232 | The History and Use of Our Earth’s Chemical Elements chlorine, fluorine, and carbon that are inert, as are the chlorofluorocarbons, and they remain

232 | The History and Use of Our Earth’s Chemical Elements chlorine, fluorine, and carbon that are inert, as are the chlorofluorocarbons, and they remain

that way until they reach the upper atmosphere, where intense UV radiation from the sun liberates the chlorine atoms for the compound. These chlorine atoms catalytically destroy ozone. An example follows:

O 3 + UV light → O 2 +O

Cl + O 3 → ClO + O 2 ClO + O → Cl + O 2 Results: 2O 3 → 3O 2

When CFCs slowly rise in the atmosphere and reach the ozone layer, they are broken down into component molecular compounds and atoms by the UV rays of the sun. Some of these chemicals then react with ozone to break it down, thus reducing the amount of O 3 . Further, some chlorine (also from the oceans) and some other elements combine with the O and O 3 to form other chemicals. This also contributes to the reduction of ozone faster than natural processes can reform it. Ozone is a renewable resource. The issue is this: can a balance be obtained between the destruction of ozone in the atmosphere, by both natural and man-made causes, and its natural regeneration?

Also of concern because of their possible connection with global warming are the hydro- carbon gases, such as methane (CH 4 ), which is produced naturally in large quantities, as the gas from the digestive process of cows, from decaying of organic matter, and from petroleum refining; and the gas carbon dioxide (CO 2 ), which is produced in nature by respiration of plants and animals, by volcanic action and forest fires, and by humans in the burning of wood, coal, gas, and oil products. Nitrogen-based compounds from automobile exhausts also contribute to the problem, but automobile exhaust gases do not directly produce ozone.

There are parallel policy issues for global warming and the periodic increase and decrease of the ozone layer, but the science is not parallel. The following are some factors to keep in mind when examining these issues.

1. There is an agreement that a “hole” (really a thin area) in the ozone layer over the Earth’s polar regions, particularly Antarctica, changes in size over periods of time. The ozone is produced over the tropics and spreads to the polar areas. But not all scientists agree on the associated causes, seriousness, dangers involved, and remedies.

2. The ozone layer is dynamic and unpredictable, which means it is constantly changing and seems to change in ways we cannot yet understand. The large thin area (hole) over Antarctica seems not only to move but also to become larger and then smaller. The ozone layer is thickest over the poles of the Earth, yet it is mostly produced over the equator. The ozone layer seems to follow some cyclic pattern that may affect the size of the thin layer over time.

3. Much of the data supporting claims on both sides of the controversy of ozone depletion and global warming need to be analyzed with great care because the issues have gone beyond the science involved. Our ability to predict long-term weather and atmospheric conditions, even with computer modeling, is limited due to the large number of variables involved. A new science called “chaoplexity,” which combines chaos theory with related

Guide to the Elements |

problems of complexity, may lead to a useful method of predicting “unpredictable” events, However, it also may not be useful.

4. Global warming may or may not be a problem related to ozone depletion. There has been a 30% increase in the amount of carbon dioxide produced by humans since the early 1700s. Carbon dioxide makes up about 0.03+% of the atmosphere. Only a small fraction of CO 2 remains in the atmosphere. Some is used by plants to make food (photosynthesis), some is dissolved in the oceans, and some combines with other elements. The argument is that CO 2 and some other gases from the burning of hydrocarbon fuels may form a “greenhouse” effect in the upper atmosphere to hold in the heat of the Earth and have some effect on the ozone layer.

According to the Council on Environmental Quality, there was a warming trend of the Earth from 1870 to 1940. This trend was reversed from 1940 to 1960 when the Earth became cooler. Several days in the 1990s were considered the warmest days on record until the year 2005, which was the warmest on record in the northern hemisphere, but not the southern hemisphere. There has been a general (average) temperature increase of about 1°F of the Earth’s atmosphere over the last 100 years. Some of this increase is a result of natural atmo- spheric conditions that tend to be cyclic, and some is a result of increased concentrations of trace gases, such as carbon dioxide, methane, CFCs, sulfur, and nitrogen compounds. Studies indicate that methane, which is an important greenhouse gas, is produced in the wetlands and the sediment of lakes in Siberia, as well as other sources such as vents in the ocean floor. Much of the controversy about proving the reality of climate change is because the wrong effects are being measured and analyzed by inadequate computer programs that do not consider all the physical, chemical, and biological variables that may affect climate change.

Today, there are over 30% more trees growing in the United States than there were 100 years ago, and we plant four trees for every three harvested, although the growth rate of these new trees may not equal the harvest rate of more mature trees. Sadly, this is not true for all countries, some of which have depleted not only their forests but also most natural vegeta- tion, causing the formation of deserts. One way of reducing the amount of carbon dioxide in the atmosphere, besides reducing the burning of hydrocarbon fuels, is to greatly increase the amount of plant life on Earth. We need to reestablish forests worldwide.

5. The U.S. government banned the use of chlorofluorocarbon aerosols in paint and spray cans in 1978. In 1986 an international agreement was adopted that required all industries to reduce the manufacture and use of CFCs by 50% by the year 2000. More recently, an outright ban on the use of Freon by industrialized countries has been agreed to. Research is being conducted to find suitable substitutes. Materials in one group of promising compounds are called HFCs and HCFCs, which are not as stable as CFCs. They break down before reaching the ozone level of the stratosphere and thus do not react with the ozone. The problem is that some of these new HCFCs are flammable and possibly carci- nogenic.

6. It is doubtful that any international agreement to control the so-called greenhouse gases by all nations can be effective. First, many developing nations will continue to develop industries that produce these gases. Second, the cost of developing alternate, nonpollut- ing energy sources is tremendous. And finally, Earth, through many natural systems and