As early as 1969, scientists noticed that the ozone layer was breaking down. Ozone (03) is a pungent and poisonous gas which floats some fifteen miles above the earths surface by shielding all living things from the suns ultraviolet light. This hole in the ozone layer, which was approximately nine million square miles large just last year, is about the size of North America. If more of the suns harmful rays reach the earth, this can lead to crop destruction, slow plankton growth, skin cancer, and other health problems including cataracts or even blindness. Our true awareness of the ozone depletion problem began in 1974 when University of California chemists F. Sherwood Rowland and Mario Molina discovered that chlorofluorocarbons (CFCs) could rise slowly to the upper atmosphere and destroy earths fragile ozone shield.CFCs were used in the manufacture of air conditioners, refrigerators, fast food containers, aerosol spray cans, and other products. The 1973 production of CFCs was at a rate of one million tons per year.
During their research, Molina concluded that each chlorine atom from CFCs collides with an ozone molecule. While ordinary oxygen molecules have two atoms, ozone is made of three oxygen atoms and is very unstable. Ozone will tend to give up one of its oxygen atoms to other gases and turn back into oxygen. In brief, the breakdown of CFCs by sunlight would set off a catalytic chain reaction in which one chlorine atom could eat up 100,000 molecules of ozone, turning them into impotent oxygen molecules.
Derived from the Greek work ozein which means to smell, ozone at the ground level gives off an acrid odor. The ozone layer is really only an eighth of an inch thick. For every 1% decrease in the ozone layer, cases of nonmelanoma skin cancer are expected to increase 5-6%. Since some CFCs take one hundred years to decompose in the atmosphere, we will live with the consequences of CFCs for another 100-150 years at least. As Vice-President Al Gore stated, While we have hardly begun to make the dramatic changes that will be necessary, it is a revolutionary step for society to recognize the problem at all.
Reactions to Molina and Rowlands 1974 discovery was minimal at best. Du Pont, the worlds largest CFC manufacturer, discredited their findings and refused to initially acknowledge the ozone problem as a serious threat to the environment.
Ozone Depletion II
Molina and Rowlands discovery would spell bad news for CFC manufacturers. More than three hundred aerosol spray products were on the market—everything from deodorants, perfumes, air fresheners, to insect sprays, lubricants, and automobile products. In 1974, it was an $8 billion business which employed more than 200,000 people.
The history of the chlorofluorocarbon is an interesting one indeed. CFCs were discovered in 1928 by Du Pont chemist Thomas Midgley,Jr. A colleague had told Midgley that the refrigeration industry needed to improve. At that time, ammonia or sulfur dioxide was used but they were not very effective. The new refrigerant must be nonflammable, nontoxic, and stable. After much experimentation, Midgley created the compound fluorocarbon. Freon was the trademark name that Du Pont gave to its new class of fluorocarbon chemicals. Freons F-11 and F-12 were the most widely used in the 1930s and now it turns out that they are the most dangerous to the ozone. Other health threats associated with the use of aerosols and CFCs include the risk of cardiac arrest when CFCs are in high concentrations. In smaller doses, they could cause changes in normal heart rhythms. Although the nations policymakers were aware of the CFC threats, it would take them the next fifteen years before any serious action would occur. American consumers did not waffle on the issue, however. The CFC-ozone theory generated more letters to politicians than any issue since Vietnam. About half of the people surveyed said they had already stopped using aerosol products. In 1984, Rowland expressed frustration and disgust that ten years after their revelation, nothing was still being done about the problem.
Unfortunately, this means that if there is a disaster in the making in the stratosphere, we are probably not going to avoid it, Rowland warned. Sadly, Rowland would be proven correct just months later when the British Antarctic Survey released data showing that the ozone hole was increasing over the South Pole. Scientist Joe Farman and his research assistants had been studying at Halley Bay, Antarctica, since 1957. Since they had spent twenty-five years there, the results of their findings had credibility. Having used the old ground-based Dobson spectrophotometers to read ultraviolet light that reached earth, however, Farman doubted his own results at first and requested brand new equipment. Nevertheless, the new equipment confirmed the previous data. The ozone had actually begun to decrease back in 1977. The Nimbus 7 satellite took ozone readings from 600 miles above the earths surface. The Antarctic ozone hole suddenly appeared before our eyes
Ozone Depletion III
Instead of congratulating the scientists on their discovery, many people criticized them for having not released their findings sooner.
One possible explanation for the 1983 ozone decrease was the volcanic eruption of El Chichon in Mexico in April 1982. Rowland theorized that the massive amounts of sulfuric acid spewn into the atmosphere could react with chlorine nitrate and cause ozone loss. Rowland and other researchers debated over this theory. After experimenting with chlorine nitrate, hydrogen chloride, and water, the group concluded that the volcano could have created some ozone depletion.
However, vehement arguments as to what was causing the ozone hole arose from the entire scientific community. A popular theory called the dynamicists theory suggested that air movement was the cause of the hole. A third theory, called the odd nitrogen theory, suggested that the solar cycle was the cause of abnormal ozone fluctuation.
In a 1985 report by NASA, statistics showed that if CFC emissions continued at 1980 rates, the ozone would decrease 4.9 to 9.4% by the next century. Even if the Antarctic hole was linked to CFCs, regulations of non aerosol uses would be difficult to control. In the 1970s, consumers had a vote and they chose to protest aerosol products. Now,however, it is harder to walk into an automobile dealership and request a car with an air conditioner free of fluorocarbon-12.
In June 1986, a series of hearings and meetings were scheduled in Washington. Both sides of the issue brought out their toughest tactics. Environmentalists and scientists testified that the greenhouse effect was a cause for concern. According to the EPA, changes in climate could cause the extinction of some species. Crops in semiarid regions would die. The number of 100øf + days would increase from 3 to 20 in Omaha, Nebraska, for example. Sea-level increases of 2-12 feet by the year 2100 could easily flood coastal cities such as New Orleans. Protecting wetlands, beaches, and even drinking water would be impossible. Just protecting our countrys east coast could cost an estimated $10-100 billion. Traces of CFC contributed to the greenhouse effect at rates comparable to carbon dioxide.
Other shocking reports stated that ultraviolet radiation could reduce seed quality, lower a species resistance to pests and diseases, damage aquatic systems, and destroy fisheries. A 25% loss in ozone would result in a 35% loss of phytoplankton, the main food source for many marine animals..
Ozone Depletion IV
Humans, too, would be greatly affected by this increased exposure to W. Ultraviolet light it could damage DNA, perhaps harming the humans immune system. Cases of skin cancer, cataracts, and visual aging would also increase. It is not yet evident whether the behavior of ozone above the Antarctic is an early warning of future changes in global ozone or whether it will always be confined to the Antarctic because of special geophysical conditions that exist there, stated NASAs Bob Watson. Antarctica is the coldest place on Earth. With the most unfriendly environment on the planet, the thirteen American scientists who set out on the first official ozone expedition in August 1986 had alot to deal with besides the weather conditions. Lead by chemist Susan Solomon, the group organized the trip in less than five months; a major accomplishment given the tasks ahead. Although much of the public wanted the group, called NOZE I (National Ozone Expedition), to come back with all of the answers, scientists realistically didnt expect them to generate much on this first outing.
Surprisingly, the instruments were performing well enough to gather solid data. In Antarctica, its a challenge to do anything. Temperatures often reach -90 F By the end of the expedition, they had gathered strong evidence to prove that chemicals were causing the rapid ozone depletion. Solomon discovered high levels of chlorine dioxide which implicated CFCs. Satellite data showed that ozone was being depleted in a huge region to at least 45 south latitude (the Southern tips of South America and Australia).
A larger and more detailed expedition was needed in 1987 to accurately solidify the chemical theory. The $10 million project would hopefully resolve many of the uncertainties from NOZE I.
On September 1 6,1986, the Alliance for Responsible CFC Policy held a press conference announcing that it would encourage the limit on the growth of CFCs. Replacing CFCs in refrigerators, air conditioners, and solvents would be much more difficult than the substitutes of aerosol sprays. The three main chemicals that needed to be replaced were: CFC-11 (used in making polyurethane foam); CFC-12 (used in refrigeration,air conditioning, and foam blowing); and CFC-113 (used as a solvent in the electronics industry). On September 14,1987, the Montreal Protocol was signed by 43 nations. The 43 countries agreed to a freeze on consumption and production of CFCs at 1986 levels by 1990; a 20% reduction by January 1,1994, and an additionalcut of 30% by January 1,1999. The Protocol stated that all nations would meet again to eventually eliminate ozone-destroying chemicals.
