argentina. The Greenfreeze uses no ozone depleting gases or global warming gases and is cost competitive with refrigerators that use these damaging gases.