The Greenhouse Effect
The earth experiences the Greenhouse Effect as a result of its atmospheric construction and the environmental practices that are performed by humans on the planet. The Greenhouse Effect is, first of all, a normal condition of the earth. It allows the earth to be a suitable location in the universe for life to inhabit and flourish. Throughout our solar system, the adjacent planets’ (Venus and Mars) distance from the sun makes the one closer to the sun (Venus) too hot and the one farther from the sun (Mars) too cold to be inhabited by life (UCAR, 2008).
Earth, which is located between these two, finds its climate to be particularly suited to the formation and proliferation of life, and the Greenhouse Effect is responsible for this phenomenon (Morganstein, 2003). The earth finds itself in the position of having a surface temperature which, when averaged, places it between the water’s boiling point (100 C) and freezing point (0 C), and this cannot be explained by the mere fact that its orbit is located at a certain average distance from the sun. Attempts to explain the earth’s suitability for life based solely on that fact have been unfruitful (Silver, 2008).
The temperatures experienced by the earth, which might be described as moderate, occur as a result of the type of atmosphere it enjoys. Had the earth possessed atmospheres like Venus or Mars, regardless of its distance from the sun, it would have inherited similar climates toward the extremes of frozen or infernal (UCAR, 2008). The atmospheric constitution of the earth creates layers that insulate with just the correct amount of strength to trap the solar energy that emanates from our star, the sun. This phenomenon is responsible in major part for the pleasant and suitable temperatures that exist on Planet Earth.
The problem with our neighbors Venus and Mars is that their insulating atmospheric layers are respectively too thin and too thick. The earth’s atmosphere possesses not only the correct thickness, but also the correct constituents in order to make the planet inhabitable. These constituents are known as “Greenhouse Gases” (UCAR, 2008; Ulph & Ulph, 1995). The Greenhouse Effect is based on the scientific phenomenon that finds gases to be excellent carriers of heat. They perform in a manner similar to the way in which the glass walls that are found within a greenhouse do.
The gases that perform this function in the atmosphere are nitrous oxide (N2O), methane (CH4), water vapor (H2O) and carbon dioxide (CO2). These gases are the most active ones within the earth’s atmosphere when the trapping of heat is taken into consideration, and they have this effect because of their special functioning in conjunction with solar radiation (Silver, 2008). The source of the heat found within our solar system is the sun, and its existence leads to the emanation of heat that comes out in various wavelengths.
The wavelength of the sun’s radiation determines (among other things) the visibility and penetrability of the light it produces. Much of the light and heat produced by the sun is visible or almost visible. This visible light, which accounts for approximately 43% of the sun’s emanated energy, becomes absorbed into the land, seas and surface plants found on the earth (Silver, 2008; UCAR, 2008). When this occurs, the light transforms into heat and is again radiated throughout the atmosphere as infrared light—which is invisible.
The remarkable Greenhouse-like atmosphere of the earth prevents it from merely heating up during the day time and freezing at night. The difference is that the contents of the earth’s atmosphere include absorbent molecules that trap and then redistribute this heat all throughout the atmospheric layer. The constant work of these molecules prevents the earth’s heat from simply being sent right back out into space (Silver, 2008). Greenhouse Gases The most commonly known greenhouse gases are carbon dioxide (CO2), which is crucial to the life of the vegetation that exists on the planet, and water vapor (H2O), which is crucial to all life.
Carbon dioxide consists of one atom of carbon bonded with two atoms of oxygen, and this bond allows for the effective absorption of infrared radiation. The saturation of this molecule with radiation leads to its vibration (heat causes particles to vibrate and become energetic). The more energy contained within the molecule, the more it vibrates, and a great deal of vibration leads to the re-emission of energy by the particle. This heat is passed on to other greenhouse gas molecules within the atmosphere (UCAR, 2008).
Water vapor (H2O) represents another greenhouse gas, and it is constituted of two hydrogen atoms and one oxygen atom. The presence of a bond between the atoms forming the molecule act in a manner similar to that described for carbon dioxide. The energetic vibrations of these molecules also lead to re-distribution of radiation into the collection of molecules that form the earth’s atmosphere. This collection also includes methane (CH4), which consists of one atom of carbon and four atoms of hydrogen, and nitrous oxide (N2O), which consist of two atoms of nitrogen and one atom of oxygen.
These gases also respond in similar ways to the infrared heat within the atmosphere. The constant trading of heat among these molecules gives the earth a level of warmth that supports life on the planet (Silver, 2008). The idea of the Greenhouse Effect, while discovered earlier, was first given its name at the beginning of the 19th century (UCAR, 2008). However, the term was used as a means of describing the functions of these gases without carrying with it any ideas of negativity.
Today, the Greenhouse Effect has negative connotations because of the fact that the activities of humans has led to an over production of greenhouse gases within the atmosphere (Silver, 2008). Much of the human activities that have proliferated since the era of industrialization have involved the burning of fossil fuels. Fossil fuels are substances such as crude oil and coal that have formed within the earth under the pressure of its internal composition, and this has taken billions of years to achieve.
These substances have therefore been fossilized within the earth and have been found to contain vast amounts of energy suitable for the powering of man-made objects ranging from large industrial machines to smaller appliances for home-use. However, the burning of these fossil fuels (an action necessary for releasing the energy found within the substance) also releases substances such as carbon and oxygen, which combine to form carbon dioxide, one of the greenhouse gases (2008).
The increase in the amount of greenhouse gas molecules within the earth’s atmosphere leads correspondingly to an increase in the amount of heat radiation and re-radiation that occurs within. While this once existed at an ideal level, since the proliferation of carbon dioxide as a result of the increased burning of fossil fuels, radiation has been released in the atmosphere at an increased rate. Since the 1950’s this has become detectable within the atmosphere, and scientists have noticed that the earth’s climate has been becoming warmer.
This phenomenon is known as Global Warming, and is occurring as a direct result of the enhancement of the earth’s Greenhouse Effect (Silver, 2008; Vitousek, 1994). An important factor that allows the Greenhouse Effect to function effectively is the part of the earth’s surface that is encountered by the sunlight when it first enters the earth’s atmosphere. The ice-caps and glaciers found at the poles and on the tips of mountains function as light reflectors that prevent the earth from absorbing too much of the light, but rather reflects it back into the atmosphere as visible and not infrared light.
This means that excess heat is allowed to escape the earth’s atmosphere. However, at this point in history the earth’s atmospheric heat is increasing because of the enhancement given to the Greenhouse Effect by the excess greenhouse gases emitted by the burning of fossil fuels. Because of this, the earth’s ice-caps and glaciers are melting rapidly. The earth’s surface is therefore becoming one that is constituted by a greater percentage of surfaces (such as land, water, grass) that absorb rather than reflect heat and light.
This compounds the amount of heat that gets released into the atmosphere as infrared radiation, and since this is the form of radiation that is absorbed and re-radiated by the atmosphere, it aids Global Warming. The cloud cover that the earth experiences at any given time also aids in the Greenhouse Effect. While it reduces the overall solar heat that penetrates into the earth’s atmosphere, it also prevents infrared radiation and other forms of reflected heat energy from readily escaping the atmosphere (Ulph & Ulph, 1995; Vitousek, 1994).
The problems arising from the Greenhouse Effect have recently become vastly politicized (EPA; Kyoto Protocol). Because of the issues facing the earth as a result of greenhouse gas emissions, international organizations have employed measures to reduce these emissions. Some countries and corporations have agreed to reduce their greenhouse emissions, while others that find it difficult have found it necessary to purchase the right to emit greenhouse gases from those who have achieved levels below the internationally set limit (Tietenberg, 2006; Paulsson, 2003).
This has been defined by Paulsson: “Entities that have adopted emission reduction targets can sell emission allowances in the case of over-compliance, or buy them from other entities in the case of exceeding the target, at international exchanges” (2003, p. 20). Despite the fact that governments and corporations have, in conjunction with scientists, been attempting to find a solution to the problem of Global Warming and the Greenhouse Effect, it is possible that the earth might have exceeded the threshold of greenhouse gases by too much, making Global Warming an irreversible phenomenon (Ulph & Ulph, 1995; Vitousek, 1994).
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