when our atmosphere is damaged

When Our Atmosphere Is Damaged
IN 1971, while en route to the moon aboard Apollo 14, Edgar Mitchell said upon viewing the earth: "It looks like a sparkling blue and white jewel." But what would a person from space see today?
If special spectacles permitted him a view of the invisible gases of earth’s atmosphere, he would see a very different picture. In the magazine India Today, Raj Chengappa wrote: "He would see giant punctures in the protective ozone shields over Antarctica and North America. Instead of a sparkling blue and white jewel he would see a dull, dirty earth filled with dark, swirling clouds of dioxides of carbon and sulphur."
What has punctured holes in our upper atmosphere’s protective shield of ozone? Is the increase of atmospheric pollutants really so dangerous?
How Ozone Is Being Destroyed
Over 60 years ago, scientists announced the discovery of a safe refrigerant that could replace others that were toxic and gave off a bad odor. The new chemical was composed of molecules having one carbon, two chlorine, and two fluorine atoms (CCl2F2). It and similar man-made chemicals are called chlorofluorocarbons (CFCs).
By the early 1970’s, the production of CFCs had grown into a huge worldwide industry. They were being used not only in refrigerators but also in aerosol spray cans, in air conditioners, in cleaning agents, and in the manufacture of fast-food containers and other plastic-foam products.
However, in September 1974, two scientists, Sherwood Rowland and Mario Molina, explained that CFCs gradually rise into the stratosphere where they eventually release their chlorine. Each chlorine atom, the scientists calculated, could destroy thousands of ozone molecules. But rather than ozone being destroyed evenly throughout the upper atmosphere, destruction of it has been much greater over the poles.
Every spring since 1979, large amounts of ozone have vanished then reappeared over the Antarctic. This seasonal drop in ozone is called the ozone hole. Moreover, in recent years the so-called hole has been getting bigger and lasting longer. In 1992, satellite measurements revealed an ozone hole of record size—larger than North America. And not much ozone was left in it. Balloon measurements revealed a drop of more than 60 percent—the lowest ever recorded.
Meanwhile, ozone levels have also been dropping in the upper atmosphere over other parts of the earth. "Latest measurements," reports the magazine New Scientist, "show that . . . there were unusually low values of ozone concentration in 1992 between latitudes 50° North and 60° North, covering Northern Europe, Russia and Canada. The ozone level was 12 per cent below normal, lower than at any time in the 35 years of continuous monitoring."
"Even the most dire predictions," states the journal Scientific American, "are now shown to have underestimated ozone loss caused by chlorofluorocarbons. . . . And yet at the time, powerful voices in government and industry strongly opposed regulations, on the grounds of incomplete scientific evidence."
An estimated 20 million tons of CFCs have already been released into the atmosphere. Since it takes years for CFCs to drift up to the stratosphere, millions of tons have not yet reached the upper atmosphere where they do their damage. However, CFCs are not the only source of ozone-destroying chlorine. "NASA estimates that about 75 tons of chlorine are deposited in the ozone layer each time a shuttle is launched," reports the magazine Popular Science.
What Consequences?
The consequences of less ozone in the upper atmosphere are not fully understood. One thing that seems certain, however, is that the amount of harmful UV (ultraviolet) radiation reaching the earth is increasing, resulting in a greater incidence of skin cancer. "During the last decade," reports the journal Earth, "the annual dose of harmful UV striking the northern hemisphere rose by about 5 percent."
Just a 1-percent rise in UV is estimated to cause a 2- to 3-percent rise in skin cancer. The African magazine Getaway states: "There are more than 8 000 new cases of skin cancer in South Africa every year . . . We have one of the lowest levels of ozone protection and one of the highest incidences of skin cancer (the connection is no coincidence)."
That the destruction of ozone in the upper atmosphere would cause an increase in skin cancer was predicted years ago by scientists Rowland and Molina. They recommended an immediate ban on the use of CFCs in aerosols in the United States. Recognizing the danger, many countries have agreed to stop production of CFCs by January 1996. In the meantime, however, the use of CFCs continues to pose a danger to life on earth.
The drop in ozone over Antarctica, reports Our Living World, "has allowed ultraviolet radiation to penetrate deeper into the ocean than previously suspected. . . . This has caused sizeable reductions in the productivity of the single-cell organisms that form the base of the oceanic food chain." Experiments also show that an increase in UV reduces the yield of many crops, posing a threat to the global food supply.
Indeed, the use of CFCs is potentially catastrophic. Yet our atmosphere is being bombarded by many other pollutants. One is an atmospheric gas that in trace amounts is vital to life on earth.
Effect of Pollution
In the mid-19th century, humans began to burn ever larger amounts of coal, gas, and oil, adding large amounts of carbon dioxide to the atmosphere. At that time the amount of this trace atmospheric gas was about 285 parts per million. But as a result of man’s increased use of fossil fuels, the amount of carbon dioxide has reached over 350 parts per million. What has been the consequence of more of this heat-trapping gas being in the atmosphere?
Many believe that the increase of carbon dioxide levels is what has caused the rise in earth’s temperatures. Other researchers, however, say that global warming is due particularly to our sun’s variability—that the sun has been emitting greater energy in recent times.
Whatever the case, the decade of the 1980’s was the hottest since records started to be kept in the mid-19th century. "The trend continued into this decade," reports the South African newspaper The Star, "with 1990 the hottest year on record, 1991 the third warmest, and 1992 . . . the tenth warmest year in the 140-year record." The slight decrease over the past two years is attributed to dust ejected into the atmosphere when Mount Pinatubo erupted in 1991.
The future effects of the increase of temperatures on earth are hotly debated. But one thing global warming evidently has done is to complicate the already difficult task of weather forecasting. New Scientist notes that wrong forecasts "may be increasingly likely as global warming changes the climate."
Many insurance companies fear that global warming will make their policies unprofitable. "Faced with [a] spate of misfortunes," admits The Economist, "some reinsurers are reducing their exposure to natural disasters. Others are talking of quitting the market altogether. . . . They are scared of uncertainty."
Significantly, in 1990, the warmest year on record, a large portion of the Arctic ice pack retreated to an unprecedented degree. This resulted in hundreds of polar bears being stranded on Wrangell Island for over a month. "With global warming," warns the magazine BBC Wildlife, "these conditions . . . might become a regular occurrence."
"Weather experts," reported an African newspaper in 1992, "are blaming global warming for a dramatic increase in the number of icebergs which are drifting north from Antarctica and presenting a hazard to ships in the south Atlantic." According to the January 1993 issue of Earth, the gradual rising of the sea level off the coast of southern California is due, in part, to a warming of the water.
Unfortunately, humans keep pumping a staggering amount of toxic gases into the atmosphere. "In the USA," states the book The Earth Report 3, "a 1989 report by the Environmental Protection Agency estimated that more than 900,000 tonnes of toxic chemicals are pumped into the air every year." This figure is considered an underestimate because it does not include exhaust fumes from millions of motor vehicles.
Shocking reports of air pollution also come from many other industrialized countries. Especially horrifying have been the recent revelations of uncontrolled air pollution in Eastern European lands during decades of Communist rule.
Earth’s trees, which absorb carbon dioxide and release oxygen, are among the victims of toxic air. New Scientist reported: "Germany’s trees are growing increasingly unhealthy, according to . . . the minister of agriculture [who said] that air pollution continues to be one of the main reasons for the forest’s failing health."
The situation is similar in the Transvaal Highveld of South Africa. "The first signs of acid rain damage are now appearing in the Eastern Transvaal where pine needles are changing from a healthy dark green to a sickly mottled beige," reports James Clarke in his book Back to Earth.
Such reports come from around the world. No country is immune. With chimney stacks that reach high into the sky, industrialized countries export their pollution to neighboring lands. Man’s record of greedy industrial development does not inspire hope.
There is, however, basis for optimism. We can be confident that our precious atmosphere will be saved from ruin. Learn in the next article how this will be accomplished.
Destruction of ozone in the upper atmosphere has led to an increase of skin cancer
What are the consequences of such pollution?