Ozone shield or ozone layer is a part of earth’s stratosphere that absorbs most of ultraviolet (UV) radiation from the sun. It is made up of high concentration of ozone (o3) as compared to other regions of the atmosphere. The ozone layer encompasses less than ten parts per million of ozone whereas the average concentration of ozone in the earth’s atmosphere is about 0.3 parts per million. The ozone layer is mainly located in the stratosphere’s lower part from approximately 30-20 kilometres above the earth though the thickness differs geographically and seasonally.
The ozone layer absorbs 99-97 percent of the medium frequency ultraviolet light from the sun that would result to damaging of the exposed forms of life near the surface. There are two forms of ozone depending on where it is in the atmosphere; stratospheric (good) and tropospheric (bad) ozone layer. Tropospheric ozone layer is closest to the earth and it poses as an air pollutant that is dangerous to breathe and results in damages to trees, vegetation and crops whereas the stratospheric ozone layer serves as a life protector and is furthest from the earth. The United Nations Assembly has appointed 16th September as the International day for ozone layer preservation.
The importance of ozone layer to Earth and life
The ozone layer is crucial to the earth as it absorbs most of sun’s ultraviolet (UV) radiation hindering most of it from reaching the surface of the Earth. UV spectrum radiation has wavelengths slightly shorter than those of visible light. UV radiation that has wavelengths between 315 and 280 nanometers is known as UV-B, and it results in damages to almost all kinds of life. By taking in most of UV-B radiation before it can even reach the surface of the earth, the ozone layer protects the Earth from the harmful effects of radiation.
In addition, stratospheric ozone also affects the distribution of temperature of the atmosphere, therefore, playing a significant role in earth’s climate regulation.
The causes of ozone layer depletion
Ozone layer depletion is as a result of the release of ozone-depleting substances (ODS) and other chlorofluorocarbons (CFCs) that were widely used as insulating foams, solvents and refrigerants. Although air is lighter than CFCs, CFCs are carried into the stratosphere through a process that can take a period of 2 to 5 years. After CFCs reaches the stratosphere, the sun’s ultraviolet radiation causes them to dismantle releasing chlorine atoms that react with ozone, initiating ozone’s destruction chemical cycles that eventually leads to ozone layer depletion.
The causes of ozone depletion have been carefully looked at for many years. Scientists have studied are depleting ozone and have tried to come with necessary means to protect what we have left, for human survival. They have looked at many solutions and continue to find new methods of saving our ozone layer. Stratospheric ozone depletion has been a main concern for the public as scientists study the depleting ozone, as they search for the causes and solutions for our depleting ozone layer.
We learn from the NOAA Research Center that, (NOAA. 2005) “Beyond being a concern of scientists, stratospheric ozone depletion has been a topic of great interest to others. In the case of the general public, few scientific issues have so thoroughly become a topic of household conversation and classroom study. Stratospheric ozone turned out to be the issue upon which the leaders of the world’s governments would “cut their teeth” when it came to addressing global scientific concerns.
At every step of the way, CSD scientists have been there: “doing the science,” helping to assess the state of scientific understanding from the many studies of the international community of researchers, and communicating the scientific findings to those who want and need the information. The entire process can best be described as “science in the service of society” Among the hundreds of researchers around the world who have studied the stratosphere, CSD scientists have played prominent roles in understanding the connection between the health of the ozone layer, 15 miles above our heads, and the activities of humankind.
Many scientists have made huge progress, learning about the depletion of our ozone layer. They study to learn what factors may have or may in the future negatively affect the ozone layer. We learn that, “In research spanning three decades, CSD has studied the chemistry and physics of the Earth’s stratosphere. A large fraction of that work has been concerned with the study of the ozone layer and the processes by which it is being depleted.
The work has involved many individual scientists and has yielded many significant scientific accomplishments, among them: identification, in laboratory and theoretical modeling studies, of the key reactions that occur in the atmosphere and that influence stratospheric ozone design and construction of instruments for making observations of the important trace gases that affect the ozone layer, including the first observations of chlorofluorocarbons (CFCs) in the stratosphere formulating the theory (later proven to be correct) of how CFCs cause the Antarctic ozone hole via ice/surface chemistry leading major ground-based and airborne field campaigns to Antarctic (in 1986 and 1987) that provided the first definitive evidence of the role of human-made CFCs in creating the ozone hole. ” We have been accustomed to using many products, that scientists feel now have contributed to our depleting ozone layer.
We read in the Futurist Journal, (Economics of Preserving the Atmosphere, 1989) that “A national phase-out of widely used ozone-depleting chemicals in the years ahead will probably impose economic hardships on the United States, according to a business-policy analyst. U. S. Environmental Protection Agency regulations to take effect in 1989 are likely to reduce domestic production of (CFCs) by more than 60% over the next decade. CFCs are thought to destroy the ultraviolet light-absorbing ozone in the earth’s atmosphere and contribute up to 20% of the greenhouse effect, which is increasing temperatures worldwide.
“Closing the Antarctic ozone hole and restoring the ozone layer around the globe eventually will compel regulators to go a step further and mandate a virtual phase-out of chlorofluorocarbons'” predicts Douglas G. Cogan of the Investor Responsibility Research Center in Washington, D. C. But CFCs favorable qualities–versatility, durability, high efficiency, low cost, and lack of toxicity–have made them an integral part of the U. S. economy, Cogan notes. The chemicals serve as a coolant for modern refrigerators and air conditioners, as a foaming agent for Styrofoam insulation and foam rubber, as a solvent for computer chips and dry cleaning, and as a propellant for aerosol-spray products. “Virtually every American household, most of the nation’s transportation fleet, and 375,000 business locations will experience withdrawal symptoms as the nation weans itself of its daily dependence on these chemicals,” says Cogan.
Costs are likely to increase for a wide range of consumer products and services because few of the alternatives to CFCs will be as inexpensive to produce. In addition, product substitutes may not be able to operate as efficiently as those using CFCs, resulting in higher their energy consumption. ” Douglas goes on to say that, “A few promising alternatives to CFCs have already entered the marketplace, but most face at least five more years of rigorous toxicity tests before commercial approval As a result, continuing demand for increasingly limited supplies of CFCs could raise their price from 60 cents a pound today to as much as $3 a pound by 1994, creating windfall profits for CFC producers. A consensus is emerging … that we must prepare for a world without CFCs'” Cogan says.
The key question for policymakers is whether we should rush to eliminate these chemicals from production–imposing greater hardships on ourselves and on our economy–or wait for more alternatives to emerge, thereby imposing more serious environmental and health consequences on future generations. ” Since scientists are so concerned about phasing out chlorofluorocarbons, it is crucial that we replace the old ways of doing things. Robert W. Pease from the Wall Street Journal explains that, (Pease, 1989) “The news earlier this month that several European countries and the U. S. have agreed to phase out the use of chlorofluorocarbons (CFCs) by the year 2000 brings before us yet again the questionable theory that CFCs cause depletion of the ozone layer. Atmospheric chemist F. Sherwood Rowland , of the University of California, Irvine, formulated the theory in the early 1970s.
His speculations, quoted widely in reports about this month’s international conference hosted by Margaret Thatcher in London, have gained so much momentum over the years that they have now become the basis for decisions that would deprive us of the only inexpensive and effective refrigerants we have for refrigeration and air conditioning. This is not because of scientific proof, but the result of the constant reiteration of disaster scenarios that range from skin cancer to DNA damage. Pronouncements in the past few weeks give the impression that all atmospheric scientists are believers, which is far from true. Many of us are still skeptical because of incompatibilities between the theory and what we know about the ozone layer. The Rowland theory ignores the equilibrium nature of ozone in the layer.
The ozone molecules are constantly being created and destroyed— both quite naturally— by the very short wavelengths of ultraviolet light from the sun. The amount of ozone in the layer depends upon an equilibrium between the two processes. This equilibrium varies markedly both over the globe and throughout the year. At very high altitudes a disrupted equilibrium is restored in a matter of minutes; at lower levels in the stratosphere, in a matter of weeks or months. In any event, repair takes place rather quickly. Depletion of ozone can occur only by reducing the equilibrium density of ozone molecules. This makes for relatively insignificant depletions.
No doubt many CFC molecules have reached the ozone layer, but it is unlikely both that they are depleting the ozone to the extent the activists say, and that such damage, even if it existed, would take centuries to repair. Since the same narrow band of ultraviolet light breaks down both CFCs, releasing their ozone-destroying chlorine, as well as oxygen, creating ozone, there is a ‘competition’ between the two processes for this necessary solar energy. The probability that an oxygen molecule will be broken apart, rather than a CFC molecule, depends upon the relative abundance of the two gases in the ozone layer. Calculations based on high-altitude CFC samplings and data supplied by the National Oceanic and Atmospheric Administration show 60,000 ozone molecules are created for every chlorine atom released from a CFC molecule.
With this probability, how can the equilibrium density of the ozone layer be materially reduced? In other words, the paucity of measurable proof of depletion may be because depletion is not actually occurring. It is of interest to note that surface measurements by the National Oceanic and Atmospheric Administration indicate that the total amount of ozone above the U. S. is actually increasing. Unable to measure depletion in an unambiguous manner, advocates of the theory have taken the `hole’ in the layer over Antarctica as indirect proof of loss of the layer over mid-latitudes. However, papers at last summer’s international ozone conference at Snowmass, Colorado, cast doubt that this phenomenon is a mirror of global ozone decline.
Perhaps the erosion of this ozone during the polar night is due to the same interaction of the solar wind with the Earth magnetic field that causes the auroras. It has been observed that this combination can destroy the ozone. Solar wind is the product of solar flares, which are becoming more frequent as sunspot activity waxes Let us not blindly follow those environmental activists who cry, ‘The sky is falling’, but let’s continue to study the sky until we know enough to make a sound decision regarding the phasing out of our best refrigerants. Remember, before CFCs, toxic ammonia and sulfur dioxide were used in our home refrigerators. ” We live in a fossil fuel economy.
The United States — not to mention much of the industrial world — relies on oil and its byproducts to quite literally fuel our economy. And we’re in deep. So deep that we have to turn to others to feed our own habit. It is estimated that the United States spends upwards of $4 billion per week on petroleum imports, and approximately one quarter of that comes from Saudi Arabia and the Persian Gulf. The fall-out of this state of affairs is multi-faceted; the ethical, economical and environmental impact is evidenced daily in the national headlines. Not only are we supporting some pretty unsavory regimes, facing escalating trade deficits and increasingly vulnerable to economic pressure, the effects on the environment may be irreversible.
The underlying problem is, the resources we rely on, i. e. , fossil fuel, coal and uranium, must be “consumed” to release energy and are limited in supply – regardless of whose inventory and timeline you believe. Furthermore, all non-renewable energy sources have some negative impact on the environment. Excavation of coal and fossil fuel destroy the landscape while their emissions contributed to air pollution and the destruction of the ozone. These effects, however, are tame in comparison to nuclear power plants where radioactive waste is the end-product. How do we stop this – as the President himself has stated – addiction? Well, during his 2006 State of the Union address, Mr. Bush proposed that the United States “replace more than 75% of our oil imports from the Middle East by 2025. ”
This is all well and good, but with hundreds of millions of dollars in Republican coffers courtesy of the Oil and Gas industry, and the President’s repeated rejection of environmental lobbyists, many would paint this as rhetoric from the good ole boy from Texas. ” There are many books that tell us about our depleting ozone layer and give us many causes and then, possible solutions. Author, Rhonda Lucas Donald tells us that, (Donald, 2002) “More than 10 miles (16 kilometers) above the surface of Earth is a part of the atmosphere called the ozone layer.
This is the layer that protects all life and we must take serious precautions to protect it. Another author who is active about protecting the ozone layer is Edward A. Parson, author of the book, (Parson, 2003) “Protecting the Ozone Layer” explains that, “Since 1985, an extraordinary reorganization of a major industrial sector has taken place to protect the global environment. ” Author Maureen Christie tells us in her book, (Christie, 2001) “The Ozone Layer: A Philosophy of Science Perspective”, that “This book tells the story of scientific understanding of the stratospheric ozone layer. ” We must first truly understand the ozone layer and the harmful factors that threaten it, before we can act.
For more answers on what every individual can do to protect the ozone layer, you can read the book, (Dotto, 1978) “The Ozone War”, by author, Lydia Dotto. There are many solutions that are in reach in stopping the depletion of the ozone. Holly Cefrey, author of the book titled, (Cofrey, 2002) “What if the Hole in the Ozone Layer Grows Larger? ” offers that, “All things in the universe are made up of one or more forms of matter”. This book should prove beneficial in learning how to protect the ozone layer from depleting. Another good book to learn how to protect the environment and the depleting ozone, is (Martins, 2006) “Ultra Violent Danger: Holes in the Ozone Layer” by author, John Martins.
We must learn all that we can about finding ways to improve our environment. Edward J. Calabrese offers much information about the ozone depletion in his book, (Calabrese, 1990 “Ozone Risk Communication and Management”. There are several ways that we can take part in protecting the ozone layer. We should only go to service facilities with EPA-certified technicians and make sure refrigerants from your vehicle that will be recovered and recycled during servicing, then repair all leaks in the a/c system (not required by federal law, but helpful in protecting the ozone layer) Although not required by federal law, this is one of the single best ways to do your part to protect the ozone layer.
About 20-30 million cars on the road today use CFC refrigerants in their air-conditioning (AC) systems. If leaky systems were repaired, it would prevent the release of millions of pounds of CFCs into the atmosphere each year. If your air conditioner needs major repairs, talk to your certified service professional about having it converted to use an alternative refrigerant and repair air conditioners. Although not required by federal law, this step prevents ozone-depleting refrigerants from escaping. Make certain that the refrigerant is recovered before the servicing. If you purchase a new A/C system or heat pump, purchase one that uses non-ozone-depleting refrigerant.
Remove the refrigerant from refrigerators, air conditioners, and dehumidifiers before disposing of them. Make sure your service technician is EPA certified and work with local officials. Help start a refrigerant recovery and recycling program in your area if none exists. Not only will a responsible appliance disposal help to protect the ozone layer, but the recovered CFC-12 from appliances can be resold, helping to recoup a portion of the costs of the program and if you suspect or witness unlawful releases of refrigerant or other improper service practices, you can file a report easily and anonymously by calling the Stratospheric Ozone Information Hotline at 1-800-296-1996.
We learn from The Union of Concerned Scientists, that, “Humans have damaged the ozone layer by adding molecules containing chlorine or bromine that lead to ozone destruction. The largest group among these are chlorofluorocarbons (CFCs). At ground level, these molecules are stable and have many uses in industrial and domestic applications. However, when they are released into the atmosphere, they drift up to the stratosphere, pushed by winds and atmospheric mixing. At that high altitude, energetic light rays (UV-C radiation) can break down such molecules in a reaction that liberates an atom of chlorine (Cl). This chlorine atom can react with ozone and break it down to chlorine oxide and O2. Chlorine oxide will break down as well, releasing the Cl to go on destroying ozone.
In fact, one Cl can destroy up to 10,000 ozone molecules! As a result, ozone in the stratosphere has been reduced to such an extent that a hole opens up above Antarctica each spring that has, in each of the past four years, measured 8. 2 million square miles — larger than the United States and Canada combined! The problem is not limited to Antarctica, however. Stratospheric ozone is being reduced over much of the globe and research shows that this allows more dangerous UV-B to reach the surface of the earth. Through extensive research, scientists identified the human-produced chemicals that are responsible for the destruction of stratospheric ozone.
As evidence emerged on the extent of the threat to the ozone layer, the international community agreed to control ozone-depleting substances and schedule a timetable for completely phasing them out. This agreement is known as the Montreal Protocol and is a monumental achievement in international cooperation and environmental protection. Furthermore, the protocol provides for an on-going process so that, as the scientific understanding of ozone depletion improved, the phasing out process could be accelerated. The agreement also provides a powerful precedent for similar international efforts to deal with global warming and loss of biodiversity.
In the United States, the Environmental Protection Agency is charged with enforcing the terms of the Montreal Protocol. The treaty provisions are given the force of law through the Clean Air Act of 1990. Accordingly, chlorofluorocarbon, carbon tetrachloride, and methyl chloroform production ended at the end of 1995; methyl bromide is currently scheduled to be phased out by 2001; and all hydro chlorofluorocarbons will be phased out by 2030. Is ozone depletion related to global warming? No. Ozone depletion and global warming are separate problems, though some agents contribute to both. Chlorofluorocarbons (CFCs) are the principle cause of ozone deletion, but they also happen to be potent heat-trapping gases.
Still, CFCs are responsible for less than 10 percent of total atmospheric warming, far less than the 63 percent contribution of carbon dioxide. Thus, attention paid to CFCs has been on their ozone depletion role. This will change as CFCs are phased out and replaced by hydro chlorofluorocarbons (HCFCs) and hydro fluorocarbons (HFCs such as R-134a). These chemicals have little or no effect on the ozone layer but are strong heat-trapping gases. As their concentration in the atmosphere is already rising, the likely net effect in the future is that reductions in the CFC-related contribution to global warming will be offset by the presence of HCFCs and HFCs.
Are CFC-replacements really ozone friendly? The chemicals that are currently replacing CFCs are either HCFCs (hydro chlorofluorocarbons) or HFCs (hydro fluorocarbons such as R-134a). HCFCs have less chlorine in them and are less susceptible to the reactions that release chlorine in the stratosphere. But they are still ozone-depleting chemicals — they just destroy far less ozone than CFCs. For example, while CFC-12 has an ozone depleting potential rating of 1. 0, HCFCs have ratings from 0. 02 – 0. 1. HCFCs will eventually be phased out by 2030, as stated in the Montreal Protocol. HFCs do not contain chlorine, so they don’t contribute to ozone destruction at all.
However, since both of these groups are potent heat-trapping gases, they are a stop-gap measure, the lesser of two evils. Eventually, we are going to need a permanent replacement for all these kinds of chemicals. ” It is crucial that everyone take part in learning the causes and solutions for our depleting ozone layer. Scientists have give us many of these solutions to do our part in saving our environment and it will take individuals like ourselves making changes, scientist who continue to study the ozone layer and the harmful effects that contribute to our depletion of the ozone layer, and the government offering support in making any changes that are necessary to protect our ozone layer.