The earth’s atmosphere is one of the most valuable natural resources. For centuries, scientists have tried to identify how the atmosphere works and what enables it to sustain life on the planet.
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Scientific advances in the last century have provided an in-depth understanding of the atmosphere; its compositions, and the effects that it has on the earth. One part of the atmosphere that scientists have studied is the ozone layer.
This film of gas is situated in a layer known as the stratosphere, and this layer lies above the troposphere and extends to 50km above the surface of the planet.
The ozone layer is an important natural component of the earth’s upper atmosphere since it has an impact on the lives of living organisms on earth.
This paper will set out to discuss the effect of the ozone layer on the earth. The paper will also highlight the damages being done to the ozone layer, mostly by human activity, and the impact that these ozone depletion will have on the lives of living organisms.
The Ozone Layer
The earth’s atmosphere is divided into several layers with the lowest region, the troposphere, supporting virtually all human activities. This lowest region extends for about 10KM in altitude and it is followed by the stratosphere.
Ozone is a naturally occurring gas that is mostly concentrated in the stratosphere. Ozone occurs in varying concentrations at different altitudes. The strongest concentration of ozone occurs at an altitude of 20 to 25 kilometers and it forms the ozone layer.
The ozone layer was first discovered by the French physicists, Charles Fabry and Henri Buisson as they were studying the chemicals in the atmosphere.
Their initial discovery was advanced by the British meteorologists G. Dobson who explored further the properties of this layer and even came up with an instrument that could measure the level of ozone in the stratosphere (Sivasakthivel 30).
Dobson discovered that the ozone layer played a crucial role in the environment by filtering out harmful UV radiation from the sun. He therefore concluded that it would be useful to measure the level of ozone in the upper atmosphere and keep track of any changes.
Dobson established a worldwide network of stations to monitor the state of the ozone in the stratosphere between 1928 and 1958 and these stations continue to function today.
Ozone is a gas made up of three oxygen atoms that are chemically bound to make up the active ozone gas. Unlike molecular oxygen, which is odorless and colorless, triatomic ozone (O3) is blue in color, exists in a liquid state and has a strong odor.
Ozone is formed in the stratosphere following a chemical reaction between the high-energy ultraviolet (UV) radiation and the normal oxygen at this altitude. The reaction between oxygen molecules and the UV splits the oxygen molecules (O2) into atomic oxygen (O).
This atomic oxygen then combines with normal diatomic oxygen molecules (O2) to form triatomic ozone (O3).
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McKinney observes that the ozone is constantly being made and broken down in earth’s atmosphere and that without human interference; a dynamic equilibrium exists between ozone production and ozone destruction (465).
The stratospheric ozone is essential to the preservation of life on the earth’s surface. Most of the stratospheric ozone is created above the tropics near the equator since the sun is almost directly overhead in these regions all year long.
The intensity of UV light at these regions is also more intense due to the sun’s positioning leading to greater photolysis. It is then moved to higher latitudes where the amount created is lower by winds ensuring that there is an almost even distribution of ozone throughout the world.
Effects of the Ozone Layer
The ozone layer is credited with the formation of more advanced life forms on earth including human beings. Sivasakthivel observes that before the development of the ozone, only primitive forms of plant life existed on the planet (30).
These primitive life forms could withstand the harsh climatic conditions caused by the direct UV radiation from the sun to the earth’s surface.
As the oxygen level in the atmosphere increased, the ozone layer was formed in the stratosphere and it began to filter out the incoming UV beta radiation that had been damaging cells on the planet. The earth was therefore able to develop and support the existence of more advanced life forms.
The ozone layer forms a blanket over the earth and acts as a protective barrier. The layer absorbs dangerous UV beta radiations that would have a destructive impact on current forms of life on the earth’s surface.
Sivasakthivel documents that the ozone layer absorbs “93-99% of the sun’s high frequency ultraviolet light, which is potentially damaging to life on earth” (30). Ozone is a very strong absorber of short wavelength UV radiation and a weak absorber of visible radiation.
This property makes it very important since the short wavelength radiation is the most damaging to earth’s living organisms.
The ozone layer keeps the earth from getting too hot by limiting the amount of heat that enters into the atmosphere. Veal asserts that the ozone layer reflects the strong and harmful UV rays from the sun back into space (235).
As a result, not all the solar radiation is allowed to reach the surface of the earth. This gas therefore contributes to the maintaining of habitable temperatures on the earth.
Without this effect of the ozone, the temperature of the earth would rise to such levels that it would be impossible to live on the earth.
In addition to keeping the earth from overheating, the ozone layer also contributes to the stabilization of temperatures on the earth. The earth is heated through the radiating process as heat is received from the sun.
At the stratospheric level, the ozone layer provides heat as the UV radiation is absorbed by oxygen and converted into ozone gas. The ozone layer also prevents all the infrared radiation emitted by the earth from escaping into space.
In this way, the ozone acts as a greenhouse gas therefore playing an important role in the climate system. Greenhouse gases are responsible for trapping heat energy in the earth therefore keeping the temperatures high even when the sun is not directly radiating the earth’s surface.
The ozone absorbs UV radiation and warms the stratosphere. The IPCC states that the ozone traps heat to warm the earth’s surface just like other greenhouse gases such as water vapor and carbon dioxide (87).
The ozone layer has a negative effect on the earth when it is found at lower altitudes. While the greatest percentage of ozone is in the stratosphere, there is 10% of ozone in the troposphere area.
Since the troposphere is the area immediately on the earth’s surface, the ozone in this atmosphere is exposed to living organism. McKinney asserts that the ozone in the lower atmosphere is undesirable and its effects are in fact harmful (465).
When ozone gas is present in the troposphere, it leads to a number of significant negative health consequences. McKinney states that ozone gas damages the air passage system by reacting with the membranes lining the windpipe (460).
Consequently, it decreases the efficiency of the lungs and leads to many respiratory disorders to individuals who breathe in the gas.
The gas also causes irritation to the eyes and is responsible for some of the eye problems such as cataracts observed in individuals who are active in environments where ozone is present.
The ozone layer moves in the lower altitudes, affects plants and crops. Green plants that are exposed to ozone exhibit a reduction in their ability to carry out photosynthesis.
Photosynthesis is a very important process for crops since it is the means through which they convert radiation from the sun into useful energy for the crop. When the photosynthesis process is interfered with by ozone, plants and crops produced limited energy and their growth is mitigated.
McKinney asserts that ozone is to blame for the decline in crop yield in some parts of the world as it reduces the ability of the plants to generate energy and produce favorable yields (463).
Ozone in the troposphere is responsible for the smog observed in many cities in the world. Ozone plays a part in the formation of photochemical smog. This type of smog occurs when a number of chemicals combine and then react with the sun’s radiation to form other chemicals (IPCC 87).
Ozone is formed when the nitrous oxides produced by industries reacts with volatile organic compounds such as methane and other alkenes. The ozone formed by this process is in significant quantities and it is a threat to human health since the gas is a respiratory irritant.
Ground level ozone has a negative impact on some of the man made substances used for a variety of purposes. Ozone is damaging to plastics, implements made of rubber, and most paints.
The damage comes from the reaction between ozone and the materials, which are weakened by the exposure (IPCC 88).
In plastics, ozone accelerates the disintegration of the chemicals making up the plastic leading to fading and cracking. The ozone layer is therefore responsible for the rapid decomposition of material on the earth’s surface.
Depletion of the Ozone
The depletion of the stratospheric ozone layer has been one of the most prominent environmental issues in the last 4 decades. Scientists studying the atmosphere over the Antarctic first observed this event in the early 1970s.
This initial discovery was followed by the detection of an ozone hole over Antarctica in the 1980s. The normal ozone concentration in the ozone layer is 300 to 350 Dobson Units (DU).
When the level of ozone falls to less than 200 DU. Intense depletion is considered to have occurred and the region can be considered to have an ozone hold.
The depletion of the ozone layer was mostly attributed to the reaction between Chlorofluorocarbons (CFCs) and the ozone in the stratosphere.
CFCs were discovered in the late 1920s and they were presented as a novel alternative to the other compounds being used for refrigeration and air conditioning (IPCC 88).
Before the discovery of CFCs, toxic and explosive compounds such as propane and ammonia were employed in refrigeration and air conditioning systems. CFCs could serve as refrigerants without exposing humans to dangers through toxicity or explosiveness.
These compounds therefore enjoyed popular use since they were thought to have little environmental impact. However, these compounds were affecting the oxygen-ozone equilibrium at the stratosphere.
The ozone molecules in the atmosphere are kept in equilibrium since about the same amount of ozone molecules created is broken down. However, human action introduces components in the atmosphere that contribute to the breakdown of the ozone (Sivasakthivel 33).
Chemicals such as chlorine and bromine are capable of reacting with the ozone therefore offsetting the natural equilibrium of the ozone-oxygen cycle.
Effects of Ozone Depletion
The destruction of the ozone layer is to blame for the abnormally high incidents of ultraviolet radiation on the surface of the earth. A reduction in ozone allows more UV beta radiation to pass through and reach the earth’s surface.
Veal asserts that the ozone layer depletion will lead to higher levels of short wavelength UV reaching the earth’s surface (235).
Studies show that in the Antarctic, where reductions in ozone level reach up to 60%, the amount of UVB measured at the surface is double the amount recorded when the ozone level is at its maximum (Veal 235).
The reduction in the concentration of ozone in some regions has led to negative health impacts. People in North America are at higher risk of suffering from skin cancer due to the fall in the concentration of ozone in the region.
The National Research Council reveals that even subtle changes in the amount of UV light reaching the surface of the earth in the narrow wavelength band are not trivial (32). This research group reveals that exposure to the UV affects many people whose skin is vulnerable to cumulative damage.
UV beta radiation is related to genetic damage to DNA molecules and it increases the risk of skin cancer in an individual.
Marine life has also been affected by the depletion of the ozone layer. The IPCC reveals that ozone layer depletion has led to a reduction in the plankton population in the ocean bodies. Plankton’s are the primary food sources for the vast fish population in the oceans.
Because of ozone layer depletion, the sea experiences higher ultraviolet radiation (Sivasakthivel 33). This creates unfavorable conditions for plankton survival.
Huge amounts of planktons have been forced to move deeper into the sea in order to avoid the damaging UV radiation leading to a loss of food for fish. Research indicates that the total plankton population has experienced a decrease with each loss of ozone.
The depletion of the ozone layer has also contributed to the climate changes currently being experienced in the world. Loss of the ozone layer has contributed to the additional heating of the earth.
The destruction of the ozone leads to less heat being available in the stratosphere and this has a warming effect in the troposphere. In addition to this, lower ozone levels mean that less UVB radiation is absorbed in the stratosphere.
More radiation therefore reaches the earth’s surface leading to an additional warming of the earth.
The National Research Council reveals that while a reduction of ozone would decrease the amount of re-radiation of infrared and therefore have a cooling effect on the earth’s surface, the warming effect caused by the additional sunlight reaching the surface of the earth is greater leading to a rise in surface temperature (31).
Solving the Ozone Problem
There have been widespread reactions from the international community to the ozone layer problem over the decades.
When scientists first brought the ozone depletion problem to the world’s attention in the 1970s, governments reacted by banning the use of chemicals known to cause ozone depletion.
Several countries, including the US imposed bans on the use of CFCS and other ozone-depleting substances (Veal 236). The early efforts to mitigate the harm done to the ozone layer were not embraced by the entire world.
Some countries continued to use Chlorofluorocarbons (CFCs) and other ozone-depleting substances even as new uses of these chemicals were discovered. There was therefore need for worldwide action to be taken in order to combat the problem.
This occurred in 1985 when a formalized international cooperation on the issue was adopted during the Vienna convention (Veal 236). This was followed by the signing of the Montreal protocol in 1987 and through this accord, nations agreed to reduce their production and use of CFCs substantially.
Thirty-seven nations signed the “Montreal Protocol on Substances that Deplete the Ozone Layer”. By signing this protocol, they officially agreed to limit their release of CFCs and cut CFC emissions by 50% in 13 years.
Veal notes that thanks to the Montreal Protocol, the irreversible destruction of the ozone layer was prevented and the ozone column amounts are no longer decreasing (236).
However, the stratospheric ozone will not recover completely until 2060 even if the current policies of ozone protection are adhered to.
This paper set out to discuss the effects of the ozone layer on the earth. It began by providing an overview of the ozone; its initial discover, and its chemical composition.
The paper highlighted that the ozone layer is constantly being made and broken down in the earth’s atmosphere through a chemical reaction involving the sun’s UV radiation. The paper has demonstrated that the ozone is a strong absorber of the harmful UV beta radiation from the sun.
It therefore has a shielding effect and makes life sustainable on the plant. The ozone also regulates the temperatures on the earth by reflecting some of the sun’s radiation into space and also acting as a greenhouse gas.
The paper has revealed that while the stratospheric ozone layer is good, the ozone in the lower region of the earth’s atmosphere is bad, harmful to the plant life, and leads to numerous negative health repercussions. The paper has highlighted the impact of human activities on the ozone.
Specifically, it has noted that the ozone depletion experienced has been blamed on the introduction of ozone damaging chemicals into the atmosphere through air pollution from human activities.
However, steps have been taken by the international community to mitigate the destruction of the ozone layer. The ozone layer is today greatly recovered and it continues to play its significant role in sustaining life on the planet.
Intergovernmental Panel on Climate Change (IPCC). Safeguarding the Ozone Layer and the Global Climate System: Special Report of the Intergovernmental Panel on Climate Change, Cambridge: Cambridge University Press, 2005. Print.
McKinney, Michael. Environmental Science: Systems and Solutions, NY: Jones & Bartlett Learning, 2007. Print.
National Research Council. Environmental impact of stratospheric flight: biological and climatic effects of aircraft emissions in the stratosphere, NY: National Academies, 1995. Print.
Sivasakthivel, Tren “Ozone Layer Depletion and Its Effects: A Review.” International Journal of Environmental Science and Development 2.1 (2011): 30-37. Print.
Veal, William. Project Earth Science, Boston: NSTA Press, 2011. Print.